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05-25-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 1
Post ID: 21667
Reply to: 21667
Planning my DSET
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Hi Romy,

I am planning my own DSET build.  I have based my speakers on your Macondo and am busy turning MDF horns in my spare time.  Once that is over I will move onto amplifiers.  I plan to build a fullrange Melquiades for a friend and then if that works out the DSET 6 or 7 channel version for myself.

Of course I have read the threads and am reasonably familiar with the evolution of DSET Melquiades in the context of your system but there are still a few questions.  The question at the front of my mind is the following hypothetical: 

“How would you proceed with another DSET build knowing what you know now?” 


If you are willing I would like to work through this in stages.  This is a project that will evolve with time as I build the speakers and move them into the new room.  Initially there will be 5 Channels:

Raal Lazy Ribbon - Direct Tube Drive
S2 into 400Hz tractrix
S2 into 250Hz tractrix
Fane 8M into 115Hz tractrix
Scanspeak 25W/8565-00 towers – 8 drivers each

Then, if the results are satisfactory and the final position of the speakers in the room permits I will experiment with:

K15/40 Midbass Horn
Injection Channel

A very familiar system to you indeed, and I hope you don’t mind me using it as my starting point.  I don’t want to spend a decade or two trying to develop a satisfying horn system from scratch so I am using your documented experiences to make a strong start so that with any luck and a measure of persistence my system is matured within a couple of years and I can let the whole diy thing pass for other endeavours. 


So, to start, I am unsure of a few things regarding the operation of your amps.

  • Bias adjustment in the first stages.  Looking at the final 6 Channel circuit diagram the bias for Channels A, B and C are all fixed and non-adjustable.  How do you manage the varying gain of the 6E5P tubes?
  • Gain structure.  What is the output from your pre-amp?  Mine is 1.5V RMS and 33 Ohm.  I am trying to get an idea about my required size for the 30K input resistor.
  •   ULF through the Scanspeak line array.  My calcs are that at 15W, the SPL at the listening chair would be about 98dB at 20Hz, and much higher at 100Hz.  This is loud enough for sure, but in your experience is the 6C33C/Scanspeak combination good near the amplifiers maximum power?  


Regards,

Anthony

05-26-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 2
Post ID: 21668
Reply to: 21667
Answers....
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 anthony wrote:
I plan to build a fullrange Melquiades for a friend and then if that works out the DSET 6 or 7 channel version for myself.

That is very good approach in my view. The problem is in this approach that you have to have high sensitively speakers that you would be able to use with that test full-range Milq. The behavior of the Full range Milq win this other speaker might be not the same as it would be with Milq.  So, generally I would suggest to have a Milq (or any other amp the you might like) to drive your particular acoustic system with all passive filtration and spend at least 6 month to feel comfortable in this configuration and to figure out your crossover strategy. (Or to develop new listening objectives and consequential frustrations). Then you can slowly to do DSET and line filtration.
 anthony wrote:
If you are willing I would like to work through this in stages.  This is a project that will evolve with time as I build the speakers and move them into the new room.  Initially there will be 5 Channels:
Raal Lazy Ribbon - Direct Tube Drive 
S2 into 400Hz tractrix
S2 into 250Hz tractrix
Fane 8M into 115Hz tractrix
Scanspeak 25W/8565-00 towers – 8 drivers each

Naturally I “endorse” this configuration and I think it might do very well. My only concern is that I feel that Raal Lazy Ribbon are a bit too wide and too midrangy for use above 12K. The standard Raal Lazy Ribbon drop 10dB at 6K that is not bad but if you made Alex to make the ribbon twice more narrow then it will have steeper drop and you have a bit more “punchier” HF with the lower filter order.  The standard Raal Lazy Ribbon as I understand are meant to be used in two-3 way acoustic system where tweeter is crossed at 2.5-3.5K, so you would need to run 3-rd or 4th order to get the result you want. BTW, I very much might be wrong about it but I do think that the narrower ribbon would be beneficial. Does it worth to pay to Alex extra for a custom job and to be able to get “some” improvement? I do not have the answer to this question.
 anthony wrote:
Bias adjustment in the first stages.  Looking at the final 6 Channel circuit diagram the bias for Channels A, B and C are all fixed and non-adjustable.  How do you manage the varying gain of the 6E5P tubes?

Yeas, there is no bias adjustment in this driver stage nether I see a need to do it. You need to adjust bias if it going away and in some other occasions but in this amp it is not necessary.  The amp is set to get 200V on the driver stage and it would mean approximately 4.3V in grid. Yes, some of the tubes have a few DB leas or more gain but you do not change “gain” by setting bias. If you have on place 190V or 210V it truly goes not make any difference. Keep neat 200V on place and near 15K load and it would be fine. Saying it I would like to note that nothing shall prevent you to add your own bias adjustment if you feel so. Just be informed that any dealing with bias line is supper affective to sound, in fact ever more then dealing with grid in my mind.  You might gain some questionable benefit by having bias fine-dialed but you would need to put a trimmer in the bias line. Well, I find it is to be at least debatable…
 anthony wrote:
Gain structure.  What is the output from your pre-amp?  Mine is 1.5V RMS and 33 Ohm.  I am trying to get an idea about my required size for the 30K input resistor.

My pream has no gain. My frontend have high output and can swing I believe 3.5V. I think Bidat at 0dB digital can push 5V but this would send the Milq grid to plate currents and you do not want to be there with indirect heating. You can calculate the gain of the amp. The driver has average of 33dB, +- a few DB. The output stage has I believe 3-4times. Then you need to subtract whatever you OPT consumes. You will not have a high gain with this amp as it is two stager. If you have a Macondo-like configuration and very large room (let sat over 800-1000 sq foot) and low output frond end and no active preamp then you will feel that you have not enough volume sometime.  The whole beauty of Milg that you have let say 4V in the input and to have the am on A1 you might run a wide range of the frond end, including high output.  The 30K input resistor is kind of less relevant in Milq DSET as the input impedance of other channels will screw all input impedance picture.
 
 anthony wrote:
ULF through the Scanspeak line array.  My calcs are that at 15W, the SPL at the listening chair would be about 98dB at 20Hz, and much higher at 100Hz.  This is loud enough for sure, but in your experience is the 6C33C/Scanspeak combination good near the amplifiers maximum power?  

You will be able to drive Scanspeak line array from Milq ONLY in case you have VERY small room, you are very lucky (as I was a few years back where the arrays were at active location of the room) and if it were not a full range but 18-22W LF only amp. Otherwise I would go for a different amp. It need o be said that it is very hard to prognosticate anything,


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-26-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 3
Post ID: 21669
Reply to: 21668
Getting hold of Alex is not easy...
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 Romy the Cat wrote:
 
That is very good approach in my view. The problem is in this approach that you have to have high sensitively speakers that you would be able to use with that test full-range Milq. The behavior of the Full range Milq win this other speaker might be not the same as it would be with Milq.  So, generally I would suggest to have a Milq (or any other amp the you might like) to drive your particular acoustic system with all passive filtration and spend at least 6 month to feel comfortable in this configuration and to figure out your crossover strategy. (Or to develop new listening objectives and consequential frustrations). Then you can slowly to do DSET and line filtration. 

I will have the fullrange Milq for a few months after it is built, so I had better be quick getting the system in some sort of shape in that time.

 Romy the Cat wrote:
My only concern is that I feel that Raal Lazy Ribbon are a bit too wide and too midrangy for use above 12K. The standard Raal Lazy Ribbon drop 10dB at 6K that is not bad but if you made Alex to make the ribbon twice more narrow then it will have steeper drop and you have a bit more “punchier” HF with the lower filter order.  The standard Raal Lazy Ribbon as I understand are meant to be used in two-3 way acoustic system where tweeter is crossed at 2.5-3.5K, so you would need to run 3-rd or 4th order to get the result you want. BTW, I very much might be wrong about it but I do think that the narrower ribbon would be beneficial. Does it worth to pay to Alex extra for a custom job and to be able to get “some” improvement? I do not have the answer to this question. 
  
I have tried to contact Alex a couple of times in the past six months with something similar to your suggestion in mind.  Both times he did not respond to my email so I figured that either I was too small a fish or that he was too busy.  Seeing no better HF option, I have recently ordered the Lazy Ribbons and I doubt that Raal would have started building them yet, but I have contacted the distributor in my country this morning to see if he is able to prompt Alex into a conversation with me about this.  We will see how it goes I suppose.  I certainly would prefer a ribbon that is dedicated to HF, but if I can't talk to the man I can't get anything special.

 Romy the Cat wrote:
Yeas, there is no bias adjustment in this driver stage nether I see a need to do it. You need to adjust bias if it going away and in some other occasions but in this amp it is not necessary.  The amp is set to get 200V on the driver stage and it would mean approximately 4.3V in grid. Yes, some of the tubes have a few DB leas or more gain but you do not change “gain” by setting bias. If you have on place 190V or 210V it truly goes not make any difference. Keep neat 200V on place and near 15K load and it would be fine. Saying it I would like to note that nothing shall prevent you to add your own bias adjustment if you feel so. Just be informed that any dealing with bias line is supper affective to sound, in fact ever more then dealing with grid in my mind.  You might gain some questionable benefit by having bias fine-dialed but you would need to put a trimmer in the bias line. Well, I find it is to be at least debatable…
  
Ok, thanks for this information.  I will follow your lead in this regard.  

 Romy the Cat wrote:
My pream has no gain. My frontend have high output and can swing I believe 3.5V. I think Bidat at 0dB digital can push 5V but this would send the Milq grid to plate currents and you do not want to be there with indirect heating. You can calculate the gain of the amp. The driver has average of 33dB, +- a few DB. The output stage has I believe 3-4times. Then you need to subtract whatever you OPT consumes. You will not have a high gain with this amp as it is two stager. If you have a Macondo-like configuration and very large room (let sat over 800-1000 sq foot) and low output frond end and no active preamp then you will feel that you have not enough volume sometime.  The whole beauty of Milg that you have let say 4V in the input and to have the am on A1 you might run a wide range of the frond end, including high output.  The 30K input resistor is kind of less relevant in Milq DSET as the input impedance of other channels will screw all input impedance picture.
 

I have talked to a fellow that has built the fullrange Milq and he has had issues with Milq gain in his system and had to dial up the gain from his preamp, which is why I asked the question here.  Looks like I may need more than 1.5V SE from my dac if your sources have at least 3.5V and your gain structure is well thought out.  My dac will give 2.7V balanced so perhaps I will need to look at a balanced input to the Milq.

 Romy the Cat wrote:
You will be able to drive Scanspeak line array from Milq ONLY in case you have VERY small room, you are very lucky (as I was a few years back where the arrays were at active location of the room) and if it were not a full range but 18-22W LF only amp. Otherwise I would go for a different amp. It need o be said that it is very hard to prognosticate anything,

My room is 285 sq ft (6.08m x 4.35m) with a vaulted ceiling (with the peak running along the long axis of the room).  It will be interesting to see where the horn stack ends up in the room and also where the bass array will be positioned.  I am not sure if this qualifies as a very small room, but it certainly is not large.
05-27-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 4
Post ID: 21670
Reply to: 21669
A dangers zone?
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Make the full-range and then you will see where you are. Still, I feel that for MF channels it is beneficial for do with a good DHT output stage instead of 6C33C and perhaps it is a good idea to use DHT driver as well. So, when you strategy your 5ch DSET do consider that you might want to do non-standard Milq for MF. The  Lazy Ribbon vs narrow  Lazy Ribbon… that is not a big deal. I would not spend too much effort to find Alex or whoever it might be. You might even chose to go for another tweeter if you would like, like some kind of exotic Japanese of not the contemporary cancroid type.  You cannot make the judgment of what you need as you do not know what kind MF amp will be driving your S2 and consequentially you do not know what tweeter will “work” for you. Remember, you do not chose the tweeter YOU like but rather you chose the tweeter that your MF channel loves. So, I would advise do not worry about the tweeter and build the system without it. Yes, you shall leave a room for it on your frame and you shall dedicate an amp to it but do not lock on the amp topology at this point as you do not know if you will be driving 16R or 0.0001R. About the amp gain – it is what it is. I do not think that 2.7V balanced will help you as converting it to single ended you will be losing the dBs. In realty I do not know what output voltages I have. I do know that with 0.5V I have a “normal” sound in my room that some people would consider too load. I think that friend of yours who has Milq sound too soft has ether too low efficiency of the acoustic system or too large room. In your case, if you have Milq driving the line away of 8 25W/8565-00 towers drivers in the room of near 300 sq and tall ceiling I would predict that you will be in a "dangers zone" and will be running out of gain.

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-27-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 5
Post ID: 21672
Reply to: 21670
DHT in the DSET
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 Romy the Cat wrote:
Make the full-range and then you will see where you are. Still, I feel that for MF channels it is beneficial for do with a good DHT output stage instead of 6C33C and perhaps it is a good idea to use DHT driver as well. So, when you strategy your 5ch DSET do consider that you might want to do non-standard Milq for MF. 

My interest is mainly in the 10Y/801A/VT25 tubes on one hand and the 45 on the other hand.  The YO186 also interests me a lot especially after reading your impressions of it in your circuit and system, but it is a very difficult tube to get a hold of and is quite expensive.  The 10Y etc. seem relatively reasonably priced and quite available, however I don't have a ready-made circuit or even knowledge of how they work with Macondo, so I am tempted to just follow your DHT lead with the 6E6P and DHT MF, especially considering that I don't want to be testing/developing amplifiers for much longer than I have to even if I may end up with a better result going the longer route.  

My primary concern about a DHT driver is the low gain of those tubes (10Y is about 8x compared to 6E5P of 32x) and having to use an input transformer to improve gain and its effect on the crossover for MF.   
 Romy the Cat wrote:
In your case, if you have Milq driving the line away of 8 25W/8565-00 towers drivers in the room of near 300 sq and tall ceiling I would predict that you will be in a "dangers zone" and will be running out of gain.

I thought I might be pushing the limit.  Do you think it would be possible to increase gain by using an input transformer on the DSET ULF channel to boost signal level?  I am not sure how this would mess with the low-pass filter.

Otherwise I could add a decent SS amp or maybe even push-pull 6C33C. 

Regards,

Anthony
05-28-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 6
Post ID: 21673
Reply to: 21672
You will see.
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 anthony wrote:
My interest is mainly in the 10Y/801A/VT25 tubes on one hand and the 45 on the other hand.  The YO186 also interests me a lot especially after reading your impressions of it in your circuit and system, but it is a very difficult tube to get a hold of and is quite expensive.  The 10Y etc. seem relatively reasonably priced and quite available, however I don't have a ready-made circuit or even knowledge of how they work with Macondo, so I am tempted to just follow your DHT lead with the 6E6P and DHT MF, especially considering that I don't want to be testing/developing amplifiers for much longer than I have to even if I may end up with a better result going the longer route.  

There are tons of very cool DHT out there and for sure 10Y is one of them. Mind you that all “publicity” of good DHT come from full-range amplification and no one know how this particular DHT will behave with your specific drive in DSET configuration. I do hear your concern about you not wiling “to be testing/developing amplifiers for much longer than I have to”. That is VERY valid point.
 anthony wrote:
My primary concern about a DHT driver is the low gain of those tubes (10Y is about 8x compared to 6E5P of 32x) and having to use an input transformer to improve gain and its effect on the crossover for MF.

Well, do not discard the  3-stages topology for MF. You need to understand that 6E5P in a way unique for 2-stages scenario and no transformers, when you need a lot of gain and a lot of voltage on grid to keep the tube in class A. Pretend that you have some kind of 12AX7 at input, this tube 0.5V bios will be very fast flooded by input voltage and you will be obligated to rise the cathode on feedback.
 anthony wrote:
I thought I might be pushing the limit.  Do you think it would be possible to increase gain by using an input transformer on the DSET ULF channel to boost signal level?  I am not sure how this would mess with the low-pass filter. Otherwise I could add a decent SS amp or maybe even push-pull 6C33C. 

I think when you have a full range Milq and drive everything from it you will see what is going. The array will be your less sensitive load and you will be calibrating everything from the LF.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-28-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 7
Post ID: 21674
Reply to: 21673
Second round of questions...
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Romy, thank-you for your help so far.  Unfortunately I now have some more hopefully simple questions regarding the "pre-final" schematic from your "6 Channel Melquiades" thread (see below).

 

6-Chennal_Melquiades_DSET_Amplifier_Rev3.jpg

 

1.    Do you have a “final version” of the schematic anywhere?
 
2.    6E5P/6E6P resistor between plate and grid.  Is this resistor influential to sound?  I notice that at one stage you used a “high-quality” S102 resistor here but later on you are not necessarily using them.
 
3.    What is the resistor in the Fundamentals Channel between the OPT and the S2?  Apart from this resistor you run the S2 without any components between it and the OPT.
 
4.    LPad for MF S2.  Are you still running the LPad between the OPT and S2?  I assume that the four resistors shown in the schematic at that position signify the LPad and not something else.
 
5.    Yellow circle with cross.  On the schematic at the lower-right side there is a yellow circle with a cross next to a 33K resistor.  I am not familiar with this annotation…could you please tell me what it is?
 
6.    Two sets of gas tubes.  Have you considered more than one set of bias, say one for LF and one for HF?  Do you think it could have any positive or negative effect?  I have no idea.
 
7.    mV Meters on B+.  Is their only purpose to check the plate voltage for the individual output stages?  Would you consider leaving them out?
 
8.    Do you use an hour meter to monitor tube life?  If so I imagine that it would be installed straight after the power switch.  Is this true?



I apologise for the bombardment.

Regards,

Anthony
05-29-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 8
Post ID: 21675
Reply to: 21674
The answers....
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 anthony wrote:
Do you have a “final version” of the schematic anywhere?
I think that the one you have might be recognized as final. The Rev2 was without DHT in MF and Rev3 was with it. I did not do anything else with the amp after that. The reality is that 5-6 or any “n” number of DSET are just a parallel implementation of the same amp with only biasing shared across all amps. The fact the biasing acts as filtration, loading and voltage divider at the same time make it somehow complex and confusing.
 
 anthony wrote:
6E5P/6E6P resistor between plate and grid.  Is this resistor influential to sound?  I notice that at one stage you used a “high-quality” S102 resistor here but later on you are not necessarily using them.
Well, the purpose of this resistor just to rise a potential of one screen over another. You can use the S102 thought and it will not hurt as they are phenomenal resistors.  I did them and I did the CMF55 and they both were fine. Did you heard any difference between Dales and S102 in the screen lifter? I honestly did not test them ONLY in this application.
 
 anthony wrote:
Is the resistor in the Fundamentals Channel between the OPT and the S2?  Apart from this resistor you run the S2 without any components between it and the OPT.
. Actually it is not a resistor connected to OTP, look closer. This is a regular screen lifter, like in your question above, it is juts drown perhaps  not so friendly but as you see the red line goes from plate and directly to OPT.
 
 anthony wrote:
.LPad for MF S2.  Are you still running the LPad between the OPT and S2?  I assume that the four resistors shown in the schematic at that position signify the LPad and not something else.
This is complicated question and I did cover it while I was dealing with it. I need to attenuate MF for ~2dB. In addition the S2 driver if it driver very “clean” has some very very minor metallic fanzines atop. My YO186 is very not neutral, it is sort of anti 10Y or anti type 45 tube. As the resole I have very interesting and I would say “simulated” MF but with very very very mild harshness atop. There are many way to deal with the mild harshness atop and one of the way is to put a very mild low pass filter before S2. It should be super low indictor that would hit the driver at 60-80Kz, wish at its low knee will hold S2 a bit at over 20Kz. Any indictors I trues combined with voltage dividers were detectable. What worked the best were not voltage dividers but the regular ugly wired attenuators, some sort of miniature rheostats.  The problem is that they are hugely inductive, much more than necessary to deal with S2 fanzines. So, I found a solution to bypass the wired attenuators with two S102 resistors, kind of building a second divider with S102 and run it along with the wired one. The S102 have ultra-low inductance and if you connect the indictors in parallel then the summazing indictors will be less than the lowers one. As the result I have literally a problem free attenuation on my MF that at the same time do take care of my S2 “fanzines”.
 
 anthony wrote:
Yellow circle with cross.  On the schematic at the lower-right side there is a yellow circle with a cross next to a 33K resistor.  I am not familiar with this annotation…could you please tell me what it is?
Well, from the annotation perspective it would looks like it was a lamp. I do not remember what it is and it looks like lamp but why the hell I took voltage to some kind of light emitting diode from B+ if I have a dedicated service 12V voltage running thought out all amp? I do not remember the answer.
 
 anthony wrote:
Two sets of gas tubes.  Have you considered more than one set of bias, say one for LF and one for HF?  Do you think it could have any positive or negative effect?  I have no idea.
It is possible to use as many gas tubes you wish, they are juts supple of negative bias. In my version I used one foe all channels. I do not know about sonic impact it has compare with own dedicated gas tube. I think own dedicated gas tube would shall be better but I made no practical experiments with it.
 
 anthony wrote:
mV Meters on B+.  Is their only purpose to check the plate voltage for the individual output stages?  Would you consider leaving them out?
Sure, the mV Meters do not need to be there. You need to have 1R  resistors and to access to left and right of them, the service points would be fine, and you then can you regular tester to measure it. I fine it is fine in a single full range but in case you have many 6C33C to deal with at the same time then it is very convenient to have the permanent meter.
 
 anthony wrote:
Do you use an hour meter to monitor tube life?  If so I imagine that it would be installed straight after the power switch.  Is this true?
You can install the hour meter anywhere you wish. If it is low voltage devise then I would put it in service voltage. I was thinking to do it but for some reasons I did not make it. Now I feel that I do not miss it and I feel that it rather was my wishful thinking devise then the actually helpful tool. If you have multiple 6C33C  for multiple channels then they will die with different tempo. Do you want to keep a chronometer for each of them? It is not to mention that knowing the tube hours is not necessary allow to know if the tube need to be replaced as some of them dies after 500 hours and some of them work for years and demonstrate no sign of aging.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-29-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
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Post #: 9
Post ID: 21677
Reply to: 21675
Between S2 and OPT...
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 Romy the Cat wrote:
 
 anthony wrote:
Is the resistor in the Fundamentals Channel between the OPT and the S2?  Apart from this resistor you run the S2 without any components between it and the OPT.
. Actually it is not a resistor connected to OTP, look closer. This is a regular screen lifter, like in your question above, it is juts drown perhaps  not so friendly but as you see the red line goes from plate and directly to OPT.

The resistor between the transducer and OPT is the one that I am not sure of.  Do you still have a resistor before the S2?
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Romy the Cat


Boston, MA
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Post #: 10
Post ID: 21679
Reply to: 21677
Exactly how I described above.
fiogf49gjkf0d
I do not nave, neither I see in the schematic, a resistor but rather an Lpad shunted with two resistors, exactly how I described above.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-01-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
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Post #: 11
Post ID: 21681
Reply to: 21679
Fundamentals Channel...
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Sorry Romy, I was not clear enough, but the resistor that I am questioning is in the Fundamentals Channel (not the MF Channel as I believe you referred to in your previous post) between the OPT and the S2.
06-01-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
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Post #: 12
Post ID: 21683
Reply to: 21681
Ah, the Fundamentals Channel!!!
fiogf49gjkf0d
 anthony wrote:
Sorry Romy, I was not clear enough, but the resistor that I am questioning is in the Fundamentals Channel (not the MF Channel as I believe you referred to in your previous post) between the OPT and the S2.
   
Ah, the Fundamentals Channel, that is totally different story. I have a regular highly inductive 16R L-pad in there, just at the speaker level. The upper knee of the Fundamentals Channel is second order 1000Hz at line-level and you do want to drive as much as possible HF out of this channel. The additional inductive roll off at top only helps to this Channel, even I do not think that it is truly auditable. 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-02-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
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Post #: 13
Post ID: 21686
Reply to: 21683
Thinking further about the MF channel...
fiogf49gjkf0d
Thanks Romy.

I have secured a couple of pair of YO186 and some 1940's Sylvania 45's to play with.  I wish the YO186 were easier to come by but I think that I now have enough for me to get a very good idea of the capabilities of the tube and circuit, and how they will suit my objectives.

Still, I am thinking about the 10Y/801A/VT25/VT62.  Romy, I understand that to bring the 10Y into Melquides I would need 7.5V for the filaments and about 400V for the plate.  Plate resistance is higher in the 10's, 5k compared to about 1.2k-1.6k for YO186/45, and I am not sure how this would affect operation of the Milq circuit particularly interstage coupling.  Reading up I have noticed that some guys prefer much more primary impedance in the OPT than the 10k specified in the 10Y datasheet, up to 16k in fact.  Of course this is in the context of a full-range implementation but I notice that the David Slagle OPT that you use for MF has a 9k primary impedance (if my memory serves me right), which is getting near there already.

I have noticed that you have written about your interest in the 10Y, and I am for sure no circuit designer, but given your experience with Milq perhaps you could share some of your thoughts about the viability of putting this tube into the Milq for MF.  Compared to the 45, I am not sure what extra the 10Y would bring as far as sound is concerned (I can only go on "impressions" of other people with other systems using the tubes differently), but seeing as though I will be starting from scratch with my DSET I would be able to add the required voltages for 10Y upfront so long as it does not look too difficult to get the tube to work with 6E6P.

Regards,

Anthony  
06-02-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 14
Post ID: 21687
Reply to: 21686
There is truly no answer.
fiogf49gjkf0d
 anthony wrote:
I have secured a couple of pair of YO186 and some 1940's Sylvania 45's to play with.  I wish the YO186 were easier to come by but I think that I now have enough for me to get a very good idea of the capabilities of the tube and circuit, and how they will suit my objectives.

Still, I am thinking about the 10Y/801A/VT25/VT62.  Romy, I understand that to bring the 10Y into Melquides I would need 7.5V for the filaments and about 400V for the plate.  Plate resistance is higher in the 10's, 5k compared to about 1.2k-1.6k for YO186/45, and I am not sure how this would affect operation of the Milq circuit particularly interstage coupling.  Reading up I have noticed that some guys prefer much more primary impedance in the OPT than the 10k specified in the 10Y datasheet, up to 16k in fact.  Of course this is in the context of a full-range implementation but I notice that the David Slagle OPT that you use for MF has a 9k primary impedance (if my memory serves me right), which is getting near there already.

I have noticed that you have written about your interest in the 10Y, and I am for sure no circuit designer, but given your experience with Milq perhaps you could share some of your thoughts about the viability of putting this tube into the Milq for MF.  Compared to the 45, I am not sure what extra the 10Y would bring as far as sound is concerned (I can only go on "impressions" of other people with other systems using the tubes differently), but seeing as though I will be starting from scratch with my DSET I would be able to add the required voltages for 10Y upfront so long as it does not look too difficult to get the tube to work with 6E6P.

Well, the YO186 and Type 45 are in way the same tubes as they to a degree might use the same OPT and have near the same operational points. You can make an amp with both tube sockets and you will be able to plug in probably 80% of DHT out there. Wherever YO186 goes you will be able to put PX4, RE604, RE-614, LK460, 610 and other does of 4V tubes, that arguably the best tube out there, In Type 45 socket you will be able to plug any 45, 50, 2A3  and many other tubes. This will give you incredible playground. Is it necessary? When I was building the amp and experimented I would say that it was. As now I feel that that it was not necessary and sine I found my winning configuration I do not take advantage of changing anything. If you want to spread the amp to use 10Y/801A/VT25/VT62 then you would need another socket with another filament voltage, might higher plate voltage and another transformer. Is it double? Of cause it does! However, if I did it again then I would not do it in context of multi-channel amplifier but rather I would make a maket amplifier able would test my ideas with it. 
 
You see, the problem is that the “best” MF amplifier for you will be NOT the best amplifier but rather the best amp that would feet into the schema of your demands and the capacities of the rest of your channels. It is VERY hard to estimate what would it be, not to mention that your audio expectation might be a moving target and most likely will be recompiled after the first revision of you project will be over. 
 
I would not be advising you about the use of 10Y as I do not have proven experience with this tube. My short and environmentally not-kosher experiments with this tube did show great potential but it was a bit wrong direction to me. The 10Y was super clean tube, kind of aka Type 45 only even “cleaner”. I however was not looking for this cleanneness in my MF but rather I was looking for a lot of distortion but very specific type of distortion. The under-voltaged YO186 gave it to me, but I would never accept that same under-voltaged sound for a good full-range amplifier.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-02-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 15
Post ID: 21688
Reply to: 21687
Of course I am putting the cart before the horse...
fiogf49gjkf0d
 Romy the Cat wrote:

However, if I did it again then I would not do it in context of multi-channel amplifier but rather I would make a maket amplifier able would test my ideas with it. 


While I do like the idea of experimenting with MF sounds and then building just one DHT into the final Milq, I think that it may take me some time to decide between the YO186 and 45 types of sounds, especially as I tune a foreign to me system to my preferences.  
 
 Romy the Cat wrote:
You see, the problem is that the “best” MF amplifier for you will be NOT the best amplifier but rather the best amp that would feet into the schema of your demands and the capacities of the rest of your channels. It is VERY hard to estimate what would it be, not to mention that your audio expectation might be a moving target and most likely will be recompiled after the first revision of you project will be over. 


Yes I am sure that you are correct about about the MF amplifier having to play properly with the other channels.  I am also quite sure that my audio expectations will be to some extent a moving target when I start to listen and tune the channels and understand what they are capable of contributing.  Hopefully I can make it all work to my satisfaction.
 
 Romy the Cat wrote:
I would not be advising you about the use of 10Y as I do not have proven experience with this tube. My short and environmentally not-kosher experiments with this tube did show great potential but it was a bit wrong direction to me. The 10Y was super clean tube, kind of aka Type 45 only even “cleaner”. I however was not looking for this cleanneness in my MF but rather I was looking for a lot of distortion but very specific type of distortion. The under-voltaged YO186 gave it to me, but I would never accept that same under-voltaged sound for a good full-range amplifier.


I am often drawn to the super-clean sound which is largely why the 10Y interests me, but I have embarked on this Macondo/Melquiades project because I think that overall the system gives me many methods to get the sounds that I want.  Although I do enjoy classical music, I do not limit myself to that genre alone plus I have two quite musical young children that will want to listen to all kinds of music as they grow up.  If the YO186, or some other "distorting" tube manages to strike me as it has you, then I think that a "clean" tube may also still be in order as the kids explore other genres.  So what I think I will do is build your MF channel as shown in the schematic, but leave room in the power supply to add a couple of more voltages so that if I feel the need down the track that I can go with the 10Y, or perhaps even a DHT driver, or both. 

Thanks for your help so far Romy.

06-03-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 16
Post ID: 21689
Reply to: 21688
That notion of super-clean sound….
fiogf49gjkf0d
 anthony wrote:
I am often drawn to the super-clean sound …. 
 I do not think that use the term of “super-clean sound” in the same way. Vienna Philharmonic does not have “super-clean sound” from the perspective of most of contemporary orchestras. They have different fingering on clarinets, different reeds on oboes, rotary trumpets, narrow trombones, valveless horns and dozens other differences, some the part of design and some of the part of usability. As the result the sound is very distinctively different very far from “clean” but it has completely deferent meaning when colorations actually do server a very positive purpose and that coloration do fort what we call today Viennese Sound. It is very difficult to go for this level of sonic creativity with audio but only after one does go there then the use of term of “super-clean sound” with some kind “offence” connotation I find reasonable. I do think that until you experiment with “non- cleanliness injections”  (in one way or other) you truly do not use the term of “super-clean sound” in the same way as I do.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-03-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 17
Post ID: 21690
Reply to: 21689
I did not tell the whole story...
fiogf49gjkf0d
 Romy the Cat wrote:
 anthony wrote:
I am often drawn to the super-clean sound …. 
 I do not think that use the term of “super-clean sound” in the same way. Vienna Philharmonic does not have “super-clean sound” from the perspective of most of contemporary orchestras. They have different fingering on clarinets, different reeds on oboes, rotary trumpets, narrow trombones, valveless horns and dozens other differences, some the part of design and some of the part of usability. As the result the sound is very distinctively different very far from “clean” but it has completely deferent meaning when colorations actually do server a very positive purpose and that coloration do fort what we call today Viennese Sound.


I chastise my father from time to time because these days he often begins stories in the middle and leaves out the beginning where the context is set, and in my previous post I left out the context regarding "super-clean".

The way that I was using "super-clean" of course has caveats:  I don't like it across the board for all (or probably most) of the music that I listen to;  some modern music that is intentionally stripped of the harmonics during production actually seems to benefit from a "super-clean" or even "sterile" playback (think electronic music in particular, or modern R&B).  I do listen to electronic music occasionally (throwback to my youth probably) and believe it or not much of it is quite well mastered and with all its tricks and quirks and hooks it does sound very good on a "super-clean" system.  But then I listen to Mahler or Elgar or Jascha Heifetz and I yearn for a greater immersion in the colours and emotions of their works..."super clean" just does not work for me there.  

 Romy the Cat wrote:
It is very difficult to go for this level of sonic creativity with audio but only after one does go there then the use of term of “super-clean sound” with some kind “offence” connotation I find reasonable. I do think that until you experiment with “non- cleanliness injections”  (in one way or other) you truly do not use the term of “super-clean sound” in the same way as I do.

Well, that, in a nutshell, is why I have chosen Macondo/Melquiades.  My version of super-clean was only working on occasion for me, and it was generally under-whelming on much of the music I love, but without building speakers and amplifiers myself and experimenting/learning for a long, long time I could not see a viable way of getting just what I want.  Hopefully Macondo/Milq will shorten the long, long time into just a long time, and I will end up with a system on which I can play any style of music to my satisfaction.

Regards,

Anthony
06-03-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 18
Post ID: 21691
Reply to: 21675
About the MF Channel Schematic...
fiogf49gjkf0d
So, looking at the schematic below...


...I have a few more questions
  1. 25 turn pot in the filament supply.  For the life of me I can't source a 25 turn pot.  The 10 turn Bourns 3590 is the closest I can find.  Do I need to keep looking for a more sensitive pot or do you think 10 turn is manageable?
  2. The fuse.  You show a fuse on this schematic (that traces back to the B+ supply) but omit it on the  6-Channel schematic that I linked to earlier in the thread.  Do you use this fuse or have you removed it?
  3. HP Filter 50R.  In the schematic above you use a 50R resistor leading into the 6E6P but omit it on the 6 Channel schematic.  As far as I can tell it is not required for the high-pass RL filter so do you use the 50R or has it been removed?
  4. Changing valves.  Could you please explain to me the process of changing valves, say from 45 to YO186?  Please treat me as an imbecile in this regard.  I am very interested in the process and think that it will help me better understand its use.  If I were to guess I would say shut down the amps; remove 45; install YO186; turn on amps; adjust 100R pot to read ???? through the measuring points; press play.  Or maybe it is simpler than that...in some photographs I notice a switch on the "DHT Island" but do not know what it is for.



06-04-2015 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 19
Post ID: 21692
Reply to: 21691
More ansvers.....
fiogf49gjkf0d
 anthony wrote:
25 turn pot in the filament supply.  For the life of me I can't source a 25 turn pot.  The 10 turn Bourns 3590 is the closest I can find.  Do I need to keep looking for a more sensitive pot or do you think 10 turn is manageable?
   
Sure it is manageable. This is just pure the matter of comfort.
 anthony wrote:
 The fuse.  You show a fuse on this schematic (that traces back to the B+ supply) but omit it on the 6-Channel schematic that I linked to earlier in the thread.  Do you use this fuse or have you removed it?
  Yes, I use 7.5A slow blow at the very entrance of the 6-Channel schematic with the amp drown in cruse mode in mid of 4A. The slow blow is critical as the amp will start up and begin to saturate the chokes it will draw instantly over 3kW. The normal consumption is 375W if I am not mistaken.
 anthony wrote:
HP Filter 50R.  In the schematic above you use a 50R resistor leading into the 6E6P but omit it on the 6 Channel schematic.  As far as I can tell it is not required for the high-pass RL filter so do you use the 50R or has it been removed?
 
Well, the 6E6P is very fast tube and have tendency for microphonic effect, in particularly while it I cold. It is a common practice to put a very small resistor (50-100R) right before the grid entrance to stop any stray noised to come to the grid and arouse the tube. This is call grid stopper. The ferrite bids serve the same purpose. So, the grid stoppers with fast tube are not part of semantics but rather a part of regular design hygiene and they are implied with those type of tubes. On the 6 Channel schematic I just did not have space to depict it but I still would use it in particularly if your wires from the coil are too long as they act as antenna picking up all imaginable dirt in the amp chasses.
 anthony wrote:
Changing valves.  Could you please explain to me the process of changing valves, say from 45 to YO186?  Please treat me as an imbecile in this regard.  I am very interested in the process and think that it will help me better understand its use.  If I were to guess I would say shut down the amps; remove 45; install YO186; turn on amps; adjust 100R pot to read ???? through the measuring points; press play.  Or maybe it is simpler than that...in some photographs I notice a switch on the "DHT Island" but do not know what it is for.
 
Yes, that is exactly how you describe the process. You adjust the 100R in order to kill the noise on the output. What I do is use mili-voltmeter on the terminal of S2 and try to set the voltage in there under 3mV. I think anything above 20mV is auditable, Anything under 10mV is dead silent. Another very important factor when you change the tube and try to compare them is that they all will have slightly different gain. So here is what I do. My tuner has 1kHz calibration tone, it is convenient and I do not need to bring a generator or test CD). 

1)    Drive the calibration tone and measure the AV at the speaker (I prefer to do it electrically  not acoustically)
2)    Follow your procedures to replace the tubes
3)    Drive the calibration tone with the new tube and measure the SAME AV at the speaker. If the AV not same then use the post OTP attenuator to make it the same. 

There is some “kind” into it. Some tubes you do not mind to drive louder (mostly dark tubes:  PX25, RE604, YO186, 2A3 with single plate for instance) and some you would like to run softer (type 45, 30, 2A3 etc…). You will end up with whatever you prefer eventually. Be advised that the output of Fundamentals, HF and Insertion channels will greatly impact how you would like to hear your MF.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-05-2015 Post does not mapped to Knowledge Tree
anthony
Posts 137
Joined on 08-18-2014

Post #: 20
Post ID: 21693
Reply to: 21692
The fuse in theMF Channel
fiogf49gjkf0d
 Romy the Cat wrote:
 anthony wrote:
 The fuse.  You show a fuse on this schematic (that traces back to the B+ supply) but omit it on the 6-Channel schematic that I linked to earlier in the thread.  Do you use this fuse or have you removed it?
  Yes, I use 7.5A slow blow at the very entrance of the 6-Channel schematic with the amp drown in cruse mode in mid of 4A. The slow blow is critical as the amp will start up and begin to saturate the chokes it will draw instantly over 3kW. The normal consumption is 375W if I am not mistaken. 

Do you still use the fuse shown in the MF channel schematic linked above (not the 6 Channel schematic)?

Regarding the mains fuses I will have to recalculate them for the mains voltage where I am...they should roughly halve for 240v.

  
 Romy the Cat wrote:

 anthony wrote:
HP Filter 50R.  In the schematic above you use a 50R resistor leading into the 6E6P but omit it on the 6 Channel schematic.  As far as I can tell it is not required for the high-pass RL filter so do you use the 50R or has it been removed?
 
Well, the 6E6P is very fast tube and have tendency for microphonic effect, in particularly while it I cold. It is a common practice to put a very small resistor (50-100R) right before the grid entrance to stop any stray noised to come to the grid and arouse the tube. This is call grid stopper. The ferrite bids serve the same purpose. So, the grid stoppers with fast tube are not part of semantics but rather a part of regular design hygiene and they are implied with those type of tubes. On the 6 Channel schematic I just did not have space to depict it but I still would use it in particularly if your wires from the coil are too long as they act as antenna picking up all imaginable dirt in the amp chasses. 


Well I would have missed that one...so thanks for that.  These will be my first amplifier builds so I will probably miss those kinds of things.  Can you think of any others that I will probably miss?

 Romy the Cat wrote:
 
Yes, that is exactly how you describe the process. You adjust the 100R in order to kill the noise on the output. What I do is use mili-voltmeter on the terminal of S2 and try to set the voltage in there under 3mV. I think anything above 20mV is auditable, Anything under 10mV is dead silent. Another very important factor when you change the tube and try to compare them is that they all will have slightly different gain. So here is what I do. My tuner has 1kHz calibration tone, it is convenient and I do not need to bring a generator or test CD). 

1)    Drive the calibration tone and measure the AV at the speaker (I prefer to do it electrically  not acoustically)
2)    Follow your procedures to replace the tubes
3)    Drive the calibration tone with the new tube and measure the SAME AV at the speaker. If the AV not same then use the post OTP attenuator to make it the same. 

There is some “kind” into it. Some tubes you do not mind to drive louder (mostly dark tubes:  PX25, RE604, YO186, 2A3 with single plate for instance) and some you would like to run softer (type 45, 30, 2A3 etc…). You will end up with whatever you prefer eventually. Be advised that the output of Fundamentals, HF and Insertion channels will greatly impact how you would like to hear your MF.


Thanks Romy, but I don't know what you mean by AV in the text above.  Do you mean dB?


One more question.  The filament supply of the MF Channel has the hum management circuitry on the 4v secondary...do you also use an artificial centre tap on the 2.5v secondary?  I just thought that it might be one of those "hygiene" things that you left off the schematic.  Likewise for the filament supplies of the other channels.

Regards,

Anthony

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