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02-21-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 21
Post ID: 6721
Reply to: 6718
6E5P for sale
Do you plan to develop this amp to a commercial product?


Yes, this is slated for production.  But I really doubt I will sell many.  Perhaps a few pairs.  It's a bit out of the mainstream.  Really need to use them with something 100dB+.  Mostly I wanted to prove out the new topology.  On paper I have come up with version #2 for 20 watts at 1 ohm output impedance.  It is a beast, using four 6080 output tubes per channel.  They don't have the linearity of the DHT, but they solve the damping factor problem.  They will be usable with a much wider range of loudspeaker.

I sort of ran into a power limit.  Without resorting to feedback, you can't get much power out of a tube amp.  Is it stupid to tie my hands like that?  Maybe.  I just wanted to make a powerful tube amp.  Doing some research, it turns out everyone else is using feedback.  From Quicksilver to Lamm, they all use it.  Lots of feedback in both PP and SE models.  That's how they get decent power and high DF.  Suppose if you're going to drive Wilsons then you need to do such.  That road isn't for me.

The IT may not be the best.  I had a lot of issues with it.  However, in the space alloted, I cannot fit a Lundahl (something like a 1635).  Believe it or not, I am using the humble Hammond 124B.  It has a lot of nickel in the core for low distortion.  It can also handle the very high voltage swings. 

jh
02-21-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 22
Post ID: 6722
Reply to: 6719
Full power ahead
I chose the 170V point as midway between the 250V supply I had for the CCS plate load.  The choice was for maximal signal swing in both directions. 

in a properly designed amplifier a transformer should clip before the active stages


Then I did it wrong.  I have it so the DHT clips into A2.  Since operation is PP, it is full class A up to 6W, then switches to class B as on tube cuts off (determined by reflected load line).  I have this set just where A2 starts on the active tube.  Thus, power is sort of cut in half as it clips.  None of the transformers saturate.  The output tranny is a humble Hammond 1615.  Current in each primary is perfectly balanced by identical CCS for each tube.  So tranny has a ton of headroom.  No dc on it.

The 25.5kHz as full power is not just very good but exceptional


Usually I get a lot more.  My "Cymbal" amp using 6H30 output tubes cranked out 95kHz. 



I did bandwidth measurements at 1W.  I doubt it falls off to much at high power at HF.  Probably moreso at LF.  A 5kHz full power sinewave showed no signs of pain.  It is a good idea to check, though.  I should plot both 1W and 6W bandwidth responses. 

02-21-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 23
Post ID: 6724
Reply to: 6722
I probably shouldn't post these...
But here it is.  I made this monoblock fit into less than a square foot.  It is tight.  I use Hammond iron throughout.  Their stuff usually works pretty good for power supplies.  I have some photos at my blog. 



The power supply is very straightforward.  One section of LC on rectifier is enough.  I forget how much ripple there is, something like 0.2Vrms.



It looks like a mess, but it's not.  The output stage is drawn push/pull.  The non-feedback type transistor CCS in each tail make sure there is perfect dc flux cancellation in the output tranny.  Cathodes are tied together at ac via C19 and C20.  Thus, your basic differential amplifier.  Here's where the trick comes in, R32, if set to zero ohms, effectively shorts the cathodes to B+.  In this case, we have two independent SE amps of opposite phase.  By adjusting R32, the ratio between SE and PP can be set for lowest distortion.  I believe Western Electric came up with this in the 1930s.  My connection is different because of the CCS, which they didn't have.

You'll not R21 sets the common mode voltage of the grids to zero volts.  C16 couples the B+ ripple directly into the grids.  Thus, the voltage seen by the tubes themselves remains constant.  This is a very effective cancellation of ripple.  You can't believe how effective this is.  There is also common mode cancellation in the output tranny.  So bias on tubes is constant, there is no operating point modulation and mixing (IMD).  The cathodes are free to follow the grids.

The driver is a triode strapped tetrode, per Dima and Romy.  I run it with a CCS load, again, no-feedback transistor source.  The output impedance of the 6E5P is roughly 1.5k, with cathode grounded (I am using cathode bias).  I discovered that the interwinding capacitance of the IT gets very unbalanced and assymetrical if R34 is zero.  Hence, I balance the primary drive impedance-wise by adding the 1.5k in series.  Ok, so now we're driving a 10k:90k IT with a 3k source.  Should be ok!  There are other issues with the IT, such as non-interleaved secondaries (one is outside the other, with higher dc resistance), resulting in two values of leakage inductance, and two main self resonances.  One at 26kHz, the other at 74kHz.  My best transient response occurs when I split up the damping.  I run very high grid resistors of 10k, which when combined with the grid capacitance forms an RC snubber for the upper resonance.  The lower one is then tackled by the 47k.  These resistors are snubbers.  I could put them inseries with small capacitors resulting in higher LF gain, but I don't like that.  I figured best to keep out as many capacitors as possible.  Anyway, it works.  I tame the HF response to an almost perfect Butterworth.  The 10k grid resistors also limit how far it can enter into A2.  That's why the overload condition looks so nice.  Now, HF rolloff is very clean, once it starts dropping, it just keeps falling.  No ultrasonic wierdness.

I will probably use these amps using the 4 ohm taps.  That still delivers 5Vrms at output.  Enough for my small room I hope. 

jh
02-21-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 24
Post ID: 6726
Reply to: 6722
A common sense of SET power measurements

 hagtech wrote:
I did bandwidth measurements at 1W.  ….  I should plot both 1W and 6W bandwidth responses.

I always feel strangely disturbed when I see people specify SET response from 2Hz to 150kHz. Here is a practice out there to consider SET response not at full power and I cannot imagine if could be more bogus measurement then that.  A response of a SET amplifier must not be measured at fraction of it’s powers. Well, one can measure whatever s/he what but those numbers should be never made public. Measuring a SET at 10% of full power is like proclaiming that a car goes 1000 miles per hour, forgetting to mention that the speedometer was calibrated in a way that each mile has 23 feet.

A lower frequency response is a properly of power and inductance. In a complete SET amp, with already made gap the inductance is fixed and plate current driven through a transformer become a factor. So, there is ONLY ONE way to measure true frequency response of SET amp: found max power into a given load at MF and to see where the SAME POWER will have -3dB at bottom and atop. Usually at the bottom 20Hz -25Hz considered incredibly good numbers; very few amps do it and most of the “cheap” SETs do 30Hz and up. Some of them roll of say at 40Hz and some of them clip at 40Hz… I heard the stores how well reputed and expensive amps were measured at 50-80Hz of full power. BTW, when I was saying the LF channel of Super Milq goes down to 7.5Hz I meant that it was full power, or 3dB less than the max amplitude that amp I capable to develop. In HF for full-range SET the 20Hz -25kHz are very good numbers at fool power…

Well, theoretically, if a person knows that his 8W for instance amp NEVER develop more than 3W to the given load then the 3W might be recognized as a reference frequency response. In reality, a 8W amp, ever driven a very efficient load of 105dB, in order to never go over 3W, the amps should be high-passed somewhere at 500Hz. I would personally would like even to have at least 6-8dB of headroom between the max signal/power an amps get from music and the moment when amp’s power max out.

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
02-21-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 25
Post ID: 6732
Reply to: 6726
Full power bandwidth
Ok, I did it a little different this time.  At full power levels, the dB meter still showed wideband response.  However, looking at the scope I could see distortion in the waveform.  So instead, I lowered the input level to -3dB from full power at 1kHz.  Then I swept frequency to where I could see the onset of distortion.  These points were at 25Hz and 19kHz.  So I suppose you could call this the "full power undistorted bandwidth".  Minus 3dB points, anyway.  Here's shot of the machine showing the 19kHz waveform.



This does not qualiify as an SE amp.  I run the output tranny as PP, no dc flux.  That's a significant advantage for bandwidth.  The 1615 tranny is quite small.  My one and only SET project achieved 65kHz at 1W through a UBT-3.

Clarion

jh
02-21-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 26
Post ID: 6735
Reply to: 6732
A “full power undistorted bandwidth”.

Jim, the “full power undistorted bandwidth” is the only bandwidth that counts, at least as I understand bandwidth. The 25Hz to 19kHz is it what would expect from a regular SET if do not spend a LOT of money for output transformer. Your amp is not SE amp and I do not know how bandwidth works in PP amps. Theoretically the no gap transformer should be helpful, in bass region but in practice I feel that a use a DC blocking parafeed capacitor overrides the no-gap OPT bass advantages. I am very much not the person who can credibly talk about amplifier topologies but a need a capacitor and transformer in sequence just does not make sense to my view of common sense.

What is actually found interesting to me, Jim, is that you are trying to make an amplifier, using a new to you solutions an active element without very organic incorporating of actual listening assessments in your design process. It is what I am unable to do, in fact I feel that listening evaluation are the only objective measurement that we have…

Rgd, 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
02-21-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 27
Post ID: 6736
Reply to: 6735
Objective Measurments
I feel that listening evaluation are the only objective measurement that we have


You are lucky to be able to bask in such luxury!  It is one thing to build an amp for yourself, constantly tweaking and upgrading.  Quite another to design a machine for public consumption, at which point things like reliability, repeatability, and manufacturability become important.  Hence, you need to understand every inch of a circuit, the voltages and currents, everything.  If listening was the only criteria, then these would not matter. 

jh
02-22-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 28
Post ID: 6737
Reply to: 6736
The long life with 5E6P tube

 hagtech wrote:
You are lucky to be able to bask in such luxury!  It is one thing to build an amp for yourself, constantly tweaking and upgrading.  Quite another to design a machine for public consumption, at which point things like reliability, repeatability, and manufacturability become important.  Hence, you need to understand every inch of a circuit, the voltages and currents, everything.  If listening was the only criteria, then these would not matter. 

Yes, sure I understand it, the public consumption machine and a machine for own tailored needs are very different thing. I am very lucky that I do not do audio as business. Still, I was taking about different things – about the decision support and the ways to assess the decision’s rational. This is however totally different subject and we are way too far from the subject of this thread.

Since you use the 5E6P in your amp it would be very interesting with time to hear your observation how this tube ages. The relatively fast life-span is the only one thing that I do not like in this tube. I usually get around a year out of 5E6P driving it at 17mA and 200V. I do not know how much I will get out of 5E6P at 35mA as I use them in the single-stage amps. The 5E6P does not dies in a year and can works for years and years but I feel it is good to replace it after a year. I would wonder to what observation about the 5E6P life-span you will come across. Particularly, since you use that tracer tools I wonder if you will be able to found any objective parameters that would signifies that the 5E6P is ready to go. I measure current and cathode emission – not always objective, unless I keep a log file for each tube and monitor how it ages. It would be cool of I was able to tag the 5E6P with unique numbers…

One more thing, Jim. Looking at your amp I see the driver tube as very short tube, shorter then it should be. I afraid that you do not use 5E6P but 5E6P-E or 5E6P-I. The 5E6P-E is identical tune to the 5E6P but it is slightly shorter. The 5E6P-E is an impulse version of 5E6P-E and it should not be used. The 5E6P-E measures identically to 5E6P but has no good sound.

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
02-22-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 29
Post ID: 6738
Reply to: 6737
Short Tube
very short tube, shorter then it should be

Hmmm, I'll have to double check.  This is actually one of the tubes you sent me.  It is a little taller than a 6H30.  I bought a bunch more off of eBay but haven't fired them up yet.

Once I get a pair of amps put together, I can start tweaking for sound.  Hopefully I am not too far off where I start.  At least I have a baseline that I know is reasonable from a technical standpoint.  I'll keep track of tube life and problems.

jh
02-22-2008 Post does not mapped to Knowledge Tree
JJ Triode
Posts 75
Joined on 09-12-2007

Post #: 30
Post ID: 6739
Reply to: 6738
Recessed tube mounting and other cosmetic issues...
Hi Jim,
Romy may not have noticed that the tubes are mounted to the circuit board below the top cover and not at the surface, so the driver in particular looks shorter than it really is.

Will the final appearance be similar to the prototype in the picture? What are the dimensions of the enclosure?

Will the PA-10 be offered as half-kit, wired or both? What will the price be, approximately?
rgs,
JJ
02-22-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 31
Post ID: 6740
Reply to: 6738
The sizes of the 6E5P family....

I do not remember what I sent to you, since I sent you for measurement perpose then it might be the impulse version of the tube. In the image below are vertical tubes from left to right:

0A2
6E5P-E (smaller)
6E6P-DR (larger)
6E5P (the largest)
0A2





"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-22-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 32
Post ID: 6742
Reply to: 6740
The Déjà vu feelings about 6E5P-E vs 6E5P

I did have the Déjà vu feelings about it as I felt that we had this conversation in past. Here we go – it was a year ago.

http://www.goodsoundclub.com/GetPost.aspx?PostID=4291

That post has both 6E5P-E and 6E5P datasheets and they are virtually the dame in data, not in sound though. I have quite a few of 6E5P-E and I use then as the test tube, while I was playing with the amp assembling. The full 6E5P is also I feel can care more power as it is physically larger and therefore better dissipates hit. I used 6E5P-E in my HF channels with success. Nowadays however, with the 6-ch Super Milq, I can’ do it as for HF channels in my current amp use 6E6P, which have very different pins layout. BTW, the 6E6P has identical pins with 7721/D3A and in some case might be almost (bias shell be changed) a drop in replacement. I was driving with 7721/D3A my HF channel...

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
02-22-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 33
Post ID: 6743
Reply to: 6739
It is a small box, driver tube is buried about 1 inch
Will the final appearance be similar to the prototype in the picture?

Yes, I can't imagine it changing much.  Parts may change, but the layout is fixed.  Size of box is 10x10x4 in inches.  Weight, I think is only 15 pounds.  Draws 95 watts from the wall.  No kit versions.  Haven't added up part prices yet, but I'd expect it to retail for roughly $6k to $7k per pair with Sovteks installed.  I may end up owning the only pair.  But hey, it's my small contribution to pushing the envelope of technology (which everyone here is doing).

jh
12-31-2008 Post mapped to one branch of Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 34
Post ID: 9310
Reply to: 4805
A commercial amp with 6E5P
fiogf49gjkf0d

Frank Blöhbaum, from Sweden I believe, have designed for Thorens a preamp that I think the first outside of Russia commercial use my 6E5P tube.

http://www.6moons.com/audioreviews/thorens4/tep3800.html

I do not know if Frank reads this site but if he does then good for him. As I see he used 6E5P as in output stage of pram, debating it with E810F for whatever reasons. I do not know if it was Srajan’s blooper or Mr. Blöhbaum blooper. I doubt that it was Srajan as he brainlessly juts print what he was told by manufactures. The E810F/7788 shell not be even to use in the same sentence as they are tubes for VERY different purposes. The D3a/7721 are far apart but roughly the same tubes as 6E5P and the D3a/7721 and 6E6P are more or less replaceable and have the same pins. I think Srajan was juts confused with too make new words for himself as I doubt that Frank would put the E810F and 6E5P in the same boat.

Anyhow, it is the first commercial use of 6E5P. It is very nice that back in 1996 Victor Khomenko of BAT was told about 6H30P and he made his best to have the price for 6H30P to shoot over the roof. Leaving out of attention of big manufactures the 6E5P still enjoy the dirt cheap price.

I think I do a great service in maintaining the popularity of 6E5P low.  To my knowledge I am the only English-writing person who talks about uniqueness and advantages of 6E5P. Since my extreme anti-DIY attitude and general anti-social mind-set towards to audio Mormonism they do not take my comments serious, in fact I was reported that a manufacture who refused to use 6E5P just because it came from Romy the Cat. It is what I always say – “Good for them and die with you little secret!” (Courtesy to “The Ritz”).

Interesting that Frank Blöhbaum will not be the first commercial amp with 6E5P that west will be hearing. Back to 2000 or 2001 a Russian company NEM (Novosibirsk Electronic Manufacturing)

http://www.shemki.com/schemes.htm

….brought on CES their new amp. It was 300B drive with a single driver that I never knew at that time and it was somthing that ignited my interest.

http://www.shemki.com/schemas/nem300b12.gif

The amp was driving small Acapealla Horns the sound was not there as the people who run the room (Canadian distributor) had no experience with sound. However, it was very auditable that the amp sounded very-very good. BTW, whatever it worth, the NEM won some kind of price at the show, like best sound, or best product. Regardless how unimportant it is but let agree that to be nominated and to win this thing in Vegas without kissing the industry asses and spending zero efforts for self-promotion was an accomplishment. Anyhow, I took a note about 6E5P right there and was wondering to use it to drive my 6C33C in two stages.  The designer on the amp and the NEM director was Sergey Rubtsov. I know that guy and I am not a big fun of him.  He is a Russian chauvinist and I very much hate this type.  At that time the 6E5P were sold for 11c -13c per tube…

Later on taking with Dima I learn that he and Russian designer Alexander Monakov independently discovered “6E5P for Sound” in 1999. Dima was fixing TV equipment and in deflection amp he saw that small tube with 8.5W plate dissipation, 30 time gain when triode and absolutely different internal construction than anything else he ever had seen. He built right the way a little buffers with it, measured it, listened it, got surprised how good it was … the rest is history…

Anyhow, I wish to welcome Frank Blöhbaum and looks like the Thorens to the 6E5P’s proudly-dysfunctional family.

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
01-01-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 35
Post ID: 9317
Reply to: 9310
Some corrections in Srajan blabbing about 6E5P.
fiogf49gjkf0d

In my post above I have mention that Srajan is in a way a brainless parrot that repeats the heard and has no ability of desire to understand what was the noise about. His comments that 6E5P and E810F are “close electrical” is a good indication how it works: a manufacture passes wind from behind and an idiot-reviewer runs around him and screams “Hurricane!”

Anyhow, mentioning that Thorens used my 6E5P in out stage I think that it would be deceives to truth if I would not correct another factual error that Srajan used in his article as selling point. Here are two paragraphs from Srajan write up:

The output valves' input capacitance is lower than the power amp's Mosfets by a factor of 1000 of course. Far more importantly, their output current is 30mA. And their output impedance 0.67 ohms. That latter is a shockingly low figure for a direct-coupled tube circuit. It means phenomenal drive over even endless interconnects. Or 600-ohm load happiness as active pro monitors present. Yousa! And for the really curious, yes, the 6E5P's close electrical -- but not pin-compatible -- cousin is the E810F which has a higher transconductance but less anode power dissipation. This preamp circuit would be capable of swinging an ungodly max +/- 60V but is naturally limited by the input signal. A standard 2V input signal translates into roughly a voltage swing of 10 (gain is 16dB). That means overkill headroom for true dynamics. And an unconditional incapacity for clipping the output stage. Ever. It's really a power amp wolf in preamp sheep skin. Blöhbaum runs his original TEP 3800 prototype [lower rights] to drive AKG K-1000 headphones with. Those are beastly inefficient and usually coupled speaker-level to amplifiers putting out 10 watts.

"I know you've lived abroad for half your life and are probably only now discovering much of the hifi scene in your native Germany. It might interest you then to know that both German print magazines and arch rivals at that already published reviews on the TEP 3800. Quite out of character, they agreed with each other and rated it among the best if not the best preamp they ever tested. It's good to observe both the Stereo and Stereoplay tests. The Stereoplay test bench delivered a graph of harmonic spectra depending on output amplitude. This graph shows why this preamp is praised for its transparency. There is no change of the relation between each specific harmonic and each other from the low end of just perceptible whispers to ear-cracking levels. The absolute value of distortion is extremely low. The measured figures of Stereo magazine show 0.0002% @ 1V output. Most high-end people believe that such low distortion will end up in anemic, cold, clinical sound. It's remarkable that especially Stereo magazine -- which is known for favoring some voodoo tricks and beliefs -- praised the musicality of the TEP 3800. Also look at the other values like channel separation of 73dB. Stereo measures that at 10kHz! One footnote: The measured output impedance of 56 ohm is for cinch. The XLR has a stunning 0.67 Ohm output impedance. "

Srajan  said that TEP 3800 uses 6E5P in output stage and I do not exactly understand how the 6E5P might be use in direct-coupling with preamp’s load, what would block DC? Does Frank Blöhbaum in this preamp uses a SS follower after 6E5P?  The most important: where is the 0.67 Ohm output impedance came from? It is obviously that 0.67 Ohm is nether 6E5P anode nether 6E5P cathode. With output current of 30mA that Srajan mentioned the 6E5P has a little bit sub 1kOhm on anode, it is very low but it is not even near 0.67R, unless it run a huge feedback. So, praising the 6E5P as out stage for TEP 3800 preamp I need to say that if the preamp do have 0.67 Ohm output impedance then it has absolutely nothing to do with 6E5P. It would be interesting to chat with Frank Blöhbaum about what he did in there. I would particularly be interested to know what he was trying to accomplish by running 6C19P in a copper chimney. However, it looks like via Srajan interpretation it as much plausible as to have a conversation with a porcupine about the Global Warming.

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
11-06-2013 Post does not mapped to Knowledge Tree
Celsius
Posts 5
Joined on 11-06-2013

Post #: 36
Post ID: 20240
Reply to: 6028
6c33 swing voltage
fiogf49gjkf0d
 Romy the Cat wrote:

Why do you think I bout a 1000 of them and closed to the rest of my life my interest in driver tubes?

Still, the 6E5P should not be measured as a driver but heard as a driver – the beauty in this tube is in its sound.

I do not know why it gave to you more power. It is a regular 32-36 times gain, it means with 4V bias you can get a lot of voltage from this tube with no problems. I uselessly drive it with 200V and you might drive it as hot at 6.5W, with 8.5W max but I would not go there. The only concern that I have, since I knew that you will be juts measure them, if I did not send you the 6E5P-E. The 6E5P-E is impulse venison of the tube and although it measures virtually identically but it does not sound as good, it is ¼ smaller as well.

BYW, the benefits that you got were so far not the 6E5P advantages but you juts stopped to use absolutely not appropriate tube (7788) to drive your 2a3. John, I am very much not in position to argue with your about tubes but to use 7788 at line voltage as … a driver is absolutely beyond my believe in mankind sincerity… :-)

The Cat


Hi Romy, this is my first comment here ( hello everybody ), but follow you for a long time, thanks for you job.

Well I try to understand but for me is not clear, the 6c33 need bias -70 to -90 at less the mine.  -80v give  160Vpp swing voltage  and 160vpp is difficult to obtain from 6E5P, I am sure that I am wrong but prefer to understand better that only copy the schematic.
I would like to change my actual driver 6ac7 who give 200Vpp but the sound is good but not great.

I find anothers driver that maybe are better, as E180F  or 6485 (6J5P) that give more swing, but I follow thinking that I am wrong only need to read here but dont understand, who can show me the way.
11-06-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 37
Post ID: 20241
Reply to: 20240
A Driver.
fiogf49gjkf0d
Celsius, I think you do not take in your equation the input voltage. If you bias 6E5P with 4.1V then it can pass 4V with no feedback.  Since the tube has under normal circumstances 33 times gain then you have 132V RMS from your driver stage, wish is if I am not mistaken 373ppV.  That is all that 6E5P can do and among the tubes that I have seen that is one of the highest voltage swinging triode that still can handle 8W on plate. If you would like to use other tubes then it would certainly do but I can only comment upon the tubes that I know and tried.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-12-2013 Post does not mapped to Knowledge Tree
Celsius
Posts 5
Joined on 11-06-2013

Post #: 38
Post ID: 20364
Reply to: 20241
6e5p can drive in full amp?
fiogf49gjkf0d
 Romy the Cat wrote:
Celsius, I think you do not take in your equation the input voltage. If you bias 6E5P with 4.1V then it can pass 4V with no feedback.  Since the tube has under normal circumstances 33 times gain then you have 132V RMS from your driver stage, wish is if I am not mistaken 373ppV.  That is all that 6E5P can do and among the tubes that I have seen that is one of the highest voltage swinging triode that still can handle 8W on plate. If you would like to use other tubes then it would certainly do but I can only comment upon the tubes that I know and tried.

Thanks Romy,  I see.

The problem is that my target is drive a 211  as full amp,  and my CD player  give a litle bit more than 1v to grid

 What do you think    1V x 33times x 2.8 give 93ppV enought to drive the 211.

I have  a small board negative voltage regulator based in lm337, Does  anybody test to use as Bias fot 6e5p ?
12-13-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 39
Post ID: 20365
Reply to: 20364
OK, try it, it is all yours.
fiogf49gjkf0d
 Celsius wrote:
The problem is that my target is drive a 211  as full amp,  and my CD player  give a litle bit more than 1v to grid. What do you think    1V x 33times x 2.8 give 93ppV enought to drive the 211.
 Well, you need another gain stage. It is not a big deal but it is way outside my expertise with Milq amplifier and then way how 5E5P works. The 5E5P has 4V on grid, so it makes sense to use it with sources that push out much more then 1V.
 Celsius wrote:
I have  a small board negative voltage regulator based in lm337, Does  anybody test to use as Bias fot 6e5p ?
 
I do not like the 5E5P sound with fixed bias, cathode bias, or with Milq bias when voltage is coming from anything else then how it done in MIlq. I understand that you can supply 15oV from anything but I in my experiments find that I like the Gas tube with 10uF cap and high resistor before grid. Any other configuration I did not like. It does not mean that you shall not excrement and it is very possible that you will find some configuration that will be even better then what I find. However, I will not be able to consult you about neither method nor result. I do advise to try my method and then trey whatever you want. If you found that your bias pleases you more ten let me know.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-13-2013 Post does not mapped to Knowledge Tree
Celsius
Posts 5
Joined on 11-06-2013

Post #: 40
Post ID: 20366
Reply to: 20365
Full amp bias
fiogf49gjkf0d
 Romy the Cat wrote:
 Celsius wrote:
The problem is that my target is drive a 211  as full amp,  and my CD player  give a litle bit more than 1v to grid. What do you think    1V x 33times x 2.8 give 93ppV enought to drive the 211.
 Well, you need another gain stage. It is not a big deal but it is way outside my expertise with Milq amplifier and then way how 5E5P works. The 5E5P has 4V on grid, so it makes sense to use it with sources that push out much more then 1V.

But three stage do not change the phase, I have ready 4P1L with the socket waiting :-) 

 Celsius wrote:
I have  a small board negative voltage regulator based in lm337, Does  anybody test to use as Bias fot 6e5p ?
 
I do not like the 5E5P sound with fixed bias, cathode bias, or with Milq bias when voltage is coming from anything else then how it done in MIlq. I understand that you can supply 15oV from anything but I in my experiments find that I like the Gas tube with 10uF cap and high resistor before grid. Any other configuration I did not like. It does not mean that you shall not excrement and it is very possible that you will find some configuration that will be even better then what I find. However, I will not be able to consult you about neither method nor result. I do advise to try my method and then trey whatever you want. If you found that your bias pleases you more ten let me know.


If I make a full amp where do you think is good to separate the bias line after the 10k resistor or before.
Thanks again for you patient

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