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09-16-2012 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 41
Post ID: 18604
Reply to: 18601
Nichicon small
fiogf49gjkf0d
Rather than using a single can my builder made a bank of 470uf units, one of which failed. I thought I'd replace the entire bank, for simplicity. 

09-16-2012 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 454
Joined on 01-07-2006

Post #: 42
Post ID: 18605
Reply to: 18604
Trouser?
fiogf49gjkf0d
At those small values mouser, didgikey etc should be ok, no?
Any reasoning behind such a approach aprt fro aviability?
Also ROmy has sunstancial capacitance at 15000u etc, do you
use 30 caps in a bank?



Cheers,
Jarek
09-16-2012 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 43
Post ID: 18606
Reply to: 18605
Bank vs single
fiogf49gjkf0d
The decision to use banks was my builder's: whether it was availability or other reasons I have not asked. I want to change to single capacitors because I like limiting the failure degrees of freedom, so to speak.
09-16-2012 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,144
Joined on 10-12-2006

Post #: 44
Post ID: 18608
Reply to: 18606
Rise Times and Jobbers
fiogf49gjkf0d
One of the reasons cited for using several smaller caps is rise/cycle time, versus 1 large cap.  I understand it is also easier to wind the smaller caps to the desired high-zoot specs.  Muse caps are said to have very low rates of failure, compared to others, and they have famously low ESR, along with excellent rise times, and good service lives.

I have no personal reason to explore this further, but I have been given to understand that Marantz used some sort of modern, industry-only "super caps" with large values in the MA-9S2.  As it has been several years since this amp hit the market, these caps might be available to jobbers now.

Best regards,
Paul S

09-16-2012 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 454
Joined on 01-07-2006

Post #: 45
Post ID: 18610
Reply to: 18608
Single vs. multiple
fiogf49gjkf0d
Yes, I've heard this theory too that paralelling caps lowers the esr/esl => better rise time.
No idea if it's true or only an excuse for not using big, hard to get and expensive single caps.

PSA quote from arandom physicsforums thread:

"In the general, the larger the capacitance, the smaller the ESR becomes. So you would have to hunt for a giant cap which would probably cost a fortune"

 http://www.physicsforums.com/showthread.php?t=422231


If that's true, this can be the "secret" behind Romy PSU philosophy.  Huge cap becomes more invisible?



Cheers,
Jarek
12-17-2012 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 46
Post ID: 18824
Reply to: 18610
6c33c socket cooling
fiogf49gjkf0d
it is worth reiterating in this thread -- and perhaps Romy should update his advice in the relevant section -- that exotic japanese teflon sockets such as the one made by yamamoto soundcraft are no good for the 6c33c, whether because of insufficient cooling or the nature of the contact i dont know but the heater contact is unstable.
Has anyone tried cooling the socket with heatpipes, i wonder?
12-17-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,535
Joined on 05-28-2004

Post #: 47
Post ID: 18825
Reply to: 18824
Do not cool socket but cool wire
fiogf49gjkf0d
 decoud wrote:
it is worth reiterating in this thread -- and perhaps Romy should update his advice in the relevant section -- that exotic japanese teflon sockets such as the one made by yamamoto soundcraft are no good for the 6c33c, whether because of insufficient cooling or the nature of the contact i dont know but the heater contact is unstable. Has anyone tried cooling the socket with heatpipes, i wonder?
I do not use the Japanese Teflon sockets but somebody have reported before at this site that they are not good. Since I did not use them I do not why they are not good but I presume that they spent time and money for relevant thing – namely the material of sockets and they did use expensive and more or less exotic Teflon. The truth is that the material of the sockets is more or less irrelevant and the key is the contraction of the pins. Usually the pines are made self-springy by the shape of the pin. The Teflon sockets use density of Teflon to provide the spring action and that might be fine for low current pins but if pin meant to care high then it might be a bit problematic from cooking perspective as Teflon is very good thermo-isolator. I do think that this time of socket still might be used if you suck outs heat from socket. Use a low gauge wire as you approach socket, take the isolation off and wide some kind of heat exchanger from that wire. It will suck out hit from the pin of the tube but I have no idea if it not going to impact sound. In other words: do not cool socket but cool wire – filament and perhaps plate.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-17-2012 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 48
Post ID: 18828
Reply to: 18825
Heatpipe wires
fiogf49gjkf0d
Yes, this is what I meant: link the pins using heatpipes to a heat exchanger, in fact I wonder if one could use the heatpipes as the filament conductors direct.
The yamamotos are beautifully made but badly designed. The receptacle of each pin is a split hollow cylinder. When the pin enters it the sides are splayed such that there is contact at only one point, not along the length of the pin as is the case with conventional septar sockets. So at high current the pins cook and you intermittently lose the connection. 
The choice of teflon for the substrate is strange. One really ought to have a material that dissociates electrical and thermal conductivity, so that the heat is transmitted from the pins to the chassis, e.g. aluminium nitride. 
02-15-2013 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 49
Post ID: 19005
Reply to: 18828
Delayed impressions
fiogf49gjkf0d
Strangely, no one but its architect has written here about the sound of the full range Melquiades, and so I thought I would say something with the benefit of several months of listening to a version of it. I say a version because though the circuit is executed essentially as in the original it is hard to know what impact incidental features of the implementation have. But then it is hard to know what impact other components of the system might have, etc, etc, we are familiar with the usual caveats.
I should also say I take it as axiomatic that playback is not a transcription of a recording but a translation; it is never the same as the original performance and it could be good for reasons that have nothing to do with the accuracy of the translation. The features of playback are correctly interpreted along the lines of the features of a musical instrument replaying the original. This means summary measures such as bandwidth, distortion, etc are neither here not there, just as they would be neither here not there if one used them to compare a Guarneri to a Stradivarius. The standard summary measures are in any event only helpful in relation to linear stationary signals, and of course what defines music is that it is aggressively non-stationary and non-linear. Nobody talks about summary measures for non-stationary signals because no such measures exist. So the objective/subjective debate in audio is mostly bullshit: we do not have adequate objective measures and never will, so the only thing that will ever matter is the quality of the subject giving you the subjective and only view anyone could possibly give. If none of this rings true to you, ignore the rest of what I say.
Now the most striking thing about the Melquiades is that it seems to handle music *intelligently*: responsively to its content. I have no idea why it should do this, but that is how it sounds. The aura of resonances that gives a musical instrument its distinctive essence is conveyed as if the pattern of distortion *adjusts* to match the pattern of resonance of the instrument itself. Someone might of course say that it is simply replicating the pattern in the input -- mere accuracy of transcription -- and it may be so, but given that amplifiers with (I would guess) substantially less distortion do not do this I suspect it is not the answer. In any event, the result is a very special capacity for tonal differentiation. It is most impressive with complex music, inevitably, for that is where tonal homogeneity is most palpably felt as a defect. And I suppose it is because that kind of music is rarely the target for an amplifier designer that we see it so rarely in the designs of others. 
02-18-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,535
Joined on 05-28-2004

Post #: 50
Post ID: 19019
Reply to: 19005
Melquiades attitude.
fiogf49gjkf0d
Thanks for comment, decoud. If you live with Melquiades for a while then you might discover that it will moderate your listening interests with time. I do not know what you are listening now but be if you spend substantial amount of time with Milq then you might find yourself to gravitate toward Wagner, Bruckner, Bach….


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-19-2013 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 51
Post ID: 19021
Reply to: 19019
Demand & architecture
fiogf49gjkf0d
It was the dismal failure of conventional playback to reproduce Wagner that first drew me in this direction; had I listened only to chamber music I might not have made the effort. Which is I suspect partly why other amplifiers are not like this: there is little evolutionary pressure for it. 
It is striking, is it not, that you rarely if ever see playback equipment endorsed by serious musicians? If that was the sensibility that mattered to the target audience that is what the advertising would be. 
02-19-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,535
Joined on 05-28-2004

Post #: 52
Post ID: 19022
Reply to: 19021
It is not only amplification…
fiogf49gjkf0d
The matter of serious musicians endorsing playback is a completely separate subject that has very little to do with audio. Regarding the amplification and large complex music – this is not only amplification. I wish I could have an amp that would do magic and would enable any playback to be able to play interestingly Wand’s crescendos and Lübeck’s harmonics. Unfortunately it is not only amplification but many other things in addition to amplification…
 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-19-2013 Post does not mapped to Knowledge Tree
miab
Canada
Posts 46
Joined on 02-07-2008

Post #: 53
Post ID: 19023
Reply to: 19023
Within the context of your system
fiogf49gjkf0d
Decoud,
 Would you mind giving some specifics of your system and room? Your observations should be considered within context. I personally have been interested in the Melquiades strengths and limitations and it is within a whole system that these observations might be most understood. Is there more you wish to share with us both positive and negative on the Melquiades?
02-21-2013 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 54
Post ID: 19033
Reply to: 19023
Multiplicities
fiogf49gjkf0d
Sure, I speak of amplification here because that is what we are talking about, but naturally playback is playback, not any of its elements taken alone.
I am not sure more detail about the entire system is helpful because no amount of detail is really detail enough when it comes to these things, except perhaps as grounds to dismiss an opinion altogether, but for what it is worth here it is. The amps are driving a pair of Danley SH-50s, suspended on wire a little above head height from the ceiling of a modest sized room. The source is unresampled digital files, fed from a custom-built linux server running on an industrial computer to an asynchronous reclocking USB to SPDIF converter and thereafter to a cheap balanced PCM1704-based DAC.  Volume control is done by custom-made TVCs. 
In theory, this setup ought not to work well. Although the SH-50s are 100db sensitive they are built with much more powerful amplification in mind and, I gather, have relatively complex cross-overs. So others might get a better result than I do. I have not identified any negatives referable to the amplifier. 
05-30-2013 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 55
Post ID: 19404
Reply to: 19033
Socket cosmesis
fiogf49gjkf0d
I know it is a trivial point, but I dislike the whiteness of valve sockets. Since neither teflon nor ceramic is easily painted I have mine covered in black nomex fabric. This is no good for the 6c33c, of course, as it needs all the breathing space it can get. Any other solutions, or does no-one give a fig?

nomexsockets.jpg
05-30-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,535
Joined on 05-28-2004

Post #: 56
Post ID: 19406
Reply to: 19404
Sockets cosmetics.
fiogf49gjkf0d
Interesting, in my amp the whiteness of the 6C33C sockets never bothered me. I think if it bother you then you might located the socket slightly below the top panel, this way you will not see them so easer. If you use ceramic base then ceramic is paintable. You might use silicone ceramic base high temperature paint, something like VHT FlameProof or Caswell coatings or alike. Be careful with spraying or brushing the socket as if you drop the paint into the pin-hole then you might say bye-bye to that socket.

Alternative option would be… to smoke the sockets. Close the pin-hole somehow and smoke the ceramic part of the sockets. You might use some kind of wick submerge info a baked of used-up durty engine oil that shall produce carbon black. That will be as black and it could be. Then you might spray it with any mat high-temperature polyurethane.

I think the negative impact of it will be that black sockets will absorb too much infrared from the tube and it will heat up the pins more than it has to be. I think 6C33C runs at 320 °C, I presume the sockets hit at the same but I will not be surprise if in black version then will go hotter. So, you need to be careful with soldering of the socket ping. Lead melts at around 330 °C and the combination of the materials the used for soldering frequently make the solder to melt much sooner sometimes as low as 200°C. So, make sure that you use a solder with high melting point or use welding.

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
05-30-2013 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 57
Post ID: 19407
Reply to: 19406
IR handling
fiogf49gjkf0d
Thanks, Romy: yes I was worried about infrared too. One option might be to use something like HEUCODUR IR Black paint, which is black in the visual spectrum but reflective in the near infra-red. I'll see if the company that makes it will send me a sample. 
06-11-2013 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 58
Post ID: 19477
Reply to: 19407
Electrocube 950 voltage variants
fiogf49gjkf0d
Romy, I imagine it is irrelevant but have you found a difference between lower and higher voltage versions of the Electocube 950 series in the coupling capacitor position in the full range Melq? I ask because a stock of 1000V has become available at an absurdly reasonable price.
06-11-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,535
Joined on 05-28-2004

Post #: 59
Post ID: 19479
Reply to: 19477
Milg's coupling capacitors.
fiogf49gjkf0d
 decoud wrote:
Romy, I imagine it is irrelevant but have you found a difference between lower and higher voltage versions of the Electocube 950 series in the coupling capacitor position in the full range Melq? I ask because a stock of 1000V has become available at an absurdly reasonable price.
Nope, I did not try the 1000V Electocube 950 caps. Theoretically the higher voltage caps would have more insulation between the turns and it might not be good but I have no practical experience with it. I would be a bit skeptical with using the “absurdly reasonable price” as a reason. For a full range you need juts two caps. Even if you pay $15 then how big deal would it be? BTW, sometime s, and muck more frequently then you think, some dealers get rid the stock on eBay and you can pick 2uF Electocube 950 for $2-$3 each. Feel free to use another good caps that you like. The multicaps by Rel are very good but it is hard to get 5uF with them. There are new Teflon caps from Germany that everyone like nowadays. I did not try them, you might…

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
06-11-2013 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 60
Post ID: 19481
Reply to: 19479
Market prices
fiogf49gjkf0d
Thanks, Romy, online dealers charge something like $50 per piece, which is ridiculous, so the objection is less to the price than to the rip off. These are 3 quid each. 
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  »  New  Melquiades For Dummies™ - step by step...  Risk...  Melquiades Amplifier  Forum     24  129066  08-29-2007
  »  New  Building Melquiades: Chronicle of full-range..  Variable Resistors...  Melquiades Amplifier  Forum     43  247001  06-09-2006
  »  New  Building Melquiades: questions and answers...  PeaceMAT XS™...  Melquiades Amplifier  Forum     96  303081  10-09-2007
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