GoodSoundClub - Romy the Cat's Audio Site

02-19-2013

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	51
Post ID:	19021
Reply to:	19019

Demand & architecture

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

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	52
Post ID:	19022
Reply to:	19021

It is not only amplification…

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

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miab
Canada
Posts 46
Joined on 02-07-2008

Post #:	53
Post ID:	19023
Reply to:	15612

Within the context of your system

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

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	54
Post ID:	19033
Reply to:	19023

Multiplicities

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

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	55
Post ID:	19404
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Socket cosmesis

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?

05-30-2013

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	56
Post ID:	19406
Reply to:	19404

Sockets cosmetics.

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

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	57
Post ID:	19407
Reply to:	19406

IR handling

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

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	58
Post ID:	19477
Reply to:	19407

Electrocube 950 voltage variants

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

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	59
Post ID:	19479
Reply to:	19477

Milg's coupling capacitors.

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

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	61
Post ID:	19482
Reply to:	19481

Oh, no!

It shall not be $50 per piece. You need to go to Electocube web site and they have a very good inventory find tool. It does shoe the actual inventory belong each of their retailer. Then call to retailer and ask the price, it will be about $5-12$ pre 2uF cap, depends how much they have in stock. Usual price was around $7. I have seen the situation that they have some odd 10-12 pieces left over from a large order and if I you get all of then they gave some sub $3 price. BTW, if you need juts 2 caps then tell to Electocube that you are building a prototype and they will send you 2-4 caps for free, juts a testing parts, if they have them in stock. Do not feel bad about it – you will not be abusing them: if you like the caps you will buy more from them. It is what I did. Do not buy any but 950. The 30 and the rest of them are very bad caps.

"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

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	62
Post ID:	19483
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International pricing?

Hm...it may have been that the retailers I found who shipped internationally overcharged: I must say I did not investigate in detail, but I know others have got similarly unreasonable quotes. The sample request is a good idea: I will do that.

07-21-2013

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DA
Posts 12
Joined on 04-10-2012

Post #:	63
Post ID:	19711
Reply to:	19483

Electrocube 950 ......

decoud , have you managed to find the Electrocube 950 2uF ? I ask because ,I have been trying for the last few months to find a pair,but with no luck.Nothing on EBay ,most retailers do not carry them or shipp internationally .So if you or anybody else have any information that may help or you have a pair of this caps that I can buy please post here or email me ( dandan9 at gmail.com ).

Anyway I'm 2-3weeks from finishing the Milq full range amps.when done I'll post the construction process .

Regards
Daniel

07-21-2013

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decoud
United Kingdom
Posts 247
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Post #:	64
Post ID:	19713
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Electrocube

Quest Components have cheap 0.68uF 950s in stock, which is what I am using (the SH50s I am driving need a high pass). I have not been able to find 2uF but have not tried Roman's idea of ringing up the factory: they should send you a couple for free without too much fuss.

11-19-2013

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	65
Post ID:	20270
Reply to:	19713

Troubleshooting full-range Melquiades

Hi Romy,
One my channels started emitting intermittent loud popping sounds, once every few minutes or so, and on inspection the current (set at 240mA) was in excess of 300 (my meters top out at 300). Assuming it is a tube problem I replaced the 6c33c, but I still get the occasional pop despite the current now being in range. It seems clear I need to check everything, and I was wondering what parameters would be key to examine here.
bw, d

11-19-2013

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	66
Post ID:	20271
Reply to:	20270

Debugging.

Hm, it is interesting. The loud popping pings in the lower MF and upper bass region are unmistakably signs of the 6C33C be gunner. Then you replaced the tube and the pings are still there. It is very highly unlikely. You might burn a cap that intermittently sorting but it is VERY unlikely. If the pings are in the frequency region that I said above then most likely that your new tube was defective or you accidently put the old tube back to the amp. Do not feel that I consider you an idiot – I did it a few times myself. When the tube is cold go figure which one is old. So, when I pull the old tube from amp I cool it doe and put immediately into trash. In your case your old tube might somehow find its way back to the amp.

If the pings that you have are at slightly higher frequency then you might have a corona in your output transformer. Some transformers are not properly varnished and even as low as 200V that Mils has might create some temp shorts between the turns with time. Take the tubes from the another amp that has no problems and if the amp still does the pinging then disconnect the OPT and plug in any other transformer. A regular power filaments transformer for 12V will do. It will give you an idea if the pings are still there. If not then contact the transformer maker – they shall replace it from free.

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

11-19-2013

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	67
Post ID:	20272
Reply to:	20271

Exploration

Many thanks, Romy; I was careful to put the old tube to one side, but it may be the new tube I put in was a defective one. I will explore with the tube from the other channel, which I know is fine.

11-25-2013

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

Post #:	69
Post ID:	20309
Reply to:	20308

The Odds on Tubes

decoud, as I have mentioned before, over the years I've always gotten about 25% bad ones of tubes from all sources, including those that were supposed to be hand picked, triple-tested, high-spec, precision-matched tubes that (of course) cost extra for all the assurances. I once had one each new driver and output tubes from a set that wound up bad at the same time in the same channel, and it took me some time to track down the problem, since it did not immediately occur to me that two new tubes could/would go bad at the same time that way. To top this, one of the two bad tubes was a new replacement for one of a "precision matched pair" I'd just exchanged because it had arrived DOA.

Best regards,
Paul S

11-26-2013

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	70
Post ID:	20315
Reply to:	20309

The lottery

Perhaps we expect too much of these things, from a different era, and very different context of application. And I imagine the cost of the EV version would exceed the 25% attrition rate of the regular versions.

11-26-2013

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	71
Post ID:	20317
Reply to:	20315

An accident.

You need to know that I consider Paul’s finding absolutely ridicules. The 6C33C are very reliable tubes with surprisingly low for Russian tubes defect rate. You juts was unlucky or most likely the person who sold to you your party of tubes sold you bad or used up tubes. The tubes from 196os were slightly better sonically but inferior mechanically. Stay with tube from 80s and you will be very rare seeing any problems.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

11-26-2013

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Paul S
San Diego, California, USA
Posts 2,657
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Post #:	72
Post ID:	20319
Reply to:	20317

Fail Safe

True enough, the 80s 6C33Cs had a much better percentage of acceptable tubes. Not so lucky with other tubes. The point, however, is that one should always try the tube before taking more drastic action, since tubes can and are known to fail in succession, in pairs, etc., ad nauseum. Another point is that tubes can fail regardless of seller assurances.

Paul S

03-23-2015

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decoud
United Kingdom
Posts 247
Joined on 03-01-2008

Post #:	73
Post ID:	21606
Reply to:	20319

Melq maintenance

Romy, now that there is more than one Melq in the wild, may we have some tips on your approach to maintenance, i.e. what parameters/tubes you generally check/replace and how often? I know the 6 channel version will be different, but there are nonetheless commonalities... For example, there has been talk about the output tube and the gas tubes, but less on the grounds for replacing the driver.

03-27-2015

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Romy the Cat

Boston, MA
Posts 10,156
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Post #:	74
Post ID:	21607
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No maintenance per se....

Hm, it is hard to say. The gas tubes last long time as I observe. I did change a few versions of them and the last that that I like last for many years. The output tubes are the ordinary suspect, I said a lot at the site about the life expectancy of 6C33C and how identify the candidate for replacement. The drivers are not very long lasting in my view. If you use the amp a few hours each day then I would change them one-twice a year. There is not a lot maintenance per se that I think this amp should have. Nowadays I a worry more not about maintenance for performance but rather a hypothetical possibility for the amps to explode for whatever reasons. I have a baby sleep right between the amps – so it is kind of a subject for me. Thankfully Milq is topologically is not the explodeable amp…

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-27-2015

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anthony
Posts 338
Joined on 08-18-2014

Post #:	75
Post ID:	21608
Reply to:	21607

Nice photo

I've seen snow from a distance whilst travelling abroad but never touched it. One day...

Romy, how do the YO-186's last? It would be nice to think that such an expensive tube lasts quite a long time. Have you had to replace them yet?

Regards,

Anthony

	Target	Threads for related reading	Most recent post in related threads	Forum	Replies	Views	Started
»	New	Melquiades For Dummies™ - step by step...	Amp still open...	Melquiades Amplifier Forum	28	213260	08-29-2007
»	New	Building Melquiades: Chronicle of full-range..	VR2 issue leading to jump in current on 6C33 tube...	Melquiades Amplifier Forum	44	432634	06-09-2006
»	New	Building Melquiades: questions and answers...	PeaceMAT XS™...	Melquiades Amplifier Forum	96	564247	10-09-2007

	Target	Threads for related reading	Most recent post in related threads	Forum	Replies	Views	Started
»	New	Melquiades For Dummies™ - step by step...	Amp still open...	Melquiades Amplifier Forum	28	213260	08-29-2007
»	New	Building Melquiades: Chronicle of full-range..	VR2 issue leading to jump in current on 6C33 tube...	Melquiades Amplifier Forum	44	432634	06-09-2006
»	New	Building Melquiades: questions and answers...	PeaceMAT XS™...	Melquiades Amplifier Forum	96	564247	10-09-2007