GoodSoundClub - Romy the Cat's Audio Site

Melquiades Amplifier
Topic: Mindless finger burning

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Posted by shannon on 12-27-2014

Delet if not proper topic. Was wanting to experiment with 6e5p driving lifeless speakers. with possible 100v swing i'm guessing way to much for regular garbage amps. What are peoples ideas for lowering output v (to like >5v?) with out destroying sound to much, besides all other problems with boring speakers and ss. All signiture features of melq must be kept(gas bias, 15k loading, 200v etc.) Is it not even possible?

Posted by Paul S on 12-28-2014
fiogf49gjkf0d Shannon, from your questions I "understand" that you want to drive lifeless speakers with a hybrid amp that features a 6E5P first stage. Is that what you want to do? What do and don't you like about your present set-up? What do you hope to change and/or gain? Best regards, Paul S

Posted by shannon on 12-28-2014
fiogf49gjkf0d You understand. that is what i want to do. This is not exactly for my present playback. I hope to gain more understanding the 6e5p. Also experiment with higher power Lf.

Posted by rowuk on 12-28-2014

The question is: why mess around with untried concepts before you try something that already has a track record. If the sound were not good would it be the driver, your output stage, the match of amp to speaker - or something else that you don't understand?
My idea is that if you even have to ask the question, you aren't ready for any answer. Romy has done an admirable job of describing what he has done and why as well as making it VERY clear that there is a process behind his system choices. An itchy trigger finger for a soldering iron was never part of his process. There is ALWAYS a reference to context when he does something.
If I were to build a SS Melquiades, the first iteration would have a simple "no gain" or very "low gain" MOSFET output stage just to lower impedance. I just don't know why I would want to.

Posted by shannon on 12-28-2014

I do not think that 6e5p driver stage withh ss could be useful for proper playback. or would it somehow be melq. I am familiar with the proven method. in the case of melq it should be followed 100% exactly. I am very greatfull for all the discoveries and philosaphy romy has provided. I try to follow his simple guidlines to good sound. I have no desire to change amplification on my playback, unless some day i fell dset would help.

Posted by Paul S on 12-28-2014

I am not the person to speak about the 6E5P but I have messed with hybrids. If you want LF power, I can say I've heard some pretty simple plate amps that "work" at LF. It would be helpful, and it might even be necessary for you to tell more about your situation and your ideas if you want to to get a conversation going. FWIW, there is already a thread about "high power SETs", if that would be of interest to you. I also recently read that the Ayon Titan has 1000V on its plate, puts out 75W, and I already wrote about the Nat SET/SS hybrid in a thread where I am looking for amps.

Best regards,
Paul S

Posted by Romy the Cat on 12-28-2014

Shannon,

I am not 100% sure what you are asking. If you want to drive SS with a single 5E6P stage then you have some difficulties. Dima had his version of SRPP with 5E6P to drive his SS and it "worked" very fine.

http://forum.vegalab.ru/showthread.php?t=36227

The same amp was eventually augmented with Milq-like bias for driver stage with very positive outcome. I have seen that some people used a transformer and a single gain 5E6P but I did not hear it.

Me

Posted by shannon on 12-28-2014
fiogf49gjkf0d I figured there would be difficulties. Thanks for the link, 117 pages of Russian, wow. Transformers came to mind. i did not know if such transformer could be made. 30:1? with wide bandwith. amorphous? I think i have ribbon mic transfo with ratio like that. and maybe i saw mc ones with high ratio.

Posted by Paul S on 12-28-2014
fiogf49gjkf0d Well, that's a mighty interesting hybrid! And talk about current! I'm going to look into that further, myself. BTW, yes, some MC SUTs are "like that'", but - obviously - they are "LV". Best regards, Paul S

Posted by Romy the Cat on 12-29-2014

I have very little familiarity with SS and with the need of the SS stage to be driven. If you want then talk to Dima directly or over the linked site, he is comfortable in English.

www.tornadoacoustics.ru/_fr/2/Zarathustra.doc

I would still employ the Milq gass bias but I would not go PP for the driver stage. Well, whatever I would do it less relevant, you can do whatever you want, the opportunities are there.

Posted by shannon on 01-29-2015
fiogf49gjkf0d Had a small amount of free time tonight. 150vac secondary, fred, 100uf, 500r, 1000uf, 30k, 5k, (like melq schema 4.4) no load voltage(b and c test point with no gas tube) 226.2vdc both lines. secondary is actually putting out 171.6 so 226.2 makes sense. wall ac is 118.9 right now.

Posted by Romy the Cat on 01-29-2015

Well, as a prototype it might work but as the Milq sound that I was implied the amp with no gas tubes in bias supply is not good in my view. I never was satisfied the way how a regular 6E5P driver 6C33C. To me it was very perfunctory and much unsophisticated. If I had this sound from Milq then I would never leave the Lamm ML2.0 realms. The whole interest I feel the amp gets with this grid bias and gas-tube-damped PS. BTW, you will have also substantially better in structure and deeper in extension bass if you go gas tube regulation in bias on 6E5P

Posted by shannon on 01-29-2015
fiogf49gjkf0d I will be fallowing the proper formula, except no chokes on gs tube supply and 30h on b+. I got that far and couldn't find the gas tubes. So untill later thats it.

Posted by shannon on 02-20-2015

couldnt get "insert iamge from gallary" to work so i attached it.
Had it working for a couple weeks. Single stage 6e5p testbed. The B+ rcore and output transformer is underneath. In the end r23 of 30k worked with 30h choke. no choke on gas tubes.

A question. There is a drift of +-10mv on the input. Do you think that is just my meter is not very good(it drifts on open air)? Is that a problem, it seems to work fine.

Posted by Romy the Cat on 02-20-2015

shannon wrote:
couldnt get "insert iamge from gallary" to work so i attached it. Had it working for a couple weeks. Single stage 6e5p testbed. The B+ rcore and output transformer is underneath. In the end r23 of 30k worked with 30h choke. no choke on gas tubes.

A question. There is a drift of +-10mv on the input. Do you think that is just my meter is not very good(it drifts on open air)? Is that a problem, it seems to work fine.

Good project. I never was able to get any good full range result from a single stage 6e5p, it was always too stiff sound to my taste but it might means nothing as there is infinite way to do it and you might do something different. It is also a gorgeous Cat, just super cute Cat, congratulations.

About the drift. This is very interesting. Are you sure that the drift does not come from the front end (preamps if you use it). Check it. If not then pull out the positive gas tube and run it only with negative tube while do not disconnect the connection cable to your preamp. See if you have drift then. If you do then trash the negative supply tube and use another one, if you do not then replace the positive gas tube. Make sure you load the tube with 15-25 mA. If you load the tubes too little they have stability problems and if you do too much then they do the same + they run hot to touch. Generally you shall not have any drift. I set the balance with +-1mA precision and it stay there for months and months. You might have 1-2mA per year, I never had more. Saying that I need to admit that a minor DC at input affects nothing but very small auditable click when you stitch the cable or in my case change volume (my preamp is DC coupled all the way though). If you have cap or transformer coupled front end or preamp then a few mA at amp input shall not be a problem, even though I would still trace the reason just because my anal retentiveness…

Rgs,
Romy the Cat

Posted by shannon on 02-21-2015

Bonkers says thanks for the compliments he is always been interested in audio pursuits. Been a while since he's had anything interesting to rub against. I wasnt paying enough attention. The gas tubes never made me feel the same way as Melquiades did to look at. I could stare at melqs gas tubes for a long time. These tubes the pink wasn't as nice or bright. I remeber a let down when i first fired it up.
Only less than 9ma before. Now over 22ma nice glow, to bright maybe. voltage drift gone.

Posted by Romy the Cat on 02-21-2015

shannon wrote:
Only less than 9ma before. Now over 22ma nice glow, to bright maybe. voltage drift gone.

I think you might have closer to 5mA before. I did see that with low load I had voltage drift. Interesting is that this effect only for 150V gas tube, the 105V gas tube are most stable at low currents for some reasons. As I said above at 15-25mA they do just fine. Feel free to play with tube rolling, particularly the negative supply tube – it will affect sound to a degree. BTW, I hate to say it but the best sounding tubes I found have the sexiest glow….

Posted by shannon on 03-04-2015

Had some fun experimenting with 6e5p driver stage.
playing with difrent output transformrs and resistors found that the stage can drive a speaker with ground connected to air. mabye this is widley know i did not know. + of speaker connected to bad output transformer - not connected to anything, sound coming out of speaker.
Main thing was 6n1p "buffer?" to lower input signal, then 6e5p stage connected to ss monoblock with 3uf 950b. sounded interesting enough to encourage me to build Zaratustrawith proper 6e5p set gassed driver stage.
Zaratustra what a beast that thing is. Is this the most powerfull fully pure class a amp in existance? i think maybe. This will take some time, something i have little of. side note: I dont think any high power, utra lf drivers, with proprer tone exist. bass array is still the only option.

Posted by Romy the Cat on 03-04-2015

It is not to mention that 6n1p is not very good sounding tube… It is interesting that you have built Zaratustra with gas driven 6e5p. I do not feel that it is “most powerful fully pure class A amp in existence”. Power is power and it is defiled the current you output stage can handle. I have AB version of Zaratustra for a while and I loved it, even though I do not know how to compare it to other amps out there. I kind of like the gas biased 6e5p sound and I feel that Zaratustra, even there it had SS output stage did have the similar type of sound as I appreciate in Milq. I think to say anything more definitive it would be necessary to render Zaratustra in good final version in pure class A1 of over 150W and let it to drive some truly great full range speaker of 95dB. Dima made for me a superbly interesting version of Zaratustra that might run from 100 to 350W in A1 and at the same time to be very small and compact package. It shamelessly sits in my basement, I have tone of the things to finish it up and another day then my life will be free from sleepless nights, crying babies and formula mixing I will make it to work… send you a picture of your Zaratustra, it would be very interesting to see it.

Rgs, Romy

Posted by shannon on 03-04-2015

My wording was bad. I am building zarathustra but am a long long way from completion. I do not have the capabilities to just whip one up.
Yes the 6n1p was from the old days when i thought i had discovered good sound, i'm sure i still don't know(but im happy). It and 6n2p are the start of the journey to finding your site.
I needed something to lower the sorce line level voltage. I was just using junk i had in storage to test the possibility of my idea. I should have read your site more. I would have found that, of course, you have already done hybrid 6e5p to the extreme.
Yes this 150 to 350w a1 version i read about in the vega lab. If not the most powerfull, very powerfull at any rate. And it can heat your house.
Its a massive project. You have a life and spectacular playback already. No shame in it sitting in your basement.

Posted by Romy the Cat on 03-04-2015

I told somewhere at the site about my idea of Zarathustra. The amp as good as it is but I want to make it super compact and with max efficiency. The efficiency I was considering to get by making the secondary of output stage switchable. I got from Pletrone a monster tutorial transformer with 6 taps from 45 to 105V if I am not mistaken as it was quite long time back. With 16 transistors per side it gave me up to 350W in A1. The while idea was how to dissipate that huge amount of heat on a very small chassis. So, I found a company that makes in-tube heat sinks. They use some special aluminum that has much higher thermal coactivity and they can make it any size and profile. I do not remember what I ordered but it was something like this:

http://www.fischerelektronik.de/web_fischer/en_GB/heatsinks/D04/Cooling%20aggregates%20with%20axial%20fan/PR/LA17_/index.xhtml

The transistors were sitting atop of 1” copper plate that is pressed to the heat sink pipe via mica sheet. The control board is a second layer and… their layer… The whole assembly is truly spectacular and the whole amp (with no PS) is leas then ½ cube foot. Dima did a very slick job with it.

I do need a powerful amps but it is only for my ULF channels. To run two super powerful amps to drive under 20Hz is a bit too rich. From another perspective if I do not do it then no one will and no one would know if under 20Hz amplification the A1 matters. The whole idea with the way how I envision the amp that I might easy to move the A class across the power range. So if my ULF towers need let say 120W then I can set the A/B conversion on the amp to let say 80W (lowering the ideal current) and be able to observe if there is any sonic difference.

I am a bit hesitant as Zarathustra is not DC amp. I know that Lamm use to publicly complained about LF and DC amp. I do agree with him: a straight DC power amp is a problem, at least among what I heard. However, I kill DC mode by cup-coupled line-level crossover and I do recognize much better result. I still do not take out of gave the concept of DC power amp. I think it might be not DC-coupling but the specific bad implementations that I dealt with. I use DC pre-amp that does superb job and I do not see any LF problem, so why I shall have it with power amp?

Posted by Paul S on 03-05-2015

Well, I remember being "astounded" years ago by Crown's "DC" amps' LF capabilities with an ever-widening range of LF "tasks". More recently, I was "impressed" by plate-amp-driven subs at THE show. I haven't gotten to ULF with my system yet, but I presently think it's more a matter of tailoring the amp to the speakers (and the room, of course). While I hold intellectually to the notion of "musicality", I have to admit that the plate amps "got the job done", with no apologies necessary. I do love SET for the "bass" part of Music; but it seems that things change as the frequency drops, At this point, I would not immediately over think or overspend on really low frequency amplification, because I am not at all sure it's necessary to do it, just as I'm pretty sure Class A/B would "work" at least as well as well as Class A in this situation, given equal attention to load matching.

Paul S

Posted by Romy the Cat on 03-05-2015

Yes, the modified Crown DC amps have been good candidates for ULF driving. They have the 1kW model that was great if you need to burn some power and to introduce negative output impedance to the ULF. It required a LF filtration however and the ULF was losing primary resonance in this setting…. I still do not know how good or bag it was be for relative terms, it is very hard to make concussions about relative quality of ULF in different rooms and with different installations.

Posted by shannon on 03-05-2015
fiogf49gjkf0d when talking ulf are we talking array of aura 18(the old ones not new junk), or something else

Posted by Romy the Cat on 03-06-2015

ULF is a consent not implementation. I did experimented ULF based upon aura 18 in past and now I have the line-array with 10” ScanSpeeks. The ULF is something that you should not be able to hear without rest of the system. With my current ULF when it up you will not be able to say that it is running. Sometime you will be able to hear that “some kind event” is going one but you won’t be able to associate it with anything harmonic.

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