I am sick of failing amplifiers

Jono · May 31, 2020

I have used a Supratek Cabernet 300B preamp for 12 years with zero problems other than having to change the odd rectifier.And yet some people complain about these having messy wiring because they use shortest path hardwiring.It is the amps with neatly bundled together wiring and printed circuit boards [in combination with tubes] that seem to be more likely to give trouble.
Also for power amps another Bakoon convert here.They have the essence of a really good SET sound without the apparent problems.

I think the ultimate products for build quality,reliability and parts and service backup is Accuphase.

jazdoc · May 31, 2020

Hey Rex,
Just catching up on this thread. Sorry for all the troubles. You’ve got an open invitation to listen to the Found Music amps over here.

Kingrex · May 31, 2020

jazdoc said:
Hey Rex,
Just catching up on this thread. Sorry for all the troubles. You’ve got an open invitation to listen to the Found Music amps over here.

Thanks. Would love too. I should have bought Scott's copper version. I just wanted to try SET. I'm going to send mine to Audion to be updated. The distributor is pretty proud of the amp. He thinks an old amp like mine can be improved upon. Brought up to snuff. I believe he is right. Lesson learned, get serial numbers and find out what your really getting before you buy used.

Atmasphere · Jun 1, 2020

Hear Here said:
That's no good if the SET uses 45, PX-25, 300B etc as their output valve. 20% of 4-8 watts is 0.8 to 1.6 watts output. How many speakers will be able to offer volume satisfaction to their listeners with that sort of power? When I used PX-25 to power my 102 dB speakers they had to work at far more than 20% much of the time - but they did sound divine!

Peter

If your speakers are 102dB, depending on the size of your room almost any of the amps you listed would probably do the job. 102dB is pretty loud and you have 2 channels of that and only needing a watt to do it; obviously the type 45 is challenged, but to be fair, the type 45 tube is best used with headphones, and was originally built when headphones and some pretty crazy looking horns were the only way you could listen to your Atwater-Kent. The main reason the lower powered SETs sound better otherwise is bandwidth- you can get bandwidth that goes from less than 20Hz to well past 50KHz, which is next to impossible with higher powered SETs. Bandwidth is important to prevent phase shift, which affects the soundstage and the tonality of the amplifier, even though the amp might measure flat in the area of the tonality affected.

Its the bandwidth thing and the lack of a speaker with enough efficiency that prevents most people from having any idea of what their SETs actually do. This is part of why I think OTLs are a better approach- you can still use triodes, you get more power, more bandwidth, lower distortion without sacrificing the good bits that SETs do- so they are practical on a wider range of speakers.

analogsa · Jun 1, 2020

Atmasphere said:
The main reason the lower powered SETs sound better otherwise is bandwidth- you can get bandwidth that goes from less than 20Hz to well past 50KHz, which is next to impossible with higher powered SETs.

You make it look like an issue with the triodes, while they would happily amplify from zero to many MHz. The 10k and 20k transformers otoh...not everyone can wind.

Atmasphere · Jun 1, 2020

analogsa said:
You make it look like an issue with the triodes, while they would happily amplify from zero to many MHz. The 10k and 20k transformers otoh...not everyone can wind.

Yes, the triodes are very wide bandwidth- the output transformers aren't. And the bigger you make the transformer- the more limited its bandwidth. This is true of push-pull amps too, but to a much lessor degree- to give you an idea, a 60 watt P-P amp can have bandwidth out to 100KHz, while a 7 or 8 watt SET has troubles getting past 20KHz unless its rolled off a bit on the bottom.

Kingrex · Jun 12, 2020

A bit of good news. I got my Casablanca back from repair. It is the kt88/el34 amp that was noisy as can be. I'm shocked at how fixing internal grounding issues and a little circuit rework can knock noise down so dramatically. These amps are very quiet now. When I first turned them on and biased them, I was thinking something may be wrong as there was no noise from the speakers. When I finally put a file through HQ Player, music started to play. I now have one solid amp back in play.

Empirical Audio · Jun 12, 2020

Kingrex said:
A bit of good news. I got my Casablanca back from repair. It is the kt88/el34 amp that was noisy as can be. I'm shocked at how fixing internal grounding issues and a little circuit rework can knock noise down so dramatically. These amps are very quiet now. When I first turned them on and biased them, I was thinking something may be wrong as there was no noise from the speakers. When I finally put a file through HQ Player, music started to play. I now have one solid amp back in play.

Have you ever tried the Genalex KT-66 to replace the EL-34's? These NOS tubes are excellent and last a long time. English-made, most from the 60's. You can find them on ebay usually. I would avoid the modern versions.

Kingrex · Jun 12, 2020

Empirical Audio said:
Have you ever tried the Genalex KT-66 to replace the EL-34's? These NOS tubes are excellent and last a long time. English-made, most from the 60's. You can find them on ebay usually. I would avoid the modern versions.

I have some NOS JAN Phillips 6CA7 . I should try them again. If If I remember, they are a little soft and I like the kt88 punch.

Kingrex · Jun 13, 2020

I had my new repaired amps on. I was sitting in the next room with music on in the background. I was posting about amps. Then I hear a pretty loud POP. I run in the room. I'm looking at tubes to see if one is dead. I'm leaning into an amp and another loud POP. I jump, my dog runs. I then laugh and lean the stack of records back up that had flopped over on my floor.

Empirical Audio · Jun 13, 2020

Kingrex said:
I have some NOS JAN Phillips 6CA7 . I should try them again. If If I remember, they are a little soft and I like the kt88 punch.

These replace the EL-34's not the KT-88's.

Kingrex · Jun 13, 2020

Empirical Audio said:
These replace the EL-34's not the KT-88's.

Not sure what you mean. Via the bios I can use either kt88 or el34 or derivative of them

Empirical Audio · Jun 13, 2020

Kingrex said:
Not sure what you mean. Via the bios I can use either kt88 or el34 or derivative of them

I thought your amps had both EL-34 and KT-88. EL-34 is sometimes used as a driving tube to the output tube.

Kingrex · Jun 13, 2020

Empirical Audio said:
I thought your amps had both EL-34 and KT-88. EL-34 is sometimes used as a driving tube to the output tube.

Kingrex · Jun 13, 2020

Kingrex said:
View attachment 66202

12ax7 to 6sn7 to power tube. Power tube is el34 to kt88

Empirical Audio · Jun 13, 2020

Kingrex said:
12ax7 to 6sn7 to power tube. Power tube is el34 to kt88

Got it. Have you tried a Russian 1578 for the 6SN7? Best tube out there. See:

https://www.whatsbestforum.com/threads/shootout-of-nos-6sn7-tubes.30637/page-5#post-654704

I've been using 6H8C Russian military tubes for years and find the 70's and 80's 1578 version to be the best. Available on ebay from Russian and Ukranians.

Kingrex · Jun 13, 2020

Empirical Audio said:
Got it. Have you tried a Russian 1578 for the 6SN7? Best tube out there. See:

https://www.whatsbestforum.com/threads/shootout-of-nos-6sn7-tubes.30637/page-5#post-654704

I've been using 6H8C Russian military tubes for years and find the 70's and 80's 1578 version to be the best. Available on ebay from Russian and Ukranians.

I will look those up. The driver does not impact sound much in this amp. The tech who made it sold me a Bomb set of Siemens input tubes. I have tried 4 different power tubes. Im actually starting to enjoy this amp more and more. Its not as pure and real as the Black Shadow. But its veil and shadow actually help to blend the horn and woofers. Its a bit softer and less real, but easy to listen too.

Atmasphere · Jun 15, 2020

@Kingrex glad to hear they are working out. One of the changes we did should have had the amp sounding more transparent. Are you finding that to be the case?

Kingrex · Jun 15, 2020

Hello Ralph, The amps are playing excellent, thank you. They are super quiet. They are very clean and as clear as I remember. To be fair, I had them out of my system for a few weeks with another set in. Its hard to remember what is what. Pulling a pair of SET monoblocks out and putting the KT88 push pull back in, you hear what SET does. It took a few days but now I am starting to really like these amps again. The EICO circuit is what it is. Its decent. These amps do have inherent veil and softening of the sound. But, oddly this is working good with my speakers. I voiced my speakers with these amps. The speakers are a little forward. The SET was a little aggressive in that sense. I could hear the horn standing apart from the woofers. With the amps you repaired back in, the blend of drivers is much better. Its a more relaxed and easy system to listen too.

Here's a funny story. I'm sitting typing with music in the background. I hear a big POP. I jump up thinking I have a tube failing. I look at one amp. I go over to the other. I'm bent over looking at the tubes and another big POP. I jump, my dog panics. I then calmly go and lean the pile of records back up that had flopped on the the floor. Hahaaa on me!!!

Thanks again for your help. You all were very prompt. You honed in on the issues and completely mitigated them. You turned a set of amps I was thinking of throwing into the trash into a nice well playing product again. I highly recommend Atmasphere repair services to anyone who needs help.

Kingrex · Jun 15, 2020

Well, the Black Shadow are in the mail to be repaired. True Audiophile, the importer has had a field day of laughs over me. You paid what, those tubes are garbage, those amps are so old they needs a total overhaul. I feel the fool but hey, every crowd has one. Not sure why I didn't just dump them for a fair price and take the loss. In order to get them to spec I will be into them for more than a new set.

If I learned anything, when you buy a used amp, demand the serial number and ensure you know what you are getting. I took forum chatter from the seller and extrapolated what I thought was truth. The serial numbers told a different story. Had I asked I would have known more.

I hope these amps turn out. True Audiophile says they are one of the best amps Audion makes. Just the version I got are so far behind the curve. This transaction is really making me question ever buying anything used again. Who knows what trash your getting. Who had had their hands in. What did they do. Did they abuse it. Has it had non factory tech messing with it. I was going to get a used SS amp but I'm now thinking no. Buying used is a bad idea. Most everything I got new has been a blessing. Accept for the Casablanca. The used stuff has not been the success I hoped for. Well, my PAP Trio 15 have worked out. But I don't have factory support.. And the owner forum is on Facebook. I won't touch that site. I don't even use Prime at Whole Foods. I have an account for work, but I won't give them my phone. Have you read the small print.

I will throw a glimmer of hope. When I did have the Black Shadow in, I did note they were producing the most pure and natural violins and horns my system has reproduced yet. There were blend issues with my speakers. And whistling microphonics, I believe mostly from the failing capacitors. I guess that is the real reason I sent them to be upgraded. I think the base product and circuit has the potential to be a fantastic amp. And I think the guys at True Audiophile are excellent backers of the product.

I am sick of failing amplifiers

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