OT: Show us your DIY tube amps

**alancohen** · May 15th, 2013, 05:59 PM

Originally Posted by Altec Best

Thanks Alan for the offer !

I'll even sweeten it: I'll bring 'em to you so you can compare on your speakers and front end. You'll have to make the coffee though.

**gortnipper** · May 15th, 2013, 06:40 PM

Originally Posted by tinpan

Here's my one of Audio Note Interstage Mono Blocks. It's 300b tubes in parallel.

How do you like these? I was very interested in these a while back, but they were a bit to pricey for me at the time and I ended up going down another road when I got a killer cheap deal on a very nicely built up Sun Audio 2A3SE amp.

I have three DIY SET amps that were built by a friend of mine who recently passed away. He was a prolific DIYer and these were his pride and joys. I bought two of them from him prior to his passing, and the third was gifted to me by him in exchange for liquidating his audio related estate when he was terminally ill.

The first is a set of 5842/45 monos in solid copper chassis. They were built around the basic Monkey design, as interpreted by Thorsten Loesch - Calculating DC coupled Single Ended Valve Amplifiers - Part #1 - Page 2 - diyAudio. These are very, very nice sounding.

The red one is a E180F/300B design based on this schematic AudioRoundTable.com: Group Build => SE 300B Project, Part 11 - The Amplifier Schematic These are very clean, but slightly rolled off on the top ? but I know the problem here and simply have to change out a variable R pot for a fixed R.

The green one is a 12HG7/845 based on a low-voltage implementation designed for the GM70 and adapted by Ken for the 845 to run at 750v on the plate. 8-10w clean output + ~15w headroom - How to Make a Transmitter Class Amp

I am just starting down the road of biamping my GPA-IIIs, and have a hot-rodded Rane AC23 ? replaced all the ICs with better quality and the ?? jacks with RCAs. Should be interesting.

**gortnipper** · May 15th, 2013, 11:31 PM

Originally Posted by Altec Best

I have a question for you guys.What do you think are the best sounding Tubes for you die hard tube guys. KT88's

I try not to buy used power tubes, since the "NOS" ones can be very pricey with very few of them truly New Old Stock - especially with DHTs.

I have had a couple of KT88 amps, and used a fair few 6550s in there as well. The 60s Tung Sol 6550s were very nice, but pricey. Penta tubes (a reseller that did a lot of QC on Shuggie tubes) were very nice, but you cant get them anymore. But, I think the best option now is the Golden Lion reissue KT88s.

Jim McShane is a highly reputable seller, is a joy to do business with, and is into restoring old Citation amps as well.

Tube & Information Page

**RonSSS** · May 16th, 2013, 10:28 AM

I have been using Svetlana 300B's, but the quality is rather poor, they can't be found, and I'm down to my last 4. Will have to find replacements. Ugh. Or convert to 6550/KT88 in Triode mode.
I run the things rather hard.
I have 10 or so Tung Sol 6550 (used) and about the same of the GE (NOS) although in my Citation, I liked the Tung Sol better.
Haven't visited McShanes page forever, so thanks for the link!

Ron

**tinpan** · May 16th, 2013, 11:07 AM

I absolutely love the Interstage Monoblocks. I am saving to buy another pair to drive my A4's

**alancohen** · May 16th, 2013, 12:03 PM

Originally Posted by tinpan

I absolutely love the Interstage Monoblocks. I am saving to buy another pair to drive my A4's

Is that really $4500 for the kit!? Why?

**gortnipper** · May 16th, 2013, 05:02 PM

Originally Posted by RonSSS

I have been using Svetlana 300B's, but the quality is rather poor, they can't be found, and I'm down to my last 4. Will have to find replacements. Ugh. Or convert to 6550/KT88 in Triode mode.
I run the things rather hard.
I have 10 or so Tung Sol 6550 (used) and about the same of the GE (NOS) although in my Citation, I liked the Tung Sol better.
Haven't visited McShanes page forever, so thanks for the link!

Ron

Youre welcome!

The Svetlana's are not that great, I have a pair and I am not impressed with them at all. Nor am I with the bog-standard Chinese ones. I think JJ (got a pair with the red amp) and TJ meshies are the good, albeit slightly pricier priced options. I am very impressed with my EML 2A3 tubes (nice birthday pressie!), and I am sure their 300B are great as well, but they are very expensive.

**analog addict** · May 16th, 2013, 06:13 PM

Originally Posted by alancohen

As far as "replacing tubes all the time", again, it depends on the circuit. A well designed amp should be able to provide many years of service for the tubes. Reliability is job #1 for an amp designer.

I'd actually beg to differ on that one, at least for the designer I know. Dennis Had could care less if your tubes last 2000 hours or 10,000 hours. He designs amps with performance in mind. It's all about the power and the sound. I have a early prototype 6BQ5 amp built out of a modded Zenith, and he runs the 6BQ5s hard enough that some of my tubes will exhibit a faint orange glow on the plates. It's a bit disconcerning the first time you notice it, and that amp will quickly sort out which of your tubes are good and not so good. I just got it back from him after a tune up, and he said that it's putting out about 8 WPC, which is huge for a single ended 6BQ5.

Anyway, as far as tubes, I prefer the smaller triodes, such as 2A3s and 45s for their oh so sweet sound, and 6BQ5s for a SEP design. Dennis also has a new 807 based amp which I will eventually have an example of, and he raves about that one a lot....

**gortnipper** · May 16th, 2013, 07:49 PM

Originally Posted by analog addict

I'd actually beg to differ on that one, at least for the designer I know. Dennis Had could care less if your tubes last 2000 hours or 10,000 hours. He designs amps with performance in mind. It's all about the power and the sound. I have a early prototype 6BQ5 amp built out of a modded Zenith, and he runs the 6BQ5s hard enough that some of my tubes will exhibit a faint orange glow on the plates. It's a bit disconcerning the first time you notice it, and that amp will quickly sort out which of your tubes are good and not so good. I just got it back from him after a tune up, and he said that it's putting out about 8 WPC, which is huge for a single ended 6BQ5.

I have had Cary amps and a Cary pre, and I have known a few good techs that have worked on Cary gear. I liked them, but you are right, Dennis' designs do not respect the tubes very well and they do burn through them - regardless if how good they are.

A very well respected local tech I use when stuff gets over our heads actually called said his amps' design that he worked on "did some questionable and dirty things" (like just simply reducing the bias point in "standby" mode).

**alancohen** · May 16th, 2013, 10:25 PM

Originally Posted by analog addict

I'd actually beg to differ on that one, at least for the designer I know. Dennis Had could care less if your tubes last 2000 hours or 10,000 hours. He designs amps with performance in mind. It's all about the power and the sound.

I guess different strokes for different folks. I can't think of any successful amplifier designer/manufacturer that would include in their marketing literature the phrase, "We could care less if your tubes last 2000 hours or 10,000 hours."

Reliability in any piece of equipment is not the main thing, it's everything. Personally, I would never buy an amplifier where I had to worry about tubes frying every time I turn it on. And I really can't see how pushing a tube to its limits enhances anything. It might boost a little power, but it can't improve its sonic characteristics. I find it hard to believe you have to sacrifice reliability to gain performance.