[terriblepaulz]

I am lucky to have recently done business with a guy who learned I was into headphones (we both own 325s). He is a retired engineer, gearhead, DIY guy etc. He's into vintage electronics, esp. tube gear. About 3 months ago he dropped off a tube amp that he had quickly thrown together from some stuff in his workshop. He admitted it hummed. It did. He told me he would solve the problem by building another amp using better stuff (apparently he collects a lot of vintage electronics). He also asked me a bunch of questions for specs.

A few days ago he dropped off the new iteration. He told me the design is based on one by Eric Barbour from an old issue of Vacuum Tube Valley Magazine. It has a gain stage using two 6SN7s (in this case matched NOS GEs w/ side getters), and a single 6BX7 for output (NOS Sylvania tall bottle). There are 2 5W output transformers, presumably for the speaker binding posts he installed (for a future upgrade of the office system). He put a 24 step volume pot, and a 4 step gain switch (actually an attenuator on the gain stage, set at -30db, -20db, -10db, and 0). He also dropped off some schematics which I don't understand.

I took some pics which I hope to post soon. The guts look a little inelegant but efficient. I really have no idea of the quality of the parts or their implementation, and I am not quite sure I can appreciate what I have here, but I am having a blast. This amp is significantly quieter than the first, but there are still two noise floor issues. There is a hum (impercebtible with the Beyers, barely perceptible with the Grados, and only slightly more so with Vibes). There is also a hiss, but only perceptible at the highest gain setting at max volume with the Grados.

I have not started tube rolling yet (he dropped of a small sample of NOS tubes from his collection), but look forward to exploring. I am pretty sure what I am enjoying so much is the "tubey" sound of this amp. Any comments from the peanut gallery? I know - pics pics pics. I'll get to it.

http://picasaweb.google.com/lh/photo...eat=directlink

http://picasaweb.google.com/lh/photo...eat=directlink

http://picasaweb.google.com/lh/photo...eat=directlink

http://picasaweb.google.com/lh/photo...eat=directlink

 

[elrod-tom]

Wow...you have great friends!

Can't wait to see the pics...

 

[krmathis]

Sure looks like a clean build. Nice!
Great friend!

 

[apatN]

Aw I envy you. Such a nice friend and he did a wonderful job as the unit looks clean.

 

[compuryan]

If a tube amp fell on my lap I think I'd be in pain. But hey, it looks great. Congratulations!

 

[elrod-tom]

Nice...I dunno what you mean about the insides though. I don't want to mention any names of any manufacturers, but it looks a lot better than some stuff that I've seen that's pretty highly regarded.

Nice work...you have a nice friend.

 

[Kees]

Congratulations!
That's a nice amp.
A bit more than nice even, as far as I can see.
He's done this before.

 

[mrarroyo]

That is a great looking amp, I hope you get many hours of enjoyment out of it. BTW, I just placed a couple of pillows on my lap in case you want to drop the amp on me lap!

 

[terriblepaulz]

Quote:

Originally Posted by elrod-tom /img/forum/go_quote.gif Nice...I dunno what you mean about the insides though. I don't want to mention any names of any manufacturers, but it looks a lot better than some stuff that I've seen that's pretty highly regarded. Nice work...you have a nice friend.

I was being cautious. The only "inelegant" thing is the dabs of bluish cement or putty. I am blown away so far by the sound of this amp with all my cans (even Portapros

).

Quote:

Originally Posted by Kees /img/forum/go_quote.gif Congratulations! That's a nice amp. A bit more than nice even, as far as I can see. He's done this before.

Yeah, I am beginning to get that feeling. My guy has a great affection for all things vintage electronics.

Some questions to the tube-heads:

Are there any other amps or designs that use a similar tube configuration?

Any 6SN7 recommendations?

My guy gave me a 6BL7 to roll for the output. What should I expect in contrast to the 6BX7? Any recommendations for either of these tubes?

 

[les_garten]

Is the house next door for sale?

 

[terriblepaulz]

Quote:

Originally Posted by les_garten /img/forum/go_quote.gif Is the house next door for sale?

?

 

[les_garten]

Quote:

Originally Posted by terriblepaulz /img/forum/go_quote.gif ?

Anybody who lives in a neighborhood where free amps are raining down, is living in a neighborhood where I want to live!

 

[bikeboy999]

Quote:

Originally Posted by les_garten /img/forum/go_quote.gif Anybody who lives in a neighborhood where free amps are raining down, is living in a neighborhood where I want to live!

As the owner of a 15 ft Grado extension cord. My thoughts that you were go to gang a few together and run them through window to "borrow" the amp! Ha Ha.


B

 

[Uncle Erik]

That's a nice-looking amp! Have you hooked a pair of speakers to it yet?

Innards look good, too. All point-to-point and cleanly built.

If you like Barbour's amps, there are plans for an OTL headphone amp by him over at Headwize.

As for tuberolling, well, if you like the sound why change? There are differences between tubes, but it's more like ordering the same meal at a restaurant a few weeks apart. Never quite the same twice, but you can enjoy it every time. I keep tubes around mostly as spares - I prefer to add music or different headphones to hunting NOS rarities.

 

[les_garten]

Quote:

Originally Posted by bikeboy999 /img/forum/go_quote.gif As the owner of a 15 ft Grado extension cord. My thoughts that you were go to gang a few together and run them through window to "borrow" the amp! Ha Ha. B

Believe me, once I moved in....

I wonder if he has Cable TV?