[phkd]

Hi there amp guys.

I want to design and build a quality tube amplifier for my master's thesis. I have a bachelors degree in electrical engineering and have built some simple, solid-state headphone amps.

I want to step it up a bit and do a high quality tube amp now. What I am hoping to get from this community is basically anything you are willing to give me. Resources on how to design an amp with tubes, universal pointers aimed at preserving build and sound quality (things like isolate the power supply, don't run ground lines near signal lines, etc.), someone or some people to bounce ideas off of, quality component sellers, anything of that nature.

I really hope some of you guys can help me, I've seen pictures of some very impressive DIY tube amps, so I know the talent is around!

thanks in advance,
-Anthony

 

[tomb]

There's always a tube hybrid. Plenty of documentation here: DIYForums.org
and here: MAX

 

[phkd]

oh wow, a whole website forum for this sort of thing. thanks tomb!

 

[el_matt0]

hmmm..depending on your experience in DIY and your electrical background. you may want to check this out:
HeadWize - Project: All-Triode Direct-Drive Amps for Electrostatic and Electret Headphones by Kevin Gilmore
its going to be substantially harder than something like a MHMAX (and more dangerous if your not experienced working with tube voltages), but the end result im pretty sure would be that much more jaw dropping. this is in a totally separate league from what ive heard. and not to mention i hear it pairs up incredibly with a lot of stax's - wow their heads off for your thesis defence!

 

[phkd]

oh, headwize has a lot of stuff too! thanks so much guys. anything else?

 

[JadeEast]

Here is a nice page with lots of info.
Not so much a step by step how to but basic technical info.
Electronics 27
I believe the "bible" is the "The Radiotron Designer's Handbook".
The website http://www.tubecad.com/ is an amazing resource.

 

[Uncle Erik]

Quote:

Originally Posted by phkd /img/forum/go_quote.gif oh, headwize has a lot of stuff too! thanks so much guys. anything else?

Yes! Try here:

Pete Millett's DIY Audio pages

For books on designing and building tube gear, I recommend Beginner's Guide to Tube Audio Design and Audio Reality by Bruce Rozenblit. You can find his site here:

OTL DIY Vacuum Tube Amplifiers Stereo Preamplifiers High End Audio Kits

Two must-have books are these:

Amazon.com: Valve Amplifiers, Third Edition: Morgan Jones: Books

Amazon.com: Building Valve Amplifiers: Morgan Jones: Books

Both are excellent and do a great job of helping you design and build tube headphone amps.

Keep us updated on your project!

 

[phkd]

Wow, you guys are awesome.

Maybe I'll build a few extra, provided the first one works, and donate them to you guys!

Expect this thread to die for a while I do the research and acquire the parts, (since my thesis due date is a year from now), but I will revive it once I really get going and use it as a status thread.

 

[synaesthetic]

If you make a good design I'll buy one from you. =D

 

[phkd]

So I have been poking around and looking at various tube-amp schematics, I have found, according to most, that tube amps work best with higher-impedance headphones, as a general rule. Why is this? Are there exceptions?

I ask this because I was hoping to use my Alessandro MS-2's (and hopefully someday, the PS-1) with my amp. I mean, if something like the HD650 would be a better match with a tube amp, then that's just an excuse to buy another pair of headphone

But I really like the MS-2's, I was really hoping to use them.

Can anyone shed some light on this subject for me? I mean, I am quite experienced with building electronics, but am fairly unfamiliar with tubes and the theory behind them. ...I'm gonna go read the tube faq thread again, bye!

edit: found the answer to my own question.

And synaesthetic, what headphones do you have for home use?

 

[phkd]

Hello again, Well I am almost done with the design with my amp. I started it long ago and have been working on it on-and-off. I was hoping to get some specific help from anyone with the time and insight.

So my output is going to be a Cathode follower and I want to use an active current source load, but I am not really sure how to implement it. Actually, this idea was a suggestion from my advisor. I was going to use a purely resistive load, but as he told me, the is not very efficient and will be physically hot. He would not tell me, however, how to design a proper current source for my follower. I am going to include the output stage below and what I had for a load, can anyone out there help me design a current source to replace those 23k resistors? much thanks!!!

I forgot to draw it, but there is a ground obviously under the resistor network.

 

[boomana]

phkd, you might want to post this up in the DIY section of head-fi. There's a lot of knowledge and experience there, and not all those guys are looking in this forum.

 

[tomb]

Quote:

Originally Posted by boomana /img/forum/go_quote.gif phkd, you might want to post this up in the DIY section of head-fi. There's a lot of knowledge and experience there, and not all those guys are looking in this forum.

Yep - some of us look in occasionally, though.

phkd, what you've drawn doesn't look like such a hot design. The last thing in the world you'd want is a huge resistor network between the grounded cathode and ground. May I suggest that you start out with one of the many proven designs that we've already linked for you - rather than trying to design something on your own? There are so many things involved with trying to design your own that it's impossible to enumerate them. There's also a huge amount of knowledge to be gained by building a few of the already-prepared designs, first. This knowledge is not something that can be imparted easily - it's related to your own preferences and ideas that you make through discovery in assembling an amp.

Boomana is absolutely correct, though. You need to post your questions in the DIY section.

 

[Sherwood]

You're coming pretty close to your expected thesis due date, no? Hoping to graduate soon?

 

[phkd]

Quote:

Originally Posted by Sherwood /img/forum/go_quote.gif You're coming pretty close to your expected thesis due date, no? Hoping to graduate soon?

haha thanks, dad. I still have a few years to finish it, since I'm going part-time now.

I will check out the DIY section... I actually took that output from a design in the headwize library of projects. It was supposed to be more of a placeholder so I could do circuit analysis, but I am really stuck finding resources on designing a good current source for my CF.

And unfortunately I cannot build a design that already exists for this project because in this case it would be plagiarism. I have some background in electronics (a B.Eng + 2 years of EE work) but none in vacuum tubes. I didn't realize how much there was to designing a tube amp!

Oh well.