designing a new tube amp - Head-Fi: Covering Headphones, Earphones and Portable Audio

kheldar · #1 (**permalink**) 03-05-2003, 07:15 PM

Hi,

if someone wanted to design a new tube amp from scratch, is there anything in particular one needs to look for in the prospective tubes?

I was thinking of trying to build a 300b headphone amp, and I know the tubes are seriously over powered for most headphones, but are they a bad choice in that they are going to make my phones explode? or just overpriced for the little amount of power i need?

has anyone ever done a 300b headphone amp before? (diy i mean, i have seen the manley amp... evil... i want one )

clamchowder · #2 (**permalink**) 03-05-2003, 08:01 PM

WoW~~~~I don't think it's suitable stuff for the head-Amp.....
Not to mention, the cost you have to invest for the tube-price in order to build 300B....
There is several tubel-amp design on www.headwize.com/
namely: morgan J and Andrea!!!etc....think they are more suitable for the head Amps and ,of course, don't cost too much..

cheers
clamchowder

kheldar · #3 (**permalink**) 03-05-2003, 11:21 PM

That is definatly true, a pair of 300b's is quite expensive (i have seen no-name ones atarting at 75 or so a pair...) but if all you needed were a pair of tubes for the whole amp instead of 10 or 12 like some of the other amps to get the power, and the fact that there are a number of high quality good sounding 300's out there.

I guess the question i should ask is, other then insanity, is there any reason i couldn't do this?

clamchowder · #4 (**permalink**) 03-05-2003, 11:36 PM

Nope!!!.....
but every 300B I've seen so far, was power Amps that run the couple of speakers w/ high dB.....So If you thinking about hookingup the headphone on it. I think you have to recal. every current values and choose parts for it...from the scrap?......and due to the 300B working spec. I'm not even sure this will work!!!.....probably not!!

cheers
clamchowder

KTpG · #5 (**permalink**) 03-06-2003, 01:19 AM

I shall borrow your thread for a sec...

I have four 6L6GC's laying around... would it be plausible to incorporate them into a headphone amp?

clamchowder · #6 (**permalink**) 03-06-2003, 02:01 AM

Quote:

Originally posted by KTpG
I shall borrow your thread for a sec...

I have four 6L6GC's laying around... would it be plausible to incorporate them into a headphone amp?

It's a push pull 25~30 Watt Tubes, So considering it's working voltage range,as I mentioned above, I don't think we can get it to integrate into the Headphone Amps. headphone amp is sorta preamp w/ headphone out jack on it.....^^
And there is headphone that requires power Amp. namely: K1000.
but most of cans work w/ preamp Spec.

cheers
clamchowder

kheldar · #7 (**permalink**) 03-06-2003, 02:13 AM

but that is just the maximum (or at least normal) configuration. What if you made a low gain amp configureation to use those tubes? I know most of the headhone tubes that are ideal are extremely low power, but also low microphonics, and low distortion.

clamchowder · #8 (**permalink**) 03-06-2003, 02:33 AM

Sorry!!! dear~~I haven't tried it down to the headphone Amp ranges since I'm not that optimistic on that tuning... But maybe if you post a question to the "headwize" ,I think you can get some empirical answers hopefully w/ data or schem.... I hope......

cheers
clamchowder

Joe Lau · #9 (**permalink**) 03-06-2003, 08:16 AM

Yes ! It is possible to made a 300B Headphone amps if you don't care the price and you need more technique to solve the Hum problem. Direct Heat tube is more sensitive to Hum. I had use 2A3 to build Headphone amps and it need a very clean power supplier on plate and even Filament supply should be clean.

aeberbach · #10 (**permalink**) 03-06-2003, 08:49 AM

The Morgan Jones tube amp book, "Valve Amplifiers" is really worth buying. I don't think it would be a good idea to use 300B or 2A3 because as others have mentioned you need expensive tubes, but also you need expensive transformers for the output, and you will almost certainly not be able to use either of these alone - you need a tube to amplify the signal so that it is suitable to drive those output tubes. This book also covers OTL designs, helping you to eliminate transformers if you want (but they're not nearly so expensive if you're not using 2A3/300B).

The 300B tubes are awesome driving K1000s though. I have Welborne labs monoblocks, and the ASL 300B amps are recommended by Headroom. None of us at the recent Grado labs meet in NY were unimpressed by the Carey. If you have to start with 300B why not get a Consonance "Billie" or similar kit to modify? You'd probably never get the parts together yourself for less money. A n0rh se9 might be a good chassis to start bashing on too.

There is a schematic up on the Welborne Labs page under newsletter->pipeline showing an ultra-simple 6GM8/ECC86 amp design - simple as long as you throw out the battery power supply that is. As Ron says on his page, they're surprisingly cheap tubes.

clamchowder · #11 (**permalink**) 03-06-2003, 12:53 PM

Yeah~~~300B was one of best Amps I've ever tried on k1000...
Even though it takes about 2 hours of warming up time to sound really great(major reason I turn to TR), It's one of my best pick yet. And I truly love to see someone try tuning 300b to down to the headamps, and settingup and prviding the gudeline of best tuning values and parts specs, for the fellow tube lovers.

cheers
clamchowder

kheldar · #12 (**permalink**) 03-06-2003, 01:19 PM

Aebebach, is that book still in print? I was looking for some tube books at the book store the other day and didn't see anything.

Mr. Lau, thanks for the info. Is there an insane 300b version of the MG-Head coming soon? that would be realy cool =)

What software do most people use to create tube amps with?

Hirsch · #13 (**permalink**) 03-06-2003, 02:38 PM

One of my favorite amps for headphones is the Fisher 400 receiver, which throws 20+ watts from the speaker output straight at the headphone jack through an attenuating resistor. The sound is excellent. If it could be done in the 60's, I suspect it can be done now.

clamchowder · #14 (**permalink**) 03-06-2003, 03:30 PM

I fully agree~~fisher 400 is one of kind.
but if you gonna DIY that thing it'll cost probably several thousands....and more... Not to mention All about tuning you have to go through...till you get a decent sound like original fisher 400,and even original needs a great amount of tuning for better sounds. Beside Im'm not sure it's 300B and It's got a nice phone stage inside to drive headphone.....anyway it's really o.k. for me!!

cheers
clamchowder

aeberbach · #15 (**permalink**) 03-07-2003, 01:00 AM

You should still be able to find "Valve Amplifiers". It's out of print on Amazon but I would try Angela and other hobbyists places.