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Old 4th July 2010, 08:27 PM   #1
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Default Best Possible Tube Headphone Amp

Hello All,

I have a pair of 880dt Beyers that I rewired and have measured at 275 Ohms. I have built many solid state amps in order to drive my phones. They have all been portable amps and are thus not the BEST possible sound I can get. I have settled on tube amps as the way to get the musical bliss that we are all seeking (please correct me if this information is not correct). I have plenty of experience with electronics and have been building Tesla Coils for years (so the high voltages of tubes aren't gonna phase me), but Tubes are a new frontier for me. So I please ask for your patience and understanding.

With all of that said - Here is what I want to achieve.

I want to build the best possible headphone amplifier and I'm willing to pay for it. I do not want to compromise any parts. (however, if one part is gonna run me $600 and there is a $120 version that is REALLY REALLY close to being as sexy - please let me know). Otherwise I'm looking for the wisdom and experience that you guys can offer.

Please don't hold back.


Graham
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Old 4th July 2010, 09:51 PM   #2
Gluca is offline Gluca  Italy
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Graham

this is my take on headphone amp for BD. I own and enjoy a DT990 (600ohm) but you can use this amp to drive the lower impedance of yours

Click the image to open in full size.

the output autoformer is not available but you can replace it with a parafeed 10k:600ohm. I don't know how much gain you need, let me know ... I'll try to comment on that. The 1k resistor sets the operating points for both the tube so you'll need to tweak it a bit.

PSU is pretty simple: full wave into LC filter. No need for more as the CCS is taking care of the noise. Tubes a re all cheap, CCS is cheap, loading L and OPT are not. I'd say you need a 500$ budget in parts.

Gianluca
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Old 4th July 2010, 10:32 PM   #3
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I don't know if it's the best possible, but it is a circuit that I made a long time ago that I thought sounded pretty good. I've never seen it before, and maybe that's because it sucks... But I was dumb enough to build it and listen to it.

Sheldon


Click the image to open in full size.

Click the image to open in full size.
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Old 4th July 2010, 10:33 PM   #4
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Hello,
Tubes are nice. OpAmps with a BUF634 output are nice and a lot cheaper.
My first tube headphone amplifier was a bootleg Mapletree Audio EAR. Check this link. Ear+ Stereo Headphone Amplifier
You might also consider TTVJ, handmade by Pete Millett for Todd, 307A possibly the best Single End Triode headphone amplifier. Last price check was ~ $7,000.
I have made several SET HP amplifiers. The one I like best is a 6BQ6GTB with custom 8000 : 300 ohm Eletra Print balanced output transformers. I also have a pair of Edcor 5000 : 300 ohm 3 watts transformers (about $20 each) these are much cheaper but still sound very nice.
DT
All just for fun!
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Old 4th July 2010, 11:34 PM   #5
Gordy is offline Gordy  United Kingdom
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On the menu tonight we have...

Input >
Volume control
Grid stopper
6H30 triode
...about 20-25mA, with about 80V on the plate and about -3V of bias
...CCS anode load (use cascode of DN2540, as shown by Gluca in above post)
...LED as cathode bias element
Parallel feed output (AC coupled) via decent quality capacitor
Sowter 8665 wired 6:1
[ DC heaters ]

(If you have ground loop issues / local interference issues then add a Sowter / Jensen 1:1 transformer at the input).

If your objective is performance then you simply don't need any more than this amp.

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Old 5th July 2010, 12:12 AM   #6
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Quote:
Originally Posted by Gordy View Post
(If you have ground loop issues / local interference issues then add a Sowter / Jensen 1:1 transformer at the input).
Or CineMag.

se
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Old 6th July 2010, 01:06 AM   #7
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Thank you everyone. And thank you Gordy for your confidence. I appreciate it when someone takes an initiative.

Let's go from Gordy's concept. Do you have a schematic you could send? I am completely new to tubes - It helps me a lot to know how these parts are interacting with eachother instead of just knowing what's the best and not why.

I know it's asking too much to have people explain how each and every component interacts - that's just silly; however, what I do ask is that we have a discussion about important parts and why they are the best for their job. And a schematic to see how these mothers are interacting would sure help a novice who just willingly bit off more than he could chew.



P.S. I'm considering building this amp:
http://www.audiodesignguide.com/my/O...ion_82_ocl.gif

Can anyone please comment on it - in comparison to Gordy's amp - and to top quality amps in general.

And any ideas how much each amp will cost?



Graham

Last edited by Grahamwjohnson; 6th July 2010 at 01:23 AM. Reason: Punctuation
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Old 6th July 2010, 03:52 AM   #8
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If you can live with just hi-z here's a otl hp amp designed by Joe Lowe and posted to USENET in the mid 90s. I built one and still use it. Great-open-sound. Here's the original post:

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

I have just designed and built a circuit you may be interested in. It uses a Russian 6922 (6DJ8) driving 6CL6 cathode follower outputs. The sound is fantastic, you can really hear the "monster image" with headphones.

If you look at the requirements for a tube that can directly drive a low impedance, very few have what it takes. Looking at the RCA tube manual the formula for the required Gm for instance is:

(umhos)= 1,000,000/ Zo (ohms)

This narrows the list to about five types. You also need a tube with a low plate resistance and high dissipation so we can pass some current.

I took a hint from video gear of the tube era, they always used the 6CL6 as the output stage to drive 75 Ohm loads. (flat to 4.2 Mhz!)

Joe
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

I have just designed and built a circut you may be interested in. It uses
a Russian 6922 (6DJ8) driving 6CL6 cathode follower outputs. The sound is
fantastic, you can really hear the "monster image" with headphones.

If you look at the requirements for a tube that can directly drive a low
impedance, very few have what it takes. Looking at the RCA tube manual
the formula for the required Gm for instance is:

(umhos)= 1,000,000/ Zo (ohms)

This narrows the list to about five types. You also need a tube with a
low plate resistance and high dissapation so we can pass some current.

I took a hint from video gear of the tube era, they always used the 6CL6
as the output stage to drive 75 Ohm loads. (flat to 4.2 Mhz!)

Joe

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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Old 6th July 2010, 04:18 AM   #9
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Hello GrahamwJohnson.
Want to know how stuff works take small bites and chew slowly. Start with these two links.
http://hollowstate.netfirms.com/earplusdesign.pdf
http://www.tubecad.com/articles_2003..._Amplifier.pdf
Then go over to tubelab.com and read about the Simple SE amplifier. Build the Simple SE with a 500 volt center tap power transformer. Checkout Hammondmfg.com . For a 250 to 300 ohm headphone use an Edcor GXSE3-300-5K output transformer. This amplifier will rock. I built one. This one can be completed as a first project for ~$400 or less.
Next there is no best amplifier. Just build one. Start easy with a kit of sorts then venture into that transformerless split phase push pull thing that you posted.

DT
All just for fun!

Last edited by DualTriode; 6th July 2010 at 04:20 AM. Reason: delete an oops!
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Old 6th July 2010, 06:30 AM   #10
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Thank your for your reply DT: however, I'm doing this project mainly because I have a pair of headphones that I want to TRULY maximize right now. And I don't want to pay someone $5000 for something that I would love and enjoy making myself for much cheaper. I'm willing to put in the money, so I'm simply asking the world what the best we have to offer in terms of sound quality. I'm not settling for anything less; I'll catch up with the knowledge - I'm not concerned. But my task needs to be taken seriously otherwise forums are of no help to me. Because almost all previous endeavors have done by myself because people don't give honest answers. I'm not saying your reply wasn't honest, but we both know it's not the best, boyo.

Graham
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