[JoshK]

I've been kick around some sketches on paper. Not high on my priority list of projects to complete but wondered if there are any tube diy'ers out there that have built a DHT headphone amp. Sounds like a good project. Commercial ones would be a fortune.

 

[dsavitsk]

Quote:

Originally Posted by JoshK I've been kick around some sketches on paper. Not high on my priority list of projects to complete but wondered if there are any tube diy'ers out there that have built a DHT headphone amp. Sounds like a good project.

I am almost done with one, though it is not a pure tube circuit. I have had it working on breadboard, but am now just futzing with a HV regulator before I case it up. Mine is a 01A parafeed circuit. I am using a solid stage CCS and magnequest output transformers. This is then coupled to a mosfet buffer which is DC coupled to the phones. So far, sound is very good.

Quote:

Originally Posted by JoshK Commercial ones would be a fortune.

Turns out DIY ones are a fortune too.

 

[motherone]

dsavtisk,

Hope you'll post the design/pics when you're done! I'm definitely interested in building a DHT amp at some point for myself (after I get my HPDACs done, of course...)

 

[JoshK]

Certainly they are not cheap to make, but not what I consider a fortune. The iron adds up though. I was thinking more along the lines of an Aikido inspired stage and a tube buffer based on DHTs. If I did it this way, the Aikido gain stage could be part of my line stage too but one output would go to tube buffer for HPs.

 

[raja]

Old thread but one that's worth responding to regardless.
 
I put together a DAC output stage by Ultranalog that is able to drive headphones like the Senn HD580/600/650 directly. Output impedance with the Sowter 8650 9:1 transformers is around 100 ohms so you should be able to get away with Senn HD800s too. 
 
The tubes used are the 3a5 dual triodes (they are a little microphonic), with an old directltyy heated AZ1 meshplate rectifier, but the  overall presentation is absolutely sublime. The filaments can be supplied by batteries so no AC hum. 
 
As a volume control I was using Sowter TVCs. 
 
The DACs I've changed a few times, I started off with Pioneer Legato DACs, the went over to Wolfson. I'm now going to use the 32 bit Buffalo by the guys over at Twisted Pear with a digital volume control, so the phones will sit directly on the output side of the DAC eliminating the need for an extra component in the signal path while the 32bit headroom of the DAC provides enough headroom for volume control without sacrificing as much detail as the TVCs or a potentiometer would. 
 
The entire setup should cost around $700~$800 to build (that's including the DAC) and would rival commercial offerings costing MULTITUDES more. 
 
 
I like this little setup so much I asked dutch transformer specialst Pieter Treurniet wind me some custom amorphous output transformers, which arrived last year. I'm just waiting for the Twisted Pear guys to get another batch of the Buffalos ready so I cna put the whole lot together..
 
-Raja