[lostspyder]

I'm using a pimeta right now to drive my dt-880's. I've got an itch to build something new, and have always been fascinated by tube amps. Plus ive heard that the beyers benefit a lot from tube amplification. So it comes down to this - Millet Hybrid or SOHA Hybrid. I want to keep the cost under 120$, Ive got two RK27's and intend to build an enclosure, so that should save me quite a bit.

Or should I build the PPA?

 

[tomb]

The PPA won't address your fascination with tubes. Also, with both the PPA and the Millett, you'll be hard-pressed to make your budget. Although, with the PPA it could be close.

The most expensive thing on the SOHA is the transformer and one of the pots you have, if that's what you are going to use. That's assuming you don't go crazy purchasing some Amperex 7316's for the 12AU7.

 

[lostspyder]

Ive also got HA3-5002's left over too. So between the Millet and the SOHA, cost aside, which would be the better amp?

and from what I understand, the Millet uses a tube for all amplification, and a buffer to supply current, but the SOHA looks like it uses an opamp without any buffer - does it use the opamp as a buffer or amp?

 

[tomb]

Quote:

Originally Posted by lostspyder /img/forum/go_quote.gif Ive also got HA3-5002's left over too. So between the Millet and the SOHA, cost aside, which would be the better amp? and from what I understand, the Millet uses a tube for all amplification, and a buffer to supply current, but the SOHA looks like it uses an opamp without any buffer - does it use the opamp as a buffer or amp?

I'm not sure Tangent sells the PPAV1 board anymore and I don't believe the Intersils have any use on the V2 board. You can use the Intersils on the old revMH Millett Hybrid, but that's about it these days.

The SOHA uses the opamp as a unity gain current buffer - one of the shortcomings of the design, but then it was originally never designed to cost more than $50.

 

[thunder]

What is a unity gain current buffer and how does it work ? Could something like this be used in place of the op-amp ? >http://www.triode-systems.com/uploads/photos/112.png If so what would one half to do to make it work ?

 

[lostspyder]

From what I understand, a buffer is a 1:1 'amp', ie what goes in goes out - no actual 'amplifaction' takes place. But what it does is supply more current, and removes the current load from the device doing the voltage amplification.

Think of it as analogous to a 'powerloader' from the aliens movie - the character has to move, but the buffer/powerloader can life a lot more, and because of this the charicter is less fatigued and has more precise movements.

basically a little bit of work on the first device can to a lot of work by the buffer.

Quote:

Originally Posted by thunder /img/forum/go_quote.gif What is a unity gain current buffer and how does it work ? Could something like this be used in place of the op-amp ? >http://www.triode-systems.com/uploads/photos/112.png If so what would one half to do to make it work ?

 

[Cauhtemoc]

Quote:

Originally Posted by lostspyder From what I understand, a buffer is a 1:1 'amp', ie what goes in goes out - no actual 'amplifaction' takes place. But what it does is supply more current, and removes the current load from the device doing the voltage amplification. Think of it as analogous to a 'powerloader' from the aliens movie - the character has to move, but the buffer/powerloader can life a lot more, and because of this the charicter is less fatigued and has more precise movements. basically a little bit of work on the first device can to a lot of work by the buffer.

Correct (and nice reference to the Alien movie!).

Quote:

Originally Posted by thunder What is a unity gain current buffer and how does it work ? Could something like this be used in place of the op-amp ? >http://www.triode-systems.com/uploads/photos/112.png If so what would one half to do to make it work ?

While it could be used, the output impedance is very high. If you want a transformerless all-tube headphone amplifier, take a look at John Broskie's Aikido amplifier here, or Andrea Ciuffoli's amplifier over at HeadWize here. Both of these have an output impedance of about 200 ohms. This is still high, but it's managable