DHT preamps

[deepak]

Some poking around has led me to believe that DHT preamps should be really (really) good or their proponents are just very vocal about their choice

I'm wondering what people here think?

26 tube DHT preamp

another 26 DHT

[deepak]

Bump

[dsavitsk]

There is some argument that DHT's have lower distortion than IDHT's. However, a small signal DHT preamp requires considerably more work and attention to detail than does an IDHT preamp, so it may be that were an IDHT preamp built with the same attention to detail, it would sound just as good. Also, people building with DHTs tend to go all out on parts, so again, perhaps building an IDHT preamp with the same attention to parts would sound just as good. Additionally, there is some contention that the big open sound people seem to like from DHTs is actually just a microphonic artifact from the filament resulting in a sort of reverb effect. Thus, the sound may be a sort of effect added to the signal.

My own DHT headphone amp sounds pretty good to me -- certainly better than most other amps I've built. But, I can't say that this isn't because of the attention to detail, the parts, or the microphonics. On the other hand, it could be the tube.

[deepak]

Thanks for the info! No doubt it will be pretty difficult to get a DHT pre built.

If the power amp I end up with has enough gain I'm tempted to just go with a TVC. The Raven, looks like another good one.

Edited April 26, 2009 by deepak

[deepak]

relying on the power amp to provide enough gain, as opposed to using a source with a hot output, seems like a good way to introduce noise, in that situation. might be something to think about (sure you have).

You are right I haven't done the math yet since I don't even know what power amp I'll end up, but from what I'm reading a 2 vrms source (mine is 2.1) should be good with a lot of amps. The other thing I have to work out is impedance matching.

Another gripe with most of the TVCs I see is they are very limited with the number of attenuation steps, and to get something done custom by a company like S&B (doubtful they even sell loose transformers any more) would be big $$$

[luvdunhill]

Another gripe with most of the TVCs I see is they are very limited with the number of attenuation steps, and to get something done custom by a company like S&B (doubtful they even sell loose transformers any more) would be big $$$

While this might be an issue in theory, I've found not so much in practice with the TVC or autoformer approaches. Just careful system matching is all that's really required. For some reason, coarser steps do not feel as course with the inductive approaches, I'm not sure why that is, but it seems to be the case to me at least.

[deepak]

While this might be an issue in theory, I've found not so much in practice with the TVC or autoformer approaches. Just careful system matching is all that's really required. For some reason, coarser steps do not feel as course with the inductive approaches, I'm not sure why that is, but it seems to be the case to me at least.

I suppose I'd have to try it, but a lot of my listening would be low to low-medium volumes.

[luvdunhill]

I suppose I'd have to try it, but a lot of my listening would be low to low-medium volumes.

If this is the case, just ensure you don't have too much gain in your system, then the steps will feel just right at lower volumes.