Looking for a preamp to build!

[Dougie085]

I've been kind of thinking about building a preamp. Here are the problems. Firstly I'd like to be able to add a digital display eventually maybe the TPA one whenever they get it together or what not. Secondly I'd like to be able to do 2.1 I'd like to try and have a sub output and I'm really not sure how to do it. So this is what I'm looking for tube or solid state and not horribly expensive. My amps right now is a ChipAmp but will probably soon be switching to the Ref RevC. Source is a TPA Opus DAC with USB and SPDIF inputs. Not really sure what other input you guys think I should include?

[whubbard]

Well I can't help you with the display aspect, as I think that would involve a much more complicated circuit that most DIY pre-amps have, but around here many people recommend the 'pumpkin' pre-amp.
Pumpkin

I personally went with Hugh Dean's GK-1m (its a tube based pre-amp, wonderful little thing).

here is someone with a display:
Video
Very basic, but it works

I would think the best way to do the display would be to build a separate circuit and link it into the preamp circuit, but for audio...the preamp circuit should be your main focus.

-West

[Dougie085]

Yeah the display would basically be the source switcher and volume control and a few people sell them. Twistedpear is supposed to have one eventually its just been a long time in the making I thought the pumpkin was a really high gain preamp for like the F4?

I thought about doing an Aikido but I'm not sure how to do the sub output.

[kuroguy]

I'm working on a line preamp which has a LCD display and BasicX BX-24 microcontroller that will control the LCD and a set of relays to switch sources. I also plan to use the BX-24 to control a motor pot for volume. The BX-24 can be had for $39 and an lcd can be had for $15. I'm currently writing the code for the microcontroller and designing the relay board. Hopefully I'll have it complete in a month or two.

[theAnonymous1]

Originally posted by kuroguy
I'm working on a line preamp which has a LCD display and BasicX BX-24 microcontroller that will control the LCD and a set of relays to switch sources. I also plan to use the BX-24 to control a motor pot for volume. The BX-24 can be had for $39 and an lcd can be had for $15. I'm currently writing the code for the microcontroller and designing the relay board. Hopefully I'll have it complete in a month or two.

Is there a reason why you decided to go with a potentiometer instead of a digital volume IC like the TI PGA23xx series? It's seems like an awful waste of a microcontroller just to use a regular pot.

[orthoefer]

I think you should check out what Jos Vaneijndhoven is doing in the Netherlands. He can ship his parts/kits internationally, and I can personally recommend his stuff.

Link to preamp

Link to separately available attenuator

[glt]

I buit one based on a beta IRVC2 board from http://www.tauntek.com/. It supports remote and display. I am using 2 PGA2320 to take the balanced output of TPA Opus DAC into balanced Hypex amps (4 channels) You can see some pictures of my project here: http://picasaweb.google.com/bugandan...ey=hyMeTYNunuc

[kuroguy]

Originally posted by theAnonymous1


Is there a reason why you decided to go with a potentiometer instead of a digital volume IC like the TI PGA23xx series? It's seems like an awful waste of a microcontroller just to use a regular pot.

Actually, the Microcontroller is necessary in order for my wife to be able to use the stereo. I would have been content with a passive source selector box with volume control. As these things tend to get complicated I figured that it would be easier if there was a plain english display showing her what settings to make on the preamp. It also makes it easy to configure many switches with the press of a single button.