[jonnywolfet]

hello all,
i am going to build a 4 channel (for bi-amping) lm3875 amp with integrated pre-amp, but i am completely unsure as what to use as the pre itself. would any headphone amp suffice? what would you suggest?
as allways, your input is appreciated.
thanks
jon

 

[t52]

probably you don't even need a preamp, as you can adjust the gain of the lm3875s to your needs...

 

[jonnywolfet]

really? from what i have heard, poweramps based around the lm3875 benefit sonically from an active pre.

 

[Magsy]

Two different camps but I prefer a pre. I am currently running only a passive attenuator and it is lacking the punch it has from a pre.

I have used my Pimeta as a pre but the best sound is on the end of the M³, that said if you don't need a headamp in there it is overkill

Most use a simple OPA627 style Cmoy as a pre...

Don't forget if you use anything that has an active ground/3 channel design then you must use the input ground as output ground, not the active ground.

 

[Garbz]

I use a simple 50k pot. There's no really good reason to build a pre. I used my electrocompaniet ECI-3 as a pre-amp to it, and it sounded no different than a passive attenuator. Mind you I guess it would also depend on the specific circuit implimentation.

 

[motherone]

The easiest preamp that's close to what a lot of the diyaudio folks use would be the MINT. Basically just the opamp + buffer. That would probably work pretty well for a preamp to a gainclone.

I'm just finishing up a GC myself, and I have a line-powered mint laying around, so I may try it.

 

[MisterX]

http://us.hifidiy.net/Article.asp?ArticleId=157

 

[dsavitsk]

I used this: http://www.ecp.cc/ss-bpp.html which is a ton better than an opamp, is very easy to build, and is very cheap. I have tried lots of versions and lots of different power supplies, and have found it to be a good project to tinker with as there is lots you can do to tune it.

 

[flecom]

I used my millett for a pre on my gainclone and it sounded quite nice

 

[Garbz]

http://sound.westhost.com/project01.htm that caught my attention while surfing Elliots website today. You may be interested.

 

[t52]

i'd probably use some sort of buffer right before the gainclone amps and after the volume pot. for simplicity reasons i'd use an opamp in unity gain config... doesn't apply to my setup though because i have an active crossover before my gainclones and so these are driven directly by opamp outputs anyways.