which phono preamp? (Thorsten's or RJM's)

[needtubes]

I recently purchased a turntable and am now in need of a preamp for it. I would really like to keep it as simple as possible, but still have very good sound (detailed, warm, smooth highs and mids).

I first was looking into Project 06 over at ESP, but decided against the multi-stage design because it would cost too much for opamps. Then I stumbled upon Thorsten's "El Cheapo Phono Pre" circuit... You can find it here if you need the reference (though I think most know of it).

I really liked this circuit... it was much simpler and is supposed to sound really good. I cannot get the parts he recommends, however... so I suppose mine will not sound as good.

I then was looking through the forums and found RJM's phono pre... it is on here somewhere. It is a tad simpler than Thorsten's, but not really tried and true. Not many (if any) people have built it and reported that it sounds good.

I am not sure which to go with... Thorsten's is just slightly more expensive, but which would be better?

(oh BTW- in Thorsten's circuit, could the value of the 681k resistor to ground from non-inverting input of the opamp be lowered to 562k-ohms? I cannot get 681k from my supplier)

Thanks all

[Ropie]

There's quite a detailed thread on simple phono preamps here:

http://www.ampchipdiy.com/phpBB2/viewtopic.php?t=218

Also descried is how to reduce Thorstens circuit to MM input only, which should reduce the cost for you.

I'm sure you can reduce the value of the resistor you mention, then change it at a later date when you can get hold of a 681k

[needtubes]

Thanks!

I am rather new to this... so I am a little lost in this area. Now I am off to read the link...

[cbrodersen]

I build Richard's op-amp based phono pre three years ago, and it's quite good, especially if you follow all his (optional) enhancements to the power supply. MM only, however.

I'm actually thinking now of building a tube unit, in my ongoing quest to be "totally tubular." One that has caught my eye is Joe Curcio's tube-based "Sarah" phono pre. This one can be had as a kit (unstuffed PCBs) for around $200. And it's switchable for MM and MC.

I'm really enthusiatic about Joe's tube-based DAC that I built in 2002, and if the Sarah has a similar sonic signature to the DAC, it should be a winner.

[needtubes]

Ok, I think I have finally settled on a combination of both of these. I am going to use the values and parts specified in Thorsten's preamp, but have everything wired to a dual opamp as per RJM's. I will be using Wima FKP2, Solen, and Elna Cerafine caps, and Vishay/Dale and Holco resistors... so it won't be too bad off of what Thorsten recommends. Maybe a tad on the dark sounding side if anything... but if I use a different opamp I might be able to brighten things up a little. I just hope I didn't forget any parts...

[Werner]

Originally posted by needtubes
and Vishay/Dale and Holco resistors...

You really don't need to splash out for exotic resistors. Spend the money on two opamps instead of a dual one, and pay close attention to the power supply.

If you can handle SMD you may want to consider the AD8610 opamp in Thorsten's circuit.

[needtubes]

The resistors aren't really much more than the normal ones I use... and I have used Holco before with MUCH better results than the normal resistors I have used previously. And besides... I already have tons of opamps (I build headphone amps for people).

My plan was to use the dual opamp config so that I could use any opamp I wanted. I could just very simply drop in the dual opamps I have, or use the Browndog adapter to use two single opamps in the same config. I also could save on the power supply caps... since those were the most expensive parts I bought.

Opamps I have:
NJM5532
OPA2132PA
OPA2132P
OPA2227P
OPA2604AP
OPA637BP
AD823
AD648JN
AD843KN
AD845KN

and maybe some more I forgot... So, I have enough to play around with a little to see which are best.

[dshoaf]

Hi, Perhaps a bit late to the conversation but I'm quite happy with my PassDIY Pearl phono pre. You can find info at www.passdiy.com under the Preamp section. It is an all discrete, two-stage pre with the RIAA curve components in between the 2 stages. Lots of built-on-board regulation. You'll be into it for around $250 if you purchase the board and semiconductors from PassDIY.

Search the PassDIY section here at DIYAudio.com for other comments on it. Since its MM-only, I've also added a couple of Lundahl MC transformers for my Denon DL-103R.

Cheers,

David

[powertriode]

Has anyone tried the PhonoDude of Mr. Doede Douma???

Looks very neat, and its got tubes!!!

He can supply a PCB

http://www.dddac.de/tp06.htm

[needtubes]

Well, it is a tad late to change my mind... but not too late to find preamps for my next upgrade.

I looked at the Pass labs amp, actually, but thought it would cost too much. My total for this first preamp was supposed to be at absolute MAX $50... but I was hoping for a lot less. I spent around $30 in the end, which wasn't too bad.

The tube PCB is nice... I was really wanting a PCB to make the amp look more professional... but I suppose I can just put a cover on it and not tell anyone. I found a couple of PCB's, but they were all $30+ for just the board.