Tweaking a Phono Preamp

[Conrad Hoffman]

Thank you all for your replies.

Alex, I think I misunderstood one detail on your schematic because I saw -24V. I thought that meant there would need to be a power supply that delivers +24V and -24V.

Also, I don't understand what are R_CH_1, R_CH2 and R_CH_3.


Conrad, I studied your schematic but can't be sure if I understand some details. It's about the V1, V2 and V3. Is V1 the signal input? And are V2 and V3 power inputs of 15V?

Since I still like the idea of using JFETS I'm still looking at the newer version of the BoozHound preamp. Obviously they've added 3 more JFETS and they possibly did that because there was not enough gain.

So, looking at their revised circuit, is it worth building? I mean, does it look like the 2 added stages might actually solve my problem of not enough gain? If so, this might be a solution in my case, since I've already built their old circuit, and I'd just be adding to my existing build.

Yes, V1 is the AC input signal and V2/V3 are the opamp supply voltages. The schematic is just a screen capture from LTSpice. I've used this design for many years and not much can top it.

That said, there are many dozens of preamp circuits out there to try, which is half the fun of it.

[Frankentronics]

I think in my case it makes sense to continue troubleshooting the circuit that I've already built and then perhaps build some other preamps later. I already have most of the components and I'm learning.

The next logical step would be to expand the circuit the way BoozHound Labs expanded theirs and simply build their Deluxe version.



But I have a question.

I am going to be building a stereo circuit, so can I use the upper part of the circuit to power up both channels at the same time?
I made a quick revision on the schematic to show what I mean.



Thanks...

[Wombat]

The original Boozhound/ Le pacific two Jfet circuit has LOADS of gain, I have used this circuit for years in conjunction with an Ortofon 2M black MM cart, the likely reason they made it more complex is because of noise...

[david77]

The MMC3 cartridge is a Moving Coil cartridge, so has a lot less output voltage. As I understand it from quick googling the circuit you built is meant to be used with MM (Moving Magnet) cartridges.
The Deluxe version seems to be the one you want for MC cartridges, the first JFET stage providing additional gain.