First, I like to thank Wayne for creating this design and sharing it
with us greedy boyz, and Jim for putting together the kits to help
us build this preamp.
Aside from the PCB and kit parts, the rest were recycled from old projects.
Unfortunately my transformer has some mechanical noise, which I find a bit
surprising given the relatively low current draw. Also one channel had a problem at
initial power up, which was traced to some flux residual at Q4. Cleaning that
fixed the issue. The rail voltages are +/-20V, coming from simple LM317/LM337
regulars.
The sound is very good and so far I don't feel anything is amiss when listening through
it. I may rebuild this in a new case in the future, with a switch to allow for
more inputs and a new transformer to avoid the mechnical noise. But for now,
I will enjoy it as is.
Dennis
with us greedy boyz, and Jim for putting together the kits to help
us build this preamp.
Aside from the PCB and kit parts, the rest were recycled from old projects.
Unfortunately my transformer has some mechanical noise, which I find a bit
surprising given the relatively low current draw. Also one channel had a problem at
initial power up, which was traced to some flux residual at Q4. Cleaning that
fixed the issue. The rail voltages are +/-20V, coming from simple LM317/LM337
regulars.
The sound is very good and so far I don't feel anything is amiss when listening through
it. I may rebuild this in a new case in the future, with a switch to allow for
more inputs and a new transformer to avoid the mechnical noise. But for now,
I will enjoy it as is.
Dennis
Great to hear Dennis!
A friend came over yesterday and he brought his new SIT-3 to listen to. (Wow, fantastic amp...
) Had to try the Wayne's Burning OpAmp project with it, and the general consensus was that it was a very, very nice match! The SIT needs a bit more voltage on it's inputs for full power, my Wayne BAF Linestage is running on 18v rails and outputs a beautiful 3.1vRMS (9vPk-Pk) which was enough to drive it to as loud as we wanted to hear it.
My golden rule for DIY projects is simple - when it's genuinely quiet, double check the AC connections for safety, place the lid on it, and don't mess with it anymore. Just enjoy. That's my plan, an I'm very much looking forward to having this in my system for a while!
A friend came over yesterday and he brought his new SIT-3 to listen to. (Wow, fantastic amp...
) Had to try the Wayne's Burning OpAmp project with it, and the general consensus was that it was a very, very nice match! The SIT needs a bit more voltage on it's inputs for full power, my Wayne BAF Linestage is running on 18v rails and outputs a beautiful 3.1vRMS (9vPk-Pk) which was enough to drive it to as loud as we wanted to hear it. My golden rule for DIY projects is simple - when it's genuinely quiet, double check the AC connections for safety, place the lid on it, and don't mess with it anymore. Just enjoy. That's my plan, an I'm very much looking forward to having this in my system for a while!
Speaking of gain, I’m thinking of using the larger output devices into the 1:5 encore used in the M2.
Should work nicely in a F4.
https://www.edcorusa.com/Content/Manuals/PC600-15K.pdf
Should work nicely in a F4.
https://www.edcorusa.com/Content/Manuals/PC600-15K.pdf
Thanks for all the reviews! Looking like a winner!
Not that I am aware. Baby steps for the Greedy Boyz
Not that I am aware. Baby steps for the Greedy Boyz
Building this Power supply now and a couple of questions arise:
1. I think I know the answer to this one, but in abundance of caution, this is going to be a Bipolar supply so needs the J1 and J2 jumpers, right?
2. R3....it is a bag of three resistors, not sure which of these to use, and it works in conjunction with C6 and C10, which isnt quite as confusing since C6, (and C5) are only one value in kit, 4.7 kuF @ 35v, as well as C10 .01 uF @ 100v. Which R3 do I use? Instructions say they range in value from .33 to 10 ohms. I have a large black pair that measure 1.0 ohm, another smaller pair that measure 9.9 (assume that is the 10 ohm), and a slightly smaller pair that measure 3.4 ohms. Not sure which to use for my situation.
Thanks for any help here,
Russellc
Hey there.
I measured a gain of 3.63x (with 2V RMS input) into 25K ohms. (I didn't try
a lower impedance.) The distortion was 0.009% and I too used +/-18V rails.
(I made a mistake in my original report a few posts back.)
Having spent a bit more time with it, I have to say it really is a
nice preamp. If you already have the purple boards, I highly recommend you
just build it. Do not fear the SMD jfets. (Use flux and clean up afterward).
As for the lack of mounting holes, the Adafruit edge mouting kit should be
fine. I hobbled something together with standoffs and nuts. If I were
to do it again, I probably would just use standoffs and hot glue.
The rest of the construction is straigtforward.
Even with my El Cheapo build (recycled case, humming transformer, simple regulator
supply with little capacitance, no input switching) I am very happy with its objective
and subjective performance. But I think that is the point of this circuit:
A high performance design using readily available parts that is cheap
and easy to build. At the same time, I don't think any attention you lavish on it
(say, a nice volume pot and quiet power supply) will be wasted.
I used a 100K cheapie pot since that's what I happen to have and the preamp is
quiet.
And yes, it works very well with a SIT3.
Dennis
I measured a gain of 3.63x (with 2V RMS input) into 25K ohms. (I didn't try
a lower impedance.) The distortion was 0.009% and I too used +/-18V rails.
(I made a mistake in my original report a few posts back.)
Having spent a bit more time with it, I have to say it really is a
nice preamp. If you already have the purple boards, I highly recommend you
just build it. Do not fear the SMD jfets. (Use flux and clean up afterward).
As for the lack of mounting holes, the Adafruit edge mouting kit should be
fine. I hobbled something together with standoffs and nuts. If I were
to do it again, I probably would just use standoffs and hot glue.
The rest of the construction is straigtforward.
Even with my El Cheapo build (recycled case, humming transformer, simple regulator
supply with little capacitance, no input switching) I am very happy with its objective
and subjective performance. But I think that is the point of this circuit:
A high performance design using readily available parts that is cheap
and easy to build. At the same time, I don't think any attention you lavish on it
(say, a nice volume pot and quiet power supply) will be wasted.
I used a 100K cheapie pot since that's what I happen to have and the preamp is
quiet.
And yes, it works very well with a SIT3.
Dennis
New-ish builder here (but not first build), and I need some help figuring something out... so warning... potential dumb questions ahead. I am going big on this pre amp (big for me at least), and have 4 of these lovely purple pcbs. I will be hooking it up to a Vicol Audio Maya R2R relay based attenuator/ source selector which I already possess (yes I have two boards for balanced).
I understand how to make this preamp solely SE RCA, or solely balanced. But I don't understand how to make this preamp where SE and Balanced can coexist so to speak. I apologize if I am not using the correct terminology here or describing this adequately... I'm still learning. I have only two sources (one SE, one Bal) but I have both SE and Bal amps and I would like to be able to use them all in the various ways they are meant to be enjoyed. I have been reading and researching this on my own, but feel like I am going in circles. Thanks in advance
I guess what I am trying to ask, is what do I need to do to make this preamp both balanced and SE rca... for both inputs and outputs? Once again, sorry if I did not ask this question right.
I understand how to make this preamp solely SE RCA, or solely balanced. But I don't understand how to make this preamp where SE and Balanced can coexist so to speak. I apologize if I am not using the correct terminology here or describing this adequately... I'm still learning. I have only two sources (one SE, one Bal) but I have both SE and Bal amps and I would like to be able to use them all in the various ways they are meant to be enjoyed. I have been reading and researching this on my own, but feel like I am going in circles. Thanks in advance
I guess what I am trying to ask, is what do I need to do to make this preamp both balanced and SE rca... for both inputs and outputs? Once again, sorry if I did not ask this question right.
So sissy outputs failed to bring the details out in the music when pushing through the edcors. The midrange was very nice but that’s about it. My wimpy supply had to go. It’s designed for 18V but put out +/- 12V. So I tied it into the F4 supply, it had no choice but to make music now. At 3V Input it started to distort. I think the cause is my tiny supply wires. When I order and replace the output devices I’ll test it again and then we’ll see if we can create “Wayne’s M4.”
Photo from spy cam instead of Satellite.
Photo from spy cam instead of Satellite.
