Scott Liebers Labs 1731 Op Amps

looking forward to this! i've been dragging my feet on this, but i hope to get up some good stuff by weekends end

i think your spot on J K the sll really clean sounding Gar colored. I'm probably crazy but loosely reminded me of the difference of an elam 251 and a u47 in sound color if that makes sense i mean it almost sound like you changed  mics [ i know you didn't] gonna need both

About a week ago I was trying to tighten up the wiring in my diy 3124 and I accidentally switched the 48v and 16v wires.
Bad dumb move as I sent 48v to my 4 beloved sl-2520s. I put some other doa's temporarily as I hope to maybe try to save them (I'm hoping its just the transistors) but I can tell the difference. Its not that the others are bad by any means but the sl-2520s are just exceptional. If I can't fix them; I'll have no choice but to get a few more. At least two anyways.

I was surprised when I got my hands on some original Melcor 1731s and the RCA labeled ones which are the same. From all the descriptions on the web, I thought 1731s were more colored than the 2520. That's not what I found when I listened to and measured the originals. I made mine as close as I could to the originals including using the original output transistors.

I think these would do well on acoustic instruments. I've found they work well in console summing amps to give nice clean detail with a tight punchy low end.

Another flavor to add to the pot.

The Gar does have a nice thickness to it.  I can see where that would be a nice color for certain things.  Like spices, you have to be careful how much you put in the pot though.

You are most welcome.  It gets pretty tight trying to work the smd parts off the board.  
Like I said, I've been in your shoes many times and have blown stuff up.  I'd rather have you making music with fixed or new SL-2520s rather than sweat over trying to fix them yourself.

whats the vocal chain, Samar into helios?

Here is how I heard them. It is a sweet switcher that sends the same signal to each opamp and then you select which one you want to listen to. That way you can switch fast and clean to each different op amp to hear the difference. It makes listening test much easier!

Tell us more please!!

Yeah. Want to share your opinion?

Well, I wish I could say I built that and it was my idea. I didn't and it wasn't. That is something Scott Liebers built up so he could tune his designs by ear. I think he also uses it to burn in op amps and test them before they ship. He knew I wasn't super excited about 1731's so he told me I should come down to his place and listen to them in comparison to other op amps. I am glad I did. It was very informative.

Scott had a few different versions of his new 1731 we listened to as well 2520's and a few other random opamps. I think he landed in a great spot with his 1731. His was by far the closets to the original. His gets the tonal balance and color of the original for sure. At first I was listening for the differences between his and the original Melcore. But then after a few mins of listening I started to just listen to the changes each version was doing to the music. After that, I actually preferred his version compared to that vintage Melcore. The vintage one was just a touch sleepy sounding.

I honestly had zero interest in the 1731's until I heard these. It was pretty interesting. Since then I tried them in different spots in my console summing buss. I found a combination that I really like between the 1731's and the Red dots. I was shocked by the tonal difference between placement of the Red Dots and 1731's in the ACA and booster amps. Pretty cool and not subtle.

I grabbed another pair from him and I have to test them in a few other spots. I have a feeling they would be cool in 312's and in eq's. So, I need to finish up a few other things and try that.

I am curious to hear the samples Tony will be doing and anything else you guys come up with.

Yeah, the board in Dan's pic is a test jig I threw together to burn in opamps. It has led VU meters on each opamp so I can visually tell if one isn't working when I fire them up before I go through the listening and measuring process. It has a relay tapped solo bus that allows me to switch down the line and listen/measure the output of each opamp. The boards are 4 channels each. I made them to be daisy chained so I can do up to 12 at a time. I just need to stuff the other 2 boards when I get time.

I didn't realize how useful it is for auditioning different opamps until I started using it. All opamps are loaded the same on the output and then switch through the same output transformer when soloed.