View Single Post
Old 23rd November 2016
  #10
Here for the gear
It's been a long time I unfortunately lost my original login details I am the one who started this controversial post many years ago

To JakePaul et al I kind of find it funny...

Has nobody stopped to question the function of the Tantalum caps both in this circuit and the original 1073, or even glanced at the 1073 schematics?

I can't pretend to be an expert and still learning as much as I can... but to me these look like bypass capacitors, not at all in the signal path! I'd even bet changing them back to Electrolytic would have negligible effect on the audio.

The cap values changed were 22uF people... Let me say that again 22uF
So JakePaul good luck finding a 22uF Polystyrene Capacitor, and yes there are probably other film caps available at 22uF but is there really a point in ending up with more cap than preamp, for bypassing?

This was 3 years ago I am still learning but can't believe people are glossing over the details of where the capacitors are used in the circuit!

I did a swap back to the original output transformer to take some measurements for doulos30 back in 2013, that was a long time ago now and have since lost that data. So if doulos30 is still around he'll have to take my word for it that there was more than a negligible difference in measured frequency response between the two output transformers.

Since the original Mod I luckily acquired a dedicated MIC Level Marinair transformer so have a complete set on the input now.

My advice to anyone modding their GAP PRE73 is to concentrate on the Transformers mainly you can experiment with other components, but I think you're unlikely to gain much from it. Familiarize yourself with the schematics of the 1073 (Which this is based on) to help you make decisions.

I still stand by my reasoning for chaning to Tantalum caps; the original 1073 use them instead of electrolytic capacitors. But
I doubt this change made much of a difference, and now would probably not bother with the change.

Jim Williams made some good points about the FR Series Caps

I still use my GAP PRE73 with all the mods from the original post with NO problems, no death by tantalum yet! It gives me the bite and frequency response I was looking for.
My main pre is a GTQ2 (thanks for the great pre Geoff ) and an API 512c (in The Channel Strip package) in among those this modded PRE 73 still finds a place now and then, and is a lot more portable!

With that said I think it's time to drop the mic and