APT HOLMAN preamp

[dragon]

I'm think about sending my APT Holman preamp out for update/upgrade. I've seen two places on the the net - "Stereo Repair - In House Service Company" & "Audio Proz". Anyone with experience with them or is there somewhere else to send it?

 

[Toasted Almond]

Let me know how that works out for you. I have a Holman also.

 

[Nakdoc]

I do repairs for Apt products. Aside from replacing the mute relay, what mods did you have in mind? The electrolytics inside were nothing special, but they were used sparingly in the signal path. Everything else is discrete. Better RCA connectors might be nice. The thing about the Apt is is is very neutral sounding. I used one for years, but went with a more dynamic sounding pre. I wonder if some power supply upgrades might improve dynamics?

 

[soundmotor]

Replace the opamps.

IIRC, it has TL082's or earlier in it.

There is a raft of better opamps available now.

 

[dragon]

Apt Holman

I do repairs for Apt products. Aside from replacing the mute relay, what mods did you have in mind? The electrolytics inside were nothing special, but they were used sparingly in the signal path. Everything else is discrete. Better RCA connectors might be nice. The thing about the Apt is is is very neutral sounding. I used one for years, but went with a more dynamic sounding pre. I wonder if some power supply upgrades might improve dynamics?

I guess the mute relay is a common problem. Besides that I'd like to replace all the caps, clean pots and gold RCA's would be nice too. Power supply upgrades sound nice but expensive. send me a email address. I have to go now but I'll be back in a couple of hours. ggomen@kc.rr.com

 

[Nakdoc]

I looked at the Audio proz site. The only "critical part" is the FET/transistor differential pair used in the phono preamp. I know the original was selected for low noise, but I am not aware that a "better" FET exists. I have an FET I use when the original fails that performs within spec. I suppose one migh find a quieter one, but the Apt was already silent! Changing the final buffer opamp might change things a bit, but this device is not used for voltage gain. Easy to do though. For the Audio Proz price I could almost goldplate the whole thing). The rest sounds like good practical stuff. I am a big fan of non-polar electrolytics in the signal path. Poly bypass caps are easy to do. I agree that the volume control is best left alone (sexy it is, hate to loose that)

 

[dragon]

So what do you think? The caps, opamps, relay, non-polar electrolytics in signal path, RCA's - what else?

 

[dragon]

Let me know how that works out for you. I have a Holman also.

Looks like I'm going to hook up with AK brother NakDoc. Sounds like I can get the most bang for my buck. If you have any ideas, like what you'd like to do to yours, let me know. God I love this stuff.