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Calling all APT Holman experts

Gazdatronik

Gazdatronik

Super Member
I just finished recapping the APT preamp, only the electrolytics. The metal foils and the chiclets remain. It sounds pretty much the same to me, minus the hum issue and the headphone amp imbalance that was there before. Yay.

Is it necessary to re-calibrate it, as in, are any of the caps in the audio path?

I will do it if required, I can borrow a Fluke 99B in a hurry.
 
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May I jump in with a somewhat relevant question? I have an APT Holman preamp. Was looking on that big auction site and found a capacitor "kit" for 64 bills plus shipping. Do these look like decent caps? And is the price nice? TIA.
 
starcopy said:
May I jump in with a somewhat relevant question? I have an APT Holman preamp. Was looking on that big auction site and found a capacitor "kit" for 64 bills plus shipping. Do these look like decent caps? And is the price nice? TIA.
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I think I paid about 20 bucks for all Nichicons. One thing I would do is get larger 50v versions of the two 1000uf power supply caps. I got the 35v short leads to work but would have liked them to be bigger for the larger distance between the leads.

All the other caps dropped in at the original spec with no issue.

64 $ is a little high, Its already enough work putting them in, and marginal extra time to compile a list of caps.

Somebody at audiokarma has already made a list of caps to buy, and it is correct. I verified my list against his and I had missed a couple that are hard to see.
 
Hey, @Gazdatronik, thanks for the quick, quality feedback -- and your additional tips on how to best recap my APT Holman preamp. Really terrific info. I'm glad I can do better than $60ish for the caps -- have so many other pieces of tech to upgrade. I'll search AK and see if I can find that list of caps to buy for the APT Holman preamp. I'm eager to see what this preamp can really do. BTW, I believe you also gave me some advice a while ago about cleaning (and replacing) this preamp's speaker relay. Many thanks.
 
starcopy said:
Hey, @Gazdatronik, thanks for the quick, quality feedback -- and your additional tips on how to best recap my APT Holman preamp. Really terrific info. I'm glad I can do better than $60ish for the caps -- have so many other pieces of tech to upgrade. I'll search AK and see if I can find that list of caps to buy for the APT Holman preamp. I'm eager to see what this preamp can really do. BTW, I believe you also gave me some advice a while ago about cleaning (and replacing) this preamp's speaker relay. Many thanks.
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I happen to be behind the machine i did my ordering on. here is the list I ordered from
5 x 1uf 50v
6 x 22uf 25v (axial)
2 x 47uf 16v
4 x 100uf 16v
2 x 100uf 25v
2 x 22uf 16v
12 x 10uf 35v
6 x 10uf 16v
2 x 1000uf 35v

I made sure to get all Nichicon, although there are other brads that are just as reputable.
Just make very sure you mark polarity of the caps. As helpful and complete as the screen printing directly on the boards are, some of the components are so densely packed that the pluses and minuses run into each other.

The service manual was a big help. While you are in there, look for bad solder joints, I found several in mine.
 
Excellent. Saved me a ton of time. And gave me the push I needed to begin upgrading/restoring that preamp. Very much appreciated. Wish I could return the favor.
 
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