Need advice regarding preamp

anitab54 · 2275

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Offline Paul Joppa

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Reply #15 on: June 06, 2020, 07:02:54 PM
Both preamps are Foreplay 2 - I can tell from the label on the power transformers.

In the most recent picture that Paul Birkeland (yes there are two Pauls) posted, near the top, he indicated in red the two terminals that should be connected. A green wire goes to the center terminal of that terminal strip (labeled 13) and the one to the left of it (terminal 14) is the other. A short wire between these terminals should be soldered at each end. Technically, this connects the signal ground to the chassis ground - you can see that terminal 13 is bolted to the chassis.

(Whoever does the soldering should be aware that the copper signal ground wire passing through terminal 14 has a really tough plastic coating. Just in case - this calls for 60/40 tin/lead electronic solder with rosin flux; find someone who knows what that means!)

Back in the day (it came out in 1998 if I recall correctly), many customers but not all had a hum problem that was resolved with this modification, and I see from the picture you posted most recently that yours does not have this connection. So there is a good chance that this will resolve the hum prroblem. There are of course many other things that could have caused the hum, so you can't be certain it will work until it is tried.

You do not need a schematic to do this.

I also see from you last photo that this preamp has the stepped attenuators,  fancy boutique audiophile capacitors (the large yellow cylinders), and the current sources (the four small circuit boards) - so this is a top-of-the-line version of the Foreplay 2.

Paul Joppa


Offline Paul Birkeland

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Reply #16 on: June 07, 2020, 05:58:25 AM
Yes, I think it's a smart idea to try soldering a wire between those two terminals.  That could save you all the repair costs.  You could use this kit for the soldering part:
https://www.amazon.com/ANBES-Soldering-Iron-Kit-Electronics/dp/B06XZ31W3M/ref=sr_1_2?dchild=1&keywords=soldering+tool+kit&qid=1591545429&sr=8-2

For the piece of wire, if you have a cat5 networking cable sitting around, you can cut it apart and use the wire out of that to connect the two terminals.  YouTube has plentiful soldering videos as well.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline anitab54

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Reply #17 on: June 08, 2020, 10:29:30 AM
I talked to Howard (who suggested I buy these). He wants me to send in to you. Thank you for all of your help. You guys are great!! I will put both preamps in one box that you send me. You will fix one and check out the 2nd one and fix the second one if needed. I will pay $125 now and the shipping if that is allowed, but if I owe more for the 2nd amp, of course I will pay you. Additionally, I'd like to have you check out the amps which I know are $125 each also. I will feel much better if you bless them and I will get a receipt or something that shows you looked at them. One day, I will try to be brave and build a kit. And thank you again so much for your patience with me.



Offline Paul Birkeland

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Reply #18 on: June 08, 2020, 10:42:18 AM
If you're sending all of that in, let's just do both Foreplays for one repair fee in one repair box. 

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Karl5150

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Reply #19 on: June 08, 2020, 10:43:18 AM
Anita,
Do all the bottleheads following this a favor and post a photo once they are up and running in your system.
Good luck and good sound.

Karl
Downstairs: Planar3>PH-16>Stereomour II>OB Betsy+
Upstairs: RP1>Eros/CD5004>Seductor (2x Monoblocks)>FH3
Office: Modi Uber 2/Sirius>SEX2.1.1>µFonken FF85WK + DC160 subs
BR: FiiO M6>SEX3.0.1>ScanSpeak 10F + TangBand W6 (Mono)/DT770Pro
Garage: X12 streamer>Quicksand>Minimus 77


Offline anitab54

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Reply #20 on: June 08, 2020, 10:50:52 AM
This reply is for Paul Joppa. I was trying to not be a pest, but I would like to explain this a little better. Someone built the kits for 2 amps and 1 preamp and sold them to a guy named Paul. Paul used them and the preamp developed a hum and instead of fixing he bought a second preamp. He sold me the 2 amps and the working preamp and offered me the humming preamp at a discounted price. We had Howard's guy Mike move the working preamp into the light colored box to match the light colored amp boxes. And the humming preamp that you said is a foreplay II is in the different colored box. I have no idea if the preamp in the light colored box is a foreplay I or II, is so that's why I want it checked out too. I want to keep the best one, and Howard can have the other one :)



Offline anitab54

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Reply #21 on: June 08, 2020, 10:54:30 AM
Thank you :) I just need to know now how to order the boxes. You said both preamps will fit into one box. I am happy to post a photo when I get them back. I found out yesterday that my Klipsch La Scala speakers are 1977 (not '80's) and I think they will be happy together. Thanks again.



Offline Paul Birkeland

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Reply #22 on: June 08, 2020, 10:58:18 AM
You would order three of these:
https://bottlehead.com/product/repair-service/

I let Eileen know that the one for the Foreplay needs to be sized to take two Foreplays. 

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline anitab54

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Reply #23 on: June 08, 2020, 11:09:47 AM
ordered. Thanks.



Offline Paul Joppa

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Reply #24 on: June 08, 2020, 03:05:53 PM
Thanks for clarifying, Anita. I love that they have some history beyond the DIY community!

Looking again at the first picture you posted, of all four amps, it seems clear that both preamps are Foreplay II. You said before that the first one developed a hum, but I missed the significance of that the first time. It probably means that the missing "ground" connection is not the problem, but rather something else is, so you would have wanted to send them in anyhow.

Don't worry about being a pest; we are all happy to help people learn about audio - it's fundamental to the kit business, after all.   :^)

Paul Joppa