Assistance regarding troubleshooting a new BeePre build [resolved]

[Audionorth]

The POS out is correct and Pin 3 shows 0v so the C4S must be the problem. . .

Any thoughts on what is likely the culprit . . . I re-soldered all the connections and the wires on the bottom board of C4S.   It is wired correctly . . . replace various parts?

Thanks!
M-

[Paul Birkeland]

You can swap the C4S boards side to side to be 100% sure.

The issues I see with C4S board usually revolve around poor soldering on the MJE5731A.  Miswired jumpers are a close second.

[Audionorth]

Thanks for your patience. . .

I switched the C4S boards and the fault followed the board. Good news . . .

Bad news . . . I replaced the PN2907 transistor and then an MJE5731A "OA/IA end" (because I didn't know what else to try). . . neither corrected the problem. 

The jumpers are correct and solidly soldered so what ever the fault is it's obscure (at least to me) . . .

Regards,
M-

[Paul Birkeland]

You could inquire about ordering up a replacement board from replacementparts(at)bottlehead(dot)com. 

[jjvornov]

Just to second Paul's suggestion, I had a BeePre problem child. It had intermittent problems, I destroyed one of the boards trying to resolder, it went in for repair then started up again.

I finally replaced the flaky board (and one of the 300b sockets which was loose in one of the contacts) and now I have a perfectly functioning BeePre. Definite was worth just starting over with the bad board.

[Audionorth]

I did send an e-mail to Bottlehead replacement parts and will order a new C4S board.  I am optimistic this will resolve the issue. . .

Thanks,
M-

[Audionorth]

 . . .the C4S replacement kit showed up a couple days early and once soldered together all the voltages came into balance  . . . my Beepre is now up and running . . . no noise, or microphonics, just music!

Thanks for all who supported me in this endeavor.

M-

[jjvornov]

So glad to hear it worked out. Enjoy, it's a great preamp

[Audionorth]

I thought for completeness I should post the final pics of this build.  My comments above regarding "no micro-phonics" was in a different system than pictured here and I was a bit over enthusiastic. Once I inserted it into the system shown (a second system comprised of a Cambridge Audio Transport, Audio Creative DDDAC 1794 Kit; WAD 300B PSE kit, and Club-27 Amy Speaker kit) the challenge of micro-phonics was discovered. . .

Fortunately the fix is straight forward as found here on the forum. The "larger" of the red weights is 1.5 lbs with the "smaller" being the .5 lbs (not sure I really need both).  I'm currently using Sophia Carbon tubes because I had them on hand. . . The "kling/klong" type noise heard periodically with these specific Carbon Plate tubes is simultaneously kinda annoying and interesting . . . the sonics are really good though! The stock tubes were also very good without the added noise . . I'm still relationship building with this machine and therefore will spare you my cliched attempt to describe my musical experience . . . you're welcome! 

I did buy some chokes for the B+ supply but may or may not attempt to mount them primarily due to the crowded real estate of this amp . . . and likely hood I wouldn't be able to tell the difference . . .?

Overall, the project ended up being a success!. . . also, I'm still using my BH Sex 2.1 w/C4S for headphones on a regular basis when the family is not in the mood for music. . .

Thanks for the making these fabulous kits available and the support when it was needed!

[Paul Birkeland]

Power supply chokes are extremely helpful for knocking down power supply noise a lot without knocking down the available voltage as much.  Power supply noise isn't an issue in the BeePre (thanks to the hybrid shunt regulator), nor is voltage drop (also thanks to the regulator).  I'm glad you got things sorted!

[Thermioniclife]

Hey Audionorth,
If you have not installed the chokes you purchased don't bother, keep them for another project.
I ran my Beepre for a month then installed chokes and in my opinion they did not make a difference.
Did the spikes on the Beepre base help with microphonics?
I have the .5 Lb flask weights and they helped a great deal but not as much as I would have liked.
have a nice day.

[Audionorth]

After reading other's responses I decided not to install the chokes . . . Thanks for the feedback regarding your experience. . . . sounds like I made the right choice.

I have (IIRC) both a 5lb and 2.5lb weight on each tube.  I'm not convinced I gained much with the spikes but all the micro-phonic reducing strategies combined have worked since I don't currently have any issues unless I'm physically touching the amp or base it sits on . . . 

[Doc B.]

Spikes are for the reverse problem, keeping a speaker from putting energy into the floor - energy moves V . We are trying to keep energy from the floor out of the tube structure - energy moves ^. I found that Herbie's Tenderfeet helped (where the heck are mine? they disappeared in the move). Sorbothane hemispheres tend to distort (squash) with time and lose effectiveness in comparison with the Tenderfeet. An excellent, extremely ghetto way to isolate the preamp from vibration through the equipment shelf is to put it on several layers of bubble wrap.