F4 power amplifier - Page 488

PKI · 7th October 2020, 09:09 PM

BTW I have my new built running nice with the Aikido preamp. I like what I hear a lot.

ggetzoff · 8th October 2020, 01:22 AM

Quote:

Originally Posted by peppennino

Decware clone?

No, RH84.

RH Amplifiers: RH84 amplifier - revision 2

peppennino · 8th October 2020, 08:13 AM

Very nice schematic

soldersmoker · 8th October 2020, 02:15 PM

Uh-oh. I was moving my main stereo to another room when I fumbled my F4 and semi-dropped it, managing to recover so it didn't hit the floor, though it landed in a chair. When I listened later, one channel was about 1/3 the loudness of the other. Switching loudspeaker connections confirmed that one channel was weak (but I'm not 100% sure it's not the preamp yet; to be confirmed later). Aside from looking for anything broken and maybe checking the bias, is there any other troubleshooting tricks I can try?

Zen Mod · 8th October 2020, 03:27 PM

preamp or not, confirm ....... then troubleshoot amp, only if needed

ggetzoff · 8th October 2020, 05:35 PM

Quote:

Originally Posted by soldersmoker

Uh-oh. I was moving my main stereo to another room when I fumbled my F4 and semi-dropped it, managing to recover so it didn't hit the floor, though it landed in a chair. When I listened later, one channel was about 1/3 the loudness of the other. Switching loudspeaker connections confirmed that one channel was weak (but I'm not 100% sure it's not the preamp yet; to be confirmed later). Aside from looking for anything broken and maybe checking the bias, is there any other troubleshooting tricks I can try?

Maybe just a cracked solder joint. Check the bias on that channel. Hit all of the joints with your iron.

soldersmoker · 8th October 2020, 07:03 PM

Oops. Yes, it looks like one of the tubes in the preamp is in need of replacement. Never mind! But at least I know how to proceed in the future in the unlikely event I need to fix the amp. Thanks, everybody.

cal3713 · 3rd December 2020, 03:46 AM

Hi folks. So I was reading about some $20k+ amps and read that each rail had it's own power supply transformer. This cued me to realize that I had a totally unused transformer in my power supply and could easily try this out for my f4 monoblocks (image below). Both transformers are identical, 400v anteks with dual 18v secondaries.

My question is, if I do this, what should I do with the extra secondaries. I read recommendations to just heat shrink each wire and then tie up the pair. Other people recommended connecting them in parallel to a single rectifier.

Any opinions from this group?

Thanks as always.

6L6 · 3rd December 2020, 05:07 AM

Parallel the secondaries on each transformer. Then you have 2 transformers with only one secondary each. One transformer per rail. Voila!

cal3713 · 3rd December 2020, 05:17 AM

Great, thanks.

I read that there could be some problems if the windings weren't matched even if nominally rated as identical. Was thinking that really wouldn't be a problem here, but thought I'd go ahead and check. In many cases, I think the concern came from using identically rated secondaries across different transformers, thereby increasing the chances of voltage differences.

8th October 2020, 08:13 AM	#4873
peppennino diyAudio Member Join Date: Oct 2005 Location: Sicily	Very nice schematic __________________ "Diyers are the happiest audiophiles: they have the opportunity to be deeply involved in what they are doing and it provides a lot of satisfaction". Nelson Pass

8th October 2020, 03:27 PM	#4875
Zen Mod Official Court Jester diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	preamp or not, confirm ....... then troubleshoot amp, only if needed __________________ my Papa is smarter than your Nelson ! clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM

3rd December 2020, 05:07 AM	#4879
6L6 diyAudio Moderator Join Date: Oct 2010 Location: Denver, Colorado	Parallel the secondaries on each transformer. Then you have 2 transformers with only one secondary each. One transformer per rail. Voila! __________________ Illustrated Build Guides - Pass F4 - Pass B1 - Pass F5 - Pearl 2 - O2 HPA - Hagerman Bugle 2 - Pass Aleph J - Me at BAF'13 -Pass F5Turbo - BA-3 Amp - BA-3 Preamp -F6- -AmpCampAmp -Me at BAF'18 -Me at BAF'19

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7th October 2020, 09:09 PM	#4871
PKI diyAudio Member Join Date: Aug 2011	BTW I have my new built running nice with the Aikido preamp. I like what I hear a lot.

8th October 2020, 02:15 PM	#4874
soldersmoker diyAudio Member Join Date: Aug 2005	Uh-oh. I was moving my main stereo to another room when I fumbled my F4 and semi-dropped it, managing to recover so it didn't hit the floor, though it landed in a chair. When I listened later, one channel was about 1/3 the loudness of the other. Switching loudspeaker connections confirmed that one channel was weak (but I'm not 100% sure it's not the preamp yet; to be confirmed later). Aside from looking for anything broken and maybe checking the bias, is there any other troubleshooting tricks I can try?

8th October 2020, 07:03 PM	#4877
soldersmoker diyAudio Member Join Date: Aug 2005	Oops. Yes, it looks like one of the tubes in the preamp is in need of replacement. Never mind! But at least I know how to proceed in the future in the unlikely event I need to fix the amp. Thanks, everybody.

3rd December 2020, 05:17 AM	#4880
cal3713 diyAudio Member Join Date: Mar 2014	Great, thanks. I read that there could be some problems if the windings weren't matched even if nominally rated as identical. Was thinking that really wouldn't be a problem here, but thought I'd go ahead and check. In many cases, I think the concern came from using identically rated secondaries across different transformers, thereby increasing the chances of voltage differences.