Vintage HiFi Audio Forum
Audio Discussion => DIY => Topic started by: TNRabbit on January 31, 2012, 02:22:04 PM
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I have 3 of the 4 amps done. 3 & 4 are stainless steel chassis~
Amp 1: built at CF
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03658.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03659.jpg)
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(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03666.jpg)
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(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03669.jpg)
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(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03675.jpg)
Amp 2
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03676.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03677.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03678.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03679.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03680.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03681.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03682.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03683.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03684.jpg)
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(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03697.jpg)
Amp 3: trying to troubleshoot a low output on this one right now.
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03698.jpg)
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(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03713.jpg)
Followup pics of amp 3 with the zener diodes added:
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03722.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03723.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03724.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03725.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03726.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03727.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03728.jpg)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03729.jpg)
Here's a couple of videos with them running various speakers. They dig LOW for little bitty things!
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/th_20120127001803.jpg) (http://s251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/?action=view¤t=20120127001803.mp4)
(http://i1049.photobucket.com/albums/s386/tinpan49/th_CarverfestAmps1.jpg) (http://s1049.photobucket.com/albums/s386/tinpan49/?action=view¤t=CarverfestAmps1.mp4)
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(http://www.parts-express.com/images/item_large/060-370_l.jpg)
BTW, if anyone needs a power switch for a project, these are FANTASTIC and only $1.69:
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=060-370&scqty=4 (http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=060-370&scqty=4)
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Very cool Rabbit! 8) It's great that you have been documenting your builds. I have yet to build mine... :-[
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Thanks, Rev~
i worked like a maniac at first, then took a long break when I got two completed early on & had issues with them. Got those ironed out last week & now once I get the issue fixed on #3, 4 won't take long at all.
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Rabbit, If you do well making these amps, you should see if you can work for Bob Farinelli and keep making Bob Carver amps and get paid for it!
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Amp 3 was giving me fits with low output. Figured it out by accident this morning; started prodding on components while I had it running & found a bad solder joint on this resistor/cap from input tube 1:
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC03735_marked.jpg)
It's alive.....ALIVE.........ALIVE!!!!
(click on this image for video)
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/th_20120201142128.jpg) (http://s251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/?action=view¤t=20120201142128.mp4)
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Rabbit, If you do well making these amps, you should see if you can work for Bob Farinelli and keep making Bob Carver amps and get paid for it!
I'd never make money with the amount of time I have in these~
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I'd never make money with the amount of time I have in these~
..Galad you got it up and running Gary!!! ;)...You are right about the time and $$$...glad I had mine built or they would still be in kit form.... :o
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Decided to upgrade the rectifier diodes about 3 weeks back.
Got the rectifier diodes in today; they don't look anything like the pics on Digikey, but the papers show the same specs:
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/DSC04062.jpg)
Sound good on this video (amp #3):
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/th_20120222233332.jpg) (http://s251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/?action=view¤t=20120222233332.mp4)
But now I have a problem with amps 3 & 4; individually, they both sound great & very quiet. When I plug the input for right channel into one & input for left channel into the other one, I get a terrible ground loop hum. I've been through every single connection; no bad solder joints or grounds. It even does this when one amp is OFF, but goes away if you UNPLUG one of them. This happens whether the input is plugged into my Zune player or not. Here's a video:
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/th_20120223010119.jpg) (http://s251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/?action=view¤t=20120223010119.mp4)
Any ideas?
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Looks like you will have to lift the ground wire of the power plug on one or both amps.
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Ran them all with only the ground/hot when I wired them.....any other ideas?
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No difference touching a wire between the chassis.
No voltage AC or DC between the chassis, but I get a WEIRD continuity reading between the two chassis' that sounds gutteral instead of the usual steady tone.....?
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maybe try reversing the polarity of the plug ?
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No difference touching a wire between the chassis.
No voltage AC or DC between the chassis, but I get a WEIRD continuity reading between the two chassis' that sounds gutteral instead of the usual steady tone.....?
Here's more info--I get .28 VDC across the other end of the input between ground & positive/hot on one amp & .30 VDC on the other amp.
Video:
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/th_20120223093915.jpg) (http://s251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/?action=view¤t=20120223093915.mp4)
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Well, swapped the polarity & still have the same problem. I'm beginning to think I may have a bad transformer.....
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Usually when there is a ground loop problem you will measure ac volts between the RCA plug and the chassis ground.
Do you still get the hum just touching the grounds of the RCA plugs to the amps ?
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Extremely small hum if touching the grounds together with a wire. HUGE hum if touching the hot with even two entirely separate interconnects. On the carversite, they suggested switching the leads on the output transformers on one amp....
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Swapping output transformer speaker wires should make no difference.
Did you try putting a ground lifter on both the power cord plugs ?
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OK, here's where I'm at:
I thought Gary swapped the power transformer already.
This is what Mike wants you to do:
Swap the output transformer leads on one amp.
Yes, I know that looks like 5hi7.
OK: tried this swap & got VERY BAD SOUNDS immediately. Sounded like a bomb whistling/dropping, followed by a very destructive sounding bass buzz getting lower & lower. Unplugged everything immediately. BAD CHOICE--note to self--don't try that again!
Also swapped the incoming power wires with no effect.
Another observation: The constant buzz sounds out of phase on the speakers; if I swap speaker leads it's in phase. However, then the music is out of phase.
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Here's the output transformer swap that was suggested:
(http://i251.photobucket.com/albums/gg286/TNRabbit/Audio/CarverFest%20Amp%20Build/OPTswapsuggestion.jpg)
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Crap. I was attempting to reverse polarity on the main input power by use a pigtail (stupid) & had a huge fireball, big bang, & blew fuses....
Amp #3 now blows the mains fuse every time I apply power to it.
Buzz is still there on #4 when they're both plugged in. No closer than I was before, but now I have a DOA amp.
So, I sent an email to Bob C. with a link to the thread on carveraudio to see what advice he could offer:
Bob's reply:
Sent: Thursday, March 1, 2012 4:20 PM
Subject: Re: Need help with CarverFest amplifiers, Please!!
Hi Gary, wow, trouble in river city!
First thing is get some good output tubes. The Electro Harmonix are great and have a nice high voltage rating.
Then replace the DC restorer 1n4148 diodes with 1n4004 units. Replace the 15 volt zener with two 5 watt units hooked in parallel. Amp should work then. As for blowing fuses immediately, check the power supply diodes for a short. Use a simple VTVM and just measure them in-circuit. If one shows a dead short, replace it. As for the hum unit, it sounds as if the AC line is somehow connected wrong. Just inspect it careful and I'm sure you will find the problem just by looking hard with your eyeballs. Be careful, because right now I think you may have a severe shock hazard on your hands with this amp until you find the trouble.
If all else fails, send them to me. I'll fix 'em right up!
No sweat,
Bob Carver
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Here while back, Bob Farinelli told me that Bob Carver LLC was going to offer a trade-in option on the new, improved Baby Black Beauties for those who built tube amps at CarverFest 2011. The new amps have improved power & output transformers....I guess we were the "Alpha Testers" ~
He gave me the details today:
Bob Farinelli
First thoughts
1. Must turn in your unit. As is, workie, no workie, tubes, no tubes, doesn't matter.
You must promise not to sell your new unit for at least a year.
It will be brand new and carry the 7 year warranty. (1 year on tubes)
We will reserve a block of serial #s starting with 001 through 030.
Retail price is $2100.
Price to those who turn in carver Fest units:
$999.
Bob (Carver) might shoot me over this, but you guys who sat with me and built amps are friends and family.
Spread the word. This is only available for amps turned in.
Thx
Bob