Forums - First Amp Done

mboxler Senior Member Posts: 69	First Amp Done 12/08/12 at 04:32:49 Decided to wire stereo. Can easily make mono using input jacks and speaker outputs. This is really the second chassis...really screwed up the first one. Sent the first one back to be repaired, as he did not have any more of this beautiful figured maple.
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mboxler Senior Member Posts: 69	Re: First Amp Done Reply #1 - 12/08/12 at 04:34:50 Inside...
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mboxler Senior Member Posts: 69	Re: First Amp Done Reply #2 - 12/08/12 at 04:39:19 Testing with zigmahornets (still unfinished), Dodd Audio Buffer, Schiit Bifrost DAC, Squeezebox Touch. Will soon drive the Klipschorns in the backround.
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Real Verified Member Posts: 21	Re: First Amp Done Reply #3 - 12/08/12 at 16:01:39 Hi Mike. It look very nice how does it sound? I'm still waiting for my board and transformers and I still have not decided on the case. Real
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mboxler Senior Member Posts: 69	Re: First Amp Done Reply #4 - 12/08/12 at 16:23:24 Odd...sounds great for a while, dull for a while, back to great... I assume it's breaking in. May hook them up to the Khorn's today for a test. If there's any speaker hum, they will let me know. Case gets really warm. May have to enlarge holes on the bottom. I'll keep you posted. Mike
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Lon Seasoned Member "Love without guts is worthless!" Philip K. D*ck Posts: 5232	Re: First Amp Done Reply #5 - 12/08/12 at 16:31:19 Looks great Mike! As for the changing sonics. . . that's likely break in.
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jpv Seasoned Member Cause inside everyone is a heavy metal kid Posts: 110	Re: First Amp Done Reply #6 - 12/11/12 at 01:15:38 Congrates on the first one. It looks great. So how does it sound with the Klipschorns? I hope they can handle all that power
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mboxler

Senior Member

Posts: 69

Re: First Amp Done
Reply #7 - 12/11/12 at 15:43:01

Still breaking in with the zigmahornets. Also a lot of tube rolling. I have a bunch I bought for my Schiit Lyr headphone amp, and the two amps can use the same driver tubes. Seem to like my National 6922's made in Japan, Mullard tooling I'm told. Great sound, less heater current than the 6N1P's (read...less heat!).

Last night, things seemed to really started to open up. The zigmahornets image so well, and the soundstage keeps getting deeper. Great timbre.

Going to open the amp up, make sure nothing is melting. May enlarge the cooling holes on the bottom while I'm at it. Also need to find some rubber footers, as it's sitting on rubber grommets to dampen the chassis.

So far so good! When I move the amp to the Khorns, I'll probably passive bi-amp, driving the bass section with a 60 watt ClassDAmplifier I built earlier this year. The tubes will drive the "top hat" section. Both amps have volume control, should be fun!

Will update when I have more info.

Mike

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« Last Edit: 12/11/12 at 15:43:35 by mboxler »

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mboxler

Senior Member

Posts: 69

Re: First Amp Done
Reply #8 - 12/19/12 at 14:57:30

Well, The party is over. Last weekend, I turned on the amp...nothing. Checked the fuse...blown.

Pulled the board out last night, starting testing components. Turns out that one of the diodes was bad.

When I originally soldered the amp together, at one time I forgot to unplug the power transformer. BIG spark, small puff of smoke near the B+ wire I was soldering, blown fuse. I replaced the fuse, and the amp ran great for a week. Thought I had gotten away with it. I wonder if that weakened the diode enough to fail a week later.

Last night, I replaced both diodes, and fired it up. No blown fuse. Started to check voltages...all over the map. Then...smoke! Unpluged the transformer, went to bed.

Wondering if the blown diode could have damaged other components. Will do some more tests.

Bummed!

Mike

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« Last Edit: 12/19/12 at 14:58:18 by mboxler »

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Lon Seasoned Member "Love without guts is worthless!" Philip K. D*ck Posts: 5232	Re: First Amp Done Reply #9 - 12/19/12 at 15:51:29 Sorry to hear that. Hope you can get it up and running.
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mboxler

Senior Member

Posts: 69

Re: First Amp Done
Reply #10 - 12/20/12 at 05:12:38

Had a couple of beers tonight, resumed trouble shooting. I couldn't find anything burned, all components checked out okay, as far as I could tell.

Connected power transformer only, powered on. Tubes glowing...NO SMOKE! Voltages are off, but attribute to outout transformers not connected (?). Voltage point C (bias for output tubes) show zero volts. Is this because output transformers not connected, or was I just shaking too much???

Connect output transformers. Power on. Waiting....Waiting...NO SMOKE! Checked voltages...

Output from diodes...426V

A 350V
B 308V
C 9.75V
D 2.95V

I let it sit for half an hour, still no smoke. I'm assuming either the mess I made de-soldering and re-soldering the diodes was burning off, or perhaps one of the transformer wires got too close to the big 'ol 1K resistor and burned a little.

I'll test some more. Can't believe it might be fixed. Will be glad to hear music again!

Mike

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jpv Seasoned Member Cause inside everyone is a heavy metal kid Posts: 110	Re: First Amp Done Reply #11 - 12/22/12 at 04:06:23 Mike, You had me worried, I'm glad to see it may have been something simple. How is the second one coming along? Is there anything you'r doing diff with that one?
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mboxler

Senior Member

Posts: 69

Re: First Amp Done
Reply #12 - 12/22/12 at 15:58:52

I sure hope that was the problem! Have things temporarily attached, and played music all day yesterday...still no smoke.

I'll be receiving the repaired second chassis today. I ordered some "better" rca input jacks. After soldering the positive wire to the RCA middle pin, I noticed that the insulator surrounding it got loose...I could spin the solder pin inside the jack. I hope the new ones don't do that.

I'll probably enlarge the vent holes I drilled on the bottom. Other than that, I'm happy with the way it is. As soon as the new RCA's arrive, I'll finish up the first one and copy everything to the second one.

Merry Christmas!

Mike

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mboxler

Senior Member

Posts: 69

Re: First Amp Done
Reply #13 - 12/29/12 at 15:08:47

Update

So far, keeps getting better! I've installed rubber footers from Ebay, and some nice Dayton RCA jacks from Parts-Express. Also installed a wooden knob, and enlarged the vent holes on the bottom of the case.

Thought the plastic film on the transformers was to protect the Edcor lettering. When I pealed them of, the lettering came off with it. Still looks good!

Replaced the RCA cables with DIY ones I made last summer...

http://www.6moons.com/audioreviews/whitelightning/moonshine.html

Really brought out the detail!

Hope to hook this up to my Klipschorns this weekend. My second chassis has been repaired, so I'm starting the second amp. Glad I wired them as stereo. Gives me the flexibility to go mono if I want. I'm surprised how much sound one can get from a couple of watts!

Mike

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jpv Seasoned Member Cause inside everyone is a heavy metal kid Posts: 110	Re: First Amp Done Reply #14 - 02/14/13 at 16:25:15 Mark, So how did the second amp come out?. I'd like to see them side by side. Also what are you using for input tubes? John
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