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SUPPORT FORUMS FOR ZKITS >> ZKIT 1 Support forum >> First Amp Done
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Message started by mboxler on 12/08/12 at 04:32:49

Title: First Amp Done
Post by mboxler on 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.

Title: Re: First Amp Done
Post by mboxler on 12/08/12 at 04:34:50

Inside...

Title: Re: First Amp Done
Post by mboxler on 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.

Title: Re: First Amp Done
Post by Real on 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

Title: Re: First Amp Done
Post by mboxler on 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

Title: Re: First Amp Done
Post by Lon on 12/08/12 at 16:31:19

Looks great Mike!

As for the changing sonics. . . that's likely break in.

Title: Re: First Amp Done
Post by jpv on 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 :)

Title: Re: First Amp Done
Post by mboxler on 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

Title: Re: First Amp Done
Post by mboxler on 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

Title: Re: First Amp Done
Post by Lon on 12/19/12 at 15:51:29

Sorry to hear that. Hope you can get it up and running.

Title: Re: First Amp Done
Post by mboxler on 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

Title: Re: First Amp Done
Post by jpv on 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?

Title: Re: First Amp Done
Post by mboxler on 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

Title: Re: First Amp Done
Post by mboxler on 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

Title: Re: First Amp Done
Post by jpv on 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

Title: Re: First Amp Done
Post by mboxler on 02/15/13 at 16:09:20

Hi John

Second amp is going slow. I received the repaired chassis Christmas Eve from Keith, the guy who built it to begin with. He did a great job. A few days later, I noticed his listings had been pulled from Ebay. I e-mailed him, just to make sure all was okay. No response. Eventually, I Googled his name, and his obituary popped up...he passed away Christmas day. Although I had never met him, I was saddened. The repair of my chassis was one of the last things he did before passing. Every time I tried to start drilling into the repaired chassis, I choked up. Strange how you can develope a relationship with someone without even meeting them.

Anyway, I'm slowing getting to the second amp. Unfortunately, the first amp seems to have a problem...highs are getting very grainy. I wonder if I damaged it more than I thought. I hope the second one sounds okay, then I'll redo the first.

I'm using a 6N1P-EV in front. What are you using? How's your amp sounding?

Mike

Title: Re: First Amp Done
Post by jpv on 02/15/13 at 18:50:10

Wow that is horrible to hear. :( That will make this amp even more special.

I am using a 6JD8 right now. I will substitue a 6922 after I do more listening with the 6DJ8.
The amp sounds really good I am very happy with it right now.
I did hook it up to my main system but I think it doesn't like my pre amp too much, I was getting a strange hum that was more of a growling sound, It startd off low them gets louder then it stop. and repeat. It did this in a period of about 1 second. It also changes in loudness with the volume control. When I hook it to my PC all is OK.
Maybe I am over driving the front end.
Life is too short not to listen to great equipment.
ITFWSWC
John

Title: Re: First Amp Done
Post by Real on 02/24/13 at 00:55:19

Hi Guys,
I just finish my amp.
I have not tried it yet, maybe tomorow?
I want to make sure one more time, to check all the conections
before I power it up.

Wish me luck.
Here is a couple photos.
Real

Title: Re: First Amp Done
Post by Real on 02/24/13 at 00:57:53

Here is the back

Title: Re: First Amp Done
Post by jpv on 02/24/13 at 16:46:46

Real,
Nice job. I like the Decware sticker you have on the back.
How did you do that?
Can we see a picture of the insides?
I know when I powered mine up for the first time it made me nervous.
Click the button and stand back and wait. I have two stitches on mine one for the heaters and one for the power. I haven't had much problem with mine. I put in a 6922 in place of the 6DJ8. I like the 6DJ8 better so I will put it back.
Good luck and Happy listening.
John

Title: Re: First Amp Done
Post by Real on 02/24/13 at 19:11:04

Hi John,

Turn it on this morning.
Voltage were fine except for one of the D location,number 8
Pin was off.
Plug in the CD player and an old pair of
Boston acoustic HD9. Great sound out of one channel.
Low volume on the other. upon closer look
I notice I Touch one of the capacitor with the soldering iron
when I was soldering one of the blue and white wire on the
output transformer. I have ordered a replacement.
Hopefully that is the only damage.
I'm very impressed with the sound.

I'll get more photos on later.
The logo was taken off the web site and printed on clear label stock.

Title: Re: First Amp Done
Post by jpv on 02/25/13 at 00:08:11

Real,
i did the same thing to my capacitors. I ordered two of them the second time around for a spare.
I was touching up some of the soldering joints when I rested the iron on the cap. I noticed it before I started it up so I had no risk of damage.
I will have to see if I can figure out how to made a sticker like that.
John

Title: Re: First Amp Done
Post by Real on 02/26/13 at 00:44:03

Hi John,

That is funy I ordered 3 just in case.

I just copy and paste the logo off the web site
and printed it on a lazer printer using clear label stock.
Make sure it is clear some say clear but are cloudy.

Here is the picture of the inside.

Real

Title: Re: First Amp Done
Post by mboxler on 08/07/13 at 17:01:33

An update on my project...warning, if I sound pumped, it's because I am.

Both amps are completed. I had to re-build the first one, as components continued to fail due to shorting the board during the inital build. I also replaced the coupling caps wih Jupiter Beeswax HT series caps.

I commissioned Al Klappenberger (alkeng.com) to build me a special version of his extreme slope (120dB) crossover from the mid to tweeter for my Klipschorns. I completed an active crossover from Marchand Electronics, with a 24dB cross at 300 Hz. One Zkit1 drives the woofers, the other connects to the new crossover. Since the bass efficiency is about 104dB, and the mid-tweeter is about 109db, the bass Zkit1 is at full volume, and the one to the passive crossover around 2-3 o'clock.

The imaging is stunning. It's as if these hugh speakers have disappeared, and the music is coming from the entire wall. I listened to "Caverna Magica" by Andreas Vollenweider, and thought I was in a cave!

I'm using the pre-outs from my AVR now, but will switch to a Schiit Bifrost DAC and Dodd audio tube preamp soon. It can only get better!

Mike