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Author Topic: New Build Stereomour II [resolved]  (Read 2872 times)

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Offline amritdesai

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New Build Stereomour II [resolved]
« on: January 04, 2016, 07:59:26 AM »
I've been waiting some time to build a stereomour unit and to say I was excited when the kit arrived is an understatement. I have a pair of Zu Audio Soul 99dB and plan to run them with this amp.

I decided to build my own base from walnut to match my speakers - I built the base frame at 6" and the top plate sits around an 1" below resting on some brackets. I'm not a huge fan of the swirly scratches on the plate so I bead blasted the surface. Overall, I like the contrast between the walnut, the silver plate and the various components that are visible on the plate.
« Last Edit: January 20, 2016, 11:35:14 AM by Caucasian Blackplate »
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Offline amritdesai

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Re: New Build Stereomour II
« Reply #1 on: January 04, 2016, 08:25:00 AM »
I don't have much experience building tube amps but recently finished a Quickie just to familiarize myself with the Bottlehead instructions, etc. I recommend for beginners to start with a project like this prior to building the Stereomour II.

I found a good set of thin needle nosed pliers to make a huge difference in handling wire, wrapping it around posts and making mechanical connections. Also, invest in a good wire stripper and light!

The amp took me about a week to build and I found the instructions to be thorough and well organized - I was very impressed. The project came together without any issues.
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Offline Natural Sound

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Re: New Build Stereomour II
« Reply #2 on: January 04, 2016, 08:37:50 AM »
Very nice job so far. I'd kill to have a selection of hardwood like that! A photo with the finished wood / Stereomour II would be appreciated. And most importantly, it would be nice to hear your impressions of the sound.

Offline amritdesai

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Re: New Build Stereomour II
« Reply #3 on: January 04, 2016, 09:54:44 AM »
While testing post 7 and 14 was reading ~ 252 VDC. This seemed a bit high... Also, at terminal 10 and 11 I was getting over 0-50KΩ closer to 65KΩ, although I think the variation in these readings were due to the position of the volume/balance controls as stated in the manual.

Because all of the other measurements were very close and within what I thought was an acceptable range I went ahead and tested the amp with speakers.
I was particularity impressed by how quiet the amp was. There is very little noise or interference - something I had to deal with more with the Quickie build.

I spent the afternoon blasting my favorite tunes really enjoying quality and character of the Stereomour II. With this amp the bass was noticeable louder and overall the sound was much more rich and textural.

More pics and impressions to follow.
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Online Paul Birkeland

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Re: New Build Stereomour II
« Reply #4 on: January 06, 2016, 09:40:16 AM »
Please do remember that the rubber feet on the wood base provide an entry point for cool air, and are part of how the amplifier maintains a reasonable temperature.

I love those big black knobs!
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline amritdesai

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Re: New Build Stereomour II
« Reply #5 on: January 09, 2016, 08:29:48 AM »
Thanks Paul! I'll put the feet on.

I decided to check all my voltages again because I was getting ~258 VDC at terminal 7.

I made the mistake of measuring terminal 32 and heard a pop :-\ Afterwards, the two LED's closer to the front of the top plate are out. Terminals 11 reads -.462VDC, terminal 14 reads -.942VDC, 15 reads .024VDC, 17 reads -.14VDC, terminal 19 reads -.129 20VDC, reads -.03VDC, and so on. Essentially, the entire left channel is out.

Clearly something happened and I have no idea where to start. Super bummer  >:(

Help would be greatly appreciated. 



« Last Edit: February 08, 2016, 03:38:36 PM by amritdesai »
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Online Paul Birkeland

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Re: New Build Stereomour II
« Reply #6 on: January 09, 2016, 08:36:04 AM »
I think you may have blown the fuse.  258V at terminal 7 is a function of the 12AT7, which may just need to run for a little while.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline amritdesai

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Re: New Build Stereomour II
« Reply #7 on: January 09, 2016, 08:48:20 AM »
Okay, I checked the fuse and it's fine.

All voltage measurements on the right channel are fine. The entire left channel is all over the place and the 2A3 tube is not heating. I hooked the amp up to a smaller set of speakers - the right channel is playing music the left channel is silent with not interference or noise.

Doing a resistance check now. Thanks again Paul for your help.
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Offline amritdesai

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Re: New Build Stereomour II
« Reply #8 on: January 09, 2016, 09:05:23 AM »
I performed a resistance check. Everything is fine. No visual damage that I can see...

Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Online Paul Birkeland

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Re: New Build Stereomour II
« Reply #9 on: January 09, 2016, 09:19:28 AM »
It's odd, the heating of the 2A3 is independent of the heating of the 12AT7, all of which are independent of the high voltage supply.

I would start by swapping tubes, just to see if anything might follow a tube. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline amritdesai

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Re: New Build Stereomour II
« Reply #10 on: January 09, 2016, 09:35:02 AM »
Paul,

I switched tubes around and same issue. Both 12AT tubes glow but only the right 2A3 tube glows (even after switching).

I really appreciate your help.
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Online Paul Birkeland

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Re: New Build Stereomour II
« Reply #11 on: January 09, 2016, 09:54:08 AM »
What AC voltage do you get between pins 1 and 4 on the 4 pin socket of the offending side?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline amritdesai

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Re: New Build Stereomour II
« Reply #12 on: January 09, 2016, 10:46:55 AM »
Paul,

D1: 0
D2: -1.34
D3: -.2
D4: 0

Thanks,

Amrit
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses

Online Paul Birkeland

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Re: New Build Stereomour II
« Reply #13 on: January 09, 2016, 10:57:05 AM »
Put your red probe on D1 and your black prove on D4, then set your meter to AC volts and see what you get.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline amritdesai

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Re: New Build Stereomour II
« Reply #14 on: January 09, 2016, 11:13:37 AM »
Getting 2.53v.

Amrit
Zu Audio soul Mk II, w radian 475
Zu Mission Cables
Stereomour II, JJ 2a3 40
Clearaudio Concept Wood Ortofon Black
Eros Phono Pre
Schiit Bifrost DAC
Synergistic Research Black Fuses