Salas hotrodded blue DCB1 build

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70C internally. Under 100C chip temp no problem. I would care more of what temperature the electrolytics will be living their life after the build will be wrapped up in a box. The board is made by the most expensive standards the most expensive fab house had to offer. Its sturdy. Fuse the primary, some hard failure would destroy anything PCB at such current settings.
 
Just verifying

I am going to use a hammond 182 series toroid for the testing.

The connection diagrams are as follows

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The wiring required is the series one right? And Blue+Grey go to the center?

Thanks again
 

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Thanks a lot Niko :)
You guys have been amazing from the start!!

I finally decided to go with the aluminum plate, since I like to have some space to add the volume controls and other things. I can always include some more heatsinking if necessary.

And finally, after triple checking everything, I got my nylon shoes on, got my trusty lamp tester and plugged it in...

And there was light :)

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To be honest that big chunk of metal got me really nervous about mains leaking and I checked it about 5 times before feeling comfortable to start measuring voltages. But all is well...

The relay clicks after a while and all leds are on.

The measurements I got with the 2x12V 120VA hammond are as follows

Vout: 9,90V and -9,95V
Offset: -0,9mV and -1,5mV
10R resistor voltage: 1,58V and 1,571V

After 5 minutes

Vout: 9,87V and -9,92V
Offset: -1,1mV and -1,5mV
10R resistor voltage: 1,57V and 1,567V

After 5 minutes I removed the lamp tester and remeasured

Vout: 9,87V and -9,92V
Offset: -0,9mV and -1,7mV
10R resistor voltage: 1,575V and 1,569V

and final measurement after 5 minutes

Vout: 9,86V and -9,91V
Offset: -1,1mV and -1,7mV
10R resistor voltage: 1,575V and 1,569V

Isn't the voltage accross the 10R resistors a bit low for its size? Could it be the 12V secondaries?

Unfortunately the only alternative I have are some 2x18V @300VA I got for my F5 build.
 

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diyAudio Chief Moderator
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Stay with that Tx. PSUs and offsets are fine. ~160mA or 200mA will not make any appreciable difference. Its all down to Vds and Vgs in the MOSFETS. When you will go high hot rod do parallel to installed 10R tests with cheap cement resistors to see your CCS currents (CCS=Rset/V across it). Then you buy adequate Mills. I suggest 1A to 1.2A. That will be enough if targeting high.
 
And then diyaudio said... let there be sound :)

I tried initially behind my plain pot passive volume control for safety.
No problem, so now I am listening to Pink Floyd through my new buffer :)


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I have used an alps 132M-20KAX4 motorized pot, neutric RCA sockets and Mundorf Supremes @0,47uF for output coupling.

First impressions are very positive. Unfortunately it' s late so...
It sounds a bit thin for now, but it could be the fresh mundorfs.
What gets you immediately by surprise is the soundstage. Very very nice :)

Next step tommorrow will be to get the side walls of the chasis set so that I can properly hook up the sockets and the pot
 

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diyAudio Chief Moderator
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Do you really need coupling capacitors? Is the amp DC input? Nice pods for the 1200 MKII btw. What does it carry? A Denon cart? See for a multi relay discrete resistors pot kit if you will keep the buffer and you absolutely need remote control. Alps is so so.
 
The amp is DC coupled to my knowledge (Electrocompaniet AW120 DMB)
I intent on building an F5 too anyway, so I will need the caps. A friend also gave me some silver-gold mundorfs. I will try these too eventually.

About the volume control, I already have a lightspeed which I intent on controling with a controlable pot and an arduino. The arduino is already working with an Apple remote and an encoder for manual operation. I just need to find some way to properly set the steps for the lightspeed pot. I got some digital pots, but their steps are not as fine as I would have liked. I will give them a try though.

About the MK2, the pods are made out of graphite. A friend makes them. They are amazing at dumping vibration and they really get any device I have used them on, on a completely new level. I also have some for the CD. Only the electrocompaniet did not like them and prefered some ebony spikes.
The MK2 carries for now a Shelter 501 when I am playing with my MC phono. When my MC phono is out for "fixing", I also use a Clearaudio Virtuoso.
 
By the way, with the ~150mAs the mosfets were absolutely cold to the touch after a few hours of listening.

I m ready to go higher :) I will leave it like that for a week or so to let it break in a bit and get a more solid idea of its sound while I work on the chassis and the volume control, and when everything else is more or less done I will hookup additional resistors.

I have some cheap 12R 5W ones which will be perfect for testing as you suggested :)

Some more first impressions after a few hours of low volume CD listening:
I have listened to a few CDs including some nice classic music by FIM (very nice mastering on most of them) and then some Classic Records. After that I switched to some plain rock and pop CDs. What got me by surprise was that some CDs that I considered really bad amazed me. Like the Metallica S&M. On the other hand some mediocre ones remained mediocre. Like the FIM Scotish Fantasy by Oistrach
The buffer seems really fast. The highs are excellent, the lows seem to go really low and are very very controlled and powerful.
I have some reservations about the mids and mid-lows but it could be because of the fresh mundorfs, the low volume and the cheapish pot.
About the soundstage, it is so freakishly wide even with that low volume. There are microdetails everywhere and the speakers have completely dissapeared. What was weird was that at some points the sounds were a bit fuzzy, almost as if the sound was out of phase. But this could also be because of the rough placement of the speakers.

My first day overall impression is that if I manage to get more focused soundstage and a bit more bite to the mids I will be crazy happy :)

In any case, the buffer is a keeper. And it had some really big shoes to fill since it replaced an Arc LS-25 and a Klimo Merlin
 
By the way, with the ~150mAs the mosfets were absolutely cold to the touch ............
This is cause for concern.
A CCS + Shunt regulator dissipates much energy. It's inherent in the design philosophy.

If the input voltage is too low then the CCS mosFET has less work to do. If it is much too low then the CCS mosFET will remain cold due to zero dissipation.

If the output current is very close to the CCS current then the Shunt mosFET will have little work to do.
If the output current equals the CCS current then the Shunt mosFET will be cold.

If Dim's observation is correct, then the CCS and the Shunt are not working.
Dim needs to properly measure the regulator and determine that it is working properly or actually report the true temperature rises of both the CCS mosFET and the Shunt mosFET.
 
I m not at home right now to measure stuff, but last night the regulator gave ~9,9V on each rail Vout.

Perhaps it was an exaggeration to say "absolutely cold". They were rather "not warm" or "finger temperature".

In any case Andrew just to play it safe, what measurements would you suggest?