Salas hotrodded blue DCB1 build - Page 286

Tea-Bag · 02:20 PM

This is the unit I now ship with the kits.

6237BG - Board level heatsinks

Some people use non at all on the 7812. I have not heard of one blowing up.

I have updated the BOM on page 1 to reflect this. There are sometimes part substitutions as kit stock as I order it is not available.
Often if one vendor runs out, they all might.

mantha3 · 3rd March 2013, 02:26 PM

Cool...

I was planning to do two sets of output using the Salas advised "100 Ohm buffer resistors Y split" This VU board has a R/L channel input...

So would I do the Y split on the two sets of RCA outputs and then run a 3rd set of outputs to this VU board I think

So I'd have for a channel output off of the DCB1 3 lines out. I'd Put 100R in line with each output RCA. Think I should run a line direct from the DBC1 to this VU board or should I put a 100R inline here to the VU as well?

stajo · 3rd March 2013, 04:50 PM

A question about CCS differences due to PMOS/NMOS Vgs differences. I had less currentdraw on the negative rail on all 4 cards, as mentioned before. The relation is about the same on all cards. Putting a 56R over 10R on negative side makes about 8,4R measured and that about balanced it out. That makes a relation 8,4/10.

Do you think this relation will stay if I grill each side a bit more? I was thinking to buy some 3,3R and 4,0R caddocks, but they dont come free.

best regards
Staffan

Tea-Bag · 3rd March 2013, 04:52 PM

Quote:

Originally Posted by stajo

A question about CCS differences due to PMOS/NMOS Vgs differences. I had less currentdraw on the negative rail on all 4 cards, as mentioned before. The relation is about the same on all cards. Putting a 56R over 10R on negative side makes about 8,4R measured and that about balanced it out. That makes a relation 8,4/10.

Do you think this relation will stay if I grill each side a bit more? I was thinking to buy some 3,3R and 4,0R caddocks, but they dont come free.

best regards
Staffan

I beleive Salas voiced it, or deemed it to sounds better out of balance this way ---- but it may not to you.
BTW, this issue occurs in the SSLV1.1 boards as well, but there you want to correct it.

stajo · 3rd March 2013, 04:59 PM

Quote:

Originally Posted by Tea-Bag

but it may not to you.

I wouldnt know, since I have not yet listened

Well, I'm working on a second hand baught malfunctioning lightspeed, thats why. Guess Ill plug'em in one day with a standard pot, but I havent yet.

Thanks
Staffan

Salas · 3rd March 2013, 05:43 PM

Quote:

Originally Posted by Tea-Bag

This is the unit I now ship with the kits.

6237BG - Board level heatsinks

Some people use non at all on the 7812. I have not heard of one blowing up.

With that one I would not draw over 300mA from the 7812 for long term reliability.

stajo · 3rd March 2013, 05:51 PM

I looked back how the values change before and after CSS adjustment.

Before:
Vout: -10,01 +9,98
DC offset L/R mA: 0,3/1,1

After:
Vout: -10,7 +10,4
DC offset L/R mA: 0,7/0,6

But after all, the values are so small it might be measuring faults, temp drifts whatever.

Salas · 3rd March 2013, 08:49 PM

Tc most likely.

stajo · 4th March 2013, 06:00 PM

Today the dare devil flew in me

Salas · 4th March 2013, 06:10 PM

To exactly balance the main CCS currents (offsetting the PMOS-NMOS Vgs dif in essence) is mostly perfectionism since the Gfs of such MOSFETs does not vary appreciably for few decades of mA dif even. But perfectionism achieved gives satisfaction and peace of mind which is a welcome factor to any hobby.

3rd March 2013, 02:16 PM	#2851
Tea-Bag not politcally affiliated diyAudio Member Join Date: Feb 2006 Location: Kennebunk Blog Entries: 7	This is the unit I now ship with the kits. 6237BG - Board level heatsinks Some people use non at all on the 7812. I have not heard of one blowing up. I have updated the BOM on page 1 to reflect this. There are sometimes part substitutions as kit stock as I order it is not available. Often if one vendor runs out, they all might. __________________ Salas Boards 2013 #2 CLICK HERE \| F6 Covertible PCB GB Boards Available \|DCB1 boards and KITS available PM\|SemiSouth R125, R100, R100A Available CLICK HERE \|F5TC Boards Sign UP CLICK HERE Last edited by Tea-Bag; 3rd March 2013 at 02:20 PM.

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3rd March 2013, 02:26 PM	#2852
mantha3 diyAudio Member Join Date: Oct 2010	Cool... I was planning to do two sets of output using the Salas advised "100 Ohm buffer resistors Y split" This VU board has a R/L channel input... So would I do the Y split on the two sets of RCA outputs and then run a 3rd set of outputs to this VU board I think So I'd have for a channel output off of the DCB1 3 lines out. I'd Put 100R in line with each output RCA. Think I should run a line direct from the DBC1 to this VU board or should I put a 100R inline here to the VU as well?

3rd March 2013, 04:50 PM	#2853
stajo diyAudio Member Join Date: Jun 2011 Location: Stockholm	A question about CCS differences due to PMOS/NMOS Vgs differences. I had less currentdraw on the negative rail on all 4 cards, as mentioned before. The relation is about the same on all cards. Putting a 56R over 10R on negative side makes about 8,4R measured and that about balanced it out. That makes a relation 8,4/10. Do you think this relation will stay if I grill each side a bit more? I was thinking to buy some 3,3R and 4,0R caddocks, but they dont come free. best regards Staffan

3rd March 2013, 05:51 PM	#2857
stajo diyAudio Member Join Date: Jun 2011 Location: Stockholm	I looked back how the values change before and after CSS adjustment. Before: Vout: -10,01 +9,98 DC offset L/R mA: 0,3/1,1 After: Vout: -10,7 +10,4 DC offset L/R mA: 0,7/0,6 But after all, the values are so small it might be measuring faults, temp drifts whatever.

3rd March 2013, 08:49 PM	#2858
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Tc most likely.

4th March 2013, 06:00 PM	#2859
stajo diyAudio Member Join Date: Jun 2011 Location: Stockholm	Today the dare devil flew in me

4th March 2013, 06:10 PM	#2860
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	To exactly balance the main CCS currents (offsetting the PMOS-NMOS Vgs dif in essence) is mostly perfectionism since the Gfs of such MOSFETs does not vary appreciably for few decades of mA dif even. But perfectionism achieved gives satisfaction and peace of mind which is a welcome factor to any hobby.