Salas hotrodded blue DCB1 build

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Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
mrWagner said:
I also have positive offset on the out.
In the build guide this is written: "If you got DC audio out offset in the +/-5mV range, just drink a beer. Forget it."
So does it have to be negative or not?
What can be done to make it negative?
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We see two JFETs electrically chained vertically in any DCB1 channel, one at the top for signal and one at the bottom with gate and source strapped together for CCS. When they are not 100% same IDSS in all temperatures and the supplies are not 100% same DCV in all temperatures there will be some little offset. Since in everything made on Earth by humans and nature there are tolerances and drifts, we inevitably measure very few mV DC on every DCB1's output at a point. Most builders report in the +/-2mV or less.
If we choose the top JFET to be the one with the slightly higher IDSS in a pair then the offset will result negative given the supplies are very near also. Theoretically we would like the bottom JFET not able to overdrive the top one. Still there is no practical difference that I have seen in THD after differences so tiny. Some builders had mutually swapped JFETs within each pair after the matching and PSUs tolerances conspired somehow to an X result in a finished board, so to try finally measure it tiniest possible and negative in polarity. For aesthetic purposes mainly since nobody reported any plausible benefit. Experimental errors and ambient temperature range can render all the above futile also. So back to square one, i.e. better kick back a beer.:D
 

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poseidonsvoice

poseidonsvoice

Member
Joined 2004
audiocircle.com/gallery/index.php?cat=48485
Paid Member
Corpius said:
Happy new year to you all!

In September I finished my DCB1 build and using it for 4 months now to my full satisfaction. Today I added an article about my build on my website for those who are interested:

Salas HOT ROD DCB1

Cheers Robert
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Fantastic Robert! What a great build to ring in the new year!

Thanks for the eye candy, and now enjoy your ear candy!

Best,
Anand.
 
Corpius

Corpius

Member
Joined 2011
ce-designs.net/
Salas said:
How much they charge for say a 100VA Toroidy with static and magnetic shield including shipping I wonder. Has anybody asked those guys?
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I bought this audio grade 400VA 2x18V toroidal transformer from toroidy two months ago. It did cost me about 75 euro's!
The quality is much higher compared to other trannies that costs the same. Epoxy filling, electromagnetic shielding, absolutely no hum and very descent primary and secondary wires. A real bargain if you'd ask me. You have to send a email to Tomasz if you want to order from Toroidy. He can send you a paypal invoice. It took about three weeks for the transformer to arrive, but he told me that they where having manufacturing problems at the time I placed my order, it should normally be shipped faster.

Here's the link to the specific transformer: TTSA0400 - Transformator AUDIO TSA400VA - napi?cie do 50 V Toroidy.pl
I had to use google translate in order to read it :) My Polish is not that good :D
 
E

Erlend Sæterdal

Member
Joined 2007
Corpius said:
I bought this audio grade 400VA 2x18V toroidal transformer from toroidy two months ago. It did cost me about 75 euro's!
The quality is much higher compared to other trannies that costs the same. Epoxy filling, electromagnetic shielding, absolutely no hum and very descent primary and secondary wires. A real bargain if you'd ask me. You have to send a email to Tomasz if you want to order from Toroidy. He can send you a paypal invoice. It took about three weeks for the transformer to arrive, but he told me that they where having manufacturing problems at the time I placed my order, it should normally be shipped faster.

Here's the link to the specific transformer: TTSA0400 - Transformator AUDIO TSA400VA - napi?cie do 50 V Toroidy.pl
I had to use google translate in order to read it :) My Polish is not that good :D
Click to expand...

You can choose to select English on the site :)
 
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