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?
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.
Attachments
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
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
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
where did you get that chassis? I like it!
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
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.
The chassis comes from Analog Metric in Honk Kong. It's a complete chassis with all holes pre-drilled. The RCA connectors, power inlet, power switch, fuse and knobs are all included, but the RCA connectors are of low quality.
edit: it also comes with some feets.
Thanks Anand, I'm already enjoying my ear candy for about 4 months.
edit: it also comes with some feets.
Thanks Anand, I'm already enjoying my ear candy for about 4 months.
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How much they charge for say a 100VA Toroidy with static and magnetic shield including shipping I wonder. Has anybody asked those guys?
Don't you try talema toroid? I paid around $100 for 160VA encapsulated, $60 open style. I think that you can get much lower price than what I get
Happy New Year ^_^
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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!How much they charge for say a 100VA Toroidy with static and magnetic shield including shipping I wonder. Has anybody asked those guys?
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
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
You can choose to select English on the site
Another good and reliable site for custom toroid transformers inside the EU is this one btw...
--> Induktive Bauteile wie Ringkerntransformatoren, Ringkerndrosseln, Induktive Bauelemente, Bauteile
For dutch citizens it should be readable without Google translate
--> Induktive Bauteile wie Ringkerntransformatoren, Ringkerndrosseln, Induktive Bauelemente, Bauteile
For dutch citizens it should be readable without Google translate
German is perfectly doable for meAnother good and reliable site for custom toroid transformers inside the EU is this one btw...
--> Induktive Bauteile wie Ringkerntransformatoren, Ringkerndrosseln, Induktive Bauelemente, Bauteile
For dutch citizens it should be readable without Google translate
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