JC-80 eBay PCBs

[AndrewT]

A good op amp has a PSRR of 100 dB!

At what frequency?

 

[dirkwright]

Dirk,
are you deaf?

A source that has an output noise of 0.1mVac 20Hz to 20kHz is atrocious.

Apply that to a headphone or to a power amp or to any subsequent music replaying system and the signal to noise ratio is unacceptable.

You're assuming that all of the noise from the power supply comes out of the output from the amplifier and that is not the case as I tried to explain.

 

[dirkwright]

At what frequency?

Is that a rhetorical question or are you incapable of looking it up yourself? Maybe you should stop asking other people to do your work.

 

[Wolfsin]

@dirkwright: I experience you as generally rude. The above is no different than what you did to me except you could not even find the information IN THIS THREAD. One or the other of us needs to stop posting here, Which shall it be?

 

[Wolfsin]

New Thread Started

I have started a new thread at

http://www.diyaudio.com/forums/forum-problems/206797-jc-80-ebay-pcbs-power-train.html#post2907934

The first post there is a warning to posters to abide by the rules. If you want examples of rudeness / trolling that will not be tolerated in part two, please read the last few posts.

I invite your continued readership in part two.

'gardz, Dick

 

[pinnocchio]

Thanks for the info pinnocchio, Can you check also what the impedance of JC-2?

I'm also thinking to invite the JC-2 KIT from EBAY, what the jc2 sound character?

You can specify what you changed, and the most recommended swaps in your opinion?

Hi Foxye,

We're not on the right thread to discuss JC-2... I will PM you.

Do

 

[john curl]

There are TWO JC-2's: The Levinson JC-2 first designed in 1973, and the Parasound JC-2 which came out after 2005.

 

[Wolfsin]

Please do not post to this thread. Instead subscribe to part two:

http://www.diyaudio.com/forums/analog-line-level/206797-jc-80-ebay-pcbs-power-train.html

 

[takis1969]

hi all

i have a same board ( jc-80 ) from jims audio but i have a little problem

i dont know value for r43,r42 resistor

please help me for this

thanks

 

[Wolfsin]

It is the fourth item in the BOM

 

[takis1969]

in my bom missing this item

this is my bom from jims audio ( https://rapidshare.com/files/2758032630/JC80_BOM.xlsx)
please look at this

 

[Wolfsin]

@takis1969 I tried but got into some website that wanted me to signup. Please ask Stanton at Jim's Audio for help if your BOM has an omission.

 

[takis1969]

today i received via mail from stanton a new copy

 

[spurlte]

What do you think of this Borbely shunt regulator. Comes with two separate regulators for both channels. All FET Low Noise Super Shunt Regulator PCB Borbely | eBay

 

[ticknpop]

. I use Erno's shunts, they are very good, but very expensive to build, many of the original semiconductors are discontinued (389/109, 313/2013), maybe there are substitutes you'll have to see.......

 

[spurlte]

Erno's shunts

. I use Erno's shunts, they are very good, but very expensive to build, many of the original semiconductors are discontinued (389/109, 313/2013), maybe there are substitutes you'll have to see.......

I found 313/2013 on ebay from Israel. I used them for my KSA 100 MKII. I hope they work. As for the 389/2013, I hoping to find subs 2SK170/2SJ74. If I do, if I understand this to be correct in some readings, that 389/109 are two in one jfets, so that I have to double the 2SK170/2SJ74s. Yes?

 

[pinnocchio]

I tested the JC-80 with Borbely Shunt and AMB Sigma 22 and found that the Sigma 22 sounded a bit better, more open and soundstage is also deeper. Borbely was also very good. I still have 2x Borbely if someone is interested with original 2SK389/J109

Ciao!
Do

 

[takis1969]

i have a question
trimmer r41 (1k) is for a adjustment dc offset;

 

[pinnocchio]

i have a question
trimmer r41 (1k) is for a adjustment dc offset;

Hi takis1969,

R41 trimmer is for Q1-Q2 and Q4-Q5 Bias. The DC offset is handled by a DC servo at the bottom of the PCB.

Ciao!
Do

 

[takis1969]

thanks

how to adjust Bias for this transistor ;