Can someone help with Mark Levinson JC-2?

Jump to Latest
#63
Hi again everyone!

I've just received a pair of Mcintosh MC30 monoblocks to match the JC-2 and I'm having trouble finding out which of the 2 switch positions should I choose for the mac, I'm quite ignorant on this matter.

According to ML "When switched to the right (factory set position) the line outputs are AC coupled for driving direct coupled power amplifiers. When switched to the left, the line outputs are direct coupled for friving AC coupled amplifiers." and MC30 has Unity-Coupled M-150B transformers.

Does anyone here know which position should the swith be?

Thanks!
 
#64
Hello everyone,
I hope this is the right thread for my question.

I have just acquired a first-generation ML JC-2, with a defective line output amplifier module.
Otherwise in good condition.

Could someone be so kind and point me toward directions where to find replacement modules? Or upgraded modules of some sort?
Is there someone out there who does good clones or upgrades?
That would be amazing, as I would love to make this unit play again. Thanks so much.
Attached a photo & link to the faulty module in question.

Dropbox - ML-JC-2.jpg - Simplify your life
 

Attachments

  • ML-JC-2.jpg
    ML-JC-2.jpg
    555.5 KB · Views: 276
Last edited:
#65
klangtausch said:
Hello everyone,
I hope this is the right thread for my question.

I have just acquired a first-generation ML JC-2, with a defective line output amplifier module.
Otherwise in good condition.

Could someone be so kind and point me toward directions where to find replacement modules? Or upgraded modules of some sort?
Is there someone out there who does good clones or upgrades?
That would be amazing, as I would love to make this unit play again. Thanks so much.
Attached a photo & link to the faulty module in question.

Dropbox - ML-JC-2.jpg - Simplify your life
Click to expand...

Hi! I have found these from Japan. I haven´t try them myself but I did see some JC-2 with this modules installed on Hifido. Once I wrote them and they answered fast, maybe it is worth a try, they have Line and Phono modules.
Good luck!

DOA016 for Mark Levinson
 
#66
ML-1 phono and JC-1-SM

Attached are four pictures from the inside of my ML-1. As seen the installed modules are labelled "A". My other modules are labelled "A4E" and "D5".
I have always believed the block between the two phono sections has been the +/-13V regulator for the phono modules. Now I understand this is the JC-1-SM. This has escaped me all these yars.
My ML-1 has been in storage for years now, but still this is of great interrest.

Regds
 

Attachments

  • IMG_3921.jpg
    IMG_3921.jpg
    154.7 KB · Views: 227
  • IMG_3922.jpg
    IMG_3922.jpg
    142.6 KB · Views: 239
  • IMG_3924.jpg
    IMG_3924.jpg
    117.8 KB · Views: 241
  • IMG_3929.jpg
    IMG_3929.jpg
    83.7 KB · Views: 233
#67
R-K Rønningstad said:
Attached are four pictures from the inside of my ML-1. As seen the installed modules are labelled "A". My other modules are labelled "A4E" and "D5".
I have always believed the block between the two phono sections has been the +/-13V regulator for the phono modules. Now I understand this is the JC-1-SM. This has escaped me all these yars.
My ML-1 has been in storage for years now, but still this is of great interrest.

Regds
Click to expand...

RK that’s right, it is the MC step up transformer and from the pictures you uploaded I can tell my modules are the D5, which means that I can get 60db. I still consider the possibility of adding a step up just to see how much natural the sound can get

Which preamp are you currently using? If I had a ML1 I wouldn’t store it for too long hehe

Regards
 
#69
From the test of the Levinson JC-2 in “Audio Magazine” April 1976: https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/70s/Audio-1976-04.pdf

A. Normal phono: 32.5 dB gain at 1 kHz. Uses system A plug-in equalizers and is for regular magnetic cartridges.
B. Normal phono: 30 dB gain at 1 kHz. Uses system B plug-in equalizers and is for high output magnetic cartridges.
C. Special Phono Equalization: For. B&K test records.
D. Moving-Coil Phono: 60 dB gain at 1 kHz. Uses JC-1SM pre-preamp with phono amplifiers. Uses D or D1 equalizers.
E. Strain Gauge: Provides equalization and d.c. excitation for certain strain gauge pickups.
F. Flat Response: Provides for flat gain of front end for microphone and other flat-gain applications.

D is flat and D1 rolls off above 7 kHz.
 
#70
R-K Rønningstad said:
From the test of the Levinson JC-2 in “Audio Magazine” April 1976: https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/70s/Audio-1976-04.pdf

A. Normal phono: 32.5 dB gain at 1 kHz. Uses system A plug-in equalizers and is for regular magnetic cartridges.
B. Normal phono: 30 dB gain at 1 kHz. Uses system B plug-in equalizers and is for high output magnetic cartridges.
C. Special Phono Equalization: For. B&K test records.
D. Moving-Coil Phono: 60 dB gain at 1 kHz. Uses JC-1SM pre-preamp with phono amplifiers. Uses D or D1 equalizers.
E. Strain Gauge: Provides equalization and d.c. excitation for certain strain gauge pickups.
F. Flat Response: Provides for flat gain of front end for microphone and other flat-gain applications.

D is flat and D1 rolls off above 7 kHz.
Click to expand...

Thanks for that info and the pdf in particular! It has very useful information! It is a very nice preamp, the only downside I find is the modules and power supply, the former are very difficult to find and quite pricey, and the latter is almost impossible to find and very expensive
 
#71
Maybe this information exist elsewhere, but it would have been nice if we could sort out all the different equalization boards (A, B, D and so on, has e.g. E ever existed?) and list them up, like this list I found at the Audio Magazine test report.
Pin-out would be nice also.
 
#72
R-K Rønningstad said:
Maybe this information exist elsewhere, but it would have been nice if we could sort out all the different equalization boards (A, B, D and so on, has e.g. E ever existed?) and list them up, like this list I found at the Audio Magazine test report.
Pin-out would be nice also.
Click to expand...

Yes indeed. In my case I have the D5 modules and the Regular phono inputs, same as you. I you have the chance to swipe and test with the other modules options that you own would be great, I don’t think many people have those in stock these days

What do you mean with pin out? Sorry I don’t understand
 
#73
Ah. I can check that with the pin-out. I mean what pins on these modules are in, out, ground and so on. But I can check my own modules and post it later on.
Yes, I intend to try the ML-1 one of these days, and I can plug in the D module I have. Must change the phono cable from the turntable as I have a balanced system these days. Later....
 
#77
A transformer is a passive device. The signal transformer for a moving coil step up design are conceptually similar to the transformer in a power supply, but much smaller.
The active circuit is built from bipolar transistors, JFETs, and/or tubes. The JC-1-SM is built from bipolar transistors as active devices.
 
#80
I checked my ML-1 now, and when both the JC-1-SM and the A-type equalizers are plugged in, the JC-1-SM is out of the circuit by its output pin going to an unused pin on the A-equalizer. Further, the A-equalizer provides a resistor (measured to 10k) between the JC-1-SM’s input pin and its “third pin” (between its input and output). I do not know it this might be the minus input or what. It is not shown on the available JC-1DC schematics.
While the JC-2 supposedly could be used with strain gauge pick-ups, I do not see this possibility with the ML-1. The reason being that these pick-up types are in need of a bias current. The old Panasonic strain gauges requires 4 mA. Anyway, neither +15V nor -15V are connected to the equalizer board. But this should be possible for the eager DIYer by taking the required voltages from the JC-1-SM position (obviously the JC-1-SM has to be removed).
 
You must log in or register to reply here.
Top Bottom