Berlant Input Transformer

[roustabout]

Hi, i don't know how to strap a Ampex transformer to the mic input of a Berlant Series 30. It does work but there is hum.  Is there someone who have done this before? Thanks

 

[CJ]

solder 6 to 7 for 150 ohm input

solder 4 and 6
solder 7 and 8

for 30 ohm input

 

[roustabout]

Thanks CJ, i've done that! I strapped it for 30ohms. But i don't know how to strap the other pins to the socket of the Berlant.

 

[roustabout]

Here's the schematic for the berlant:

 

[mjrippe]

Unless you have a mic wired for 30-50 ohms you probably want to go with the 150-250 strapping option.  The Ampex is an octal base and the Berlant has an 11 pin socket so I assume you will replace that eventually.  But with your octal socket and clip lead arrangement you would connect it as follows:

Ampex pin 4 to Berlant pin 2
Ampex pin 8 to Berlant pin 4
Ampex pin 3 to Berlant pin 6
Ampex pins 1&2 to Berlant pin 1

 

[roustabout]

Thank you! I'll try that today.

 

[mjrippe]

Those Berlants can be very nice preamps.  The ones I have recapped and modded came out very clean and quiet.  One engineer used it on a ribbon mic and complained that it didn't sound like a tube preamp!  They are not at all like the Ampex 600 series that I love for their almost stereotypical "tube preamp" sound.

 

[roustabout]

Thank you all for your help! After i've tried for hours to get a clean signal out of the Berlant without any success, i want to get rid of the parts not belonging to the signal path. Can i just cut everything exept for the tube power supply (pins 4,5,9)?

 

[mjrippe]

Hold on before you go hacking and slashing into the jungle under that chassis!  I'm not sure what you mean about pins 4, 5, 9 and the tube power supply but I see you have sent me a PM so let me get back to you there.

 

[Dainiusb]

@mjrippe would love to hear about how you quieted these down! I’ve got one that I’ve been fighting the hum on and I’m almost there, rerouted all the grounds to a bus ground, recapped where needed, but I think what’s left is hum in my input transformer. The bridging input is silent as the grave, so that’s the last thing I can think of. It’s a stancor without a lot of sealing. I set up a few metal plates as shields at various angles that have helped haha

 

[Nic marin]

this thread is a bit dated, but I need some help. I'm wokring on my first 30 series recorder for a friend.

you probably want to go with the 150-250 strapping option. The Ampex is an octal base and the Berlant has an 11 pin socket so I assume you will replace that eventually. But with your octal socket and clip lead arrangement you would connect it as follows:

Ampex pin 4 to Berlant pin 2
Ampex pin 8 to Berlant pin 4
Ampex pin 3 to Berlant pin 6
Ampex pins 1&2 to Berlant pin 1

two of my issues.

there are no markings on the 11 pin socket. a key way is there, but it looks to be homemade. I have a couple of schematics and trying to be sure I don't accidentally bring our the the smoke.. been checking the socket and have found the XLR input and ground to the case.

next thing.
has anyone tried using an 8 pin DuKane input transformer? thank you!

 

[nsalis]

You can see the pin numbering of an 11-pin socket in the appendix.

P.S. You mentioned that you were on an Ampex 30 recorder. Are you sure about the type number? I only know Ampex 30 as a tube amplifier, not as a recorder.

 

[nsalis]

this thread is a bit dated, but I need some help. I'm wokring on my first 30 series recorder for a friend.


two of my issues.

there are no markings on the 11 pin socket. a key way is there, but it looks to be homemade. I have a couple of schematics and trying to be sure I don't accidentally bring our the the smoke.. been checking the socket and have found the XLR input and ground to the case.

View attachment 132132 next thing.
has anyone tried using an 8 pin DuKane input transformer? thank you!
View attachment 132134View attachment 132135View attachment 132136

Dukane model 3A80 transformer data sheet enclosed. This is step-up (150 Ohm to 600 Ohm) transformer. The voltage applied to the input appears twice as high at the output (6 dB gain).