JCM 900 Mk3 choke values

[felipevsw]

Hello!

Firstly, I live in Brazil so I don't have access to all the fancy stuff people in the US and EU have, but we do have some local manufacturers here.

And I'm looking to install a choke on my JCM 900 Mk3 2502 combo. What specs should I be getting? Most of the "Marshall" transformers here are 5Hy 120mA.

Would that work okay? Or should I make a custom order for specific different value?

I've seen people using 3Hy as choke for 900s. Would 5Hy be too much?

Also, how many mA should it be? The ones readily available are 120~125mA. But I think I can order custom spec if needed.

Picture just as reference of the model readily available I might get. "V" stands for "vertically mounted"

 

[Jimmy Bondy]

Hello!

Firstly, I live in Brazil so I don't have access to all the fancy stuff people in the US and EU have, but we do have some local manufacturers here.

And I'm looking to install a choke on my JCM 900 Mk3 2502 combo. What specs should I be getting? Most of the "Marshall" transformers here are 5Hy 120mA.

Would that work okay? Or should I make a custom order for specific different value?

I've seen people using 3Hy as choke for 900s. Would 5Hy be too much?

Also, how many mA should it be? The ones readily available are 120~125mA. But I think I can order custom spec if needed.

Picture just as reference of the model readily available I might get. "V" stands for "vertically mounted"

View attachment 135368

A 5H choke is fine. A jcm 800 has a 5H choke.

 

[Gutch220]

The MMC-3H here is a "clone" of the Drake T-100 1471-263 which was in JMP's and JCM800's in the 70's & 80's: https://www.mercurymagnetics.com/pr...ilter_model=50-watt&filter_product-type=choke.
You'd be fine with a 3H or 5H choke and 120mA if fine for a 100w amp, let alone a 50w amp, so you're good. I don't think you'd hear much of a difference with the one you posted. They'd both work. If I were you, I'd also look into their mounting holes, but for your case, you'll need to drill holes for the bolts anyway, so just look for the proper area to mount it.
It would be interesting for you to post a before & after as far as sound clips go so we can all listen to any difference because it's not everyday that a person installs a choke on a JCM900.
good luck.