My first MP-1

[Matt_B]

I believe there is a difference in the heater sensitivity between the two. I may be wrong, however there was a clear difference in sound between the 2. Any thoughts?

The 12AX7 heater elements run at 12.6 volts and the ECC83 runs at 6.3 volts.

[Cleveland Metal]

Jay, I'm always interested hearing this stuff. Keep me up on what you see.

And Matt, I never knew that. I've plugged some into my CAE3+se too, and part of the "big" thing w/that preamp is the DC heater circuit. Interesting. I've swapped those two types back and forth forever in my Marshalls. Not that I know much about their heater circuit... Lucky I never fried one out I guess.

[horns666]

Jay, I'm always interested hearing this stuff. Keep me up on what you see.

And Matt, I never knew that. I've plugged some into my CAE3+se too, and part of the "big" thing w/that preamp is the DC heater circuit. Interesting. I've swapped those two types back and forth forever in my Marshalls. Not that I know much about their heater circuit... Lucky I never fried one out I guess.

Yes, I didn't know that as well. About a month a go, I swapped the stock ECC83 in my JMP-1 with JJ and Tung Sol 12AX7s. I thought that was just another name for 12AX7..just like 5881 is for 6L6. I thought the original Sovteks sounded best..maybe for this reason?:think:

[Matt_B]

And Matt, I never knew that. I've plugged some into my CAE3+se too, and part of the "big" thing w/that preamp is the DC heater circuit. Interesting. I've swapped those two types back and forth forever in my Marshalls. Not that I know much about their heater circuit... Lucky I never fried one out I guess.

To be blunt, I didn't know that either until recently but we're all right about the interchangeability of the tubes. Heck, when I used to sell Mesa tubes, they had "12XA7/ECC83" printed right on box.

[toejam]

So even though the voltage is different, does it change the amount of gain?

[FlyingSkull]

I don't know if it will add to the discussion but I pulled some Chinese 12AX7s from a Peavey Ultra and noticed they were a fair bit taller than Russian 12AX7 (these were Electro Harmonix). So it looks like there is some physical differences around.

[Cleveland Metal]

Every brand looks a lil different internally, some drastically.

[Jayster]

So even though the voltage is different, does it change the amount of gain?

Higher plate current equals lower gain, m'kay.

(At least I believe that's correct, this is some stuff I don't think about everyday).

Any of you amp techs correct me if I'm mistaken.

[horns666]

So I want a shorter tube for more gain..

That's not what she said!!

[jdr94]

hey jay any results yet?

[Jayster]

hey jay any results yet?

Hell Yeahs, I've got the br00tlez back.

[jdr94]

Hell Yeahs, I've got the br00tlez back.

yeah but the tube tests, were there considerable difference found in the tubes and what reasoning did you find?

[Jayster]

yeah but the tube tests, were there considerable difference found in the tubes and what reasoning did you find?

Cool, fair enough. I didn't waste the time on it - my thoughts were that it was a heater sensitivity issue, and after corroborating feedback ...... I just kind of said screw it. But I'll try to muster up some time sunday morning~ish for testing purposes.

I was surprised that nobody(amp tech type of guys), had any other feedback. So, on with the show ....

[voodooamps]

My apologies for not replying sooner, I've been under the weather with the flu that has been going around.

Trace, ever do anything to a CAE3+se?

Yes we have and thus far we have based the Mods on each players individual needs (IE: a Custom Mod).

Looking to crunch it up a bit, without losing the tone...

That is easily done and to be honest this is what most players have requested. Everyone wants to retain the same tone but with more crunch and/or distortion.

I currently have to run emg81>emg PA-2 inot the front to get it crunchy/edgy enough, and that has its own set of issues.

I understand where you are coming from, Feel free to call the shop Mon-Fri 9AM-5PM at 607-256-0465 and ask to speak with me. You can also email me directly at [email protected].


Have a great day
Trace

[voodooamps]

And Matt, I never knew that. I've plugged some into my CAE3+se too, and part of the "big" thing w/that preamp is the DC heater circuit. Interesting. I've swapped those two types back and forth forever in my Marshalls. Not that I know much about their heater circuit... Lucky I never fried one out I guess.

Generally speaking; Marshall's heaters run on AC and as with any gear there are exceptions along the way.

Yes, I didn't know that as well. About a month a go, I swapped the stock ECC83 in my JMP-1 with JJ and Tung Sol 12AX7s. I thought that was just another name for 12AX7..just like 5881 is for 6L6.

To understand the proper nomenclature you have to dig back through the years. Books can and have been written on this so I am about to over greatly simplifying a highly complex topic;

Back in the day ECC83 was a European designation where as here in the USA it was referred to as a 12AX7. 7025's came along and were a higher grade 12AX7 designed for the military. Note that these are all interchangeable, meaning they are a direct drop in for one another. 5881's were initially design much differently back in the day as they were a lot shorter. Fast forward to present day and the terminology is very different.

Regarding hum - Recently we received a lot preamp tubes that we had to where the metals in the filament/heaters was not done properly resulting in excessive hum. IE: plug in a brand new tube and it added a great deal of hum (design flaw).

It's worth noting that properly burning in tubes will help reduce a lot of sonic gremlins plus it also improves the quality of tone as well as reliability.


Hope it helps
Trace