Egnater M4 issue

[pamisano]

The issue I am having with the M4 is a ringing type of quiet feedback. If the unit is cranked with a high gain module the quiet, ringing feedback becomes a screaming feedback. I want to say that there is something loose in the chassis because when, at low volumes when the ringing is barely audible, if you lightly tap the chassis with your finger the ringing becomes more noticeable, similar to tapping a spring reverb unit. Any suggestions would be greatly appreciated.

Also, what if any issues are there with running the M4 with only two or three modules? Should there always be 4 modules installed?

Thanks,

Pete

 

[kc2eeb]

The ringing is a microphonic tube issue. It's literally feeding back like a microphone.
You can run the RM4 with only one module. No Harm.
Sometimes moving the noisy, high gain module to one of the slots
further away from the fan helps.
Ringing 98% of the time is the tube.

 

[pamisano]

It was a bad 12AT7 tube in the cassis.

Now for the next questio...Does anyone know what the 12AT7 tube in the M4 chassis is for? There are two preamp tubes on the M4 chassis, I am assuming one is for the driver (12AX7), but not sure what the other one (12AT7) is for.

Thanks,

Pete

 

[tehuk]

One is the phase inverter the other is for the first gain stage.

 

[kc2eeb]

The R4 is, I believe, approximately the same as the Randall RM4, with a few variations.
There is no phase inverter.

 

[Jaded Faith]

You are correct. A PI tube only exists on a power amp to flip the signal 180 degrees for the pairs of power tubes because they run in a push/pull configuration. So one tube in any pair is always amplifying the top part of the audio wave while the other in the pair is doing the inverse part.

The RM4 is only a preamp and has no phase inverter tube.

 

[pamisano]

Just to clarify...we are talking about the Egnater M4, not the Randall RM4, I don't know what differences there are, if any, but just want to clear up any disinformation based on the RM4.

So why would the R4 need a preamp tube for the gain stage, when each individual module has two tube for its own gain stage?

Also, does anyone know what the second tube is for? I can't get a reply from Egnater.

 

[tlingen]

Can someone say exactly what tube types go where in the M4 and also in the RM4?

 

[pamisano]

In the M4 there is a 12AX7 and a 12AT7 in the chassis, but I don't know what they are for.

 

[The Truth]

Earlier M4's were shipped with a 12AT7 but can be replaced with a 12AX7 with no issue. Mine has 12AX7's and I have no problems. Search on rig talk and there are a few threads on the subject.

 

[alaskaehlers]

I have one of the early(single channel) M4's

V1 is input

V2 in pre loop out buffer

V3 is post loop out buffer

I think

Brian(alaskaehlers)

 

[pamisano]

What do you mean by "single channel" M4? My M4 has only two preamp tubes, but I am assuming is a single channel, and does not have an effects loop.

 

[alaskaehlers]

Yeah, I have the older single channel.

They are different, mine is almost the same as the Randall RM4. It has both the series, and parallel loops.

Brian(alaskaehlers)

 

[RockManiac]

The lower tube is the input tube, the upper tube is the output tube. You can also use a 12AX7 instead of the 12AT7.

 

[pamisano]

Thanks Rockmaniac!

 

[RockManiac]

Enjoy your M4, I love mine!

 

[pamisano]

Yeah, so far love mine too! I am using a clean module (soon to be replaced by either a blackface or vox module), plexi, SL+, and an XTC. And looks like I might have a RT2/50 on the way paired with an RM4 as a backup for my M4 :wink: GAS

I find, however, that the SL+ and the XTC especially, are both pretty noisy at high gain/high volume. Not obnoxious, but enough to have to roll back the volume on my guitar after every song. I am looking into getting an ISP Decimator Rack, but wanted to know if this is par for the course with those two modules at high gain/volume settings.

Thanks,

Pete

 

[kc2eeb]

High gain is.........high gain.
Personally, I always shut the volume down on the guitar at the end of a song. I never found a noise gate that REALLY left the guitar signal unaltered.