Needs some information on my Egnater IE-4

[mcgyver]

Hi, I was wondering if someone could help me get some information from Bruce Egnater regarding a Egnater/Rocktron IE-4 I just purchased used from a guy in Kentucky.
It has four switches in the back that were added by Bruce for the previous owner. The switches are labeled 1,2,3,4. They are channel mods of some type and I am trying to get a little more information on the mods. They seem to be mid-eqs of some type. Also I have a second question. On channel 4, if I raise the gain past 9 o'clock I get a mid-level kind of steady howl. I have tried different guitars with different pick-ups, both active and passive. It still howls till I reduce the gain. Is this normal,? or should I try changing the tubes?
I tried emailing Eganater at their website and I included pictures of the switches but never received a response.
Hope someone can point me in the right direction. Or maybe the Egnater guys will read this and write me back.
Thanks in advance for your help
Jamie

 

[guitarslinger]

I have the same mod on my Pre-Rocktron IE-4.

They are voicing switches wired to relays that switch capacitor values on the tone stack of each channel. My schematic is WAY too small to read, so I can't tell you which cap is switching out. Actually, for all I know, it might not be that simple.

It's a fancy way to analogly put a dip in the mids.

I prefer all of the switches in the standard, normal position. It's still a pretty sweet mod though.


Howling on CH4 = a bad tube.

CH4 signal flow goes

V1A-->V2B-->gain-->V4B-->V5B-->V5A--> Master

so, your culprit is either the 1st, 2nd, 4th, or 5th tube.

I suggest you open it up, and start swapping tubes. I find Chinese tubes sound KILLER in the IE-4.

 

[mcgyver]

HI Gene, WOW. Thanks so much for your help. I looked all around my studio to dig up 7- 12ax7 so I could just replace them all till I bought a new set.
And you were right that took care of the howl on ch 4. The switches on my unit are on the back. And it is racked in a deep road case. So switching back and forth to tell mid- cuts. Well, frankly its a little hard to hear when you have to stop playing and go to the back of your rack. Are yours on the back too?
Also what is you opinion on the difference between the Rocktron version and the pre-Rocktron one. I read, Bruce said aside from point to point wiring and maybe better construction. That the pots were different types on each unit. So say, I set two units (one Rocktron and one Pre-Rocktron) with all the knows at twelve o'oclock. That the two units would sound a little different due to the different taper of the pots. Or something like that.
Any thoughts?

Anyway. Thank you so much for your help.
Jamie

 

[TheGrooveking]

HI Gene, WOW. Thanks so much for your help. I looked all around my studio to dig up 7- 12ax7 so I could just replace them all till I bought a new set.
And you were right that took care of the howl on ch 4. The switches on my unit are on the back. And it is racked in a deep road case. So switching back and forth to tell mid- cuts. Well, frankly its a little hard to hear when you have to stop playing and go to the back of your rack. Are yours on the back too?
Also what is you opinion on the difference between the Rocktron version and the pre-Rocktron one. I read, Bruce said aside from point to point wiring and maybe better construction. That the pots were different types on each unit. So say, I set two units (one Rocktron and one Pre-Rocktron) with all the knows at twelve o'oclock. That the two units would sound a little different due to the different taper of the pots. Or something like that.
Any thoughts?

Anyway. Thank you so much for your help.
Jamie

Yes, Bruce told me years ago when I inquired as to the difference between the pre-Rocktron ie4 and the Rocktron ie4 that the only difference really was the taper of the pots.

TheGrooveking