Egnater M4 losing Bass, could it be tubes?

[Jrm4]

Hi,
Been playing with my M4 about 2,5 years. It's been heavily used and always sounded great. It has been used about 5 days a week about 2-4 hours a day for a 2,5 years.

Suddenly today it sound didn't seem to sound right, so I was turning up bass knobs on all modules since it seemed to sound thinner and treblier and screechier. Even if module got bass full, it seems to sound "wrong".

It's not my ears since always Egnater have sounded best and full. I compared it to my other gear and something is not sounding right now.

Could it be one of those two tubes that are located on back? What are their purpose? They have metal covers on. I have never changed tubes on this M4 so could it be the symptom of this strange sound behaviour?

It's happening on all modules.. sound is thinner and ice pickier and the depth and 3d is missing..

How are the back tubes removed? Do I just pull and push the new ones back or do I have to remove the M4 cover?

Any help

 

[Felipe R]

change the tubes, first on the preamp and later on the modules. what power amp are you using?, maybe power tubes need to be changed too.

 

[Jrm4]

yep, thanks,
I'll change the 2 backside tubes first.
But, do I just pull those tubes out hard after removing metal cover, I haven't done this

If its tube it must be those, since this is happening with all modules, even with new ones and old ones..
Poweramp is fine, it has new tubes in it no prob. With other gear works fine.

 

[Felipe R]

yeah just pull those tubes out, but not so hard :wink:

 

[Jrm4]

yeah thanks, I switched the two tubes backside.
Sounds better now, bass and 3d is back.

It had Electro harmonics 12AT7EH and 12AX7EH tubes in it. 12AT7EH tube had one pin gone grey / black (2nd pin from the left if the "missing pin" is at the top. Could have that..

Had to put two 12AX7EH since no tube shop open today... will change it later.
No the sound is better but with two 12AX7EH maybe too trebly and harsh, but the bass is back and sounds better now.

Anyone opinions, for darker tone. Maybe switching JJEC83c's to some of the higain modules also.

What are the best tubes for the 2 backside slots?

 

[Viet_Hetzer]

Mullard tubes are known to be smoother and more detailed, but without being harsh or fizzy. Those might be what you are looking for.

 

[Jrm4]

Hmm, got one of Tungsol 12AX7 from a friend, We put that to backside of M4 to position V2. Hmm.. talk about good, don't know if V2 would be supposed to run with 12AT7 instead of 12AX7 but now it sounds super.. smoother and mullard like, you might want to check this tube out:

http://www.thetubestore.com/tungsol12ax7.html

Also tried JJ83c with E-rect module in postion V1 & V2. Left it in V2.. now erect sounds better also me thinks. V1 is still 12AX7EH (erect)

 

[Felipe R]

so you used to use a 12at7 on v2 ?

 

[Jrm4]

Yes the second tubeslot (lower) had EH 12AT7. Don't know if it's V2 or actually last stage V5..
Don't have effect loop on my M4 so on the backside only two tubes.

You all other using 12AX7 instead?

Anyway ordered some tubes today and will start to experiment with them later.

 

[Felipe R]

my m4 its with the effect loops, its comes with 1 12ax7 and 2 12at7 but i dont remember in which positions because when i recive it i just tried one time and change the tubes for some mullars and telefunkens ecc83 immediately, do you have the manual?, maybe the manual says something, i dont have the manual because frank at egnater never send me one, and i have email him lots of times asking for the manual :roll:

look this link:

http://www.hugeracksinc.com/board/viewtopic.php?t=15856&highlight=rm4+signal

 

[Jrm4]

Thanks.. so when looking at that diagram I think the 12AT7 was the LAST tube.

I have no manual, I have it on text file. There was no mention of tube order / signal chain.

Hmm.. just a second ago I found also the vendetta vp4 preamp manual from rocktron site. I think it's quite similar to M4? Only that M4 is modular of course. There's fuse replacing part which is handy for clumsy people like me And tube order. But that link you posted is of course a must print! thanks again.