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Mesa M6 Carbine Mega-Thread Pt Deux

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#361
MrBEAR said:
The "hiss" or "rushing air" sound being discussed does present itself on my earlier model, March '08 completion date, M6 Carbine.

That said it is at a level which is significantly lower than the "fan noise" the unit produces. This sonic disturbance remains at a constant level until the gain is increased past the 12:00 o'clock position. Results obtained with nothing plugged in vs. a passive bass plugged in are too close to call by ear.

Reducing the gain to zero, placing the master volume at 12:00 o'clock and raising the gain obtained similar results, with any discernable dB differences being negligible to the ear and most likely a moot point in a live setting. I did not plug in for this practice run, as the obtainable levels would have been "ear crushing", but again, as mentioned there is more "ambient" noise issued by the fan than the "hiss, air rush" dilemma.

This issue is not that prominent through the DI to a board, input gain PFL'd on an A&H MixWiz 16:2, while monitoring via Sennheiser HD 600's.
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This matches my experiences as well.

There appears to be a significantly large, hot(?), amount of gain employed in the gain stage via the pre-amp tube, certainly more than I personally need, so a possible suggestion for those that find this a persistent personal "niggle" would be to try swapping tubes with some known to have a lot less gain.

Just a thought and as always ymmv etc.
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Chef said:
FWIW: I've had brand new preamp tubes in brand new amps go south and create all kinds if icky and weird noises. Changing the tube out might not fix it, but, it might.

Can't hurt nothing to try.
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You guys make great points... I agree... a tube swap might be a good thing to try... especially the lower gain idea. I believe that'd be a 12AU7, right?

If nothing else, maybe the 12AX7's they use work great tonally but don't have the greatest noise floor rating out there... maybe even just a higher quality tube than stock?

MrBEAR said:
P.S. I just checked the Mute mode and there is Zero hiss emitting from either the 12's or the horn.
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I'll have to check into this... I was thinking the mute didn't affect things, but I'm probably wrong.
 
#367
Ahh Yes this is why I love TB. Very good ideas fella's. I am going to have to do some more testing, but agree that it is probably a preamp gain thing. THe thing is with this crazy loud amp, I am OK with reducing some of the gain if it results in a quiter amp but without reducing tonal quality. I understand there may subtle changes in tonal quality but with all the different tubes out there. The guy that sells the mesa here sells Groove Tubes. I had them in my aguilar and they sounded oK. Any thoughts on them? I may ask him about a lower gain tube instead of the AX7.
 
#370
dmusic148 said:
Mine hisses with or without the mute pulled, but a LOT less with it pulled.
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Hmm... that does not appear to be operating correctly, compared to my M6 Carbine anyway.

Gain @ 12:00 o'clock, preset at 5, Treble dimed, master volume at any setting, when I engage the mute mine is dead quiet, absolutely Zero noise from the speakers or horn, only the sound of the fan is left.

Something has gone awry on your M6 Carbine methinks.

Cheers,

Mr. BEAR
 
#371
MrBEAR said:
Hmm... that does not appear to be operating correctly, compared to my M6 Carbine anyway.

Gain @ 12:00 o'clock, preset at 5, Treble dimed, master volume at any setting, when I engage the mute mine is dead quiet, absolutely Zero noise from the speakers or horn, only the sound of the fan is left.

Something has gone awry on your M6 Carbine methinks.

Cheers,

Mr. BEAR
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Again, if we're talking with nothing plugged into the amp (just wanna' make sure we're on the same page here), I think whatever hiss comes from mine is also not affected by the mute, but I'll confirm later.
 
#373
I just came across about a 1/2 dozen Telefunken 12ax7s ecc83 that were in an old dynaco tube stereo preamp.
Im going to see how these sound as compared to the original Mesa tube in the fathom.


EDIT: I was just on ebay and saw what these are going for... They have been in my garage for 20 years...and in my dads basement for years before that...
time to start rolling tubes for my gear and see if these are all that different..

Vic said:
See how fickle I am? I just ordered a Tung-Sol and a Jan Philips 5751. :)
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#375
Vic said:
Again, if we're talking with nothing plugged into the amp (just wanna' make sure we're on the same page here), I think whatever hiss comes from mine is also not affected by the mute, but I'll confirm later.
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Okay Vic, I was getting a few things together for this evening's gig when I hit refresh on this thread, I ran down before packing up and tried my M6 Carbine both ways, passive bass plugged in and nothing plugged in.

Either way when the mute is engaged it is DEAD QUIET. Just to cover the options I also tried the latching footswitch mute option vs. the Pull to Mute knob and obtained the same results.

The version I have lends itself to truth in advertising, Mute is Mute, all one hears is the fan.

Something else for you to investigate.

Good choice on the JAN/Phillips 5751, IME you should enjoy the difference.

Cheers,

Mr. BEAR
 
#377
Mine makes athe same, small amount of noise...mute on, mute off...bass jacked in or not....active or passive.
Rolling the horn down on a cab with one makes it better, obviously...

Pushing input gain up makes a difference with mute off, but not with mute on.
 
#378
MrBEAR said:
Okay Vic, I was getting a few things together for this evening's gig when I hit refresh on this thread, I ran down before packing up and tried my M6 Carbine both ways, passive bass plugged in and nothing plugged in.

Either way when the mute is engaged it is DEAD QUIET. Just to cover the options I also tried the latching footswitch mute option vs. the Pull to Mute knob and obtained the same results.

The version I have lends itself to truth in advertising, Mute is Mute, all one hears is the fan.

Something else for you to investigate.

Good choice on the JAN/Phillips 5751, IME you should enjoy the difference.

Cheers,

Mr. BEAR
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Ok, some new data.

Recheck yerself on this too...

If I have the EQ flat, and both gain/master all the way down, there is a little bit of hiss coming out and that is not affected by the mute. If I turn either of them up, a little more hiss comes out, and that IS affected by the mute. So whatever is introduced by adding gain, is affected by the mute, but whatever is there as a "baseline" of noise is simply always there.

It's not much, but if you put your head in front of the cab you can hear it. I should also mention it's highly depended on how bright your cabs are. Mine are Epifani, which are particularly bright.
 
#379
Chef said:
Mine makes athe same, small amount of noise...mute on, mute off...bass jacked in or not....active or passive.
Rolling the horn down on a cab with one makes it better, obviously...

Pushing input gain up makes a difference with mute off, but not with mute on.
Click to expand...
Yup. Same here. Mine's also a Fathom, but I don't think that makes a diff.
 
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