Amp Talk

[Jimmy55]

thanks for the advice atomic, i think i will get it serviced, hope i get it sorted, cos any more of this tube buisness is gonna make my head explode. :shock:

 

[Atomic.Sheep]

lol yeh, it would mine, after emptying my wallet out like you undoubtedly did to get that baby (which is currently misbehaving).

I'm no tech, but I believe they're amplifed by each pair at the same time, and that the output of all three is sent out in parallel (ie, side by side, and not one after another)

Well I read in a couple of ther threads that some people are taking out a pair of tubes, but I didn't really understand the point to this. They admitted that it would put extra strain onto the remaining tubes (which makes sense if they are amplfied by each pair at the same time) but what this actually does is beyond me.

 

[Jimmy55]

yes i tried that, if you take out the 2 middle 6L6`s and one of the rectifier tubes you are downsizing the power by 50% which basically switches the amp to 50watts, atleast, its something like that anyway, it says in the instruction booklet which i have read thru about 893742 times

 

[NoGlassNoClass]

Use speaker wire of at least 14-16ga. Bigger is better. It will make a huge difference. Instrument cable is way too thin (usually 20ga or thinner). Sounds like ***, weak bass response. If you crank your amp, you can melt the wire and damage your output transformer!

 

[Atomic.Sheep]

You would have to crank it quite a bit to cause that to occur, but good point better be safe than sorry. I would have bought a proper speaker cable ASAP as well, but only for the reason of showing it off , but now that I know what could potentially happen I will buy one even "ASAPier" lol when I get my Mesa.

yes i tried that, if you take out the 2 middle 6L6`s and one of the rectifier tubes you are downsizing the power by 50% which basically switches the amp to 50watts, atleast, its something like that anyway, it says in the instruction booklet which i have read thru about 893742 times.

Ok, so it reduces power output, thats logical what does that do? If you have 100 watts in your standard Dual Recto and then it has 50, does that make it less loud or does it make it less gainy?

 

[jong]

Atomic Sheep: You really should read that article again (the one that you linked to). Nowhere in there does it say that it doesn't make a difference what you use for a speaker cable. I don't think that is a very good article, but since you linked to it... As NoGlass stated, an instrument cable is not sufficient to be used as a speaker cable.

Regarding reduced output (pulling tubes), 50 watts will not be as loud as 100 watts. But that is relative, it isn't half as loud as you might think. The reason for doing this is to achieve the 'sweet spot' on the amp at a slightly lower volume level. A lot of people feel that tube amps tend to sound their best when cranked, and most 100 watt amps are too loud to be used in a club. You probably won't notice any difference if you're only playing at bedroom levels.

 

[Atomic.Sheep]

Nowhere in there does it say that it doesn't make a difference what you use for a speaker cable. I don't think that is a very good article, but since you linked to it... As NoGlass stated, an instrument cable is not sufficient to be used as a speaker cable.

Yeh fair enough, that was the best article that I came across that seemed to have some decent information that seemed to have been based on some knowledge in the topic.

 

[Atomic.Sheep]

What do the 5U4s do? Because the MarkIV and the Dual Recto have the same identical tube setup otherwise, its this extra pair of 5U4s that are puzzling me.

 

[NoGlassNoClass]

The Dual- (and Triple-) rectos give you a choice of using the diode rectifiers, or tube (5U4's). All they really do is convert the incoming AC current to DC. No audio passes thru them. The diodes are much more efficient, leading to a tighter, faster response, as well as a louder amp. The tube-rec, due to its inefficiency gives a sweeter, "sagging" kind of response, which IMO is kick-*** for soloing as well as clean sounds. If you find the tube rectifiers appealing, but too loose for distorted rhythm playing, you can use GZ34/5AR4's in place of the 5U4's. This tightens things up quite a bit.

 

[Atomic.Sheep]

Aha... Cool thanx!!!

 

[screamingdaisy]

Oh also i forgot, will it make a difference to the sound if i use an ordinary guitar cable to wire my head and cab, i asked a guy in a guitar shop and he said just use a normal guitar lead, maybe this is the problem, i might go out and buy a speaker cable tomorrow if it makes a difference.

Don't use ordinary guitar cable....use speaker cable, you'll thank yourself in the long run.

 

[Atomic.Sheep]

What are the differences between the EVM (12?) and the Celestion 90?

 

[NoGlassNoClass]

The EVM12's are (were...now discontinued) a 200W speaker designed originally for PA applications. Due to the high power handling, and low resonant frequency (50Hz) they are almost impossible to drive into breakup and have very tight and deep lows. Eminence has a speaker thats supposed to be a direct replacement, the DeltaPro12A, with even higher power handling.

The Celestion/Black Shadow C90 also a high-power, tight response speaker, very similar to the Celestion classic-lead 80. Not as hard-hitting as the EV I'm sure, but certainly tighter and more "HiFi" than a V30.

 

[Atomic.Sheep]

So essentially there is no difference between them if played at low levels? And basically only Celections 90s are the main ones used/released in present day mesa's?

And also... in relation to the rectifier series, the major differences between the rectifiers is the power section/amp thing, the pre amp parts of them are very similar?

 

[NoGlassNoClass]

IMO the EV's have deeper lows at any volume. The C90's and V30's are your only choices for 12" speakers in current production amps as far as I know.

The Dual- and Triple-Rec's share the same preamp. Not sure about the single, but based on the way it sounds it cant be much different.

 

[vulture2600]

in all-tube amps, the signal from the guitar never hits any kind of diodes, even in diode rectified amps. the signal is amplified along the way completely by tubes. preamp tubes have two gain stages each, and usually set up sequentially (one gain stage after another) with eq and gain knobs in certain places along the way (the placement of these controls can completly change the sound of the amp too). this would be the preamp section of the amp. then the signal is fed to the fx loop, which on good amps is drivin by another gain stage, then the return of the fx loop goes thru another gain stage (both are at low gain settings, they just keep the signal smooth and natural sounding). then the signal hits the phase inverter tube which splits the signal into two seperate signals, one positive and one negative, then sent to the power tubes, which are in pairs. again
one is positive and one is negative in each pair. the outputs of the pairs
are combined (usually parallel) and to the output transformer and then to the speaker(s). and thats pretty much it. some amps are just very complex versions of this. the road king for example has a TON of switching, some gain stages are switched completely in and out of the signal path, along with different sets of power tubes, solid state versus tube rectifiers, and each channel has 3 different gain modes.
its all built off the same technology tho. hope this helps!

 

[no soul]

Oh also i forgot, will it make a difference to the sound if i use an ordinary guitar cable to wire my head and cab, i asked a guy in a guitar shop and he said just use a normal guitar lead, maybe this is the problem, i might go out and buy a speaker cable tomorrow if it makes a difference.

Don't use ordinary guitar cable....use speaker cable, you'll thank yourself in the long run.

you COULD use a speaker interface as an instrument cable, but you dont want to do it the other way arround. Non shielded (instrument cables) can create problems for your amp. The other guitarist in my band didnt believe me about this, until she started blowing fuses left and right. She still didnt believe me, so she took the amp to Mesa to have them look at it, and guess what they told her??