close call with single rectifier: impedence mismatching (long read)

[flank]

Re: close call with single rectifier: impedence mismatching (long read)

Kent S is a beast!

 

[Scott_F]

Re: close call with single rectifier: impedence mismatching (long read)

actualy heres an interesting piece of information. Ever wonder why older amps have a certain jack for speakers and a certain jack for extension cabs? Back in the day, Tubes were built much better and more plentiful (thus cheaper), thus tranformers were sometimes one of the parts that manufacturers skimped on, such as fender. The speaker jack is a shorting jack, it shorts the output of the tubes to ground. The transformer had a better shot at surviving that then if there was nothing connected. This is becuase with a higher load, the voltages build up in the transformer and cause it too fry. With a lower load, the tubes are under much more stress. Its much easier to replace tubes then a transformer, especialy if you dont have to rebias excelent and plentiful tubes. Anyway, Impeedance missmatching is never perfect, Matchless for example runs their El84's very hot, half the load. This is the equivilent to running 8 ohm into 4 ohm. But they dont cook very often, qualitiy of the parts is very important in this case. Tonealy, the intended tone of the amp comes from a match, so try to stay around there. Just a little bit of info for all of you.

word had it that if you took a matchless with an 8 ohm speaker and ran that speaker into the 4 ohm jack, the amp cleans up and is actually running at the "proper" impedance. I've tried it with my LIghtning clone and got a bit of difference, but nothing too much to worry about. I think where you screw up a bit is getting too far off from the target. Running a 16 ohm speaker into a 2 ohm jack., that type of stuff.

In my old Mesa Mark I, they totally recommended running at 4 or 8 ohms to find the tone you wanted. It was in the manual. Go figger...

 

[Quencho092]

Re: close call with single rectifier: impedence mismatching (long read)

I repeat, NEVER let friends borrow guitar gear.

+100000!

and might i add, not only never let friends borrow your gear, never let a clueless bandmate touch ANY of your gear ever! I almost lost a peavey classic because of my idiot drummer who begged me to carry it and fire it up, and he forgot to plug in speakers.

 

[Quencho092]

Re: close call with single rectifier: impedence mismatching (long read)

word had it that if you took a matchless with an 8 ohm speaker and ran that speaker into the 4 ohm jack, the amp cleans up and is actually running at the "proper" impedance. I've tried it with my LIghtning clone and got a bit of difference, but nothing too much to worry about. I think where you screw up a bit is getting too far off from the target. Running a 16 ohm speaker into a 2 ohm jack., that type of stuff.

In my old Mesa Mark I, they totally recommended running at 4 or 8 ohms to find the tone you wanted. It was in the manual. Go figger...

Just like we always say, Scott, big overdesigned transformers not only lend to better, bigger, and meatier tones, they also help protect an amp from impedence mismatches. A big output transformer could handle a larger impedence range than a small, inexpensive one; you also get better tube/overdrive efficiency so you are able to achieve greater volumes while the tubes work less.

 

[Jeff Seal]

Re: close call with single rectifier: impedence mismatching (long read)

...holy geez!

I absolutely have to clarify that muttonchopsrules initial diagnosis follows a very logical path....(kudos to you bro!) and no ill will should be directed to his statements....( he did accurately diagnose a possible "discrepancy"...which is more than most of my customers do!)

My point was really aimed more towards an understanding of amps in general, and in no way was intended as a personal attack or in any way as being offensive...

I mostly come here to "inform", not "intimidate"....



Jeff Seal

 

[Kent S.]

Re: close call with single rectifier: impedence mismatching (long read)

Hey Kent. LTNS.


Artie

Yeah, it's been a bit, just other things in life taking up time, hadn't been able to catch up on anything around the forum. But saw this one, and so, err, figured why not ...

 

[Kent S.]

Re: close call with single rectifier: impedence mismatching (long read)

........................................................................................................... to clarify that muttonchopsrules initial diagnosis follows a very logical path....(kudos to you bro!) and no ill will should be directed to his statements....( he did accurately diagnose a possible "discrepancy"...which is more than most of my customers do!)


Jeff Seal

I should add ... Very true, an impedance mismatch could stress a set of questionable tubes (even if new). So, it definitely would qualify as a contributing factor (or at least could -- GOD forbid, but 6 months from now Mutton might find out there is something else going on in the ampcausing a problem). My point was just to expand a bit on the whole impedance, tranny, tube thing as much as I could ... What's the old thing about the sum of the parts, not the individual parts themselves. ... :cool3:

 

[nepalnt21]

Re: close call with single rectifier: impedence mismatching (long read)

wait so turning on an amp head while it is not hooked up to a cab will fry it?