#1
instead of getting a matched quad. I heard that Mesa tubes can be used "plug and play" once the bias is set. In a Plexi style amp with 4 sockets is going with two matched pairs ok? Thanks.
#2
yea but you need to change the pairs correctly that being change the 2 inside together and the 2 outside
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#4
You don't even really need matched pairs. Any four tubes of the same type by the same manufacturer will be close enough to run safely, if at a slight bandwidth reduction.

Hell, I've run an amp with two unmatched Ruby EL34s (an EL34B and an EL34B-STR in fact), a Mullard reissue EL34 and a Sovtek 6L6WXT+ without any tone or performance issues, and that was a flimsy Chinese-made amp.

And 311etc, he's not talking about running only two tubes, so there's no need to cut the ohm load.
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#5
ah...

reading comprehension fail I thought he was saying 2 matched tubes in the title and got spun. Tonally, I prefer matched quads from the same vendor/type.

2 pairs does = 4


not a fan of mixing tubes like that tho
Last edited by 311ZOSOVHJH at Aug 23, 2011,
#6
so it should be alright? the reason im doing this is my local long & mcquade only carry mesa tubes, i think, and they only come in pairs.
#7
Quote by the hirsh
so it should be alright? the reason im doing this is my local long & mcquade only carry mesa tubes, i think, and they only come in pairs.

The amp will not explode and blast your city into a smoking crater.
Money beats soul every time.

Money beats soul...every time.

Money...beats soul...every...goddamn...time.
#8
two matched pairs of the same type of tube (all of the same kind, el34s for example) would be fine in a plexi style amp.

in any order.

others will argue, but life will go on.

sometimes they sound better that way anywho.
#10
Mesas are considered "plug and play" in Mesa amps because they're biases are cathode biased, so that they don't drift, like in fixed biased amps. Mesa makes their tubes to fall within a certain specification/range. With any amp that isn't cathode bias, you're still going to want to bias, although biasing isn't nessecary, it helps prolong the life of the tubes.

EDITED!
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Last edited by LaidBack at Aug 23, 2011,
#11
^ yes the mesa part is partially correct i think.

Actually,

Fixed Bias - you have to bias manually and there is drift - sometimes immediately after.

Cathode Bias - amp biases for you. Nothing to do (except mod it)

Non-Adjustable Fixed - No need to do anything. Valvekings are biased this way.

Mesa amps - they are fixed but designed so there is no need to do anything.


Edit: Listen to him ..... v
Last edited by 311ZOSOVHJH at Aug 23, 2011,
#12
Quote by LaidBack
Mesas are considered "plug and play" in Mesa amps because their biases are fixed so that they don't drift, like in cathode biased amps. Mesa makes their tubes to fall within a certain specification/range. With any amp that isn't fixed bias, you're still going to want to bias, although biasing isn't nessecary, it helps prolong the life of the tubes.

This is not correct. Fixed bias amps need to be biased. Cathode bias amps do not. Fixed bias means they don't have a dynamic bias, which cathode bias amps do. It does not mean that they bias does not drift (it does!) and it does not mean it doesn't need to be adjusted.

The real reason mesas are plug and play is that they run the plates at low voltages so that the bias is almost always within acceptable range. Amps that put more voltage on the plates need to be biased more carefully because they may be closer to redplating the tubes. Mesa also color codes tubes so you can use "green" or whatever sets of tubes and know they're close to the last "green" set you bought, bias-wise. That means two sets of the same color make a matched quartet.

Edit: 311 beat me to it, mostly. Non-adjustable fixed just means that the manufacturer didn't include a bias pot for whatever reason. Often, and this is the case of the Valveking as mentioned and most Mesas, the reason is low plate voltage. There's actually no difference in the bias circuit between adjustable and non-adjustable fixed bias except that there's a pot instead of a resistor in an adjustable fixed bias amp.
#13
Quote by Roc8995
This is not correct. Fixed bias amps need to be biased. Cathode bias amps do not. Fixed bias means they don't have a dynamic bias, which cathode bias amps do. It does not mean that they bias does not drift (it does!) and it does not mean it doesn't need to be adjusted.

The real reason mesas are plug and play is that they run the plates at low voltages so that the bias is almost always within acceptable range. Amps that put more voltage on the plates need to be biased more carefully because they may be closer to redplating the tubes.

Edit: 311 beat me to it, mostly. Non-adjustable fixed just means that the manufacturer didn't include a bias pot for whatever reason. Often, and this is the case of the Valveking as mentioned and most Mesas, the reason is low plate voltage. There's actually no difference in the bias circuit between adjustable and non-adjustable fixed bias except that there's a pot instead of a resistor in an adjustable fixed bias amp.




You are just on my shit today aren't you Colin? Going to fix my post now...
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#14

It's ok, the terms are very frustrating since they're named very poorly. Fixed bias means you need to bias, and "non-adjustable" doesn't mean "fixed" so you can have an "adjustable" but also a "fixed" bias on the same amp, which sounds impossible. It's a mess.
#15
Colin - I see your Edit. That makes sense.

But guys, he doesn't even have a Mesa. Based on his OP and some of his past threads I'm thinking he has a Plexi/JCM800 Clone from Ceriatone. Is that right Hirsh?

Those are a traditional fixed bias amp correct?


Edit: no sweat - you have basic idea.......v
Last edited by 311ZOSOVHJH at Aug 23, 2011,
#16
Thanks for the clarification 311 and Colin.

And I was just trying to let him know that the "plug and play" thing only works with Mesa's amps, not their tubes.
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#17
Quote by AeolianSeventh
The amp will not explode and blast your city into a smoking crater.


Too bad, I'd pay to see that....
“Ignorance more frequently begets confidence than does knowledge.”
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#18
Quote by 311ZOSOVHJH
Colin - I see your Edit. That makes sense.

But guys, he doesn't even have a Mesa. Based on his OP and some of his past threads I'm thinking he has a Plexi/JCM800 Clone from Ceriatone. Is that right Hirsh?

Those are a traditional fixed bias amp correct?

We did get off topic there-
However, the mesa color coding deal does mean that if he gets two pair of the same color, they will work as a quad. I think that's the solution.
#19
Quote by Roc8995
We did get off topic there-
However, the mesa color coding deal does mean that if he gets two pair of the same color, they will work as a quad. I think that's the solution.

Cool. And maybe that is all he is trying to accomplish.

I was only going to ask this Hirsh:

Why Mesa tubes (they are rebranded anyway)
What are you trying to accomplish with your Plexi clone? Tonally?
Where are you going to buy your tubes?
How old is your amp?
stuff like that
#20
Quote by 311ZOSOVHJH
Cool. And maybe that is all he is trying to accomplish.

I was only going to ask this Hirsh:

Why Mesa tubes (they are rebranded anyway)

Quote by the hirsh
the reason im doing this is my local long & mcquade only carry mesa tubes, i think, and they only come in pairs.


...
#23
Quote by 311ZOSOVHJH

What are you trying to accomplish with your Plexi clone? Tonally?
Where are you going to buy your tubes?
How old is your amp?
stuff like that


I'm looking for a classic rock type of tone mostly. I also want to get the tubes locally for now, just to save some unexpected trouble if the tubes fail. My amp is being built as we speak, it's a plexi clone.

Quote by AeolianSeventh

The amp will not explode and blast your city into a smoking crater.


Thats what I was looking for


Quote by 311ZOSOVHJH


i'm failing hard in this thread in the reading department.

Hirsh - I'm just sayin' maybe look at EL34 or EL34Bs from www.hotroxuk.com or something.

JJs, Mullards, SED =C= even Ruby STRs I hear are good.


I want to try some =C= because I hear a lot about them, but for now I want to buy locally. I will ask if they carry any other tubes though, hopefully they do.
#24
Quote by Roc8995
We did get off topic there-
However, the mesa color coding deal does mean that if he gets two pair of the same color, they will work as a quad. I think that's the solution.


Yeah, that is basically what I was looking for. I can bias the amp, I just want to know that I get a matched quad.