Mark III sounds dramatically better after "warming up"

[BigKD]

So I turn on my mark III, let the tubes heat up for about 30 seconds, and start playing in R2. Sounds stiff, tight, and harsh.

I then leave the amp on standby for about a half an hour and come back and start playing. Sounds WAAAAAY better.

So what's the deal? I have been noticing this phenomena for a while now. The amp does not sound right until the amp actually warms up to a certain temperature.


Is there a certain faulty part that could cause this? Could it be related to mesa's cold bias?

 

[Padd Metals]

Hi BigKD

I have a possibility to test and compare different amps in our studio. In these tests I have found your comment to be spot on! My Mark III Blue Stripe needs some serious warm up (yes, about 30 minutes) before the sound is right. But then it really is right...
It might have something to do with the bias fixed cold.
On the other hand, we have found this to be an issue with other amps as well. We had an amp shootout of two Marshall 2203's, Marshall 1987, Framus Dragon, a Bogner, H & K Tubemeister 36 and my Mark III.
The Bogner took the longest time to warm up, way more than 30 minutes. Marshall 2203's were ready after about 2 minutes. Framus, Tubemeister and the 1987 were all ready after switching them from stand by to play after only 30 seconds of warm up.
Please note that we actually biased the Bogner, Marshalls and the Framus pretty hot. Mesa and the Tubemeister can't be biased.

Actually the Bogner was a pain to bias, since the plate voltage seemed to fluctuate a lot. We didn't get it to sound just right before we measured the mains voltage entering the amp. Mains voltage fluctuated between 210 - 230 v (230 volts being the norm here). The plate voltages followed the mains voltage changes. That was the answer to poor sound and maybe at least partly explains the long heat-up time. So, check your mains voltage, it might be on the low side also.

 

[boola]

So I turn on my mark III, let the tubes heat up for about 30 seconds, and start playing in R2. Sounds stiff, tight, and harsh.

I then leave the amp on standby for about a half an hour and come back and start playing. Sounds WAAAAAY better.

So what's the deal? I have been noticing this phenomena for a while now. The amp does not sound right until the amp actually warms up to a certain temperature.


Is there a certain faulty part that could cause this? Could it be related to mesa's cold bias?

I think it's to do with a 'cold' bias too but it's quite normal. All amps (and their components) heat up as they are used. When the components in the bias circuit warm up, the idle current (bias) increases. When I adjust the bias in my Marshalls, I always bias on the cold side because I know the idle current will creep up as the amp is played, as much as 10%

So it actually makes sense that your amp is biased cold on startup, otherwise it would be biased too hot and really bass out after 30 mins instead of sounding better.

 

[BigKD]

So I turn on my mark III, let the tubes heat up for about 30 seconds, and start playing in R2. Sounds stiff, tight, and harsh.

I then leave the amp on standby for about a half an hour and come back and start playing. Sounds WAAAAAY better.

So what's the deal? I have been noticing this phenomena for a while now. The amp does not sound right until the amp actually warms up to a certain temperature.


Is there a certain faulty part that could cause this? Could it be related to mesa's cold bias?

I think it's to do with a 'cold' bias too but it's quite normal. All amps (and their components) heat up as they are used. When the components in the bias circuit warm up, the idle current (bias) increases. When I adjust the bias in my Marshalls, I always bias on the cold side because I know the idle current will creep up as the amp is played, as much as 10%

So it actually makes sense that your amp is biased cold on startup, otherwise it would be biased too hot and really bass out after 30 mins instead of sounding better.

Maybe you could play for a while to heat up the components and then bias the amp?

I'm seriously considering getting an adjustable bias pot installed in my mark IIIs! Or at least getting a probe to test out my current tubes.

 

[BigKD]

Hi BigKD

I have a possibility to test and compare different amps in our studio. In these tests I have found your comment to be spot on! My Mark III Blue Stripe needs some serious warm up (yes, about 30 minutes) before the sound is right. But then it really is right...
It might have something to do with the bias fixed cold.
On the other hand, we have found this to be an issue with other amps as well. We had an amp shootout of two Marshall 2203's, Marshall 1987, Framus Dragon, a Bogner, H & K Tubemeister 36 and my Mark III.
The Bogner took the longest time to warm up, way more than 30 minutes. Marshall 2203's were ready after about 2 minutes. Framus, Tubemeister and the 1987 were all ready after switching them from stand by to play after only 30 seconds of warm up.
Please note that we actually biased the Bogner, Marshalls and the Framus pretty hot. Mesa and the Tubemeister can't be biased.

Actually the Bogner was a pain to bias, since the plate voltage seemed to fluctuate a lot. We didn't get it to sound just right before we measured the mains voltage entering the amp. Mains voltage fluctuated between 210 - 230 v (230 volts being the norm here). The plate voltages followed the mains voltage changes. That was the answer to poor sound and maybe at least partly explains the long heat-up time. So, check your mains voltage, it might be on the low side also.

My amp runs off a furman voltage regulator these days, so my amp always sees 120v no matter what!

It's nice to have confirmation of my observations. I guess my ears still have some life in them. :lol: