Rectifier Tube Hum?

[Ribboz]

Hey everyone!
This is first post on here. Also about my first mesa! I owned a 50:50 but this is my first full mesa amp. It’s a Roadster, and so far I really enjoy it. The only issue I have is this high pitch hum. First, I assumed it was the transformers, and just accepted it. On closer examination I realized the hum is coming from the rectifier tubes. At least I think it is. I doubt the choke could make a hum noise? But the hum is right in that area. So I have two questions.

1.Do rectifier tubes put out a very high pitch hum/fizz/hiss?

2.Would replacing the tubes with a solid state rectifier plug remove the hum?

Also, any info or ideas about the cause and or removal of the hum would be greatly appreciated.

 

[domct203]

Congrats on the Roadster and Welcome to The Board.

1) I've never heard a tube externally hum. The Power Transformer is right behind the rectifier tubes, that's may be where the hum is coming from.

2) Your amp already has a solid state rectifier. Make sure all the Rectifier Tracking switches are set to diode, remove the 5U4GB Rectifier tubes, then power up the amp and see if the hum is gone.

How loud is this hum? Can you hear it over the amps sound at normal levels? My Roadster is very quiet. (until I crank her up that is!)

Have you read your manual? If you don't have one download it from MesaBoogie.com. It will explain all the features of the amp, including the Rectifier Select options.

Dom

 

[Ribboz]

Thank you for the welcome

I thought it was the transformer, but the transformers are making another hum. You can tell because its a different pitch. Also if you really get close in there, it doesn't seem to be coming from that transformer. *crosses fingers* If it were the transformers I would be really sad.

Yes I understand there is already the diode tracking which is solid state. But, since there seems to always be some type of charge going through the recto tubes, I thought I should have something in there. (I'm just going by the fact that the tubes always light up even if I'm set to diode tracking)

Its actually very quiet. Its just a high pitch sound. It's a range I find really annoying. You will pretty much always hear the amp over the sound, unless you really focus on it. But when you stop playing it becomes very obvious.

Yep, read through the whole manual First in a pdf off mesa site, then as the hard copy.

So far Google has failed me to find a a similar problem from anyone else.

 

[domct203]

As long as the amp is set to diodes it is safe to run it without the rectifier tubes. Yes, the tubes are alway supplied with filiment voltage (lit) but when the diodes are selected the filiment is the only thing in the circuit.

Dom

 

[Ribboz]

hmmm Not that I don't trust you. I will take your advice, but make sure by talking to Mesa's tech.

But, I still want to say thank you So thank you for your input

Edit: HA! It worked! Yeah just to be on the safe side I called Mesa, they were extremely polite. And they agreed that it would be safe to run it without the recto tubes. So thank you domct203, you were correct. Now, without the recto tubes its dead silent. I could forget it was on XD

 

[domct203]

Glad to hear the problem has been found.

How old are the tubes? I believe Mesa has a six (6) month warrenty on them & it would not hurt to see if they would replace them. The worst they could do is say no LOL.

Dom

 

[Ribboz]

Brand new. I opened the box last Friday.

 

[fluff191]

I stopped using 5U4G rectifier tubes cause after about 10 hours of playing, I would get small pops and strange noises, but as soon as I would flip on over to diodes, it would go away. So now I just use GZ34's without issue.

 

[domct203]

I never really cared for using the rectifier tubes until I tried NOS. Now it's the core of my Lead Tones in Ch 3.

Dom

 

[domct203]

Brand new. I opened the box last Friday.

I would call Mesa and see if they will send replacements. They might claim that since they "work" they are usable and will not be replaced. It's worth the try though.

Also, it may just be one tube that is making the noise. You can try one at a time to see if that is the case. Just don't play the amp that way, the demand on one tube will be too much. Just install one 5U4GB and power up the amp with nothing plugged in except a speaker cab. Power down and repeat with the other 5U4GB.

Dom

 

[Ribboz]

Hmmm... I till try that Dom. Thank you for the advice.

So how are those NOS tubes?

I was just gonna load up the amp with Wing C everything XD

 

[domct203]

IMO the SED =C= powertubes are the best current production powertubes currently made. I run the SV6L6GC's in both my amps. Just make sure you get them from a tube vendor that can select tubes to correctly run at Mesa's bias specs. I've had great luck with http://www.tubedepot.com/.

**** DISCLAIMER ****
Using any tube other than Mesa tubes will void your warranty.

For the money you really can't beat NOS/VOS 5U4GB's. If you shop around you can find some good deals. I picked up a pair of NOS Tung-Sol 5U4GB's for under $30.00 with shipping! I also have a pair of Sylvania 5U4GB's that I got for under $25.00 as back up. The Raytheon 5U4GB in my MKV cost me $12.00.

I think a powertube swap to =C='s is a good investment, especially if you mostly play at gig levels. If you are a bedroom player, I would wait and get accustomed to the amp first. Most of the harmonics, 3-D complexity and low-end punch of the =C='s really don't come out until you push the amp (crank it). You may want to start trying different preamp tubes first. For current production tubes a Tung-sol 12AX7 re-issue sounds great in V1. Electro Harmonix 12AX7's are a good sounding tube also, especially in V2, and some like the JJ ECC83 there also. Just be aware of the cathode follower positions of your amp ( V3 & V5 in your Roadster). All "Russian" tubes, with the exception of JJ's, can not handle the voltages in these position and will eventually fail. Your best bet there is either a JJ or Penta (Shuguang) Chinese.

You can read all about it here: http://forum.grailtone.com/viewtopic.php?f=4&t=25102&start=19

You most likely have JJ preamp tubes in there now as that is Mesa's current supplier. The tube will read "Mesa 12AX7 Russian". The Mesa Russian-1 is a Sovtek & the Russian-2 is an Electro Harmonix. IMO a full load of JJ will make the amp dark and muddy. The Roadster's manual does not have a tube task chart to explain the preamp tube functions, but you can refer to the Roadking II manual for that info as they share the same exact preamp. Once you get a feel for what effects what in the preamp, you may want to consider NOS/VOS there also.

Good Luck!

Dom

 

[Ribboz]

Thank you for all your input Dom

I was actually considering the Tungsol 12ax7?

hmmmm I'm gonna look into your NOS Tung-Sol 5U4GB

Might also pick up a Weber Mass Attenuator for bedroom volumes