Please help me with my new amp!

[Omni9X]

Hi, everyone.

Yesterday I bought a 65' Twin Reissue used for 650 dollars.

I played it at the guy's house, and it sounded fine, although it had been warming up for 30 minutes before I plugged in. He told me that there are no issues at all with the amp.

I brought it home, and this morning I plugged it in, and left the standby switch on for probably a minute, then I turned it to on.

Right when I did, the amp went from silent to having what I describe as a "rustling" sound. There was a bit of hum that correlated with the volume level, but this is independent of the hum, I think.

Anyway, I'm wondering if it could be the quality of grounding in my house, if I didn't let it warm up for long enough? If I don't let it warm up for a few minutes, what should happen?

Is this what a microphonic tube sounds like?

I only have around 100 dollars left, so I would like to not have to take it to a tech if I don't have to.

This is my first tube amp, so maybe this is normal? I didn't notice it at the guy's house, so I'm puzzled. I don't want to call the seller and offend him, as I got a great deal on it and he seemed like a really nice guy who just moved onto a bogner shiva. He said that he hasn't changed the tubes for 2.5 years, too.

Thank you very much for all of your help.

Rich.

 

[RevolutionMan]

Re: Please help me with my new amp!

It's probably a preamp tube, I've had a few that "rustled" and cracked a bit, if you've got some good preamp tubes, just switch them out one at a time to find the culprit. Some of mine that have done this were decent tubes, they just needed to warm up and settle in, then they worked fine.

 

[Gdntoneguitars]

Re: Please help me with my new amp!

Well, first off, congratulations on moving into your first tube amp, and now, welcome to some of the questions they raise as an owner.

Chances are, it could need tubes. A lot of techs and avid players will tell you that if you are putting constant use on your amp, you'll probably need to change the tubes about every year. If you're not working the amp that hard, you could go longer between changes.

You should definitely call the guy, and at least find out what he thinks it is. Maybe he could tell you if the amp has a tendency to do certain things.

If the tubes are that old, I wouldn't worry about finding out if they're microphonic, but take it to your tech, spend about $50-80 (depending what they charge in your area) and have it retubed.

You mentioned that you turned on the standby, and then the power. That could be an easy answer there, as you should be turning on your power first, then the standby after they've had a minute or so.

I've had old tubes in some of my amps, and they sound riduculous before the tubes blow, especially all the noises they made when warming up.

 

[Omni9X]

Re: Please help me with my new amp!

I meant that I had powered it on with the standby on, and then turned the standby off.

Thank you for your help, I'll talk to him today and ask him that's a known problem to him.

Rich.

 

[greendy123]

Re: Please help me with my new amp!

Actually its probably cause you turned it on with standby on already. You need to power up at least 2 mins w/ standby off, then you can turn standby on. By doing what you did, I had the same problem with no sound. You should try powering up like that. On the wait time I just wait around 5 min or even more so I'm sure the tubes are nice and warm, ready to be used.

 

[Omni9X]

Re: Please help me with my new amp!

This is great, he didn't pick up his phone. I hope I didn't get a poor deal...

How much should it cost me for someone to do a full retube on my amp? I'm thinking over 100 dollars, right?

 

[jony]

Re: Please help me with my new amp!

Someone mentioned 50 to 80 depending on how much the tech charges.

 

[HamerPlyr]

Re: Please help me with my new amp!

First, don't freak out. You've got a great amp and it's probably a minor problem. In your first post, you mentioned that it had been on standby for awhile before it was played. Should that tell us something? Maybe the previous owner knew that it needed to be really warmed up before it could be played without issues.

I'm betting that it's a preamp tube. You can get an entire set for about $60 (4 12AX7's and 2 12AT7's).

 

[Omni9X]

Re: Please help me with my new amp!

Thank you very much, guys. The preamp tubes are something I can do myself easily, right?

Only one of them is glowing, I think it's the reverb driver?

How bright should the power tube's glow be? When I turned standby off yesterday, It made a blue flash and then went back to dull orange on one of them.

Should I be worried about that?

 

[WhoFan]

Re: Please help me with my new amp!

Ya you bought a pretty good amp for your first tube amp... I in the past have bought a few amps that didn;t even work and took them to techs to get them working... I took a big chance! I have a Marshall JCM 800 head that i bought last year that needs an amp doctor.... i bought a 1965 Fender Deluxe amp that was not working at all... I had to take it to a tech... In fact i think i took it to the wrong tech! There is a guy that is a real Fender amp pro that i should of used and i think i'll drop it and the Marshall off to him to have a look at! I've gotten used to buying beat up old gear and fixing it up....

But Your Fender RI amp was a good buy... It can be fixed..... no worries... But it is probally something so minor...

 

[Rich_S]

Re: Please help me with my new amp!

Thank you very much, guys. The preamp tubes are something I can do myself easily, right?

Only one of them is glowing, I think it's the reverb driver?

How bright should the power tube's glow be? When I turned standby off yesterday, It made a blue flash and then went back to dull orange on one of them.

Should I be worried about that?

Sometimes you really have to look to see the tube's orange glow (the "heater" a.k.a "filament"), just due to lines of sight in the amp. Give a good look around, and you should see the orange heater in every tube. If there REALLY is no glow, then there's the problem. If multiple tubes are not glowing, then it's likely a bad connectionin the heater wiring, rather than a bunch of bad tubes.

Don't worry about the blue glow. It comes and goes, some amps have it some don't. It's cool looking.

 

[Scott_F]

Re: Please help me with my new amp!

Take off the preamp tube shields if this amp still has them (little metal tubes that protect and shield the preamp tubes). Take a pencil and (after the amp is warmed up with the volume up a bit) tap on each preamp tube. You can often quickly find the offending tube that way.

If you never play the normal channel, you can pull that first preamp tube all the way to the right as you are looking at the back. You'll not be able to use that Normal channel, but you get a slight gain boost in the reverb channel in the process.

 

[C-Town Mike]

Re: Please help me with my new amp!

Great amp, you'll love it. As some of the other guys mentioned, it's a really good idea to just re-tube a used amp if you have any concerns whatsoever about the age/integrity of the tubes that came with the amp. Re-tubing will freshen up the amp anyway, and make it sound even better, with the peace of mind that it shouldn't give you headaches during a live performance. There are lots of tube options out there, each with a specific character. I suggest doing the homework before buying the tubes, or advising a tech which ones you want.

 

[Gdntoneguitars]

Re: Please help me with my new amp!

I would look into getting some new tubes on the bad boy. It sounds like you got a great deal. There is a post above that told you how to determine which tubes are microphonic, or not working properly.

You can order tubes from any number of places, just talk with the people, tell them what kind of amp you have, and see what tubes they recommend to help you get what you're looking for.

It really does sound like you're not powering your amp on, and the tubes are about to go.

Go to your amp, make sure everything is turned 'off'. Turn only the POWER switch to the ON position. Go check the mail, take a leak, grab a drink, tune your guitar, make sure it is plugged into the input, and then, turn the STANDBY switch to on.

Let us all know what happens.

 

[Omni9X]

Re: Please help me with my new amp!

I took it to Bob at Eurotubes. I found out he lives next to me yesterday. He retubed it for me, and even biased it for just the cost of the tubes.

He's a great guy, and now the amp sounds so much better, and before it sounded great.

The vibrato channel is a bit noisier than the normal channel, though. This is how it was when I got it, too.

I'm thinking that it's normal to have more hum from the vibrato channel, right?

It's not bad to notice when actually playing at all, though.

Anwyay, I can't reccomend Bob at Eurotubes any more. He's a great guy, and really helped me out.

 

[Gdntoneguitars]

Re: Please help me with my new amp!

That might be the greatest ending to any tube amp related story I have ever heard. You live next to Bob from Eurotubes. Be very happy with your luck, and maybe buy a few lottery tickets while you're at it!

Congrats on getting things up an running.