My tubes don't look right.

I got an ADA MP-1 tube Pre-amp. It has two tubes. Now it seems to me that these particular tubes should be glowing a bit brighter than they are. Exactly how bright do tubes glow? Mine, I know have to be dim. I even let it warm up awhile but they got no brighter. You have to look very hard and close to tell if they are even glowing or not. I got this from some guy who I doubt ever changed the tubes. How often should I change the tubes? What brand should I go with? I think they are AX tubes not Ecc. I also have read that you can upgrade the MP-1 to four tubes. How easy is this? Would a guitar store do something like this if I find I can't do it myself? How much wood would a wood chuck chuck if a wood chuck would chuck wood? And who the hell was on the Grassy Knoll? :eek: Sorry for all the questions but this is a piece of kit I really want to get something out of. Any help much appreciated. :D

Heater filament glow is not a good way to assess tube health. Unless there isn't any glow at all. Preamp tubes are not beaten up the way power tubes are, so they should last for many, many, years. I'm running 30+ year old tubes in some of my amps, probably with 1000s of hours on 'em, and no probs.

12A_7A and ECC__ are interchangeable. The only difference is the tonal characteristics, and that's a subtle thing, subject to a lot of cork-sniffin' tonemeister disputation. Feel free to swap things around. You won't damage anything, and you may just stumble onto a magic combination.

Thanks! I really thought these guys should be giving off some light. It does sound all right. I was just worried I might be losing some tone. I'll play with it for a while and see. So if I do decide to change some tubes could I go out and get the same tubes that are in a Marshall or Boogie? What combos of tubes do you guys use?

12AU7A, 12AY7A, 12AX7A, and 12DW7A are all twin triodes, with identical pin connections. The only major difference is the available gain. The ECC tubes are the European equivalents. There are some audible differences among different brands, and years, of tubes with the same part number, so you could spend a lot of time (and money) experimenting with used, New Old Stock (NOS), and new tubes. If you like what you hear from what you have now, that's good.

If you have some tubes laying around, and you're curious, swap 'em in and try 'em out. Low-gain tubes will clean up the tone, and give you more headroom before they distort, maybe with lower output. High-gain tubes will distort more readily, and will drive your power amp harder.

Yeah your right. These tubes seem ok. By what you said I'm guessing they are mid to high gain. It would piss me off if I went and got new tubes and couldn't tell the difference. I would still like to hear from people who changed tubes to see if they think it is worth my time (and money) to change em out in the future.

I think your tubes are fine. Preamp tubes don't glow as bright as power amp tubes. It's usually a fairly dim glow in comparrison. Part of the fun with tube amps is trying different tubes to see what all tones you can achieve. If you're not very pickey about your tone, it might not make as much of a difference as it would to someone who is a tone freak. Different brands of the same tube will have different tonal characteristics. The trick is figuring out what your preamps specific tonal characteristics are, and then you can decide better what you need, to achieve what you're after. You will also need to know what role each tube playes in the preamps circuit. Here's a list of preamp tubes, and their European equivalents (if applicable), in order from highest gain to lowest gain:

>12AX7 - ECC83 - ECC803(this tube has a different tone, but similar gain)
>5751
>12AT7 - ECC81
>12DW7 - ECC832 (this is actually 2 tubes in one, half of a 12AX7 and half of a 12AU7)
>12AY7
>12AV7
>12AU7 - ECC82

Any of these tubes can be swapped out for each other. Each will have a different amount of gain and different tonal characteristics. As will different brands of each tube.

Take a look around on >this< forum. There are a lot of tone freaks and gear whores there. I'm sure there are some threads about your preamp there.

Check out >Dougs Tubes<, and >Eurotubes< when you're ready to buy new tubes, or if you have any questions. Doug and Bob are both very helpfull and generous with information and suggestions reguarding tubes.

Yes, very good. I went to the forum and used the search function to great success. There were quite a few people who hold this pre-amp in high regard. If it's modded anyway. :rolleyes: So I ordered from ada depot a software upgrade. Right now it'll really only give me more presets, but in the long run I will need it for any other mods I do. I think I'll wait for them to put together some more of the 3MT (upgrade to 3 tubes not 4 :eek: ) do it yourself packages. They also had some affordable tubes so I may consider getting some of those as well. Thanks for all the help guys. :D