| Author | Message | ||
     Ben Moore (ben) Username: ben Registered: 06-2008 |
I try to find answers here, but since some of the info is dated by a couple of years, forgive me for repeating a question. I bought my 210-hd130 from someone who posted here( I think)...so caps were clean, everything biased and working great. He even included a couple of extra tubes. These are Eurotubes. I'm anticipating quite a bit more use on this amp in the coming months and I figure the amp is going on about 2 years w/ the same tubes. So I was going to order the exact same set of tubes(if possible) from Eurotubes because I like the sound. From what I gather, since they'll be the same tubes, I can just pop them in and not worry about re-biasing the unit? thanks in advance. | ||
| Bill Traylor (bozzy369) Username: bozzy369 Registered: 02-2008 |
Ben,yes as long as the tubes you buy are matched sets,some still like to check the bias,but i'd say you could just pop them in and be safe. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Let me try to explain something. Matched tubes don't mean that they will run "OK" in your amp. You "might" be OK but you also might cook something. My experience with JJ's(and that's what I use in my MM's) is that they vary wildly. If you have the boxes that came with your Eurotubes set, they will have numbers on the boxes that will say 36, 37, 46, 46, etc., pencilled on the end. THESE are the numbers that are important, but ONLY to the distribtor that you buy from-in this case eurotubes. They mean only that they pulled XX amount of current, when tested with xx amount of voltage on HIS equipment. They are useless to anyone else. If you HAVE the original boxes that the tubes come in, you can give those numbers to Bob at Euro and he can fix you up with tubes that SHOULD be real close to what you have. Again though, you must hear the SHOULD part. Tubes drift, resistors drift, caps dry out, etc. It's best to check. I use JJ's and get great life and tone but I WORK on this stuff so it gets regular checkups and is biased PROPERLY at tubes changes. It's best to bias a little cool with these amps to promote tubes and transformer life-one shorted tube could take out a very expensive and hard to find transformer. Rant over. Mike. | ||
| Bill Traylor (bozzy369) Username: bozzy369 Registered: 02-2008 |
mike did musicman not ever make a hd-130 with the cathode based self biasing set-up? | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
The SS driver version is a cathode driven bias LIMITING type circuit(as I understand it) that sets the cathode current by limiting the amount of cathode current though a couple of resistors that can be measured to set at a desired point. If you have the SS driver version, it's KIND of a self biasing but it must be set. It is also positive voltage on the control grid instead of negative but the relationship between the cathode and anode is more negative on the cathode side. I'm not much into them but I had one for a while. I prefer the tube PI types but hey, that's just me. | ||
| Ben Moore (ben) Username: ben Registered: 06-2008 |
thanks for the info and the words of caution. I do have the original boxes for the set. So it looks like I'll order the exact same set and then find someone in North Carolina that works on Music Man amps..for maintenance purposes. This is my first "used/classic" tube amp and I don't have a clue about 'working' on it.... |