Gitfiddler Posted April 25, 2011 Posted April 25, 2011 OK, I was really tired last Friday after coming back from an out of town four day long training seminar. After dinner I went to the music room to install the new Tone Tubby 40/40 speaker into the Silverface Deluxe Reverb. I planned on doing a sound comparison with my modded Blues Jr. afterwards, so I turned on the BJ to let it warm up while I worked on the Deluxe Reverb speaker swap. Long story short, I had such a good time with the sweet tones coming from the newly installed Tone Tubby in the DR, that I forgot that I left the Blues Jr. switch 'ON'. I did not realize it until early the next morning! The amp was pretty warm to the touch, and had a slightly elevated hum coming from it. I switched it off to let things cool down a bit. It was also my wife's birthday and I had errands to run, so I could not check out the amp right away. Later that day I cranked up the BJ and plugged in the 150 Ultra. It sounded OK, but noticably less headroom than before. Maybe it is my imagination, but I could barely get a clean tone from it. The 150 has hot HRW's in it, so I plugged in my '97 Ibanez GB10 which always sounds great and clean through most amps. Again, the amp was breaking up at aroung 2! No adjusting of the Master Volume or Volume helped much. Aargh!! I was planning on having the amp upgraded with the Bill M mods, but not until a few more Gitfiddler bills got paid off. What have I done to my sweet Blues Jr.?! Have I burned something out by leaving the amp on all night long?! These are PCB amps, so could I have damaged some of its circuitry?? Have I damaged the tubes in some way?? What do you amp dudes think happened to my cleans??
kbp810 Posted April 25, 2011 Posted April 25, 2011 Sounds like the power tubes might be on there way out... I would start with swapping those and see if that fixes it.
Hfan Posted April 25, 2011 Posted April 25, 2011 Power tubes sound like a definite possibility. Do you have spare EL84s around? If you want to rule out the preamp tube (it is the 12ax7 on the far right looking at the rear of the amp), and have no spares, you can swap positions with another one of the other two12ax7's.. think there are 3. Obviously, while powered down. You can mark them with a sharpie to know where you started if, like me, you don't trust your memory.
DetroitBlues Posted April 25, 2011 Posted April 25, 2011 kbp810 to the rescue! : ) Yep! Our own personal guru of all things amplified!
DetroitBlues Posted April 25, 2011 Posted April 25, 2011 OK, I was really tired last Friday after coming back from an out of town four day long training seminar. After dinner I went to the music room to install the new Tone Tubby 40/40 speaker into the Silverface Deluxe Reverb. I planned on doing a sound comparison with my modded Blues Jr. afterwards, so I turned on the BJ to let it warm up while I worked on the Deluxe Reverb speaker swap. Long story short, I had such a good time with the sweet tones coming from the newly installed Tone Tubby in the DR, that I forgot that I left the Blues Jr. switch 'ON'. I did not realize it until early the next morning! The amp was pretty warm to the touch, and had a slightly elevated hum coming from it. I switched it off to let things cool down a bit. It was also my wife's birthday and I had errands to run, so I could not check out the amp right away. Later that day I cranked up the BJ and plugged in the 150 Ultra. It sounded OK, but noticably less headroom than before. Maybe it is my imagination, but I could barely get a clean tone from it. The 150 has hot HRW's in it, so I plugged in my '97 Ibanez GB10 which always sounds great and clean through most amps. Again, the amp was breaking up at aroung 2! No adjusting of the Master Volume or Volume helped much. Aargh!! I was planning on having the amp upgraded with the Bill M mods, but not until a few more Gitfiddler bills got paid off. What have I done to my sweet Blues Jr.?! Have I burned something out by leaving the amp on all night long?! These are PCB amps, so could I have damaged some of its circuitry?? Have I damaged the tubes in some way?? What do you amp dudes think happened to my cleans?? Wow! Love that cab! Hope its just the tubes, good luck!
pegleg32 Posted April 25, 2011 Posted April 25, 2011 Yep, one of the things that I learned with my Billm Blues Jr, is that the tubes are biased really hot and consequently they tend to burn out power tubes fairly quickly. That's what I would check.
tulk1 Posted April 25, 2011 Posted April 25, 2011 If you wore out the power tubes by leaving it on overnight just the one time, well, those puppies weren't long for this world, anyway. I'm pre-oldhimerz and leave my amps on overnight all the time. Well, more than I'd like. And I've yet to experience any problems the next morning. And one of those amps is the notorious Vox AC30CC1 - known for overheating. Seems to me if it turns out to be the tubes, you hastened their demise just a skosh. Or maybe your DR sounds sooooo good the BJ just can't compete.
Gitfiddler Posted April 25, 2011 Author Posted April 25, 2011 Thanks all (especially Brian) for the tips. I'll check out the tubes this evening. I do have a few spares lying around. Either way, the plan to have the Bill M mods done down the road remain in place. My amp tech also suggested installing a Standby switch as part of the mods. Now that really sounds like a good idea!
Hfan Posted April 25, 2011 Posted April 25, 2011 Thanks all (especially Brian) for the tips. I'll check out the tubes this evening. I do have a few spares lying around. Either way, the plan to have the Bill M mods done down the road remain in place. My amp tech also suggested installing a Standby switch as part of the mods. Now that really sounds like a good idea! He offers a standby switch mod I installed one, very simple.
Gitfiddler Posted April 25, 2011 Author Posted April 25, 2011 He offers a standby switch mod I installed one, very simple. With my recent memory lapses, (I suffer from the dreaded C.R.S. condition) I may need to install an Automatic Shutoff Switch in addition to the Standby!
schundog Posted April 26, 2011 Posted April 26, 2011 I highly recommend the BillM mods for a BJ. I had them done by the man himself, as I'm a danger to myself with a soldering iron. The addition of the presence knob and the bigger Heybour (sp?) output transformer made a big difference in mine. I also changed speakers to an Eminence Texas Heat. Great grab and go amp.
schundog Posted April 26, 2011 Posted April 26, 2011 Here is BillM's article on tracking down hum in a Blues Junior. http://billmaudio.com/wp/?page_id=882
DetroitBlues Posted April 26, 2011 Posted April 26, 2011 He offers a standby switch mod I installed one, very simple. I believe the standby switch is a mod of the existing switch that is a three position toggle instead of two. It should really help out the life of tubes too.
kbp810 Posted April 26, 2011 Posted April 26, 2011 I believe the standby switch is a mod of the existing switch that is a three position toggle instead of two. It should really help out the life of tubes too. That sounds like the best way to do it; avoid having to drill another hole in the chassis.
Hfan Posted April 26, 2011 Posted April 26, 2011 That sounds like the best way to do it; avoid having to drill another hole in the chassis. Thats what it was, remove old switch, install new and connect to the terminals (no soldering) as per instruction sheet.
Gitfiddler Posted April 27, 2011 Author Posted April 27, 2011 So what was the end result? Tube issue? Sorry, I haven't had time to work on the amp this week. Work and home stuff has my attention until the weekend. I'm thinking it will need a tube-ectomy.
DetroitBlues Posted April 27, 2011 Posted April 27, 2011 Sorry, I haven't had time to work on the amp this week. Work and home stuff has my attention until the weekend. I'm thinking it will need a tube-ectomy. No worries! Everyone's has those days. Let us know thought!
schundog Posted April 28, 2011 Posted April 28, 2011 I believe the standby switch is a mod of the existing switch that is a three position toggle instead of two. It should really help out the life of tubes too. I've followed BillM's wisdom over on the FDP for several years. Interestingly enough, he USED to say there is no need for a standby switch on a 15 Watt amp, as the voltage that hits the tubes isn't as hard as it is on a larger wattage amp. I "get" having a 3 positition switch, which is the only way possible to use a full size switch on these amps, as there isn't any more room to drill for another switch, but, according to "the old Bill," you really don't need it as far as turning the amp on cold. I see having it for giving the tubes a rest while you are on a short break, though. As always, I'd like to hear "the other Brian's" take on this.
Hfan Posted April 28, 2011 Posted April 28, 2011 I highly recommend the BillM mods for a BJ. I had them done by the man himself, as I'm a danger to myself with a soldering iron. The addition of the presence knob and the bigger Heybour (sp?) output transformer made a big difference in mine. I also changed speakers to an Eminence Texas Heat. Great grab and go amp. Schundog, Did you notice earlier breakup after installing the Hetboer x former? I did mine a while back and it seems to have earlier breakup. I have some new tubes on the way but was just wondering. Will try the new tubes and re bias and see what I find. I'm still using the origional Jensen (special design / made in Italy) speaker may be too much for it.
Hfan Posted April 28, 2011 Posted April 28, 2011 I've followed BillM's wisdom over on the FDP for several years. Interestingly enough, he USED to say there is no need for a standby switch on a 15 Watt amp, as the voltage that hits the tubes isn't as hard as it is on a larger wattage amp. I "get" having a 3 positition switch, which is the only way possible to use a full size switch on these amps, as there isn't any more room to drill for another switch, but, according to "the old Bill," you really don't need it as far as turning the amp on cold. I see having it for giving the tubes a rest while you are on a short break, though. As always, I'd like to hear "the other Brian's" take on this. Personally, I find the new switch also useful for noiselessly swapping guitars while the amp is cranked. Need to get one of those noiseless cables one of our members (forgot his name) are offering.
schundog Posted April 29, 2011 Posted April 29, 2011 Schundog, Did you notice earlier breakup after installing the Hetboer x former? I did mine a while back and it seems to have earlier breakup. I have some new tubes on the way but was just wondering. Will try the new tubes and re bias and see what I find. I'm still using the origional Jensen (special design / made in Italy) speaker may be too much for it. Hfan, no, in fact, I think the transformer HELPED the headroom, if anything. As BillM did my mods, he modded it with a trim pot that adusts the power tubes bias for longer, cooler, better-toned operation. I played it tonight through a Gibson Faded Flying V with Gibson pickups, a Heritage 170 w/ Schallers, and a MIM Jimmie Vaughan Strat. All sounded good and clean at pretty loud volumes, obviously without the "Fat" switch engaged. I don't know exactly WHAT did WHAT, as he did all of the mods at once, and then I changed the speaker relatively shortly thereafter to the Eminence Texas Heat. The only problem, if you see it that way, is I could NEVER come close to recouping my cost of modding this amp, so I guess it's with me for the long haul, which is OK by me.
Gitfiddler Posted April 30, 2011 Author Posted April 30, 2011 OK, finally got a chance to check out the distorted BJ. I think the problem was loose tubes. A couple were not seated tightly in their respective sockets, probably from my last speaker swap. Could that have caused the lack of cleans?? None of the tubes looked bad, burned or damaged. They all glowed nicely and had no loose filaments. (That is ALL I know to look for with tubes/valves!) They are a matched set of JJ's, so unless one is obviously damaged I'd like to keep them in there warming up the amp innards and my tone. Anyway, the BJ sounds better now. The cleans have come back unless I push the Master and Volume knobs past their usual clean zones. The Bill M mod project will have to wait. Just scored a nice Hermida Zen Drive pedal to put in front of this sweet little amp.
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