20th XTC popping sound issue/loop issue fixed

R

RG955TT

New member
Last night my loop just quit, click the switch and nothing, no LED or anything. Plugged in my FS from my 101B and while it lit up the LED was flashing and I could hear a relay clicking on and off. Put the correct FS back, nothing...anyone have any idea what I should be looking for here? I'll have to open her up tonight. Not too cool for such a young amp though...my 101B is got to be 10 years old and no issues ever. This 20th is almost brand new so I'm a little suprised.

This has been fixed (new led, thanks guys who helped w/this)...now on to the latest issue, popping sound even with output low it's fasirly loud, amp either get quieter, or louder with each popping noise, check output tubes, tired different set, still doing it. Opened it up and can't see anything obvious...
 
Usually the loop problems I've had with XTCs is due to the LED on the footswitch dying. Happend on 2 different amps. Since your tried a different footswitch that leads me to believe it's not that. But it could be. Try replacing the LED if the loop works without a footswitch attached. Did you try it without a footswitch plugged in and just engaged the loop from the button on the back? Or try changing the tube for the FX loop buffer.
 
Thanks for the help. I will look into the LED. Do you know specs on what I need to buy to replace it by chance? Seems wierd, my 101B going strong after 10+ years and this thing is failing after a few months. Had power amp crackle (loud snap sound) last night too, then low output, then came back full juice on it's own. Maybe a bad power amp tube. Is there info anywhere on setting Bias when retubing these things? Thanks
 
RG955TT":362vjuw6 said:
Thanks for the help. I will look into the LED. Do you know specs on what I need to buy to replace it by chance? Seems wierd, my 101B going strong after 10+ years and this thing is failing after a few months. Had power amp crackle (loud snap sound) last night too, then low output, then came back full juice on it's own. Maybe a bad power amp tube. Is there info anywhere on setting Bias when retubing these things? Thanks
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:confused: Ya, this doesn't sound good - or normal. While you're in the midst of checking LED's and definitely looking into a new quad of power tubes (is this amp brand spankin'..??), I'd also put a call in to Charley and ask his opinion. He's always a wealth of knowledge and is an awesome cat to discuss all matters Bogner with...

Hang in there - FWIW, I've had ZERO problems with my 20thA, and in addition to this, the loop issues you've been experiencing that you and I have discussed a while back may all be symptomatic to the underlying problem. Circuit, tube, relay or something.

Keep us posted.
V.
 
RG955TT":1c0cpigb said:
Last night my loop just quit, click the switch and nothing, no LED or anything. Plugged in my FS from my 101B and while it lit up the LED was flashing and I could hear a relay clicking on and off. Put the correct FS back, nothing...anyone have any idea what I should be looking for here? I'll have to open her up tonight. Not too cool for such a young amp though...my 101B is got to be 10 years old and no issues ever. This 20th is almost brand new so I'm a little suprised.
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Check the loop driver preamp tube? Should be V4. Pull it and put any 12ax tube you have in and see.

Your other problem with the crackle and power loss is a power tube but could be in the preamp section as well. Depends on what channel it happens on to determine the culprit. If it is just channel 1, it is either V1 or V6. If it is channel 2 or 3, it could be any of them, according to the tube assignment. Bogner gets the most out of the tubes the way his tone stacks are designed.

You might be better off doing a complete retube. You could have a dud or two in there.

Steve
 
Cool, thanks guys for the feedback. I tried last night to swap the power tubes (outers to inner position, inners to outside spot. I did this because the popping occurs when at half power so I figured I could maybe isolate the pair/single tube w/the issue since at half power only two of the power tubes are running, no luck, still doing it. Since it still does it it may have eliminated the power tubes as the issue (How are they paired, I guessed inner outer as the pairs) but I'm not positive.
Is there a biasing tutorial somewhere, how hard is this thing to bias, what power tubes (6L6) should I buy? Doug at Dougs tubes is suggesting =C= 6L6's (pretty pricy so I want what sounds best).

I will try replacing the LED on the pedal and go from there on the loop. The switch to turn the loop on/off on the head itself works fine so it can't be a big deal. I'm more concerned at this point w/the popping...given what I did above it may be a pre-tube issue
 
RG955TT":11cqrbvi said:
Cool, thanks guys for the feedback. I tried last night to swap the power tubes (outers to inner position, inners to outside spot. I did this because the popping occurs when at half power so I figured I could maybe isolate the pair/single tube w/the issue since at half power only two of the power tubes are running, no luck, still doing it. Since it still does it it may have eliminated the power tubes as the issue (How are they paired, I guessed inner outer as the pairs) but I'm not positive.
Is there a biasing tutorial somewhere, how hard is this thing to bias, what power tubes (6L6) should I buy? Doug at Dougs tubes is suggesting =C= 6L6's (pretty pricy so I want what sounds best).

I will try replacing the LED on the pedal and go from there on the loop. The switch to turn the loop on/off on the head itself works fine so it can't be a big deal. I'm more concerned at this point w/the popping...given what I did above it may be a pre-tube issue
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How old is the amp and did you buy it from a reputable source?

I would go for a complete re-tube, pre's and power's. If that doesn't solve the problem, let's look at the FS. Also - do give Charley a call in the Hollywood HQ... He's got the answers.

V.
 
Got the footswitch fixed. Interesting that the loop depends on the LED to switch it. I replace all the pre tubes last night and have move the output tubes to all positions trying to eliminate the op to no avail. Seems that after the pop sound, I have more volume and gain, high end and low end. It's almost like hitting the old/new switch on the back panel.
 
RG955TT":32had13g said:
Got the footswitch fixed. Interesting that the loop depends on the LED to switch it. I replace all the pre tubes last night and have move the output tubes to all positions trying to eliminate the op to no avail. Seems that after the pop sound, I have more volume and gain, high end and low end. It's almost like hitting the old/new switch on the back panel.
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And how about your original volume issue with the loop?? :confused:
V.
 
The volume issue w/the loop is still there but not really an issue anymore because I have decided to use this for livingroom and recording use only, not practical for gigging. I called and spoke to Charley at Bogner but he was really no help on the popping issue, seems to think it's power amp related but I'm not convinced myself yet. I have it appart and looking for anything obvious. Am I correct in assuming I will need a bias right or like type of device to change power tubes and re-bias? Spoiled by Diezel's ease of tube changes and biasing. Also, which tubes in the pre are the ones that are cathode based? I know it's suggested that in those spots you shouldn't use Russian or like pre tubes as they can't handle the current. What is stock in the pre's for the 20th? I was suprised to hear from Charley they are using JJ6L6's now as std power tube.
 
RG955TT":33qjizxm said:
The volume issue w/the loop is still there but not really an issue anymore because I have decided to use this for livingroom and recording use only, not practical for gigging. I called and spoke to Charley at Bogner but he was really no help on the popping issue, seems to think it's power amp related but I'm not convinced myself yet. I have it appart and looking for anything obvious. Am I correct in assuming I will need a bias right or like type of device to change power tubes and re-bias? Spoiled by Diezel's ease of tube changes and biasing. Also, which tubes in the pre are the ones that are cathode based? I know it's suggested that in those spots you shouldn't use Russian or like pre tubes as they can't handle the current. What is stock in the pre's for the 20th? I was suprised to hear from Charley they are using JJ6L6's now as std power tube.
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Just get a Weber Bias Rite to bias. It's really easy. The cathode followers in the XTC are v3/v4 or v3/v5 can't remember, but if you look, the two will be chinese tubes and the rest JJs if that's what they are using now. Used to be Sovtek LPS/Chinese.
 
RG955TT":183e0d0x said:
The volume issue w/the loop is still there but not really an issue anymore because I have decided to use this for livingroom and recording use only, not practical for gigging. I called and spoke to Charley at Bogner but he was really no help on the popping issue, seems to think it's power amp related but I'm not convinced myself yet. I have it appart and looking for anything obvious. Am I correct in assuming I will need a bias right or like type of device to change power tubes and re-bias? Spoiled by Diezel's ease of tube changes and biasing. Also, which tubes in the pre are the ones that are cathode based? I know it's suggested that in those spots you shouldn't use Russian or like pre tubes as they can't handle the current. What is stock in the pre's for the 20th? I was suprised to hear from Charley they are using JJ6L6's now as std power tube.
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All pre's are now high-grade Chinese/Shuguang 12AX7B/C in all V positions. Ya, JJ's are now stock - my 20thA came stock with JJ EL34's. I'm not fussed with the JJ's in the power section, but I'm certain some =C='s will do better when these pop. Secondly, there's the option of KT77's if I want to really get into checking tones out. The Weber Bias Rite is a good investment (even for the Diezel's as it's way better than the shunt method of back & forth).

Helluvanamp to have just in the living room :confused:

V.
 
Yeah, I know a bit extreme for the living room (lol!) but I'm single w/no kids so I can wick it up as I like and I love the sound of this thing, just that huge headshell (why the hell do these companies have to make these heads so friggen huge?)and white tolex plus the issues I'm having w/it don't make it very practical for gigging right now. We'll see, I can always buy another headshell for gigging. Anyway, I'm running out of ideas on this popping noise thing, another thing I noticed is it's independant of channel volumes so it's after the preamp section...the pop is pretty loud, also independant of the loop return volume if engaged...anyone have any other ideas on what to look for? I can take it in for service but Schrader in Chicago is about an hours drive away and I want to exhuast all possible self fixes before resorting to taking it in. Put in an old set of 6L6's from mesa just to try and it's still doing it...aghhh...I want to play this thing but I'm getting frustrated, not sure if I am hurting anything by using it to any degree. Seems the pops are most pronounced when taking amp off standby. Thanks guys for all the help so far.
 
RG955TT":1jsuvafq said:
Yeah, I know a bit extreme for the living room (lol!) but I'm single w/no kids so I can wick it up as I like and I love the sound of this thing, just that huge headshell (why the hell do these companies have to make these heads so friggen huge?)and white tolex plus the issues I'm having w/it don't make it very practical for gigging right now. We'll see, I can always buy another headshell for gigging. Anyway, I'm running out of ideas on this popping noise thing, another thing I noticed is it's independant of channel volumes so it's after the preamp section...the pop is pretty loud, also independant of the loop return volume if engaged...anyone have any other ideas on what to look for? I can take it in for service but Schrader in Chicago is about an hours drive away and I want to exhuast all possible self fixes before resorting to taking it in. Put in an old set of 6L6's from mesa just to try and it's still doing it...aghhh...I want to play this thing but I'm getting frustrated, not sure if I am hurting anything by using it to any degree. Seems the pops are most pronounced when taking amp off standby. Thanks guys for all the help so far.
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Sounds like a complete retube - period. Order a 12AX7B set and a matched quad of power valves and just DO IT. I feel for you man, I can't imagine not having mine perform 100% as ace as it is.

Keepin' the 20thA love vibe alive... :rawk:
V.
 
Its a great amp with having kids, Crank it up and you cant here them lil shits. Although mine are 15 and 16 :LOL: :LOL:
 
RG955TT":ajbgd7cy said:
In the shop for repair...this is beyond the tubes but I'm sure minor.
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Please make sure to post WTF the problem was. And as well, let us know how the loop sounds when you get 'er back... Sorry she's in the shop but best to get that "living room" amp sorted out - so that you can crank 'er to 10 to 'dust the home' and rearrange the furniture :D

Thanks,
V.
 
Picking up amp today! Was several bad solder joints that were causing intermittant issues. Low dough fix so hopefully all is well and I'm back in business.

Three things I wish all highline amp makers would have on their amps...send and return volumes for the loop so you could interface any kind of pedal of fx unit and still have plenty of volume/output, dual switchable masters for volume bump for solos, and a deep control for the really deep low end of the entire amp. If my 20th had these three things it would be the perfect amp for me. Seems even all of these high end amps (and I have several) still to me as a working player have some sort of shortcoming. I'm sure there are reasons, but for me I'm just sayin...my 2 cents. My Diezels are close but even those have some comprimises, but I still gravitate to the Bogners for the best tone (rich, thick in the lower mids etc etc.)
 
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