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Dirty-South Blues Harp forum: wail on! >
VHT special 6 tinkling sound
VHT special 6 tinkling sound
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FreeWilly
383 posts
Dec 27, 2013
10:55 AM
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Hello everyone,
some things have been said on this topic, but there isn't a specific thread for it.
Today I swapped the 6V6 on my VHTsp6 for a TAD 6v6GT-str. Sounds better: warmer and more musical. Together with the 5751 I am running (I'm slowly 'modding' it, getting to know each separate mod, next step will be a legend 10516), I like the sound. The hashness is mostly gone. I still think the amp sounds a bit flat.
The problem is this though: I get a very apparent tingly or rattly sound. When I changed back the old 6v6, I heard it there too, but not as apparent (I hadn't noticed it before). Did I do something wrong with the spring (I don't think so), or do I have a rattly tube? I tabbed the tube both cold and warm, and nothing happened. I don't think the sound is amplified. Only when shaking the tube beside my ears (out of the amp) do I get a slight sound, but it's less then on the original tube, and doesn't seem to be the cause of the noise. It seems to only occur on specific frequencies (2draw on Bb, A and G most notably).
When I closed the back back up (thus fixing the amp better then with the back off (2 of the screws fix the amp too, and not just the back panel. Without the screws, the amp can move somewhat) it's much better, but it ain't gone. (perhaps it's just better because the mechanical sound is trapped in the box more..)
I'm thinking this isn't a tube problem? Not sure, as I'm a total beginner on amps. Does anybody know what it might be, and how I could fix it? I read somewhere on here having a similar problem, but he didn't report back after some tips by bonedog.. Thread was about something else too.
Ah yeah: I tried not tightening the tube completely, leaving a small space between tube and socket. No difference....
Tips are very welcome. I'm pretty sad (I had looked forward to hearing the new tube, and now this problem came up..). Guess it's part of growing up as a harp player, but not being able to do something about this problem is a real bummer.
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Kingley
3340 posts
Dec 27, 2013
11:02 AM
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Mark Burness (5F6H) is the best man to answer your questions and hopefully he'll see the Bat Signal, don his cape and come to save the day. In the meantime the only thing that comes to my mind is that maybe the 5751 is going microphonic. Try putting a different preamp valve in and see if that stop the tinkling sound.
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FreeWilly
384 posts
Dec 27, 2013
1:31 PM
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I've sent my batman signal to 5F6H.
In the meantime: could the changing of the 6v6 make the microphonic 5751 more evident? If not, than that can't be it... I do have an ax lying around (the JJ the amp came with) that I could try.
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TheATL
75 posts
Dec 27, 2013
1:39 PM
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One way to tell if a tube is going microphonic is to gently tap on it with the eraser of a pencil. No chance you will crack the tube, compared to taping with a screwdriver. Try both tubes. If one is microphonic it will be much more sensitive to tapping than the other.
Last Edited by TheATL on Dec 27, 2013 1:40 PM
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FreeWilly
385 posts
Jan 05, 2014
9:18 AM
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Thanks for the tips guys. As said: the tube isn't microphonic. Today I went to work on the amp again. Opened it up, after I established that the noise is gone when I push the tube in the socket (holding it). I tried padding the tube-socket connection with electrical tape. No luck. Then I went to work on the socket-amp connection. Padded that with tape too. This time some luck: the rattle is less loud now. After un-taping the outer connection and putting the back up, it is much less noticeable. But still there. The stock-tube is a bit better still (but it's definitely there). After that, I tightened the cable-socket connections somewhat, as I felt they were loose. Used glue there.
But still: it's there. Perhaps people have some tips? Should I try another tube? As I can get rid of the noise by pressing the tube, I thought it can't really be the tube itself? Sounds great, apart from that rattle..
Should I use dampeners? Anybody have a source for the in Europe?
Man. This is so difficult!
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rogonzab
444 posts
Jan 05, 2014
9:35 AM
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I had that problem whit 2 of my amps.
The problem is not the tubes is the design of the amp. The speaker is to close of the tubes, and when you play the air moves de tube into a X frecuency and make it rattle (this is comon in combo amps)
All the things move into a X frecuency and when you hit that frecuency you interact whit that object. I have a electric heater that rattle when I hit a note on my guitar (is a really cool thing).
If you use a damper you are going to change the frecuency of the tube, and maybe it will help, but you need to try and see.
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Kingley
3374 posts
Jan 05, 2014
9:44 AM
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Can you hear this sound when you're playing the amp at volume? It might help if you could make an audio/video recording of the amp making this noise.
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rogonzab
445 posts
Jan 05, 2014
9:48 AM
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another thing that coul be the problems is the tube sockets.
The amps came whit plastics sockets, and when they heat they expand, so the tube is a litle loose.
If you hear the problems minutes after that you start playing (when the tubes are hot) that might be it.
You can replace those sockets whit ceramics ones.
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5F6H
1727 posts
Jan 05, 2014
10:42 AM
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I'd try reducing gain, both the preamp tube and power tube have "cathode bypass caps" which are optional (as long as you like the sound without them), you also have a bright cap on the stock amp. 90% of "tinkling/metalic" noises, that are perfecly logically blamed on tubes/sockets etc. are usually down to parasitic oscillation in the amp...this can be reduced by cutting highs & gain, the fact that this shows up on lower key harps may be an indicator, a good heavy 2 draw bend will show it.
So, maybe try a 12AY7 in V1. Try removing C11, C13 (do this anyway). C8 could be bigger at 25-50uf/25v. Try bypassing R12 with plain wire. You might also try removing C15, but if this totally kills response & makes the amp too mushy, put it back (observing correct polarity, arrow to ground & waisted end to tube pin - as with any of the cathode bypass caps).
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www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by 5F6H on Jan 05, 2014 10:43 AM
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FreeWilly
386 posts
Jan 05, 2014
12:35 PM
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Thanks for the responses guys!
I might be able to make a recording. I'm just very bad with uploading. Will consider. But it's really just a mechanical rattling sound.
Ragonzab, I'm thinking along those lines. The noise is there immediately though. BTW: Swapping sockets would involve soldering right? It all looks very tight in there. Will be difficult to solder the socket without touching cables..
5F6H, I know you know your business. So this is not doubting your hypothesis, but a follow up question: if this is indeed an oscillation problem, how would that explain that the rattling is gone when my girlfriend pushes the tube in with some force while I play the heavy 2d? Also: wouldn't the noise get considerably louder with louder volumes?
Probably, even a mechanical rattle could be helped by lowering gain? Is that a different change than just giving the tone know a whirl?
Thanks!
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5F6H
1728 posts
Jan 05, 2014
1:44 PM
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If it's a mechanical noise, it would be from something that was loose & audibly rattled...if it's not the power tube, see if you can locate it? It'll rattle just as easily if you thump the side/top of the cab. I had an amp that buzzed for months, couldn't trace it...turned out to be a loose chassis grommet & fixed with a dab of silicon. But metallic tinkling...I could be (& hope I am) wrong, but oscillation really would be my first guess.
Ahh yes, the old "girlfriend as a tube shield ploy", won't she get bored, burn her fingers ("Can't you hold your own tube?"..."Don't be silly dear, it's f@#%*$£ hot!") How hard does she have to press the tube? It's very possible she is affecting the tube's performance by touching it.
The noise may be getting worse with higher volumes, but "rattling" beyond our audio range. A dog might hear it...get your girlfrind to let go of the tube once in a while & see if it makes your dog bark? ;-)
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www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by 5F6H on Jan 05, 2014 1:48 PM
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FreeWilly
387 posts
Jan 05, 2014
2:19 PM
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Ok, I just went back to the amp and improved my tape (it was not all round the socket, now it is) and after some research removed (as recommended) C11 and 13. That was scary to do, but hey. The amp still makes sound, but I can't really test it till in the morning, as it's sundaynight here...
More tomorrow.
btw: what would removing C11 and 13 do in theory?
PS: I gave my girl an oven mint. I'm not cruel :)
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5F6H
1729 posts
Jan 05, 2014
2:42 PM
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The cylindrical cap (C13) is the cathode bypass cap for the 2nd half of V1 (12AX7 - this is really "2 tubes" in one), removing it reduces gain. The 470pf cap (C11) is a bright cap, removing it takes some highs away.
You're right to be wary of your amps innards. Always unplug it from the wall before opening it up & throw the standby switch into play mode, this will drain the caps via R25 in the time it takes you to undo & remove the chassis (not the case for all amps, so don't assume).
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www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by 5F6H on Jan 06, 2014 1:25 AM
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FreeWilly
389 posts
Jan 06, 2014
3:59 AM
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Valuable tips there!
So, just opened the volume up almost all the way, and the noise is still there. It's now down to a level where nobody at a gig would notice probably, but it's noticable. The removemend of the caps seems to have reduced feedback a little, and the sound might be less bright. It's hard to hear such things without direct a/b. Anyway I'm happy I did it.
Next step 12AY? Man, does this suck!
On the bright side: I'm no longer afraid of the inerts of my amp, and improved some things. Oh well.
Thanks for all the tips!
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FreeWilly
390 posts
Jan 09, 2014
6:26 AM
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Update time. Tape hasn't melted still, that a good thing. I ordered a socket for the 6v6, but it doesn't fit 6v6's. Bummer. Ordered a Tung-Sol 6v6 too, just to be sure it's not the tube.
With the Tung-Sol, the noise is good as gone. I did hear some with the back off, but after putting the back on (which fixes two otherwise loose screws) the sound is good as gone. I found 1 of my G's to have it on the 1 blow now. The lowest note I play. My gigging G didn't have it.. So it's a frequency thing. Apparently the note went down now. Still, it's way quieter than it was, and now it's not there on the 2 draw on an A harp. Kinda... important note.
Which leads me to not wanting to order another socket and solder it in (seems complicated enough in the tight space). I'm now just left with the question if I should request a refund on the Tad 6v6gt-str. Was it a bad tube, or is this acceptable (I mean, apart from the noise, it did work). I haven't a/b'd them, but I would say there is not much between the tad and Tung-Sol as far as sound's concerned. Perhaps the Tad is a bit darker? And perhaps has a bit more body?
Oh well. Thanks for the help. And thanks in advance for any comments/answers! Difficult business this tube-amp getting right thing is!
Last Edited by FreeWilly on Jan 09, 2014 7:18 AM
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5F6H
1731 posts
Jan 09, 2014
8:56 AM
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If you get the tinkling with the TAD & no other 6V6, then yes, blame the tube & ask for a refund...don't be surprised if they refuse, or suggest that you try it in another known good amp.
Amps amplify the sound going in, so if you have reed rattle going in, it will come out the speaker, so eliminate noises that can be generated before the amp first.
Tube amps aren't that difficult, or really any more difficult than other amps (many things you can change are simple), but you must stick to realistic expectation, you bought a cheap amp with a view to modding it (great, cheap amps can be superb, you'll learn some things), rather than bought a product to do what you specifically want...get there with patience you will.
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www.myspace.com/markburness
http://www.facebook.com/markburness
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FreeWilly
401 posts
Jan 24, 2014
12:46 PM
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Hey guys,
now that I have a soundcloud account, I thought I'd share a clip of the noise with y'all. Been doing some tube-swapping today. This is the VHT sp 6 with the TAD 6v6-str.
Last Edited by FreeWilly on Jan 24, 2014 12:46 PM
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5F6H
1738 posts
Jan 25, 2014
6:19 AM
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I can hear a crackling/static sound at the higher amplitudes, this doesn't sound like metallic tinkling...but that doesn't tell us much in itself. If it goes away when you sub out the power tube, then I wouldn't sweat it?
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www.myspace.com/markburness
http://www.facebook.com/markburness
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FreeWilly
403 posts
Jan 25, 2014
11:05 AM
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Heya,
Well, with the Tung-Sol, it's much better. The AT brought it out more than the 5751 I think, but it's good as gone.
The recording does subdue the tone a bit btw. It sounds more metal-like and higher in real life...
But your right, I'm not sweating over it too much now. Just wanted to post it, so other people can relate/share/learn whatever.
Thanks for listening!
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FreeWilly
404 posts
Jan 25, 2014
11:05 AM
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Heya,
Well, with the Tung-Sol, it's much better. The AT brought it out more than the 5751 I think, but it's good as gone.
The recording does subdue the tone a bit btw. It sounds more metal-like and higher in real life...
But your right, I'm not sweating over it too much now. Just wanted to post it, so other people can relate/share/learn whatever.
Thanks for listening!
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