new build 36lite with vvr

[chaliapin]

Ok, don't shoot me, I said I'd tried the other combo and speaker. But not since I replaced the coupling caps. It's now Sounding good through the open back single V30. Dunno is it my dodgy cab a dodgy speaker or just a bad speaker cable. But those things I can work out! I also need to do some sound testing not surrounded by all the vibrating junk you can see in my living room!

[Bieworm]

Not shooting here… but for us it’s very important that the correct information is being given, as completely as possible. It’s not easy to work on an amp that’s not in front of us.

[chaliapin]

Thanks bieworm,

Just a quick potshot then! Fair enough! I did check with the other combo, I just didn't check it AGAIN...

[chaliapin]

Im losing the will chasing a metallic vibration buzz in the guitar sound, turning into unmusical distortion at high volume. Almost certain it's coming through the speaker and not external or cab vibration. Can't get any crackles or strange stuff happening when chopsticking ANYWHERE. tried several pre amp tubes, not much difference. Can't find any microphonic tubes by tapping or wiggling gently when powered up. Tightened all nuts and bolts. Can't find anything consistently making a difference. Different speakers, both speaker jacks, both input jacks, different guitars, different leads.

Feel like the gain and volume are a bit different each time I power it up but I may just be sending myself crazy. And deaf.

2 questions

Can I mix and match the Russian and jj power tubes when switching them in and out?

Can I make an extra long speaker cable using fairly heavy cable for 240vac mains voltage so as to get the chassis further from the speaker to reduce possible microphonics? If not what are the requirements for speaker cable? Can I use hifi speaker cable?

Thanks everyone.

[Bieworm]

Try swapping out speakers between the good cab and the doubtful one. See if the noise follows the speaker or the cab.
online about ‘cone cry’

[chaliapin]

Thanks bie, it's a 2x10 and 1x12. Both tens sound the same individually. I took the combo chassis out of the 1x12 combo as it did have its very own buzz. All three speakers now producing the same metallic vibration like a loose screw. Could that be a tube even if holding them while playing make no difference?

[Bieworm]

Maybe a microphonic tube?

[chaliapin]

I know ive been here a few times before but I think im just down to a buzz in my badly made cab. It sounds great with the chassis sat on top. Cranky when it's fitted into the box.

I was struggling to locate the issue as I was dealing with an iffy tube, a bad box and a rattling box of screws on a shelf! I can't actually find anywhere in my house to crank it up where something isn't rattling! What do you people without a music room do? Test outside?

[Bieworm]

I know ive been here a few times before but I think im just down to a buzz in my badly made cab. It sounds great with the chassis sat on top. Cranky when it's fitted into the box.

I was struggling to locate the issue as I was dealing with an iffy tube, a bad box and a rattling box of screws on a shelf! I can't actually find anywhere in my house to crank it up where something isn't rattling! What do you people without a music room do? Test outside?

lol

[chaliapin]

So im not really into this type 3mv still. Doesn't really do much. But now I've cut a hole what shall I do with it? Seen circuits which switch out one of the power tubes in an 18watt to leave a single power tube, I think it's just grounding the grid? What would a switch grounding 3/4 grids do?

Also seen an MV just controlling two of four power tubes, not sure if it's combining PI or grounding grids.

Seems like a selective MV might be more fun/ interesting. Seems like no standard MV circuit will provide lower volume distortion as it's reducing power tube distortion. I think id rather play quieter and cleaner with the normal volume. Got a vvr PCB on the way so will try that also.

[chaliapin]

Testing outside was actually a serious question!

[Bieworm]

Depends on the type of outside. The noise will be harder to determine though

[chaliapin]

Unless it's making a weird noise like a sheep I'd say it should work...

[chaliapin]

So ive been messing with bits of insulation strip to isolate the chassis in the combo with zero effect. The amp is sounding great with the chassis sat on top of the combo box. Can't get rid of it by sitting on or applying pressure to any of the cab, nor by holding each tube still whilst playing. No funny noises tapping tubes with the volume up. Can I now discount a microphonic tube?

Just had a listen to a YouTube of Watkins dominator, to be honest mine sounds more like that than the 18/36 watt rock tones on other clips. Im very happy with that!

[chaliapin]

Ok, I was sure yesterday it was the box but now I think maybe something microphonic. Amp is beautiful with the chassis sat on top. With it screwed in there's a crackle at particular pitches particularly on pick attack. With the chassis sat just inside the bottom of the combo, still nasty. This continues as the chassis is moved back further away from the speaker until the chassis is out of the box.

Question is can I ever fix this or do I give up and build a head and cab?

I did reduce the metallic vibration sound in the treble with heat shrink on the unused rectifier pins which were rattling slightly. But there's still something funky going on...

[chaliapin]

Well it's almost definitely not a tubes problem, I've switched them all about and round with very little difference. Still sounds great not in the box, nasty vibrating sound on certain pitches when the chassis in inside the cab. I could have made several head cabinets in the time ive been messing about with it. So any suggestions or should I just get cutting wood...?

[Bieworm]

Well it's almost definitely not a tubes problem, I've switched them all about and round with very little difference. Still sounds great not in the box, nasty vibrating sound on certain pitches when the chassis in inside the cab. I could have made several head cabinets in the time ive been messing about with it. So any suggestions or should I just get cutting wood...?

Maybe the EL84 are making mechanical noises? There are tube rings for that… those spring retainers can be a pita too…

[JMPGuitars]

Mount the chassis in the cabinet properly. Try shaking it and see if you hear anything. If not, place the cabinet on a pair of gym shoes (no contact with cabinet and floor) and play it and see if you still hear the weird noise. Or just build more cabinets.

[chaliapin]

I'm going round in circles and feeling quite defeated. Managed to have a break and play it outside today. Chassis still not mounted and tried another speaker in another combo as well. Nasty crackle static at high volume playing loud on the low E. It's worse with some pre amp valves than others but can't get rid of it. Have several pretty new jj s, a pair of old electro harmonix and even an old groove tubes ay7 I found hanging around. Rectifier is a ten year old previously unused jj gz34s.

I have 8 Russian el84s and 2jj. Out of those only 2 have properly low voltage on the grid pin, ( less than 30mv) it's not my soldering/ sockets, as the voltages follow the tubes. Pairing those two either side of the pp with a more leaky valve gives a steady 50-60 mv on the grids which seems ok?

Im about a week away from starting working properly 7 days a week until November and becoming a dad again in the summer and I desperately want this working properly!

Im not really expecting answers, just whinging really, but any suggestions appreciated.

[JMPGuitars]

Two things.

1. JJs are terrible. Don't use them.

2. I don't know what your noise issue sounds like, but have you tried the Paul Ruby mod? You can see it on the Superlite TMB docs.