6G16-A/Weber treble pot question

[Voxacthirtee]

Hi Folks,
Putting together a 6G16, just about everything works, no hum, no noise, sounds fine (once a have the treble pot over 3/4)
And therein lies the problem.

I'm using the tapped pot, i pulled it out(happens on both channels)
tested the pot. Seems fine. The treble caps block DC and pass the ac signal. So they seem fine

I know its just a simple wiring issue but in looking at the weber schematic, the weber layout,
and the wiring diagram on the site for the tapped pot, i swear there's a mistake there somewhere.
I also seem to have potentiometer dyslexia as this always gives me a headache for some reason.

Just so i know its not me going nuts, i thought i'd ask here.
Looking at the back of the pot, with the lugs on top,
i know the right hand lug is the tap.
So then the center is the second lug IN from the left.
Right so far?

The Weber "Layout" has the feed from the Treble cap attached to the right lug.
I didn't wire it this way as i thought it was wrong. Now, i wired most of it a while ago, then finished it recently, so i forget exactly how i came to that conclusion, but it still seems wrong.

Can anybody just set me straight on this one? No idea why i'm hitting a wall on this, but i am. I've actually tried a couple combinations, and i still get
no difference in treble until about 3/4.
So i thought i'd ask before soldering and unsoldering, rinse, repeat....


if the the lugs are, looking from the back, lugs on top...
it should be

------Left ----------- Center ------------ Right----------------Tap-----

-------???------------????----------------????----------------?????


I know this is probably simple, it's just driving me nuts, and if anyone has built one, i'd sure appreciate the help

[Blackburn]

I built that amp minus the verb and I like it very much for the cleans. The trem is nice, but not as great as the Princeton's IMO.

I drew this up just for you. Here's how you need to wire that pot...

[ToneMerc]

I wish someone would clone the original Stackpole 350/70 tap pot in true function and form factor. I've found the 16mm Weber pot to be nowhere close to the original in taper nor resistive values, especially the tap port.

TM

[Voxacthirtee]

Thanks for the pic.
I think i actually tried that way.

I'm starting to think i got a couple crappy pots.

To my understanding you are supposed to have it be "Flat"
at (around)5 and then you roll off down to 1 and boost up to 10.

I was getting literally no change from 1 to 8 then a very narrow band where i could actually control the treble.

I also wish you could get an accurate reproduction, but i guess we take what we can get for now.

I will wire it up like the pic and report back.

thanks again

[martin manning]

If you want to ditch the small pot format you can do it like this: https://tubeamparchive.com/viewtopic.ph ... 334#193334

[Blackburn]

From the schematic, to Weber's drawing, that is the correct way to wire it. As far as the pot falling flat (No pun intended ) in terms of quality, taper, etc. That's for you to decide. I just fired up mine and the treble sweep is very minor (Albeit, noticeable) between zero and around 1 O'clock and then it gets pretty ice picky pretty fast. I'm sure the quality is lacking and I wouldn't do another amp with a tapped pot circuit, at least not one with Weber's. It's an interesting amp, but very clean and I can't say I care much at all for it when it breaks up. Just a nice clean amp that can be jangly or jazzy depending on your controls.

[Voxacthirtee]

Thanks for the help.
Just rewired to your diagtam, which i am confident is correct, and i still get the usual.
Sounds a bit dull until 8 on the treble, then sounds really good, but i have little control of the treble in that range.
I can only get ice picky if i turn up the volume and roll off the bass.
Both channels the same.
Using a tele w/ humbuckers(not a brite guit) 11's, playing through a 2x10 cab that has old 50's alnicos....not a brite signal chain, but still. I really hear no change until 8 on the treb.
Doublechecked just about everything in the build. Caps are good, wiring is correct, checked wire for continuity, everything seems to be getting where it needs to be.

Puzzled....

[Blackburn]

Sounds exactly like what I've experienced. Very thin margin where the treble really changes. It's the pot. Maybe it's my setup that I don't mind, but I do only play that amp clean and not often. Move it a hair and try to find that good point where it works if you don't want to just install a standard treble pot without a tap. Maybe mod the treble cap?

[Teleguy61]

Doug Hoffman also sells a tapped pot:
http://hoffmanamps.com/MyStore/perlshop ... =610261169

[Blackburn]

Thanks for that. I'd not looked at Hoffman's site in a while and I've never seen an On/Off switching 1M Alpha pot. Been using CTS push/pulls, which are fine, but I love Alphas. The 10MRA also has me curious. I wonder if his 350k tapped is better than Weber's. Both look like Alphas. Hmmmm...

[Voxacthirtee]

It actually sounds fine, it just seems wrong.
I suppose on amps like these, you find the "good" tone and mostly stick to it, but it would be nice to have it more usable.

Maybe i'll pester Weber for a new pair to see if quality has improved at all.

You mention you get "control" at about 1 oclock, which i would take, as i get it around 3 or 4.

It does sound good though. Only ever played a friends brown Concert years ago, but kinda built this as i wanted something with reverb and tremolo.
(most of my other builds have been ac30 style and plexi stuff)

[Mark]

I bought spare pots from Weber and compared them to the originals in my 6G7a amp. The problem is the taper of the Weber pot, it is either 10 or 15% which gives the response you are getting, the original pots work so well as they have a 30% taper while the bass pot has a 10% taper. This give a very useable sweep in the tone controls, the Dumble amps are quite picky about the treble pot too.

Weber does sell pots with a 30% taper but not the 350K pots. I have brought this to their attention many years ago and they weren't particularly interested.
Ask Weber For a 250K pot with a 30% taper, they can supply one if you ask.

[Voxacthirtee]

Thanks for all the help and info guys.

I ended up using the 500k pot method with the 75k and 1M1 resistors and it works like a charm.
Sounds like i get treble response at about 5 on the dial.
I'm happier with it now, even if it sounds the same.
Shame the Weber QC is so low....

[unbiased]

I have a brown Super that uses the tapped pot. It wasn't working very well, cutting out, losing volume and such so I replaced it using the Weber pot and it worked very well. The other channel was fine and the response sounds very close between the two. I offer this as it was not a scratch build but a replacement and the issue was resolved. I am going to clean and restore the original and if successful, re-install it but for now the amp sounds fine.