Weber advice redo or new kit

[wavey63]

I have an 18tmb Weber I built years ago and although it’s good, it could be better. It needs retiring to neaten it up and I want to get a more controlled tone. It seems a bit over the top. So question is should I save the board and just redo it and see what happens or keep the chassis and iron and start anew or scrap it all? Thanks guys!!!

[JMPGuitars]

I think the consensus would probably be that you're better off with a layout/schematic from our download section vs. the weber layout. But the real question is if you want to build a whole new board or not. Truth be told, it's probably easier to get what you want with a new board, as long as you do a good job planning ahead.

[wavey63]

Jmp that’s where I’m leaning towards. I was eyeing Richies layout and thinking of doing that. I haven’t had time yet to look at the sections in depth. Maybe after work... or during. Lol

[wavey63]

Best place to source a board and/or parts? I like Tubesandmore but they don’t have boards for the 18watt. Should I just make my own?

[rock_mumbles]

(to OP) I'm not a fan of the transformers used in that kit ...

[wavey63]

They are on the small side. I don’t have a lot of funds to use towards the amp. Trying to make it as close to what I want as cheaply as possible ... the same old shell game.

[wavey63]

So I started to clean up the amp and found the source of some hum... bad ground scheme in the pots. So I actually like the amp but want to see if it can be tamed a bit. Maybe taking the gain down by half or so to low for better clean up when rolling off the guitars volume. Maybe brighten the normal channel as well. Any advice? Also I notice for some reason the schematic called for a 100uf 50v cap in the bias section but I have a 2200uf in there. What is the damage to tone or amp with this far out value? I don’t have the proper value now but plan on doing a parts order soon. Thanks guys.

[JMPGuitars]

So I started to clean up the amp and found the source of some hum... bad ground scheme in the pots. So I actually like the amp but want to see if it can be tamed a bit. Maybe taking the gain down by half or so to low for better clean up when rolling off the guitars volume. Maybe brighten the normal channel as well. Any advice? Also I notice for some reason the schematic called for a 100uf 50v cap in the bias section but I have a 2200uf in there. What is the damage to tone or amp with this far out value? I don’t have the proper value now but plan on doing a parts order soon. Thanks guys.

Don't worry about the 2200uF too much. The higher value gives a tighter bass response. This is a fairly common practice. The value is sometimes raised between 1000 to 2200uF.

Since it sounds like you're going to stick with the build and clean it up, you should post some high res photos of it so we can give you some feedback on how things look.

[wavey63]

Jmp I have totally decided to stick with the current setup/circuit. I figured I’d try to learn as much as I can about the circuit and how to adjust gain, tone, etc before I redo it. That way, if I make a mess of it I can just fix it when I do a final go-through. The main thing for me now is to try to get more usable sweep on the volume control to allow for slightly more clean(I know there won’t be much and that’s ok) and less bass.

[JMPGuitars]

The main thing for me now is to try to get more usable sweep on the volume control to allow for slightly more clean(I know there won’t be much and that’s ok) and less bass.

What's your B+ voltage reading at? If the voltage is too low, it could make your amp sound muddy and reduce your headroom.

[wavey63]

Jmp I got 287 B+ at the junction of the 2X100k resistors. I did voltages per the chart I found online. Everything seems to be ok.
V1. 1-176 3-1.28 6-173 8-1.34
V2. 1-215. 2-44. 3-93. 7-44. 8-93
V3. 1-124. 3-2.3. 6-271. 8-127
V4. 3-11. 7-335. 9-320
V5. 3-11. 7-335. 9-320
V6. 1-283. 3-338. 7-284

Do they seem ok to you?

[JMPGuitars]

Your B+ is the voltage reading you're getting from pin 3 of V6. 338 is a little low. Ideally you should be around 345. For a little more headroom, and less muddiness, try bringing the B+ up to 350. You could go slightly higher than that but much more and you risk losing the character of the amp.

If the PT is wired correctly with good solder joints, and not capable of supplying enough voltage, then you may want to go with rock_mumbles implied advice and replace the transformers. You could also try a different EZ81 and see if that affects the output voltage.

For your other voltages, you can compare to our chart: storage/Voltage-Chart.htm

Thanks,
Josh

[wavey63]

Thanks! I forgot to mention I’m using a Weber copper rectifier. Will that mess with the voltages? Also how do I increase the B+ ? I was hoping to not spend a lot of money on the amp. I may as well start from scratch at some point. I like the amp and the sound overall, just looking to fine tune it. I was afraid of the transformer issue. They look a bit small but then again I’m not even sure it’s an issue yet.

[JMPGuitars]

Thanks! I forgot to mention I’m using a Weber copper rectifier. Will that mess with the voltages? Also how do I increase the B+ ? I was hoping to not spend a lot of money on the amp. I may as well start from scratch at some point. I like the amp and the sound overall, just looking to fine tune it. I was afraid of the transformer issue. They look a bit small but then again I’m not even sure it’s an issue yet.

The copper cap will affect the voltage. Different copper caps drop the voltage different amounts. I would take it out and try an EZ81 and see what your voltage is with it if that's an option. Copper caps are like fake rectifiers, different rectifiers also drop different voltage levels.

[wavey63]

I just remembered I have an old Realistic tube hifi that I was going to redo at some point or try to turn into a guitar amp. It’s stereo with 4 el84 output tubes. Could any of that iron be used to replace what I have or even build a new amp etc?

[JMPGuitars]

I just remembered I have an old Realistic tube hifi that I was going to redo at some point or try to turn into a guitar amp. It’s stereo with 4 el84 output tubes. Could any of that iron be used to replace what I have or even build a new amp etc?

You need to find out what transformers you have in there, but most likely that would be better for a different amp project.

Do you know what copper cap model you have in there?

[wavey63]

I have the WCA4. How would I test to see what kind of amp I could use the trannys for? I would love to do another 18 watt but different circuit. I really want to thank you for all the help. Being home bound is driving me nuts so I’ve been modding and learning while I’m down. Lol.

[JMPGuitars]

According to their site, the WCA4 has a 28 volt drop. I don't remember for sure, but I think the EZ81 drops about 15 volts or somewhere around there. So switching the copper cap for an EZ81 should put the B+ in a better range.

Another option to raise the B+ would be to go with a solid state rectifier, but that might make it too high. I would start with the EZ81 and see where you are.

Regarding the other amp project, are there any markings on the transformers to identify the brand/model of them? Maybe post some photos of them...

[wavey63]

Thanks JMP. I’ll post pics tomorrow. I have an ez81 or two that I can try in the morning. I stopped using it because of paranoia about it failing and my amp melting down. Lol. Btw if you’re ever in CT I’ll buy you a beer or two for the help. Cheers!

[wavey63]

I attached pics of the transformers and huts of the hifi. Th PT has specs on it. What do you think?