Tweed 5B3 Deluxe - try and try again - tone's not quite there...

[infiniteposse]

Hi all-

I've been on the fence about selling off my Tweed Deluxe 5B3 for a little while now. I've just never fallen for the sound of it and while I can sort of see what folks like about them, I just don't think this amp quite has it. I bought the amp a couple of years ago immediately had it recapped as it had had little use in probably a decade and also some questionable changes made here and there. The tech I brought it to did good work and put decent caps in, but nothing particularly special or esoteric. None of the good stuff in the amp was salvageable cap-wise, so none of that mojo made it. The speaker in the amp when I got it was a field coil, so I got a early 60's Jensen P12Q in there. Tranny's luckily did survive just fine.

Despite doing what would normally be the correct way forward, it just never rocked my world. The amp sounds harsh in the highs, flat in the lows and biting in the mids... Just not the fairy book experience I had hoped to have with one of these classic amps. The good news was I got the amp extremly cheap and didn't pay royally for it.

I decided tonight to take it to my regular tech (not the gentleman who first worked on it) to take a look and see if he could hear what I was or wasn't hearing. We tried a different vintage P12Q he had in the shop and also some different 6V6's which did improve the lowend slightly, but the overall tone was still lackluster.

We decided to try some new things to improve the sound of the amp. He's going to install some Jupiter caps in that he's been reading a lot of good things about to try and get a little closer to the sound it might have had in it's better days. He's also going to check out the baffle as it seems to have some flex in it and might need to be looked at.

Anything else come to mind to look into? Are there bits and bobs from the 5C3, 5D3 or 5E3 designs you guys might recommend him trying out?

Any thoughts appreciated!

[SatelliteAmps]

A couple of things right off the bat. First is that those amps don't usually have a lot of low end, so you might be chasing something the amp isn't capable of. Just want to throw that out there.

The 5B3 didn't come with a field coil. To put one in would require a bit of rewiring of the power supply to make it work. Is the original OT still connected and working ok? You mention a few other modifications. Has the amp been completely returned to stock?

You mention the baffle having flex, where is it flexing? Those baffles are only held in by 4 screws, and are supposed to be able to flex a bit. Is there some sort of noise issue coming from the baffle? Tightening the baffle alone would not cure the issues you are discussing.

Using different types of caps might help a little bit, but it will probably only make as much of a difference as the speaker and tube change did. Minor tone alteration, not major sound change.

Might just still need something returned to original.

[infiniteposse]

Hi Adam-

Thanks so much for the feedback. So yes, when I got the amp the first thing done to it was return it to stock. Luckily, the guy who did the modding was a firmer Tektronix engineer who was really savvy and didn't hose anything in the amp. All transformers survived.

The flex in the baffle was noticed while trying to track down some nasty rattle and also when trying to figure out why the amp sounded a little anemic. I'm not sure if the rattle we heard was from the baffle or not. My tech's going to have his cab guy take a gander at the amp and see how everything looks just to make sure its all tight and solid.

Re: cap changes, I know it won't be a different amp all together, I guess I'm just hoping for some nuance to be there afterwards. The thing I like about my older amps is that they inherently have some funk/mojo/character to them without me doing anything. This guy sounds a bit stiff and reserved. The breakup is also just sort of blah, which is exactly what I wouldn't expect out of one of these amps.

The other thing my tech noticed when comparing schematics of the 5B3 to later designs like the 5E3 was that there was a higher (?) value cap accross one of the inputs that he said would load down the guitar and perhaps choke some of the harmonic content. Forgive my mangling what he likely said, but he thought a cap value change at the input might open things up a bit...

Any thoughts of speaker choices that might be cool to try?

Thanks again for the help Adam. Appreciated!

[davemccarthy707]

I think the big difference is the preamp tubes. Those 6sc7 tubes are gonna be a little rounder sounding than the 12a#7 type tubes. Unfortunately I don't think any speaker/cap tinkering is gonna get rid of that.
Cheers.

[SatelliteAmps]

I don't think that you will find a better sounding speaker for that amp. That is a great speaker for that tone.

The 6SC7 are a bit smoother, but those amps can still sound amazing. Great blues tones, but not overly insane drive tones.

As far as mod's go to a 5B3, your tech can remove the .05uf on the input. Another thing to try would be to rebias the amp to run a lot hotter (coldly biased amps can sound very sterile and boring). Those amps can take it. There are a lot of other little options, but it is hard to say exactly where else to go with it, without seeing it and hearing it.

A few more drastic options would be to redesign the PI to drive the output harder, or also to even change the preamp section to a 5E3 style (I wouldn't, because those amps can sound great on their own).

[tweedtwin]

Satellite Amps,

I just found this thread. I have a 1949 TV front deluxe.
What does removing the .05 cap do to the sound? Do you mean the first cap on the circuit board? My amp could use a bit more gain.

Thanks, Tweedtwin

[SatelliteAmps]

The first cap that we are talking about is the one directly after the input jack(s). Fender started at a .05, then a .1, then none at all. I prefer none at all, as it lets more signal frequencies through.

[tweedtwin]

Thanks very much Adam. I will try it out! One more question though, looking at the 5E3 layout, the first thing on the left hand side of the board is a 25/25 cap and an 820 ohm resistor. Do I leave this out as well?

Thanks Tweedtwin

[phsyconoodler]

No,that's the cathode resistor and cap.Leave that out and the amp won't work.I don't see that in a 5B3 anywhere.The 5E3 has it.

[jay42]

The schematic and layout are at Blue Guitar...if there's a 25uF||820 then it's not stock yet.

http://www.blueguitar.org/new/schem/fender/5b3_lay.jpg
http://www.blueguitar.org/new/schem/fender/5b3_sch.jpg