New Fender "type" amp build suggestions

[Bieworm]

Wow! That must have been a PITA to perform!!

[Bieworm]

hey Dave.. a tip for future builds:
those Alpha post come in 2 different thread sizes. I believe metric (8mm) and imperical (9.5mm). Well, the latter has a longer thread than the metric. When I use the metric type it's a close call to tighten the nut.. it's barely on with the 2mm thick chassis and 2mm thick faceplate. The imperical type has a few turns extra over the metric, and there are no nut tightening issues whatsoever.
I can see you used the metric type. Those have a little lug you have to remove. It's part of the cast body and you break it off with a plier. The imperical type have a stamped body an the lug needs to be bent sideways.
Better yet, drill an extra hole in the chassis for the lug so the pot will stay put no matter what (that's what the lug is intended for) but ime the lug is too high and will stick through the 2mm chassis, piercing the faceplate. Since I use acrylic faceplates they tend to break at those spots..

[foreverstrung]

Wow! That must have been a PITA to perform!!

I’m like a dog with a bone with this kind of stuff. Can’t stop till I get it all done. It was a pain, but not too bad. Now though, I’m hyper aware of the finished product. Not just functional, but aesthetically too.
Unfortunately this amp needs to sit on my workbench all weekend until that face plate comes early next week.

I did get some good news. Dirk at Tube Town said he got WDS to build me that Jupiter speaker you suggested so that I can avoid custom tariffs and duty costs which would likely double the cost of the already pricey speaker. I don’t know when it’ll show up just yet, but that’s kind of cool
Dave

[Bieworm]

WGS builds the Jupiter speakers. They are built to required specs, but in fact they are WGS speakers with a Jupiter label. FWIW Jupiter and WGS are in my opinion equally good. I have the Jupiter 12L in mine at the moment. I need the extra headroom lately, and I find myself playing this amp almost exclusively for the past 6 months or so.

[foreverstrung]

hey Dave.. a tip for future builds:
those Alpha post come in 2 different thread sizes. I believe metric (8mm) and imperical (9.5mm). Well, the latter has a longer thread than the metric. When I use the metric type it's a close call to tighten the nut.. it's barely on with the 2mm thick chassis and 2mm thick faceplate. The imperical type has a few turns extra over the metric, and there are no nut tightening issues whatsoever.
I can see you used the metric type. Those have a little lug you have to remove. It's part of the cast body and you break it off with a plier. The imperical type have a stamped body an the lug needs to be bent sideways.
Better yet, drill an extra hole in the chassis for the lug so the pot will stay put no matter what (that's what the lug is intended for) but ime the lug is too high and will stick through the 2mm chassis, piercing the faceplate. Since I use acrylic faceplates they tend to break at those spots..

Since I've got to wait for this faceplate anyways, I've gone ahead and ordered these longer shaft pots for express delivery tomorrow
Dave

[JMPGuitars]

My custom chassis has cutouts for the potentiometer position pin. If it's sticking through the faceplate on your chassis, then you're probably not using the lock washer. If you are using the lock washer, you can add a regular washer to pull the pin back so it doesn't protrude.

[foreverstrung]

My custom chassis has cutouts for the potentiometer position pin. If it's sticking through the faceplate on your chassis, then you're probably not using the lock washer. If you are using the lock washer, you can add a regular washer to pull the pin back so it doesn't protrude.

I learned a lot on this project so far and I’m still not across the finish line so theirs still lessons to be learned, I’m sure. The different bushing length Bieworm pointed out is a great recent example. But starting with a blank chassis, (layout lesson was big) the little position holes to keep pots in place I just thought was too much. Not the actual work, but my ability to get them precisely in the correct location, that was then, next time I will drill them out.
Hopefully with these new, ever so slightly, longer threaded bushings, I’ll be able to use a lock washer on. In fact, these new pots (5), I can drill out the position holes. The other pots that have the correct bushing length, I’ll know for sure if I have the space after the new plate arrives (1/16” thick). Should be ok, but those position pins (3), I snapped off. Lazy, I know. It won’t happen again

[JMPGuitars]

These are the lessons best remembered.

[foreverstrung]

Question.
So I'm using the vintage twin reverb cabinet I mentioned at the beginning of this project but I'm only going to use one 12" speaker. Should I just use 1 side of the baffle as it is or remove the center section of this baffle and cut out a new baffle to overlay on the perimeter of the old baffle that is still remaining?
I could go either way.
If I keep the original baffle and just use one side, I keep the original vintage cabinet in tact and am able to always add a 2nd 12" speaker if I choose to
But If I use a new baffle and make the modifications, the build is complete. 100% finished. Done. Fin. not lopsided. I'm OCD. 1 speaker just to one side I'm afraid may be a "bee in my bonnet", so to speak and drive me mad.
Thx
Dave

[Bieworm]

I would just make a new baffle. It will always be out of balance with the original baffle and only one speaker installed.

[JMPGuitars]

I'd build it as is first and see how it sounds. I love the sound of detuned cabinets, and I'm curious what you'd think of a combo like that. You can always replace the baffle if you don't love it.

Install the speaker on the side farther from the heavier transformer. That might help with balance.

[Bieworm]

I am curious how that will turn out. I thought the whole principle of a detuned cab involved a closed back? I read an article about that a while ago. It is also necessary to have a different size hole than the one where the speaker is mounted IIRC.

https://www.diyaudio.com/community/thre ... ed.241151/

[JMPGuitars]

All those things contribute to the sound of the cabinet. Different hole sizes will change things too. I don't put that much thought or effort into it. My 2x12 cabs are only partially closed back, and there's a big difference when only 1 speaker is installed.

[foreverstrung]

hey Dave.. a tip for future builds:
those Alpha post come in 2 different thread sizes. I believe metric (8mm) and imperical (9.5mm). Well, the latter has a longer thread than the metric. When I use the metric type it's a close call to tighten the nut.. it's barely on with the 2mm thick chassis and 2mm thick faceplate. The imperical type has a few turns extra over the metric, and there are no nut tightening issues whatsoever.
I can see you used the metric type. Those have a little lug you have to remove. It's part of the cast body and you break it off with a plier. The imperical type have a stamped body an the lug needs to be bent sideways.

I’ve replaced all the 8mm short shaft/threaded bushings with 9.5mm. The problem I’m running into is this dual 250k master volume pot. Mojotone, Tube Depot, Amplified parts and a couple other places I checked all only have this full sized, 8mm threaded bushing. No 9.5mm. StewMac has a 9.5, but it’s a mini. (Pic) Narrow diameter shaft. I’m good with all of that, but tell me, will this smaller dual pot work the same way, (at least as I need) for a MV? To be clear, I realize that that technically it will work. It's a stacked 250k/250k, but as far as using this smaller pot in an amp. I don't believe this mini pot was designed to be used in this kind of application. Maybe it doesn't matter at all.
Thx
Dave
Update: I picked up a Bourns dual 250k pot @ Moucer with a 3/8" threadsed bushing.
https://www.mouser.com/ProductDetail/65 ... GTR01254A2
It'll be here friday/saturday. Moucer is here in Texas, so usually quick shipping

[Bieworm]

The pot size doesn't really matter at all. Lots of (cheap) amps use those without significant problems. It's usually a psychological process that urges people to use the 24mm ones. The 16mm pots have a different feel that makes one believe they are of inferior quality. If it's a respected brand I don't see any problems whatsoever.
But beware of the knurled shaft type. It's hard to make a steady connection when mounting the knob. And it will more than often offset the turning of them.

[JMPGuitars]

There are both good and bad quality of both pot sizes. There are also overkill/oversized pots of higher quality.

[foreverstrung]

But beware of the knurled shaft type. It's hard to make a steady connection when mounting the knob. And it will more than often offset the turning of them.

Have you tried these? I just picked up a set because this Bourn pot is knurled split shaft. These were only $7 for 4 of them.

[JMPGuitars]

Have you tried these?

Some knobs come with those. I think I usually have to remove them from Q-Parts knobs.

[foreverstrung]

So I've had this rig up and running the last couple of days and am running it through it's paces. It sounds great but has a couple of issues maybe you can help me pin it down.
I'm getting some hiss/noise not too dissimilar to a grounding hum....at higher volumes, which is not too surprising, all things considered, but it's thier more so than in any of my other amps. Still, on it's own, acceptable. Not complaining
The main issue I'm having is adding pedals. 1 pedal no issue. 2 not bad. 3 pedals is still ok (some pedal react better this far up the chain). 4 pedals a high pitched noise. Obviously i've switched multiple pedals around. Still can't get past 4 pedals.......I've considered the power brick and also outlet locations and perhaps too many on a circuit, but it does not behave this way with any of my other amps
2nd, the NFB switch has a very unlovely sound when engaged and I'd like to eliminate it for a couple reasons. One because of its location. Will I be able to do that without any issues? I don't believe so, but thought I'd run it past you.
Reverb and Vibrato are spot on
Thx
Dave

[Bieworm]

About the noises:
- hard to determine whether your amp is noisier than mine. It isn’t the quietest amp when the MV is dimed. I keep mine at 7 to 8. Never needed more volume anyway
- about the pedals.. fir starters some pedals are noisier than others. IE digital pedals like echo or delay. I use the truetone 1spot pro with my pedals to eliminate the noise of those pedals. Often it is a ground loop thang that you tackle with isolated power supply (1spot, Cioks, Voodoolab,..)

The NFB can be let on permanently by going from the 4 or 8 ohm tap of the OT and wire it directly to the NFB resistor.