Vibroclone project - advice required

[robinbowes]

Hi,

I'm putting my SF Bandmaster Reverb into a 1x15 combo cabinet and need a little advice regarding mounting the speaker and the baffle.

Here it is so far:



I have a 1x15 4 ohm Weber California to put in and have tolex and grille cloth to go on when I've finished the construction.

Anyway, my questions...

As the baffle will be covered by grille cloth, I will be mounting the speaker from the rear. Can anyone tell me where I can buy the speaker mounting studs and nuts from in the UK? i.e. the ones that mount from the front with 1/2" of wood screw thread under the head to hold them in place?

The guy who built the cabinet for me has used 4 screws from the front to attach the baffle to the battens. However, that won't be possible when I fit the grille cloth. So, how should I mount the baffle? Screws through the battens from the rear?

Thanks for any tips.

R.

[tubeswell]

So, how should I mount the baffle? Screws through the battens from the rear?

Yep, that works for me.

Cheers

[tubeswell]

Also on a princeton tweedy type amp I recently built, I used tee nuts (blind clamp nuts) clamped to the front of the baffle to bolt in the speaker from the back of the baffle, without having to take the grille off.

[PRNDL]

It appears that you've copied a homemade baffle board that isn't correct.

You are correct in that Fender baffle boards are mounted with a screw from inside the amp that goes through the stringers.

Also, there's a 1" strip of plywood around the edges, which adds support and gives the screw more wood to bite into. A triangle piece goes on the upper left corner for the Fender logo.

I'd also check the width of the plywood. The speaker board is 3/8" BC and the strip is thinner (1/8"?).

Yours looks well made and fits correctly, but may be too thick, which will reduce vibration. Some believe that cabinet vibration is a big part of tone.

Here's a photo that shows a Fender baffle board for a Princeton Reverb

[MWJB]

Hi Robin,

I have 4x T nuts with screws going spare..drop me a private message and I'll post them to you. BK Electric in Southend do metric T nuts (BKelec.com).

Don't know where to buy the screws you describe in UK, I sometimes use the BF style screws (no reverse thread) you can get them from TAD (Germany), or even Hoffmanamps in the US if you have a few bits to buy (I often get stuff quicker from Hoffman than from UK/Euro outlets). They work fine if you drill the right size hole (3.5mm?).

As PRNDL says, you want the batons around the edge of the baffle board, as well as being technically correct it reduces the chance of the grill cloth rattling against the baffle board.

[PRNDL]

It looks like you have good woodworking skills, so I thought you might appreciate seeing how to make a correct one.

One the plus side, you could use regular screws to mount the speakers, since the thin strip gives clearance. Fender uses 1" or so black screws with a triangle head that can be counter sunk for flush mounting.

On the minus side, making another baffle board takes more work and material.

The one you have looks fine. Four long screws counter sunk will be fine. T-screws are even better.

As for the mounting screws, I've used wallboard screws in the past for my homemade amps, but am switching to shiny screws similar to the ones Fender uses.

The question is how authentic (vintage accurate) do you want your Fender amp to be, and what your opinion is on quality parts in a homemade amp. For me, the wallboard screws do a great job, but another tech would laugh. I have a box of shiny screws, so switching is no big deal.

[robinbowes]

It appears that you've copied a homemade baffle board that isn't correct.

You are correct in that Fender baffle boards are mounted with a screw from inside the amp that goes through the stringers.

Also, there's a 1" strip of plywood around the edges, which adds support and gives the screw more wood to bite into. A triangle piece goes on the upper left corner for the Fender logo.

I'd also check the width of the plywood. The speaker board is 3/8" BC and the strip is thinner (1/8"?).

Yours looks well made and fits correctly, but may be too thick, which will reduce vibration. Some believe that cabinet vibration is a big part of tone.

Here's a photo that shows a Fender baffle board for a Princeton Reverb

Hi,

Thanks for this information.

The cabinet is actually built according to some plans I bought on ebay. The baffle board is 3/4". As it's so thick, I should get away without the additional plywood strips. I can always build a new baffle at some stage in the future if I'm not happy with this one.

Do you have any more detailed pics of the Princeton baffle board - I can't quite make out the strips in that picture?

Thanks,

R.

[robinbowes]

It looks like you have good woodworking skills, so I thought you might appreciate seeing how to make a correct one.

One the plus side, you could use regular screws to mount the speakers, since the thin strip gives clearance. Fender uses 1" or so black screws with a triangle head that can be counter sunk for flush mounting.

On the minus side, making another baffle board takes more work and material.

The one you have looks fine. Four long screws counter sunk will be fine. T-screws are even better.

As for the mounting screws, I've used wallboard screws in the past for my homemade amps, but am switching to shiny screws similar to the ones Fender uses.

The question is how authentic (vintage accurate) do you want your Fender amp to be, and what your opinion is on quality parts in a homemade amp. For me, the wallboard screws do a great job, but another tech would laugh. I have a box of shiny screws, so switching is no big deal.

I wish I could claim credit for the cab, but I had it made by a mate from the pub who works in a local woodworking shop! It's all finger-jointed with rounded edges. He's done a really good job.

Regarding the speaker mounting, did you mean just use woodworking screws from the rear? I'm a little wary of doing that since it's a 15" speaker and quite heavy. I suppose it would do as a temporary measure.

I'm not too bothered about authentic - the amp itself has been extensively modified (London Power Pre-Amp kit, channel switching, etc.) and I'll possibly doing some more to it in the future (get rid of ultra-linear mode, black-facing, etc.)

Cheers,

R.

[robinbowes]

Hi Robin,

I have 4x T nuts with screws going spare..drop me a private message and I'll post them to you. BK Electric in Southend do metric T nuts (BKelec.com).

Don't know where to buy the screws you describe in UK, I sometimes use the BF style screws (no reverse thread) you can get them from TAD (Germany), or even Hoffmanamps in the US if you have a few bits to buy (I often get stuff quicker from Hoffman than from UK/Euro outlets). They work fine if you drill the right size hole (3.5mm?).

As PRNDL says, you want the batons around the edge of the baffle board, as well as being technically correct it reduces the chance of the grill cloth rattling against the baffle board.

Thanks for the offer. I actually have some t-nuts, I was just hoping to get hold of the "proper" studs.

I've ordered some from Ampwares (yes, I know what they're like) so I'll sit tight and wait to see when/if they arrive.

Two things I haven't sourced yet are a Fender logo and a replacement front panel. The front panel will be a custom one as I've got additional controls on my amp (the left-most knob is a gain control for the dirty channel and one of the middle pair of input jacks the footswitch socket). Any suggestions?

R.

[PRNDL]

The cabinet is actually built according to some plans I bought on ebay. The baffle board is 3/4". As it's so thick, I should get away without the additional plywood strips. I can always build a new baffle at some stage in the future if I'm not happy with this one.

Do you have any more detailed pics of the Princeton baffle board - I can't quite make out the strips in that picture?

That's the only photo I have of the front part.
The total thickness of the baffle and strips is 3/4", which is why I mentioned redoing it would involve making a new board.

Regarding the speaker mounting, did you mean just use woodworking screws from the rear? I'm a little wary of doing that since it's a 15" speaker and quite heavy. I suppose it would do as a temporary measure.

Fender uses shiny steel screws, which are similar to sheet metal screws. You probably want 3 or 4 per side to secure it.

[robinbowes]

That's the only photo I have of the front part.
The total thickness of the baffle and strips is 3/4", which is why I mentioned redoing it would involve making a new board.

Fender uses shiny steel screws, which are similar to sheet metal screws. You probably want 3 or 4 per side to secure it.

Thanks for the information.

I'll let you know how I get on.

R.

[robinbowes]

Update

OK guys, I promised an update, so here we go.

My Ampwares order arrived (eventually) so I could now mount my speaker using the "proper" studs. I've screwed the baffle in from the back using just 4 screws for now (2 per side). I will certainly add more screws before I've finished (I only had 4 the right length) and I may add another batton acress the bottom to secure the baffle more rigidly.

This is how it looks:



(That's a Japanese "Fotoflame" Strat, with Kinman pickups and electronics)

And the sound? Pretty damn good. I think I'll need to play with the eq a little to voice the channels, but the overall sound is excellent.

I might get round to applying the grille cloth and tolex by this time next year!!

Thanks for the advice.

R.

[Bruce / Mission Amps]

OK guys, I promised an update, so here we go.

My Ampwares order arrived (eventually) so I could now mount my speaker using the "proper" studs. I've screwed the baffle in from the back using just 4 screws for now (2 per side). I will certainly add more screws before I've finished (I only had 4 the right length) and I may add another batton acress the bottom to secure the baffle more rigidly.

This is how it looks:



(That's a Japanese "Fotoflame" Strat, with Kinman pickups and electronics)

And the sound? Pretty damn good. I think I'll need to play with the eq a little to voice the channels, but the overall sound is excellent.

I might get round to applying the grille cloth and tolex by this time next year!!

Thanks for the advice.

R.

Hopefully when you do install some grille cloth it won't buzz so bad you pull your hair out.
That is the reason for the .25" thick 1.5" plywood strips around the perimeter of the baffle, mentioned in one of the earlier posts.
It keeps the grille cloth off the actual baffle board and eliminates about 95% of grille cloth buzz.

Since your baffle board is .75" thick, and your cabinet's internal baffle board cleats are set, you can have a new baffle board made with some high quality, marine grade, .5" Baltic birch plywood (very strong).
Then install the .25"x1.5" strips on the outside of the new one "correctly" and get the same flush, carcass edge to grille cloth finish reveal you'd have now.

[robinbowes]

Hopefully when you do install some grille cloth it won't buzz so bad you pull your hair out.
That is the reason for the .25" thick 1.5" plywood strips around the perimeter of the baffle, mentioned in one of the earlier posts.
It keeps the grille cloth off the actual baffle board and eliminates about 95% of grille cloth buzz.

Since your baffle board is .75" thick, and your cabinet's internal baffle board cleats are set, you can have a new baffle board made with some high quality, marine grade, .5" Baltic birch plywood (very strong).
Then install the .25"x1.5" strips on the outside of the new one "correctly" and get the same flush, carcass edge to grille cloth finish reveal you'd have now.

Ah, I wondered what it was for.

I'll see how it goes, and bear that in mind. It won't take long to knock up another baffle board.

Thanks for the tip.

R.