Any 40W AB763 w/1-15" players out there?

[tdvt]

I ended up with a second '79 Ultralinear Pro Reverb a few weeks ago & as I have another exactly the same nearly rebuilt in the stock configuration, I am thinking of modding the second one.

The second Pro had more water damage than the first & the particle-board baffle needs to be replaced, which planted the seed of trying a 15" in it.

I am apparently not that up on SRV-lore as the guitar-internet is more or less in a yank about his Vibroverb(s) with a 15" JBL, while I never really made that association.

Not many Fenders came with 15"s & the differences in the various AB763 circuits are so minimal, that I have to think that the different speaker response is a big reason that particular amp is so coveted (besides the SRV connection).


Anyone have some seat-time playing an AB763 through a 15"?  I understand the surf guys are partial to 15"s.

[tdvt]

On this era amp, other than eliminating the built-in boost circuit, adjusting the rail voltage & defeating the UL, it seems the overall circuit is not far off a standard blackface, so this thread might belong in the speaker/cabinet board.

More speaker related I suppose.

[PRR]

The 15" JBL lead (non-Bass) is a special thing. Aside from the most efficiency on the planet, it is reasonably well voiced, even to the point that it handles voice well (not an easy thing to reproduce known spoken voice).

The original E-V 15L was chasing it but didn't go as far.

Drawback of fifteens: treble is beamy. Either your ear is hit by the beam (BRIGHT!!), or many lobes (Peaky!), or it sounds dull. And HEAVY (though not as bad as two decent twelves).

[tubeswell]

I love JBL-D130F as a guitar speaker. I recently sold a 75 Dual Showman Reverb Cab with 2 of these in it - it was just getting too heavy for me to lug - but I couldn't bear to dismantle a vintage DSR cab, as crappy as the condition of the cab was, it was full of vintage mojo and would have been a criminal act. The buyer got lucky - but he was a good 30-40 years younger and fitter than me. I play a lot of surf and rockabilly etc.


Keyboard and LAP/pedal steel guitar players love 1 x 15 Vibrosonic Reverbs

[tdvt]

The 15" JBL lead (non-Bass) is a special thing. Aside from the most efficiency on the planet, it is reasonably well voiced, even to the point that it handles voice well (not an easy thing to reproduce known spoken voice).

The original E-V 15L was chasing it but didn't go as far.

Drawback of fifteens: treble is beamy. Either your ear is hit by the beam (BRIGHT!!), or many lobes (Peaky!), or it sounds dull. And HEAVY (though not as bad as two decent twelves).

I love JBL-D130F as a guitar speaker. I recently sold a 75 Dual Showman Reverb Cab with 2 of these in it - it was just getting too heavy for me to lug - but I couldn't bear to dismantle a vintage DSR cab, as crappy as the condition of the cab was, it was full of vintage mojo and would have been a criminal act. The buyer got lucky - but he was a good 30-40 years younger and fitter than me. I play a lot of surf and rockabilly etc.

Keyboard and LAP/pedal steel guitar players love 1 x 15 Vibrosonic Reverbs

I was always a fan of EV 15s, in fact I still have 2 in TL606 road cabs (used for bass) but even those are no fun to move these days. I also have two EV Force 15s pulled from some EV PA cabs...might be a good candidate.

I can relate to applying the criteria of heavy, the idea of trying a fifteen was partly born out of paring things down to save weight, though it would be minimal using a cast frame replacement.

While I feel the same about mucking with almost-vintage stuff, I am thinking this amp will be brought back into service fairly modded, as it is in sorry enough condition that I won't be undoing much.  I will likely re-build the board because of the wax/crazy wiring, put in a new OT & change out the various odds & ends to back-date the circuit.
 

[g-man]

Deleted

[stratomaster]

I use a Weber Michigan 15 on a Twin Custom 15 where the tone stack was modified to .022uF on the mids cap. 

Big bottom end and diffuse highs with a somewhat relaxed or sluggish response is the best way I can describe it.  Definitely a different feel from my 2x12 Twin Reverb, even with the same tone stack mod. 

I'm of the opinion that you need defined highs to give low notes the proper note definition and separation. Otherwise it'll get boomy and mushy.  This arrangement almost borders an boomy and undefined.  Legend has it that the cathode caps were reduced in SRVs Vibroverb to combat this. 

There's a Tonequest article detailing one of his Vibroverbs.  If I remember correctly the takeaway was that the modified amp is unplayable except at extreme volumes where the amp's compression and saturation tame the voicing modifications done to combat the inherent boominess, sluggish-ness, and tendency to distort. 

If I were building a Vibroverb I'd probably shoot for a 2.2-3.3uF cathode cap in the first stage and leave everything else per schematic.  I'm wanting to do this exact thing with the Twin Custom 15 as time allows.

[dogburn]

I don't have personal experience, but I know (via a magazine interview) that Poison Ivy of The Cramps used to play a blackface Pro Reverb with a 15" speaker, and kept a 2x12 Pro Reverb on stage as backup. You can find a lot of Youtube videos of The Cramps playing live where she would be using that amp.

[tdvt]

Thanks to all for weighing in. This is the kind of stuff I was wondering about.

I'm not setting out to build a Vibroverb per se, but when you put a 15 in a AB763 combo cab, it seems that is what you get more or less.  Had to Google the Twin Custom 15, so I guess it's not always a Vibroverb...

Point taken about smaller 1st stage coupling caps. The change is something I have experienced first-hand (learned about it here) & I have been implementing that mod as a matter of course, using values somewhere between 4.7uF to10uF (so far). I run several variations on the AMPBOOKS Calculators before I start swapping things out.  Good results so far.

It doesn't surprise me in the least the the SRV amps would have been tweaked to the edge of instability with LOUD as the norm. Saw him a couple of times but everything was loud then anyway.

I did come across the beaming issue mentioned a few times while researching this, some use those beam-blockers to try to manage it. Don't know if they really work or not.

[PRR]

save weight, though it would be minimal using a cast frame replacement.

Serious speakers have serious magnets. The two major changes were the shift from Alnico to ferrite (more weight for the same flux) then much later the offering of Niobiums (MUCH less weight for the flux but more expense). Nio may be worth it for less painful transport of high-output speakers.

My last major purchase was JBL E130s, and people were bichin about the crappy ferrite compared to classic Alnico D130s. (When he passed, we discovered that Ted had C130s in his amp, a model JBL doesn't document.)

[tdvt]

save weight, though it would be minimal using a cast frame replacement.

Serious speakers have serious magnets. The two major changes were the shift from Alnico to ferrite (more weight for the same flux) then much later the offering of Niobiums (MUCH less weight for the flux but more expense). Nio may be worth it for less painful transport of high-output speakers.

I have already made the switch to Neo speakers for my gig rig (bass). As I was always a 15 guy (never cared for 10s), I was surprised to end up with some Eminence Neo 12s. Tried 15s too but like the 12s better.
Amazing output in a light-weight package

[WiderGates]

Hei,
which Neos do you use? I also like 12" Speakers for bass.

[waldner]

I converted a Bandmaster Reverb into a 64 Vibroverb, (pretty close with some mods) and use a JBL D130 reconed by Weber with the same cone they use in their 15" Neomag speaker.   I love it.  I've gig'd with it several times and it's great.  A bit heavy to carry, but not ridiculous.  Highly recommended. 


The attached pic was taken before I put in the newly reconed JBL D130 with a paper dust cap for less aggressive highs.

[tdvt]

Hei,
which Neos do you use? I also like 12" Speakers for bass.

I use the Kappalite 3012LF in a Greenboy-ish 12Cube cab w/6" mid. Tried both the 12 & 15 of the Kapalites, sold the 15. Second cab has no mid.

Not really that different from each other as I play pretty old-school thump w/mid-scoop.

I converted a Bandmaster Reverb into a 64 Vibroverb, (pretty close with some mods) and use a JBL D130 reconed by Weber with the same cone they use in their 15" Neomag speaker.   I love it.  I've gig'd with it several times and it's great.  A bit heavy to carry, but not ridiculous.  Highly recommended. 

The attached pic was taken before I put in the newly reconed JBL D130 with a paper dust cap for less aggressive highs.

Beautiful job, you went all in, faceplate & all!

The late 70s SF Pro I'm thinking of backdating has mid on both channels, plus a MV, so not a faithful clone but should be quite tweak-able with those extra features.

Glad to hear you like the 15.

[MWaldorf]

You might also consider the Weber NeoMag 15.  It can be set up like a JBL D130 with the aluminum dust cap, or you can dial that back with a fabric cap and different cone options.  It weighs 8 lbs.  I've got a Showman which I run through 2 Weber NeoMag 15s and not only does it sound pretty great, the two neomags weight about the same as a single D130.  I also put a NeoMag 15 in an Ampeg Gemini I, another winning combination.