JBL D-123

Laurent Brondel · Post by **Laurent Brondel** » Fri Mar 21, 2014 11:11 am

I am waiting for a pair to arrive and couldn't find any definite specs on them. Do you guys think they can handle the 22w of a Deluxe Reverb?

Roe · Post by **Roe** » Fri Mar 21, 2014 12:13 pm

sounds risky if you dime the amp with a fuzz pedal for a long period of time

Laurent Brondel · Post by **Laurent Brondel** » Fri Mar 21, 2014 12:49 pm

Thanks, can I assume it would be fine with the volume just before breakup (around 3). Do you know the power rating of the D-123?

RCGPNY1 · Post by **RCGPNY1** » Fri Mar 21, 2014 4:13 pm

The D123 is actually a "full range" speaker designed for hifi. As with most JBL speakers, it's power handling is dependant on how its loaded.
The D123 was designed for a ported, bass relfex enclosure, and gave a power handling of about 60 watts. In an open back cab its handling is halved to 30 watts..this is more a mechanical limit than a thermal one. With heavy distortion it would be possible to make one fail in a Deluxe .

Laurent Brondel · Post by **Laurent Brondel** » Sat Mar 22, 2014 7:55 pm

Thanks. Any experience with this speaker in a guitar amp, like a Deluxe Reverb or a brown Princeton?

didit · Post by **didit** » Mon Mar 24, 2014 4:21 pm

Laurent Brondel wrote:Thanks. Any experience with this speaker in a guitar amp, like a Deluxe Reverb or a brown Princeton?

Yes. Or at least almost -- is a Princeton Reverb close enough. It works very well -- clean and clear just as you'd expect; and quite efficient. Unless/until it's overdriven, which this Princeton can do easily. I'd be reluctant to put one in a Deluxe.

I have some in a ported 2 x 12" that's excellent too.

Best .. Ian

Bob S · Post by **Bob S** » Mon Mar 24, 2014 11:16 pm

I've got 4 in an over-sized 4 x 12 closed back cab.
Works fine for AC30 / Rocket outputs - 30/35W.
50W heads make me nervous with that cab. Good ones are getting scarce.
The flat pancake design allowed them to be fitted into walls with limited space behind them.
They are the old JBL designer's favorite guitar speaker.
IMHO for clean they have no equal.
Good luck with yours.
Almost forgot - check the phase is the same on both with a battery.
Push or pull on the positive half cycle is open to debate.
They are backwards to most normal speakers though.

RCGPNY1 · Post by **RCGPNY1** » Wed Mar 26, 2014 2:50 pm

The D120F is the way to go for a guitar amp. Back before JBL made musical instrument loudspeakers, alot of people used the D123 and blew them up. One of the engineers at JBL beefed it up...larger voice coil gap,
a doped surrond to prevent tearing and a less shallow cone. Even so, original D120's are 60 watt speakers. They do possess that great clean JBL sound....and for some a great overdrive tone...Duane Allman used
D120's in open back Marshall cabs with 50 watt heads...He sounds pretty good...no?

didit · Post by **didit** » Wed Mar 26, 2014 5:14 pm

RCGPNY1 wrote:The D120F is the way to go for a guitar amp.

There's a D120F in my '64 DR and so I'd have to agree it's a wonderful speaker -- though clean originals cost a ransom. I'd be delighted to have a 4x12, though only if a road crew comes as part of the package.

I am real comfortable pushing 30W+ through my 2xD123. It's got much and more that I like about D120 except big thump bottom end. It's definitely not Allman Bros. or even close. Still, in a Thiel style cabinet D123 bottom end is much more controlled; and I still wouldn't crank up full blast using it.

And otherwise in open back they are easily driven to an unhappy unpleasant distortion, as I noted earlier.

Best .. Ian

Laurent Brondel · Post by **Laurent Brondel** » Wed Mar 26, 2014 5:27 pm

Speaking of Thiele style cabs, do you guys know where to find the plans to build one? And would simply doubling the width work for a 2 x 12?

Teleguy61 · Post by **Teleguy61** » Wed Mar 26, 2014 6:30 pm

Laurent Brondel wrote:Speaking of Thiele style cabs, do you guys know where to find the plans to build one? And would simply doubling the width work for a 2 x 12?

http://www.google.com/url?sa=t&rct=j&q= ... 8703,d.aWc

Designed for the EVM 12L speaker. I have used them with K120s and Weber Neomag 12s, and they sound excellent.
With an EVM 12L in it, built to specs, the cab weighs 38lbs.
Hefty, and a ton of sound.

didit · Post by **didit** » Wed Mar 26, 2014 6:35 pm

A couple more comments --

1. 2x12 designs borrow half of the 4x12 Thiel design so search for that.
2. Using EV dimensions etc. works well with similar speakers, which D123 really isn't; so consider in the style of vs actual clone or get T/S numbers for D123 and do the engineering to dimension correctly.

Best .. Ian

Laurent Brondel · Post by **Laurent Brondel** » Wed Mar 26, 2014 9:17 pm

I intend to put the D-123 pair in a couple of brownface Princetons, I am hoping it will tame a bit the mid-heavy tone.
I am asking about the Thiele design for one EVM 12L Classic, and a pair of Eminence Beta 12 A I use for bass with a mid '60 Carlsbro head and currently a Bandmaster cab, which is not ideal.

I am trying the EVM 12L Classic in a Deluxe Reverb now, not crazy about it at all -the treble cap is not clipped-, the amp sounds so much better (to me anyway) with a late '60 Jensen C12N.

Teleguy61 · Post by **Teleguy61** » Thu Mar 27, 2014 3:46 am

https://www.jblpro.com/pub/manuals/enclgde.pdf‎

This link will take to JBL cabinet dimensions, just another take.

Bill Moore · Post by **Bill Moore** » Thu Mar 27, 2014 3:04 pm

I have built a few of the 1/2 4-12 cabs, never used anything but EVM's in them though.

The Amp Garage

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