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Is there any ways to run two 8 omhs speakers with my Deluxe Reverb ?

tuumbaq

Member
Messages
580
I have 2 spare 8 omhs speakers and an empty 2x12 cab... I would very much like to run those with my Deluxe Reverb but from my understanding the amp will only take an 8 omhs load ... Can it be modified? Or is there an trick I could do with the wiring to make it work with the amp ?
 

TweeDLX

Member
Messages
3,756
If you unplug the internal speaker and run only the cab for a 4ohm load (depending on how you wire them-I'd opt for parallel at 4 ohms) you should be fine. Most amps can stand a one-step mismatch from 8 to 4. It will sound a bit different, but you may not notice it.
 

DaveKS

Member
Messages
16,716
You can wire the 2 speakers in series (I think? can't ever remember) and it will show an 8 ohm load.
Yep, either will work, just if you present it with a 4ohm load don't crank it and you should be ok. The wiring in in series would absolutely work but won't sound exactly the same as in parallel.

Maybe someone with more real time, hands on, tech knowledge of this amp and it's OT will chime in.

But you know, if your gigging life depends on it, good 16ohm speakers are not that hard to find.
 

pdf64

Member
Messages
6,955
As DRs have been manufactured over many years and things change, it's beneficial to clarify the the approximate age of the amp.
Whatever, power tubes will work at their best, eg best tone, working life, power output, when used into the intended load.
An OT upgrade with alternative output impedances should be cheap to buy and fit, and will avoid compromising such key attributes.
http://www.classictone.net/40-18038.html
Pete
 

twangbanger

Member
Messages
1,492
As DRs have been manufactured over many years and things change, it's beneficial to clarify the the approximate age of the amp.
Whatever, power tubes will work at their best, eg best tone, working life, power output, when used into the intended load.
An OT upgrade with alternative output impedances should be cheap to buy and fit, and will avoid compromising such key attributes.
http://www.classictone.net/40-18038.html
Pete
:agree I used one of those OT's in a recent project . Very impressed .
 

michael patrick

Silver Supporting Member
Messages
10,701
You can wire the 2 speakers in series (I think? can't ever remember) and it will show an 8 ohm load.
No. With 2 8-ohm speakers you can only get 4-ohms by wiring them parallel or 16 ohms by wiring them in series.

You can't get an 8-ohm load from two 8-ohm speakers.
 

TweeDLX

Member
Messages
3,756
No. With 2 8-ohm speakers you can only get 4-ohms by wiring them parallel or 16 ohms by wiring them in series.

You can't get an 8-ohm load from two 8-ohm speakers.
^^^ This is correct.
Pete's suggestion of a new OT with 4/8/16 ohm taps is where I would go. Just remember that you shouldn't run the speaker in the amp cab at the same time as the two in the separate speaker cab. That will give you a really odd mismatch.
 

CDA

Indigenous Donkey
Messages
349
You can run that amp all day long at 4 ohms.

Don't run it without a load, but fender shunts the output signal to ground via a switching jack if you do not have something plugged in anyways. No load = bad. A speaker that sounds good to you when you play = if you like it use it.

Notice the extension jack, they are quite capable of driving 4 ohm loads. This isn't audiophile ratchet trash we're talking about here..
 

phsyconoodler

Member
Messages
4,315
It's all about the output transformer primary resistance. The Deluxe Reverb uses a 6.6k load on the primary which allows you to use 4,8 or 16 ohm speaker loads with no issues at all.
The optimum load for a pair of 6v6's is 8k,so you will not have any issues at all. Leo Fender likely knew this when he chose a 6.6k load for the DR.
 

pdf64

Member
Messages
6,955
It's all about the output transformer primary resistance
My view is that the 6V6 plate dissipation is the key point at issue.
Clearly the OT primary impedance will affect it but so will the VB+ level.

The Deluxe Reverb uses a 6.6k load on the primary which allows you to use 4,8 or 16 ohm speaker loads with no issues at all
Connect a 4 ohm load to the secondary and that changes to 3k3 which together with a high VB+ of >400V may result in overdissipation of the 6V6 plates.
Connect a 16 ohm load and the resulting primary impedance will be 13k2 which may result in overdissipation of the 6V6 screen grids at high signal levels.
I'm not aware that 3k3 or 13k2 primary load impedances are normally selected for a pair of 6V6.

The optimum load for a pair of 6v6's is 8k
Surely that depends on balancing numerous constraints, one of which is VB+. Note that the manufacturer's info sheet suggested operating conditions in which 8k is the p-p load has a VB+ of 285V, see http://www.mif.pg.gda.pl/homepages/frank/sheets/135/6/6V6GTA.pdf
Whereas the DR B+ is around 400V.

The optimum load for a pair of 6v6's is 8k... Leo Fender likely knew this when he chose a 6.6k load for the DR
I don't follow the rationale of this.
If 8k is the optimum, why choose a lower value?
Having chosen that lower than optimal value, why facilitate it being halved via the provision of a parallel output socket?

My guess is that there wasn't much consideration of the tube constraints going on, rather Fender tried and got away with it, but perhaps that should be viewed in the context of the time, when great 6V6 were readily available.
Pete
 

Peteyvee

Premium Platinum Member
Messages
56,051
Maybe I missed it somewhere, but this is a reissue you're talking about swapping the OT on, right?

You don't want to pull the original OT out of an original BF (or even a SF) unless you have a very good reason to do so and are prepared to lose money if you resell it...
 

pdf64

Member
Messages
6,955
The idea is to take the original OT out and keep it safe, then refit it when selling.
 
Last edited:

Stu Blue

Member
Messages
3,166
Back in the '70s I put a 16ohm Celestion G12H in a Deluxe Reverb (69?) and it actually gave tiny bit more watts (1-2) into 16ohm instead of 8ohms (according to my tech at the time). When I joined TGP there was post from John Phillips saying the same thing.

Neither my tech or John gave any special explanation for this... which should not happen...should be less watts with the mismatch... maybe English/Export model transformer? Whether this works with RI Drs I've no idea but the notion that 16 or 8ohm are equally cool was true of the export sixties ones.
 

Guitar55

Who was that masked man?
Messages
9,212
I'm thinking of adding a second 8 Ohm 12" speaker cab for my DR, probably semi-closed. I have a Mercury Magnetics OT (8 Ohm) and my hope is that it will just feel a bit 'bigger with two 12's.
BTW, the DR has a Cannabis Rex and that's what I'm thinking of using in the cab.

Can anyone recommend a good cab for the DR to sit on?
 

zzmoore

Member
Messages
7,095
Maybe I have been clueless the whole time.:eek:

The OP is proposing to run a 2x12 at 4 Ohms.....is that really any different than what thousands of Deluxe Players have done over the years...run an 8 Ohm speaker off the Ext Jack.?
 

Guitar55

Who was that masked man?
Messages
9,212
Have they? I know it's possible but I wasn't sure that people actually do it.
 

roadfilm

Member
Messages
3,039
Maybe I have been clueless the whole time.:eek:

The OP is proposing to run a 2x12 at 4 Ohms.....is that really any different than what thousands of Deluxe Players have done over the years...run an 8 Ohm speaker off the Ext Jack.?
This ^^^^^^
I highly doubt that Leo Fender expected people to change out transformers and such in order to use the extension jack. It's meant to plug another cab in and go.
 




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