Super reverb external speaker jack question

[Toxophilite]

grrr I hate it when itdumps your whole post if your extension is too big!!
Anyway here I go again


I have a 1980 super reverb 4x 16 ohm speakers 4 ohm load min
it has an extension speaker jack labelled for 4 ohms as well
The schematic seems to suggest that it maybe switches taps on the OPT when you plug i an external cab as well??? Not sure if I have that right
Can someone explain it?


also I usually run a mini leslie unit that uses a 4ohm 6x9" speaker in a little rotating cylinder out of that jack
i recently had to replace the speaker in the leslie unit with another 4 ohm 6x9 but with a larger magnet


It now seems to loose  power with the leslie unit plugged in
it might've to some extant before but i didn't notice it
i am however playing the amp at about 4-4.5 on the volume rather than the 2-3 I used to have it at

[sluckey]

I have a 1980 super reverb 4x 16 ohm speakers 4 ohm load min
it has an extension speaker jack labelled for 4 ohms as well
The schematic seems to suggest that it maybe switches taps on the OPT when you plug i an external cab as well??? Not sure if I have that right
Can someone explain it?

According to the schematic you posted, that's right. The external speaker jack is a switching jack. If you only have the internal speakers connected, the switching jack connects to the 4Ω tap on the OT. When you plug in an external cab (should be 4Ω) the switching jack connects to the 2Ω tap on the OT. You should be fine using your 4Ω Leslie connected to this amp.

There have been several slightly different SR amps thru the years. This one is an oddball SR. This is the only one with a multi-tap OT secondary. All the other SRs have a 2Ω tap only and no switching jack for the external jack. Are you sure this schematic matches your amp?

[Toxophilite]

Thanks for the replies!
Mine is an early 1980 (which falls within the realm of that schematic) the serial number shows that
It says 4 ohms on both jacks
Also to back that up it has 4  16 ohm speakers run in parallel making a  4 ohm load(I've tested them with my meter, both individually and all together) Just like the diagram shown
It has the push pull master volume (though that's been disconnected as the pot blew apart many years ago)
So I'm 99% sure this is the schematic for my amp
And it's rated at 70 watts RMS on the back

[PRR]

If it switches impedance when the EXT SP jack is used, then your internal speaker gets 35 watts (down from all 70 watts) and the external gets 35 Watts.

> a 4ohm 6x9" speaker

35 Watts of full-range loud guitar is a LOT! for any six-by-nine. I'm not surprised you had to replace one. Better get them at the car-sound store: they come in pairs and I suspect you will need spares.

I would think about wiring the internal 4-cone array to the 4 Ohm tap, and add a connection to the 2 Ohm tap *just* for the 6X9 Leslie. The big array will get most of the 70 Watts. The 6x9 (4 ohms on 2 ohm tap) will get around 18 Watts, which is not out-of-line with what 6x9s get in modern car stereos. Of course the 6x9 will be softer, but I'm sure you didn't expect a 6x9 to keep-up with a quad array of large cones.

The 6x9 will also live longer with a 100uFd non-polar (speaker crossover) capacitor in series. This keeps the bass out, and much of the power, and most of the excess travel. This should not harm the Leslie effect, because a 6x9 is totally omni-directional below 800Hz; any way it faces sounds nearly the same as far as bass goes. a 6x9 will give fair to good directivity 800-8KHz, those are the tones it should be working with.

[Toxophilite]

Admittedly I had been using the first for the past 8 years..a lot! and it was pretty dried out. I think it had a few cracks when I first pulled the unit from a Baldwin organ and I fixed them but it eventually became a little too cracked
But I never had my amp past 3 then as I was playing with a quieter combo
Now I have a loud rock band too and i get the amp up to 4!! and sometimes beyond to 4.5! crazy
That's when it seems more apparent
THe new speaker seems to be holding u[
Do I put the cap on the hot wire prior to the speaker? between the speaker posts?.I have to research crossovers

[Willabe]

also I usually run a mini leslie unit that uses a 4ohm 6x9" speaker in a little rotating cylinder out of that jack

Can you post some pictures of it?


                Brad   

[sluckey]

Here's one...

http://www.ebay.com/itm/VINTAGE-LESLIE-TREMOLO-UNIT-PART-NUMBER-121-000120-GREAT-FOR-ORGAN-OR-GUITAR-/121397599401?pt=LH_DefaultDomain_0&hash=item1c43dc5ca9

[Willabe]

Huh, Ok, thanks.


                    Brad   

[Toxophilite]

That's not the one I have , Though I've seen one of those . Mine is smaller.
it's an upright cylinder about 10 inches diameter on top and standing about a foot or so high. 2 speed.
I'll get a picture up today

[Toxophilite]

here you go
here's my unit
The cables are wrapped around it for transport
The unit was pulled from an organ and then had a hasty ply frame made around it to try it out..and it's stayed the same since. With the addition of a handle. I kept wanting to make a fancy box for it and just never did. People like it alot! "What the hell is that thing??"  I used an extension chord for the power and foot switch as I wanted something pretty skookum as it has AC going through it.
Works like a hot damn
When I put the new speaker with a bigger magnet in it I had to add to the metal weights that were bolted to the inside of the drum on the opposite side. I tried it out without adjusting the weights and it quite literally started to walk off the bench I had it on.

[Willabe]

Huh, a little smaller, thanks.


                   Brad   

[Toxophilite]

My new (to me)1978 Super Reverb is identical in every way to my 1980 (that've I've been using for years)
except that the speaker jacks are labelled for a 2 ohm load instead of 4ohm..hmmmm (and I guess the speakers are 8ohm)
How would that work with the 4 ohm leslie would that split the power more like what was suggested by PRR?
Maybe I'll give it a whirl

[sluckey]

I would just replace the 6x9 with an 8Ω speaker (16Ω would be even better) and not worry about it.

I would not want to plug a 4Ω speaker in the EXT jack of that older SR.

[Toxophilite]

Out of curiousity Why is that?
i do however have a 8ohm 6X9 and it has whizzer cone too

[Toxophilite]

By the by both amps have the switchable tap dealy with the ext jack

[sluckey]

A higher impedance speaker cab will have less loading effect when plugged into a SR amp.

[Toxophilite]

Something is a little funny then
I put this 8ohm 6 x 9 into my little leslie and tried plugged into the ext jack on the 2ohm 1978 super
The leslie was quite loud, and the super got a lot quieter
That doesn't make sense

[Toxophilite]

OKay I put an 8 ohm speaker in my leslie unit and inserted a 100 uh non polarized cap into the + line to the speaker
On the 2ohm 1978 SR it works pretty well, I don't lose as much amp sound and I still get a nice noticeable chorus and tremelo effect


On the 4ohm 1980 SR there's practically no difference in the amp sound with the speaker plugged in to the ext jack
But I can barely hear the leslie (it almost might as well not be there)


To me this seems the reverse of how it should be
Do I have it turned around in my head???






For fun I tried unhooking one of the 8 ohm speakers in the 1978 SR and hooking the leslie up at that point but it wass too quite then as well. i think I need to be about 1/3 volume at least to hear it.