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“Plug and Play” speaker jack plate, wiring

Ringhammer

Ringhammer

Supporting Member
Sep 3, 2016
3,526
18,162
S. F. Bay Area
#1
6DF068C4-05B3-40F7-9202-353BF30C155B.jpeg


949EBE00-98F9-4524-A3BE-2E8A9943DE2F.jpeg


Has anyone used one of these, seems like the same thing the newer SVT810's do.

In my case I'll be using 4 x 8ohm 12's, so my config will be more like 4 ohm left, 4 ohm right, 2 ohm mono(?), and 8 ohm mono. I think. However I'm hoping someone knows how I need to wire this for sure. I don't know who makes this thing.

I think I am supposed to wire the left two 8 ohm speakers in parallel to one pair (red/white?) and the right two 8 ohm speakers in parallel to the other pair (black/green), and then if I plug one speaker cable ONLY into the jack marked "4 ohm mono", I will actually be at 2 ohms, OR if I plug one speaker cable ONLY into the jack marked "16 ohm mono" I will actually be at 8 ohms, OR if I plug one speaker cable into the jack marked "8 ohm left" AND one speaker cable into the jack marked "8 ohm right" I can bi-amp with an amp that has two 4 ohm rated outputs, or two separate amps with 4 ohm outs, since the left and rights will be 4 ohm, not 8 as marked. (I'll be breaking out the label maker for sure)

Likely will only use the jack that is marked 16 ohm mono, which will be 8 ohm for me, but could be fun to have the bi-amp option, making left and right actually be top and bottom.

Hoping for confirmation on my logic from someone with experience, thanks in advance.
 
#2
All your calculations seem correct -- now if you can just get the right wires in the right places. Edit: do you have an ohm meter or continuity checker of some sort? If you don't have the color code for the output wires, you need to confirm what's what.

And yeah, do use the label maker -- that 2-ohm load for the whole cab could really be disastrous for an unsuspecting user.
 
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#3
Yep, I have a meter, I may use 1k resistors to act as my speaker load and then the math is easy, and can confirm the operation/configuration of it. I'll just wire in a 1k resistor where an 8 ohm speaker would go and I should have the following results when I read the speaker cable T/R when plugged into the jacks as follows:

left and right (marked 8 ohm) should be 500k each
The 2 ohm mono will be 250k
The 16 ohm mono will be 2k
 
#4
That all sounds right, except in the last line, you need to now call that the 8-ohm mono input. Your method of confirmation sounds a bit more complicated than it needs to be, but it seems like you have a good handle on it. I wouldn't bother with simulating the two loads in each of the two parallel circuits; nothing changes in those branches, so you could substitute a single resistor for each parallel branch -- with the resulting change in the parallel and series resistance values, of course - 500 for the parallel (2-ohm mono) jack and 2K for the for the series (8-ohm mono) jack. But as I say, it sounds like you got it.

Uhmmm... it occurs to me to ask what your plan is for this cab? More specifically, are you going to be driving all or part of it with a tube amp? I'm asking because there are some potential hazards with patching or repatching this input plate with a powered-up tube amp. Also, the tiny contact point that makes the "normal-ed" connection inside the jacks will be somewhat vulnerable and prone to failure -- those cheap plastic jacks aren't as robust as one might like. If you start having problems, that would be the likely cause. (This would be the point where my stodgy old alter-ego self would ask, "do you really need all that patching capability?"... I'll try to keep that viewpoint at bay. :D) Good luck with it! :thumbsup:
 
#5
Mostly just using it cause it's there, and I'm sure I'll use the 8 ohm mono at all times, plugged into my 6550 converted V4 (not B). Might be fun to bi-amp in the studio using my SVT 4Pro or SVT 5Pro. If there is any detectable weaknesses with the jacks while I'm testing I will probably ditch it, strip the guts and just use two of the jack holes with two jacks in parallel so I could connect a 2nd 8 ohm to it and just wire all the speakers in series/parallel for 8 ohm.
 
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#8
Not that the "plug and play" jack plate doesn't appear to isolate the left & right sleeves.

With a BTL amp, this could be damaging to the amp.
 
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#11
Ringhammer said:
BTL?
Click to expand...
Bridge-tied load. It's an amplifier circuit topography in which two amps are bridged and are amplifying the same signal differentially, which is to say, in opposite polarities (sort of). It's a common topology in modern Class-D amplifiers. What @agedhorse is saying is the '-' output terminal of those amps is "hot", just like the '+' terminal is -- if you short it to an earth ground (like an amp's chassis) or to another amp's hot lead, you'll be shorting out the output and the thing likely goes "pffft!". Which is what you'd be doing if you connected a BTL-type topography amp's (like many, if not most, Class-D) output via quarter-phone plugs to this input panel.

Sounds like a good enough reason to not do this, IMO, but ya pays your money and ya takes your chances.
 
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#13
The main thing I'll do with this cabinet is one speaker cable to the 16ohm mono jack (which will be 8 ohm in my application) and plugged into my V4 with the switch in the 8 ohm position.

The other thing I was curious about was using my old SVT with it, by plugging the speaker out of the SVT to one of the 8 ohm (4 ohm in my application) jacks and the EXT speaker out to the other 8 ohm (4 ohm to me). Since the SVT can run 2 4 ohm cabs I think this should work.

If I have a speaker cable plugged into each of those jacks on the cabinet and there is no continuity between any T/R or T/T or R/R then wouldn't that be safe?
 
#15
Based on the schematics accessed via the links @coreyfyfe posted, if you use the 16 ohm mono jack, (which will be the 8 ohm mono jack when the cabinet is loaded with the speakers you plan to use), you will be putting power from your amp through a couple of switched contacts in the other two jacks. You will also be running power through both left & right loads in series. I'm not suggesting it won't work, but there are points of failure that are usually avoided in modern speaker cabs. You might possibly experience some reliability issues with the switches in the series wiring, but at least you will have parallel paths through two speakers on the left and two speakers on the right that should give some continuity redundancy within each side. Series wiring of speakers is nothing new, but having "series only" wiring between the amp and speaker loads, along with the jack switches in the signal path would worry me a little. I'd want to make sure the contacts on all jacks are in as good a shape as possible.

55BEF76F-F1FF-4E34-9CB4-F81A4B4635CA.jpeg
 
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#16
After all the discussion around this thing, with the "possible points of failure" and the fact that this will almost always be used with my modified V4 tube head, I think it is smart to just use this:

15D9E976-7675-4999-90A7-2137A466FEA5.jpeg
95E599E4-99E3-44AA-ADEA-EA956CB8E3D4.jpeg


Genuine Ampeg, simple 8 ohm (in my case) cabinet, with the ability the chain a second 8 ohm cab, and bonus Speakon connectors. I've had this that came from a wrecked 1999 810AV particleboard cab that had a giant hole where one of the casters was. I salvaged the AV grille, towel bar, corners, and the non-"dark" speakers. Those went into a nice birch plywood 2007 810, which has the Ampeg version of this plug-and-play thing. I think this is a better choice to fill the hole and keep things simple and reliable.

Also, maybe that plug and play thing is more for guitar cabs/amps, which maybe have less power running through all that switching??
 
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#18
Ringhammer said:
After all the discussion around this thing, with the "possible points of failure" and the fact that this will almost always be used with my modified V4 tube head, I think it is smart to just use this:

View attachment 4791508 View attachment 4791509

Genuine Ampeg, simple 8 ohm (in my case) cabinet, with the ability the chain a second 8 ohm cab, and bonus Speakon connectors. I've had this that came from a wrecked 1999 810AV particleboard cab that had a giant hole where one of the casters was. I salvaged the AV grille, towel bar, corners, and the non-"dark" speakers. Those went into a nice birch plywood 2007 810, which has the Ampeg version of this plug-and-play thing. I think this is a better choice to fill the hole and keep things simple and reliable.

Also, maybe that plug and play thing is more for guitar cabs/amps, which maybe have less power running through all that switching??
Click to expand...

Looks "more reliable"
 
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#19
In case anyone is still following, what is the effect of insulating the back and top/bottom/sides of a sealed cabinet? I have some insulating material that came from that same 1999 SVT 810AV that the back plate came from, which was also a sealed cabinet, but deeper. The material is about 3/4" thick. Wondering if I should put some on the back AND sides, or just back or just sides, or not at all. This the v4 cab with the BP-122's.
 
#20
It depends.

It does several things, most importantly it decreases mid reflections that can then pass through the paper of the cone and combine (with a short delay) with the incident signal off of the cones. Some like no damping, some like a little and some like a lot.
 
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