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Ampeg 810 wiring mod

B

bassmedic

May 15, 2012
17
2
#1
Hello all,

I'm new to TB and am also the new owner of a very used Ampeg SVT810. It needs some work. The rat fur needs to come off, 2 speakers need replacimg but for $270 I couldn't turn it down.

I will soon be in possession of a B4R to push it and in part that head is motivating my question. The B4R has 2 separate power amps that can push 500 watts each at 2 ohms or they can be bridged mono for 1000 watts at 4 ohms.

The jack plate on the cab currently has a single 1/4 input. As I believe all ampeg fridges are, it is wired for a 4 ohm load. I want to go to speakon connectors and will change the jack plate entirely if needed for this project.

I would like to rewire the cab to have the top 4 and bottom 4 speakers wired separately to 2 4ohm loads (I realize this may require changing all the speakers pending on the impedance of the current ones), and then install 2 speakon inputs in parallel for each half and running a power cable between them for a collective 2 ohm load for the whole cab. This would be so I could run 500 watts to the cab from one side of the amp and have the other side to run 500 watts to 2 svt-18's when I can find/afford them (this is my dream rig of doom). There would be a third input to come in from the amp obviously. And then (I think this is where it gets complicated) have a 4th speakon jack wired to run all 8 10's at a 4 ohm load so I can use the mono bridge option on the amp for 1000 watts at 4 ohms.

I know this complex but any help would be greatly appreciated. Either way I'll have pictures up when I start the refirb and the wiring mod if its possible.
 
#2
The drivers are 32 ohms each. So If You wire the top 4 and bottom 4 separately, they will be 8 ohms per 4-10's.
Depending on the vintage of the cab (having 1/4" jacks only, I'd guess that it is fairly old), Installing a new jack plate with speakon connectors is not a bad idea and wouldn't be a super complicated job.
 
#3
JMac4strngr said:
The drivers are 32 ohms each. So If You wire the top 4 and bottom 4 separately, they will be 8 ohms per 4-10's.
Depending on the vintage of the cab (having 1/4" jacks only, I'd guess that it is fairly old), Installing a new jack plate with speakon connectors is not a bad idea and wouldn't be a super complicated job.
Click to expand...

+1

There is no way to wire the cab into two 4 Ohm sections with out replacing all of the drivers. Even doing so isnt worth what you will gain. I would re-wire the cab like the current ones are now, two 8 ohm sections and one with both sections in parallel. The wattage gain you think you want isnt going to net you much if any volume.
 
#6
Thanks for all the so far everyone. I'm not trying to increase the amount of wattage I can put to the cabinet, more so I'm trying to increase my options for putting power to it and additional cabs later on. I know 1k watts is a lot of head room for that cab and don't plan on turn the volume anywhere near 11.......
 
#7
bassmedic said:
Thanks for all the so far everyone. I'm not trying to increase the amount of wattage I can put to the cabinet, more so I'm trying to increase my options for putting power to it and additional cabs later on. I know 1k watts is a lot of head room for that cab and don't plan on turn the volume anywhere near 11.......
Click to expand...


Having the cab as two 8 Ohms loads or one 4 Ohm is more versatile.
 
#9
Thanks so much for all the advice so far. I'm not trying to increase the wattage handling. More so I'm trying to increase my options for putting power to it and additional cads as well. The B4R present a few unique opportunities for power distribution. I know 1k watts is a lot of head room for that cab and I don't plan on putting the volume anywhere near 11.....
 
#10
I'm not trying to increase the wattage handling... I'm trying to increase my options for putting power to it ... I don't plan on putting the volume anywhere near 11.....
Click to expand...

Then what's the point of rewiring the cab down to 2 ohms? Your options for using the cab with different heads in the future are much better with a 4 ohm cab than with a 2 ohm cab. Also I'm just guessing, but your pair of 18s are likely going to be 4 ohms as well.

IMO it's not worth the effort or the cost of rewiring that cab. Just replace the broken speakers with some Eminence B810s and get to rocking.
 
#11
The point of making it 2 ohms was to get 500 watts to it with only one side of the amp. Then the other side of the amp would be open for the 18's. The 4th input i spoke of would combine the upper and lower halfs for a 4 ohm load.

I'm starting to see how far fetched this is but i was trying to get the most out of the amp.
 
#12
bassmedic said:
The point of making it 2 ohms was to get 500 watts to it with only one side of the amp. Then the other side of the amp would be open for the 18's. The 4th input i spoke of would combine the upper and lower halfs for a 4 ohm load.

I'm starting to see how far fetched this is but i was trying to get the most out of the amp.
Click to expand...

Well the only way to get it to a 2 Ohm load is to replace all the drivers. If thats what you really want to do, its your money. For me I would rather spend that money on different gear, like a second 810. Two 4 Ohm 810s in parallel will be a 2 ohm load. I know that throws your 218 plans out the window, but those cabs are not going to add anything to your sound.
 
#13
bassmedic said:
The point of making it 2 ohms was to get 500 watts to it with only one side of the amp. Then the other side of the amp would be open for the 18's. The 4th input i spoke of would combine the upper and lower halfs for a 4 ohm load.

I'm starting to see how far fetched this is but i was trying to get the most out of the amp.
Click to expand...

The more power (voltage, really, but it kind of ends up at the same place) you apply to a speaker the louder it gets. When it stops getting louder with more input it starts sounding ugly.

If you don't use all the power you have now with an 8 ohm load, you will simply use a lower percentage of the higher theoretically available power if you go to the trouble and expense of replacing the drivers to make the 810 a 2 ohm load (and it'll surely sound different, too). More circularly, you won't use more power than you use, whether the amp delivering that power is barely capable of the power level you actually need, or could put out 10 times more power if called upon to do so.
 
#17
IMO/FWIW- You'd do better to leave the 810 with a single 4 ohm input, either 1/4" or NL-4 Speakon inputs or both for versatility sake. You could add another identical 810, if Your volume needs justify it. If You dont like the tonal performance of a SVT 810 on its own, I would venture to say Your best bet would be go try some different cabs that sound like You want, and build in multiples of the same from there to reach the volume level that suits Your needs.
 
#18
Well, I was looking forward to a need project but I think yall just saved me a lot of money. I still get to play a little getting it all cleaned up and back to 100%. Now I just need to track down the 6 digit serial number to find out how old it is.
 

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