Powered woofers and filters

[abboudc]

I have a pair of rocket Rs 1000s with 8" powered woofers. The woofers are powered via a subwoofer plate amp and one of them has died.

I'm having metal plates made to cover the amp hole, and planned on powering the woofer with an external amp. So far so good.

Questions:
The woofer was fed via a line level jumper from the speakers main terminals. How to feed a sub amp with only RCA ins?

I plan on doing the same to the non dead one as any amp from av123 is a time bomb. Short of two plate amps with low pass filters, what would you do? I was looking at the Dayton sa1000. Also looking at decent powered stereo amps, but not sure how I'd be able to do a low pass filter before it hits the amp?

Thanks for any suggestions.

 

[j_garcia]

Emotiva is also supposed to be releasing a component sub amp, I might wait for that. The SA1000 will likely work too though. The problem with using an amp other than the original, is that amp was likely tailored to that driver to some extent (x-over, limiting or boost, power, etc...). That doesn't mean another amp won't work, but it may not work perfectly no matter how good it is.

To feed the amp, just use the main preamp outs (not the LFE) from the receiver and set them to large.

 

[TLS Guy]

I have a pair of rocket Rs 1000s with 8" powered woofers. The woofers are powered via a subwoofer plate amp and one of them has died.

I'm having metal plates made to cover the amp hole, and planned on powering the woofer with an external amp. So far so good.

Questions:
The woofer was fed via a line level jumper from the speakers main terminals. How to feed a sub amp with only RCA ins?

I plan on doing the same to the non dead one as any amp from av123 is a time bomb. Short of two plate amps with low pass filters, what would you do? I was looking at the Dayton sa1000. Also looking at decent powered stereo amps, but not sure how I'd be able to do a low pass filter before it hits the amp?

Thanks for any suggestions.

Your plan is not going to work.

Those are woofers and not subs. An electronic crossover needs to be designed to replicate the one in the original plate amps.

If the handbook tells you the crossover frequency, order and Type (LR, Butterworth etc, then I can likely help you, by designing and building the correct aciveh low pass filter for you. You would need two.

If the information is not available, then you need to send me the working amp before it fails, so I can measure it and replicate the response.

If there is no technical specification available and the other one fails before being measured, then you will be SOL.

 

[abboudc]

There is no crossover on the woofer. It's a completely separate box. The amp controlled the crossover. It's basically a standalone sub.

I'd have to split the pre out as it still needs to go to the amp powering the rest of the tower...

 

[j_garcia]

I don't think it is a "stand alone" sub, it is like TLS said, but the x-over was factored into the amp OR it was filtered by the passive x-over before amplification. Do you have a pic of the "jumper" you mentioned from the top portion to the amp? If it was passively filtered, then you either have to do what was mentioned (recreate the filter) or figure out a way to go from speaker level to line level to feed the new amp. If the filter was built into the amp, then you need to replicate what it was doing.

 

[walter duque]

Does the rear of your speakers look anything like mine. They can be powered with the jumper wire to the sub or directly from sub output. Tops are not powered. I would sell what you have and get some good speakers and a seperate sub. IMO powered speakers are not that great and mine are not on the cheap side.

 

[TLS Guy]

There is no crossover on the woofer. It's a completely separate box. The amp controlled the crossover. It's basically a standalone sub.

I'd have to split the pre out as it still needs to go to the amp powering the rest of the tower...

I think that is very unlikely. It only makes sense to use a separate amp for the woofer if there is an active crossover ahead of the amp, likely in the same case as the amp.

When I get a chance I will see what information is still available on those speakers.

 

[abboudc]

Thanks all.

TLS, could you tell me the difference between a low pass filter and active crossover? The plate amp had 3 knobs, one for phase, one for gain and one for frequency (I thought this was the low pass?)

Walter, my speakers look like yours. There are a pair of binding posts on top, and what appears to be a subwoofer plate amp on bottom. There's a jumper wire with banana plugs that goes between them.

I was told that the top without the bottom is the same as a rocket 850 by Sean Parque, who built crossover network upgrades for this model. The chamber below is sealed with the 8" woofer on the side. I was thinking of swapping it out with a Dayton 8" sub driver...but still wasn't sure what to do about the low pass...

I have 2 SVS subs now (1 tv12 ultra and a pc16-46+).
I'll try and post some pics. They didn't come with a manual (I don't think anything from av123 did!)

The same amp (gsw-300) was also used on the strata mini. I disassembled/destroyed the broken one today to get the plate to the metal shop, there's a large transformer, amp board, and controller/input board. It looked to me like a generic sub amp, especially since it has regular RCA ins, which this type of config has no need for?

The frequency knob goes from 30hz to 150 Hz

 

[j_garcia]

So that means there was no crossover for that thing IMO. It sounds like they were just using the controls of the generic amp. If that is the case, I'd just disconnect them and leave them like that. A buddy of mine has 850s and I felt they sounded pretty good. Especially since you already have two good subs, I don't see a real benefit in having those 8" drivers complicating matters with the existing subs unless you are trying to use them for music full range with no subs.

 

[STRONGBADF1]

Get in touch with Sean (the owner) at The Skiing Ninja. He worked at AV123 and then went out on his own. He might have the inside info or parts you need. Skiing Ninja

Manual

 

[abboudc]

Get in touch with Sean (the owner) at The Skiing Ninja. He worked at AV123 and then went out on his own. He might have the inside info or parts you need. Skiing Ninja

Manual

I tried that already. Sean told me he does have any more amps, but pointed me to two other guys that might. Neither did. He said something like "all is not lost, you basically have rocket 850s now".

 

[walter duque]

These Madisound Speaker Store are the amps used in my towers. They can be used from the jumpers or from your sub out. You do need power to your tops from your amp. Keiga are good amps, mine have been abused for the last 15 years and still going strong. They are driving dual 8" subs.

 

[TLS Guy]

Thanks all.

TLS, could you tell me the difference between a low pass filter and active crossover? The plate amp had 3 knobs, one for phase, one for gain and one for frequency (I thought this was the low pass?)

Walter, my speakers look like yours. There are a pair of binding posts on top, and what appears to be a subwoofer plate amp on bottom. There's a jumper wire with banana plugs that goes between them.

I was told that the top without the bottom is the same as a rocket 850 by Sean Parque, who built crossover network upgrades for this model. The chamber below is sealed with the 8" woofer on the side. I was thinking of swapping it out with a Dayton 8" sub driver...but still wasn't sure what to do about the low pass...

I have 2 SVS subs now (1 tv12 ultra and a pc16-46+).
I'll try and post some pics. They didn't come with a manual (I don't think anything from av123 did!)

The same amp (gsw-300) was also used on the strata mini. I disassembled/destroyed the broken one today to get the plate to the metal shop, there's a large transformer, amp board, and controller/input board. It looked to me like a generic sub amp, especially since it has regular RCA ins, which this type of config has no need for?

The frequency knob goes from 30hz to 150 Hz

A low pass filter is half of a two way crossover, or the bottom third of a three way, it can be active or passive.

So the amp does have a variable low pass filter. It seems to be a generic sub plate amp. That is a pretty crude design.

I agree I would forget about using the lower half of those speakers with the 8" driver and just use the top half and your subs.