27 year old sub incorporated with rears? 1 amp 2 subs?


Novice Member
Hello guys,

Unique situation that i think boils down to 2 or 3 questions and also what I have available to me.
1st is can I transform a sub box into a rear/sub wall mount. Explanation will follow :)
2nd is can I run 2 subs of one amp and if so really need some advice here. Again more to follow.

Ok so ill try and break down what I'm trying to do and why and hopefully you guys will get the drift and at the same time realise that i am a newbie here lol

Currently I have a pair of Diamond 220's front, 10CM Centre, Kef 100w 8"sub, Some old Aiwa random rears running off a Pioneer LX73 with plans to update the rears to diamonds and upgrade the sub.
The reason I'm wondering about subs in rears is that i have 2 8" boxes that are very uniquely shaped , originally intended to be wall mounted and I also just recently found a 27 year old 400w Bumper series pro sub speaker that I've have had laying around since 1993 lol.

I was shocked to find that this speaker that's been in my attic going on a decade and full of rust and all sorts still actually worked :?
My next step was to cut and route to increase the 8" to a 10" hole in one of these weird shaped boxes and mount it. I then disassembled my kef and run the sub off of the kef amp using the knobs to adjust. I did not mount the amp just Frankensteined it for testing and what can i say, 2" makes a difference and the extra wattage is appreciated :) Bearing in mind originally this speaker was open ported, passive with i think a high pass filter that i used to plug straight into and amp and now its mounted in a sealed enclosure and I'm in love with the tone.

So while shopping around i was considering 2 more 220's for the rear and seeing as they dropped to £99 at richersounds I'm seriously considering grabbing some.
I also noticed the 9.0 at £49 a pair and my mind started wondering what would be the pros and cons of buying either of the above solely for the purposes of removing and mounting the speakers into my current boxes? I would have space to mount 2 x 220s or 4 x 9.0 for the same price :/

Increased floor space
Could not have 2x subs on floor, only if wall mountable
If possible then all wires can run outside property easily (we have a bunny and have to hide all wires anyway )
Can use existing boxes (cost effective, love look, sub already sounds good (not sure once rears incorporated)
Price of the Wharfedale's right now

Reducing box area could effect sub sound
Need to consider amp cost
not sure if i can match sub driver (or if i got close enough if it would even make a difference running off of same amp.
Boxes are large , but again do gain floor space, so...

To kind of round up this essay..
I need to know what to consider when incorporating my mid rears into a custom sub box i intend to wall mount? I imagine that i would have to make sure the sub is internally sealed off from the mounted diamonds drivers as to avoid the air pressure from the sub adversely effective the driver of the diamonds?

Am i going to be able to match a sub driver to this old speaker? If this just a question of matching watts/ohms and then good brand?

How do i choose the amp that will power 2 x 400w woofers? This little 100w kef amp is doing a really good job here but doubt it will deal with a pair, or would it? My only requirements would be volume and crossover in terms of functions as I'm used to what i have.

Will leave it there for now as its all i can currently think of including and my wording sucks when I try to explain things! Hopefully I've shared enough to get this idea going, thanks


Distinguished Member
If you are trying to use "old" speaker(s), ....you'll need to know more tech... but I fancy over time speaker suspension will fail and once you put power in, then the faults will show.... If yr time is valuable, prob better to buy something new and hope it satisfies.
I didn't read the room size - so why do you need two Subs? / Woofers tend to be from 80-Hz up, whereas Subs are below this, typically 2-octaves and do need quite a lot of amplifier-power, as LF generation is inefficient. In addition you need a v.steep cutoff filter to prevent the sub amp responding to those 80Hz signals . . . an area that is largely non-fulfilled IMHO - even if you are Electronics DIYer... there is little "practical" advice about... Peerless suggested 24dB/octave which is mighty difficult... yet do not suggest any \"starting-point". Indeed my 10" Peerless is still unused as I can't find a suitable filter . . . all the other things are much easier, but not until I can achieve the 24dB/octave... and be able to measure it.
Have you tried BK Electronics? They make a series of 8" subs which are ready-to-go ( includes Amp+Filter )... about £500, I guess . . . . quite suitable for most "domestic" rooms.
Hope that helps, - H.

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