Passive subs
I want to know if this is possible.
Start out with stereo 2-way speakers with passive xovers.
For power a single stereo power amp.
Now we want to add a single 12” sub.
This sub must get its power from that same power amp.
No self powered sub or dual voice coil woofer.
No adding another woofer.
Thanks
I want to know if this is possible.
Start out with stereo 2-way speakers with passive xovers.
For power a single stereo power amp.
Now we want to add a single 12” sub.
This sub must get its power from that same power amp.
No self powered sub or dual voice coil woofer.
No adding another woofer.
Thanks
depends on whether your amp can handle the load, I've seen such a connection suggested many years ago - an inductor from each side of the stereo amp to the single woofer.
I'm guessing that BTL amps need not apply, & if any strange earth loops occur, you may see the magic smoke escaping...
I'm guessing that BTL amps need not apply, & if any strange earth loops occur, you may see the magic smoke escaping...
Sure. You can high and low pass the two channels and feed the low pass outputs to a transformer which sums them to mono for a sub-woofer.
As a mental exercise this is fine. But you are probably going to spend more on the tranny than you would on a decent DVC woofer. I guess if you have an old power transformer with dual secondaries laying around it could work. Level matching to the mains becomes the issue at that point.
If this is a "scrounge from the parts bin" type of project, then you are better off going out and finding an old receiver or integrated amp to drive the sub. A $20 special off of Craiglist or your local Goodwill could work.
-bill
I thought a transformer would be suggested.
The center back to the sub?
What kind of transformer and where to find it?
Thanks
I've had passive subs for many years and they work fine. Used them with a few different configurations of gear. I have left and right though. Passive crossovers are about 80hz.
Also, if the amp is capable of bridged operation then the following *may* work:
1) invert one of the input channels.
2) invert the corresponding main speaker hookup for that channel (so that the phase is correct)
3) run the sub in parallel across the two positive outputs from the amp.
Caution should be taken - this is a good way to smoke the amp and maybe your input source.
-bill
1) invert one of the input channels.
2) invert the corresponding main speaker hookup for that channel (so that the phase is correct)
3) run the sub in parallel across the two positive outputs from the amp.
Caution should be taken - this is a good way to smoke the amp and maybe your input source.
-bill
Hi,
It will work if the amplifier channels are 4 ohm capable, the subwoofer
is 8ohms, the speakers 8 ohms or the speakers are 4ohms with a series
capacitor applied to each, but might mess up the bass alignment.
The sub would need a passive filter, big inductor + capacitor.
Or possibly get something like this :
TDA7294 2.1ch amplifier board 80W*2+160W SUB + heatsink | eBay
rgds, sreten.
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I guess it will help if I explain the project.
This project is for retail sale. This is not a one-off for my garage,
We need to keep an eye on cost and price point.
The top speaker is a 1” compression driver and a 5-1/4” woofer.
Coaxial and no horn.
With this top a single 12” woofer for a sub is more than enough.
To use two 12” drivers would be a waste of money.
The customer wants to buy all drivers from a single manufacturer.
The manufacturer does not offer anything smaller than 12” driver for a sub.
It does not offer a dual voice coil driver (My first pick).
For keeping the cost down we are restricting the design to a single stereo power amp. No additional power amp such as a plate amp which again moves the price point up.
We do have an example building a proper Y-Cord for line level.
It is purely resistive, but it would not see more than a couple of volts
Trying to use it for this purpose would turn it into a radiant heater.
It would take some HUGE resistors.
What I expected to hear was using a transformer.
Top and bottom to the power amp outputs and the center tap to the sub driver.
The trouble is I don’t know much about transformers. I would not know which one to use or even if I was correct to use it at all.
I hope this clears things up.
Thanks
I am doing this for a friend. I have already surmised that a transformer capable of handling the juice involved might cost a great deal.
OTOH One of these pro drivers also cost a great deal.
On the subject of inverting the output and looking at 2 ohms, we are not selling the power amp. The customer has to source it elsewhere so there can be no restrictions. I don't see our customers buying the latest Crown or QSC power amp. More likely a Behringer or worse.
In your case, with the restrictions you have in place, my personal opinion would be that you need to have separate left and right subwoofer drivers, 8 ohms if you can. That'll give you the best possible compatibility rate with a wide variety of amplifiers and make it a little easier to design the subwoofer crossover.
Just my opinion.
Just my opinion.
How about something like the JBL SB-5 (Triple Chamber Bandpass). Doesn't need to be isobaric. Two woofers will do.
Hmmm.....
If you need to ask here it seems you are way out of your depth.
Your clueless and so is your customer, not a good combination.
Your requrements are clueless, you are bound to fail.
rgds, sreten.
Any idea what utter nonsense the above is ?
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I love sreten man, he has the bedside manner of a sledgehammer! I wish you lived closer to me, I think we'd have a blast with a case of beer and some old LPs 😉
Party on brother!
sreten;2890656]Hmmm.....
<<<<<<<<<
If you need to ask here it seems you are way out of your depth.
<<<<<<<<<
Well I have been at this long enough to know when I need to ask for information.
I also posted on Pro Sound LAB (Live Audio Board).
Though I spent many more years on the old Bass List, before this place was created I found many people there who had more than a clue.
I expect there are quite a few people here that I could learn from.
<<<<<<<<<
Your clueless and so is your customer, not a good combination.
<<<<<<<<<<
LOL
Opinions vary, but few people have jumped to that conclusion (Lately).
<<<<<<<<<<<<<<<
Your requirements are clueless, you are bound to fail.
<<<<<<<<<<<<<<
My customer has been running a regional sound company and other related sound tasks for decades and has the respect of the live sound community.
We both knew this search might not be successful, but it was worth checking out.
Too Tall
rgds, sreten.
<<<<<<<<<
If you need to ask here it seems you are way out of your depth.
<<<<<<<<<
Well I have been at this long enough to know when I need to ask for information.
I also posted on Pro Sound LAB (Live Audio Board).
Though I spent many more years on the old Bass List, before this place was created I found many people there who had more than a clue.
I expect there are quite a few people here that I could learn from.
<<<<<<<<<
Your clueless and so is your customer, not a good combination.
<<<<<<<<<<
LOL
Opinions vary, but few people have jumped to that conclusion (Lately).
<<<<<<<<<<<<<<<
Your requirements are clueless, you are bound to fail.
<<<<<<<<<<<<<<
My customer has been running a regional sound company and other related sound tasks for decades and has the respect of the live sound community.
We both knew this search might not be successful, but it was worth checking out.
Too Tall
rgds, sreten.
Too Tall,
Forget the transformers for bass, they will cost more than a 12", and be heavier.
While I agree with most of sreten’s points, most bass is still mixed center live or on recordings, a passive sub could be used from one side of a stereo system with no problem for most music, assuming the 5.25” can play well down to around 100 Hz. If it can't, the sub is a woofer anyway.
Since the 12” is presumably of at least the sensitivity of the pair of 5.25” midrange and a proper passive crossover presents a relatively uniform impedance between the bass speaker and midrange speaker, no problem on the side loaded with both.
The side with the top cabinet only may present a tricky load for some amplifiers, though from experience many passively crossed woofers are burnt up in pro use, leaving the mid/high functional and I have not heard of amps blowing up from that scenario.
As far as the HF driver on the coax, is that a 1" diaphragm or exit size?
A one inch exit would indicate a fairly large voice coil for a 5.25", and reduce cone area, both reducing sensitivity, I could see how one decent 12" could kick over the pair of 5.25".
That said, with most live applications wanting 10 dB more LF than mid frequency, matching a pair of 12" subs with a pair of 5.25" makes more sense, and the subs then can be used with pole mounts to put the top boxes on.
Art
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This may not be so.
The 12” driver costs over $300 and in this case the extra weight may not be an issue.
This may be the biggest problem.
If the mids do not reach far enough down then your ears will tell you where the sub box is.
When this happens the usual setup has two subs and they are placed near each top box.
He knows that most of the bass info is mixed down the middle. That said I do not know if he is willing to “cheat” even that little bit.
All the drivers are top shelf pro drivers.
1” throat.
Thanks,
I still hope to find a transformer that will combine the two signals at speaker level. If that is the best way to go.
Best...very subjective. In my opinion, I wouldn't consider it to be the "best" solution.
If you're building, or trying to build a commercially viable speaker, it would be best to build something typical if you're looking for bass response rather than try to build some kind of single subwoofer that uses transformers and wizardry to be compatible with the vast majority of amplifiers.
If you want something marketable, build a pair of 3 ways that go down low enough to be good...or do small 2 ways with a sub for each one.
Remember, the more atypical you build this thing, the harder it's going to be to make a system that's widely acceptable for consumers.
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