Hello community.
Apologies from the off if my descriptions and or nomenclature is a little off as I am new to this.
I bought a pair of Seas L22 RNX/P 8ohm woofers. They came from a seller on eBay whom had used for testing purposes. They were a steal.
The seller seems very knowledgeable and tells me he has spent 25 years designing speakers.
I asked his advice on best application for these and the answer was to use these in a 3 way that he has experience with. Whether actual or simulated I don't know.
The advice I recieved was...
Suggested ideal midrange driver - SEAS 120mm model MCA 12 RC
Suggested ideal tweeter - Scan - Speak 19mm fabric dome model D2010 / 851100 ( available from Falcon Acoustics for example )
Enclosure 30litres
Floor standing cabinet the most practical , but the woofer AND the midrange drivers should be angled back 30 degrees from the vertical . with the design placing the midrange driver at the same height as your ears at your typical seated listening position.
The tweeter should be on a perpendicular panel , "pointing" parallel with your room floor.
The drivers should be mounted with the chassis as close as practical to each other ,( i.e. minimum gaps ), in a vertical array.
Crossover approximate guide values ; ( All 1st order / 6db per octave )
Woofer - run direct. If you really feel the need to tame the upper break - up then use the lowest - loss ferrite core inductor you can find of around 1 mH value.
Midrange - trial @ 7uF capacitor value. Fine - tune with values of 1uF either side of this value.
Tweeter - Trial @ 2.5uF. Fine tune with increments of around 0.2 uF each stage.
Use the best quality polypropylene capacitors you can afford . ( generally rated @ 100v or greater for this application ).
No , no resistors . The worst thing you can do to the music signal from an amplifier is corrupt it by passing it through a resistor ; and the next worst thing you can do is to make it pass through an inductor !
So the above are extracts from email correspondence.
I have no reason to doubt any of this as it is beyond my knowledge anyway, but having been on this forum for a few months now I haven't come across many multiway designs that don't have a 'proper' XO. Unlike this advice that is suggesting simple filtering...if that's the right word.
I don't expect anyone to model all of this, I was just after more opinions. I shall not be commencing building these any time too soon as I only have the Seas 8" and the other drivers are a decent investment for me. I may even not go ahead and use the 8" for another project. Maybe a WAW.
Thanks all
James
Apologies from the off if my descriptions and or nomenclature is a little off as I am new to this.
I bought a pair of Seas L22 RNX/P 8ohm woofers. They came from a seller on eBay whom had used for testing purposes. They were a steal.
The seller seems very knowledgeable and tells me he has spent 25 years designing speakers.
I asked his advice on best application for these and the answer was to use these in a 3 way that he has experience with. Whether actual or simulated I don't know.
The advice I recieved was...
Suggested ideal midrange driver - SEAS 120mm model MCA 12 RC
Suggested ideal tweeter - Scan - Speak 19mm fabric dome model D2010 / 851100 ( available from Falcon Acoustics for example )
Enclosure 30litres
Floor standing cabinet the most practical , but the woofer AND the midrange drivers should be angled back 30 degrees from the vertical . with the design placing the midrange driver at the same height as your ears at your typical seated listening position.
The tweeter should be on a perpendicular panel , "pointing" parallel with your room floor.
The drivers should be mounted with the chassis as close as practical to each other ,( i.e. minimum gaps ), in a vertical array.
Crossover approximate guide values ; ( All 1st order / 6db per octave )
Woofer - run direct. If you really feel the need to tame the upper break - up then use the lowest - loss ferrite core inductor you can find of around 1 mH value.
Midrange - trial @ 7uF capacitor value. Fine - tune with values of 1uF either side of this value.
Tweeter - Trial @ 2.5uF. Fine tune with increments of around 0.2 uF each stage.
Use the best quality polypropylene capacitors you can afford . ( generally rated @ 100v or greater for this application ).
No , no resistors . The worst thing you can do to the music signal from an amplifier is corrupt it by passing it through a resistor ; and the next worst thing you can do is to make it pass through an inductor !
So the above are extracts from email correspondence.
I have no reason to doubt any of this as it is beyond my knowledge anyway, but having been on this forum for a few months now I haven't come across many multiway designs that don't have a 'proper' XO. Unlike this advice that is suggesting simple filtering...if that's the right word.
I don't expect anyone to model all of this, I was just after more opinions. I shall not be commencing building these any time too soon as I only have the Seas 8" and the other drivers are a decent investment for me. I may even not go ahead and use the 8" for another project. Maybe a WAW.
Thanks all
James
Yeah, no...
Long story short, they're a bit clueless.
So he used this 10" metal-coned driver with very little filtering, and then sold it. That says it all, I think. Drivers like that need a notch filter aimed directly at the breakup peak so that it can be suitably attenuated. The peak was around 4kHz - expect a very "zingy" sound that quickly goes from "interesting" to "turn it off immediately". Instead of a notch filter, a crossover in the 300Hz region would probably get the resonance down far enough so that it's not excited. I'd probably still put the notch in place, though.
Next up, he's suggesting a highpass filter on a 5" midrange driver at just under 3kHz, which is really where the tweeter ought to come in.
If he got rid of the driver(s), he obviously wasn't pleased with them, and I can see why!
Resistors aren't evil. In fact, they're about the least evil thing you can do to an audio signal - all they do is attenuate. No phase shift, no weirdness. I guarantee that any audio signal that's ever been recorded will have gone through many many resistors, and they still seem to come out okay.
Inductors are the least-wonderful of all passive components, but so long as you pick the right one for the task, they're fairly benign.
I must say that I'm quite jealous you managed to get those drivers. I've been looking to do a final/reference HiFi build for a while, and an all-metal 3-way is one of the contenders.
Chris
Long story short, they're a bit clueless.
So he used this 10" metal-coned driver with very little filtering, and then sold it. That says it all, I think. Drivers like that need a notch filter aimed directly at the breakup peak so that it can be suitably attenuated. The peak was around 4kHz - expect a very "zingy" sound that quickly goes from "interesting" to "turn it off immediately". Instead of a notch filter, a crossover in the 300Hz region would probably get the resonance down far enough so that it's not excited. I'd probably still put the notch in place, though.
Next up, he's suggesting a highpass filter on a 5" midrange driver at just under 3kHz, which is really where the tweeter ought to come in.
If he got rid of the driver(s), he obviously wasn't pleased with them, and I can see why!
Resistors aren't evil. In fact, they're about the least evil thing you can do to an audio signal - all they do is attenuate. No phase shift, no weirdness. I guarantee that any audio signal that's ever been recorded will have gone through many many resistors, and they still seem to come out okay.
Inductors are the least-wonderful of all passive components, but so long as you pick the right one for the task, they're fairly benign.
I must say that I'm quite jealous you managed to get those drivers. I've been looking to do a final/reference HiFi build for a while, and an all-metal 3-way is one of the contenders.
Chris
Thank you all for your prompt and insightful replies.
Interesting indeed!
I did ask him all this after the purchase, so his words weren't there to persuade me into buying . I am pleased I bought them as they are lovely things to behold but perhaps beyond my present skill level to implement properly. Seas website doesn't have any plans for this driver.
Interesting indeed!
I did ask him all this after the purchase, so his words weren't there to persuade me into buying . I am pleased I bought them as they are lovely things to behold but perhaps beyond my present skill level to implement properly. Seas website doesn't have any plans for this driver.
It's an excellent driver, but the advice you got from the seller was -how can I put this charitably?- not of the same order.
Running the L22 filterless is not a very bright idea, unless you happen to enjoy listening to the 20dB bell mode at ~4KHz & those above, along with the savage HD and IMD that result. Most people don't; this driver was optimised for use up to about 1.5KHz. You might get away with about 1.8KHz if your low-pass is steep enough and you stamp on the primary breakup sufficiently. A 1mH inductor, to chronically understate the case, is not sufficient.
1st order electrical high pass on mid & tweeter without consideration for impedance, frequency or polar response? Not a great idea. No low-pass on the mid without consideration for frequency & polar response? Same. No consideration for level matching? Same again, and the comment about resistors is absolutely bizzare, since they are in fact the most linear and least intrusive of all passive components. The worst thing you can pass a 'music signal' through? Not even remotely close. Putting it through a set of speakers created using the advice the seller gave you would be rather more damaging though.
Running the L22 filterless is not a very bright idea, unless you happen to enjoy listening to the 20dB bell mode at ~4KHz & those above, along with the savage HD and IMD that result. Most people don't; this driver was optimised for use up to about 1.5KHz. You might get away with about 1.8KHz if your low-pass is steep enough and you stamp on the primary breakup sufficiently. A 1mH inductor, to chronically understate the case, is not sufficient.
1st order electrical high pass on mid & tweeter without consideration for impedance, frequency or polar response? Not a great idea. No low-pass on the mid without consideration for frequency & polar response? Same. No consideration for level matching? Same again, and the comment about resistors is absolutely bizzare, since they are in fact the most linear and least intrusive of all passive components. The worst thing you can pass a 'music signal' through? Not even remotely close. Putting it through a set of speakers created using the advice the seller gave you would be rather more damaging though.
Quite. As noted, it's an excellent driver, you just have to use it properly. Incidentally, you'll be looking for a very long time if you want a woofer that you don't have to run with a crossover. While some can (as in 'can') be easier to use than others, it isn't as simple as all that if you want good results.
I wouldn't sell them. They look alright as basses in a three way:
H1252-08 L22RNX/P
Very similar to these Excel units:
E0022-08S W22EX001
Loads of designs for those:
DIY-Loudspeakers
Seems that second order bass is doable, a mere 4.7mH and 47uF:
PMS-EXCEL
Three ways are all the same:
I see nothing difficult about adapting any of the W22EX001 designs. Nothing difficult in adapting the 3 way classic for a quieter woofer either: SEAS-3-Way-Classic
H1252-08 L22RNX/P
Very similar to these Excel units:
E0022-08S W22EX001
Loads of designs for those:
DIY-Loudspeakers
Seems that second order bass is doable, a mere 4.7mH and 47uF:
PMS-EXCEL
Three ways are all the same:
I see nothing difficult about adapting any of the W22EX001 designs. Nothing difficult in adapting the 3 way classic for a quieter woofer either: SEAS-3-Way-Classic
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As I understand a WAW (Woofer-assisted Wideband) setup is a full range driver taking duty from (for example) 400Hz up and a woofer filling in the bottom end.
You will probably need some crossover of sorts - to make sure the full range and woofer match their intended targets, and to protect the full range from overexcursion.
From what I can tell - no difference to a 2 way except crossover point and an emphasis on choosing a full range driver so a tweeter is not required as per typical 3 way.
You will probably need some crossover of sorts - to make sure the full range and woofer match their intended targets, and to protect the full range from overexcursion.
From what I can tell - no difference to a 2 way except crossover point and an emphasis on choosing a full range driver so a tweeter is not required as per typical 3 way.
One is a subset of the other.
WAW (Woofer Assisted Wideband, for anyone wondering) is a full-range driver crossed to a woofer. This means you can move the crossover down away from the critical hearing range (1-5kHz). It's still a 2-way system, but it's not what I'd call a conventional 2-way, which would be a midbass driver and tweeter, with a crossover in the 1-5kHz range.
So,
2-way systems can be divided (by my arbitrary definitions) according to crossover frequency like this:
<1kHz - WAW
1-6kHz - conventional 2-way
>6kHz - Full-range driver with a supertweeter
We could probably argue all day about the exact frequencies, but those numbers will do well as a guide.
A WAW has a few advantages, which I'll go through below:
- Crossover is in a range where our hearing isn't particularly sensitive
- Drivers are basically time-aligned since the wavelengths are long
- You're well away from cone break-up etc
- You've got most of the full-range midrange magic, but with useful low-frequency capabilities
- Some full-range drivers extend well into the treble, too.
For now, I'd try to find some decent 3" full-range drivers to get started with. Something I'd like to see done is the Nola Brio Trio mid-high range, but a WAW format. Might be fun. Lots of info here: Need help building open baffle/bass reflex hybrid
There's a lot out there to discover.
Chris
That is again Chris...and Dave B
I have actually cut my teeth with a quick and dirty 3" full range. They sound great but obviously have their limitations.
Ikea Variara full range with Faital Pro 3fe22
I have actually cut my teeth with a quick and dirty 3" full range. They sound great but obviously have their limitations.
Ikea Variara full range with Faital Pro 3fe22
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For a ~ 4KHz breakup, I'm using a 25uF and 0.05mH notch. The L22 is very similar to L26 in breakup pattern / primary node so you could try either and see which one is more effective.
I don't know the sensitivity of the full range you are planning. you will want to aim for a net 85dB with the L22 for a flat on-axis response.
I have WAF to consider aswell as WAW!
But yes sounds like a plan.
The 3fe22 are pretty sensitive. 91 or 92db iirc. Does that mean I need to attenuate these to the 85db mentioned if I intend to keep using these as the full range?
Maybe the Seas warrants a higher calibre driver pairing than the Faital. Albeit I am very impressed with them for the money and my simple implementation.
I'm guessing a WAW has to be all on axis.....so no placing the Seas boxes as one would a pair of subs.?!
But yes sounds like a plan.
The 3fe22 are pretty sensitive. 91 or 92db iirc. Does that mean I need to attenuate these to the 85db mentioned if I intend to keep using these as the full range?
Maybe the Seas warrants a higher calibre driver pairing than the Faital. Albeit I am very impressed with them for the money and my simple implementation.
I'm guessing a WAW has to be all on axis.....so no placing the Seas boxes as one would a pair of subs.?!
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You really want the drivers to be within 1/4wavelength at the crossover frequency. Larger seperations can work, but there are compromises.
You could use the Seas drivers as subwoofers, but they can do more. Full-range drivers do best when they're not flapping around trying to reproduce low frequencies.
A useful trick is to aim to cross over at or near the baffle step frequency, so that if you want more or less BSC, all you need to do is change the level of the full-range unit.
Chris
You could use the Seas drivers as subwoofers, but they can do more. Full-range drivers do best when they're not flapping around trying to reproduce low frequencies.
A useful trick is to aim to cross over at or near the baffle step frequency, so that if you want more or less BSC, all you need to do is change the level of the full-range unit.
Chris
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