Catalogue values for the woofer are Re 6.9 Fs 39/40 Qms 6.623Qes0.506 Vas 32.8
SD 214cm<2
Stated SPL is 90dB but I know that is taken at the peak in response at the top end, where-as the domes 89dB is reasonable
I'm wondering if the lack of bass is simply baffle step and adding a second woofer rear facing would be the easiest way to get around the perceived lack of grunt down low, and this assumes room placement is already optimal
I have an old Jaycar catalogue open here and where the PDF shows a 22uF cap the catalogue recommends 33uF
First tho I would correct the coil orientation and phase
SD 214cm<2
Stated SPL is 90dB but I know that is taken at the peak in response at the top end, where-as the domes 89dB is reasonable
I'm wondering if the lack of bass is simply baffle step and adding a second woofer rear facing would be the easiest way to get around the perceived lack of grunt down low, and this assumes room placement is already optimal
I have an old Jaycar catalogue open here and where the PDF shows a 22uF cap the catalogue recommends 33uF
First tho I would correct the coil orientation and phase
Not sure what Jaycar cat you have but the figures you quote for the woofer are not what is in my 1999 cat for the CW-2137 page 43.
QMS 7.632
Qes 0.364
Vas 98Lt
I can't see Fs or SD in my specs.
I've tried running the woofer from the x-over with nothing else connected and it's not as easy as it sounds . But the punch is definitely missing.
I'm still working on it.
Not sure if I want to start changing the actual physical layout of the PCB. I think the first thing I'm going to try is to raise the roll off to the woofer. My calcs say it is too low.
Talbit
QMS 7.632
Qes 0.364
Vas 98Lt
I can't see Fs or SD in my specs.
I've tried running the woofer from the x-over with nothing else connected and it's not as easy as it sounds . But the punch is definitely missing.
I'm still working on it.
Not sure if I want to start changing the actual physical layout of the PCB. I think the first thing I'm going to try is to raise the roll off to the woofer. My calcs say it is too low.
Talbit
Sorry Talbit I gave the specs for the better woofer CW 2136. The cheaper woofer is a different driver entirely and to get deep bass needs more than one woofer and a huge box. I happen to have a quad of these spare too, I was saving them for a midbass in an OB speaker but the new house is too small for OB
BTW you have your email filter ON
BTW you have your email filter ON
The simplest thing you can do to check phasing is to place the two speakers face to face, about 50mm apart, and drive both with a mono signal.
1. Take a listen
2. Swap the polarity of connection to one speaker
One of these will produce lots of bass, the other virtually none.
If the drivers/ crossover is wired correctly, you will get strong bass on the "in phase" configuration.
If that shows things are set up ok, then you cAn probably set aside box alignment and gross wiring.
From there onwards things get progressively more complex, and you really need a measurement setup.
Things to consider are:
- Crossover design
- wrong drivers
- crap drivers
I am far from a Jaycar fanboy, but I do credit them with more ability than selling complete rubbish.
Interested to hear the result of the "simple and idiot proof" phase test first though.
1. Take a listen
2. Swap the polarity of connection to one speaker
One of these will produce lots of bass, the other virtually none.
If the drivers/ crossover is wired correctly, you will get strong bass on the "in phase" configuration.
If that shows things are set up ok, then you cAn probably set aside box alignment and gross wiring.
From there onwards things get progressively more complex, and you really need a measurement setup.
Things to consider are:
- Crossover design
- wrong drivers
- crap drivers
I am far from a Jaycar fanboy, but I do credit them with more ability than selling complete rubbish.
Interested to hear the result of the "simple and idiot proof" phase test first though.
Thanks Googlyone,
I'm only testing with one speaker at the moment so the phasing between the two speakers is irrelevant. I'm still working on it but checking this forum as I go just in case someone comes on who has a pair.
I'm starting to think that maybe it is the woofer that isn't responsive enough and that I might have to pad down the mid and tweeter and then wind up the wick on the amp or get a better woofer. That would explain why the Loudness switch makes such a big difference. But will a new woofer solve my problem?
I just reconnected my Paradigms again. Now that's the way it's meant to sound!
My benchmark is the Skywalker Symphony Orchestra "Star Wars" CD I have. Track 7 "The Asteroid Field" has a large bass drum. Beautiful on the Paradigms but just average on the JC-50. If I can get the JC-50 to sound the bass drum the way it should then I'll be happy. Yes I know it'll never sound the same but at least I know what I'm aiming for.
This speaker design game is very difficult. There is only one way to reproduce the sound of a Buffett S1 clarinet and that is by playing a Buffett S1 clarinet live! And then a different player will sound different and that's because of the shape of his skull and even how many fillings he has. Seriously!
Talbit
I'm only testing with one speaker at the moment so the phasing between the two speakers is irrelevant. I'm still working on it but checking this forum as I go just in case someone comes on who has a pair.
I'm starting to think that maybe it is the woofer that isn't responsive enough and that I might have to pad down the mid and tweeter and then wind up the wick on the amp or get a better woofer. That would explain why the Loudness switch makes such a big difference. But will a new woofer solve my problem?
I just reconnected my Paradigms again. Now that's the way it's meant to sound!
My benchmark is the Skywalker Symphony Orchestra "Star Wars" CD I have. Track 7 "The Asteroid Field" has a large bass drum. Beautiful on the Paradigms but just average on the JC-50. If I can get the JC-50 to sound the bass drum the way it should then I'll be happy. Yes I know it'll never sound the same but at least I know what I'm aiming for.
This speaker design game is very difficult. There is only one way to reproduce the sound of a Buffett S1 clarinet and that is by playing a Buffett S1 clarinet live! And then a different player will sound different and that's because of the shape of his skull and even how many fillings he has. Seriously!
Talbit
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No that would be unfair!
More like doing an A/B test between the JC-50 pair and the Paradigm pair. Just as a quick comparison.
I recalculated a crossover of 700Hz and looked on the Jaycar site for the crossover coils and it looks like they are not going to stock them any more. Might have to wind my own.
I recon the designer has come up with the L & C values by experimentation. It must have taken a lot of work.
The way I understand it, the woofer L.P. L/C values should be the same as the Mid high pass L/C values. But it's probably not as simple as that. By my calcs, there is a gap of about 780 Hz between the woofer and the mid in the original design. It certainly sounds like it to my ear even though they published a fairly flat response curve for the whole speaker.
My wife asks Why are you bothering and my reply is Because I won't be beaten!
Talbit
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Talbit, the inductor and capacitor values are based/calculated on the drivers impedence at the specific crossover frequency points these values can be a lot higher than the nominal values. eg an 8ohm woofer may have an impedence of 15ohms at 700hz. you need to measure the impedence at the crossover points and use these values for calculating the inductors and capacitors. cheers Greg
The problem with those Jaycar drivers is that published data are unreliable and nobody measures the actual TS-parameters. Nevertheless I do attach a simulation of the Jaycar JC-50 speaker (microphone distance 3 m). I assumed the woofer (Jaycar CW-2137) to be identical to the MCM55-1215 and the midrange (Jaycar CM-2092) to the Dayton DC50F-8. Cabinet and port dimensions are estimated. The crossover certainly is not completely wrong, but the midrange seems to be too loud by some dBs. I recommend to try a 2.2 ohm resistor in front of the midrange filter.
Attachments
Thanks Henry and Dizzi and to everyone who has contributed - How did we ever survive without the Internet?I recommend to try a 2.2 ohm resistor in front of the midrange filter.
I'll work through your ideas. Yes I'm aware that it's not just a simple matter or plugging in the published figures. I am also aware that the drivers and the cabinet overall requires airtight sealing and I've adhered to that requirement but still no luck.
Dizzi, Thanks for the simulations. Nice work! But the published plot of the whole unit also looked very good. And simulations are not the same as my "Golden Ears". That's what makes me think that the original design is different to what I actually have on my lounge room floor.
I'm not sure where you suggest the 2.2R should go. Across the actual driver? Placing it "in front of the midrange filter" would appear to suggest at the input to the whole setup. I see the D19 has a voltage divider across it. Is this what you are suggesting?
Someone earlier suggested getting the woofer right first then work on the mid and tweeter later. It's the woofer I'm having trouble with.
Regards
Talbit
I'll disagree with Dissi here about padding down the midrange. I personally hate to throw away midrange SPL as heat
Try something else first
Simply disconnect the woofers and listen for a while to see how the midrange on its own performs for you. If the upper midrange is OK then it's a woofer problem
Personally I think the designer got it slightly wrong, I don't think it needs the resonance peak filter when crossing that dome that high as it exhibits a near perfect second order closed box roll-off at ~350Hz
Try something else first
Simply disconnect the woofers and listen for a while to see how the midrange on its own performs for you. If the upper midrange is OK then it's a woofer problem
Personally I think the designer got it slightly wrong, I don't think it needs the resonance peak filter when crossing that dome that high as it exhibits a near perfect second order closed box roll-off at ~350Hz
As I said in an earlier post I think the lack of percieved bass is a baffle step problem
True Audio TechTopics: Diffraction Loss
Baffle Step Compensation
This would sound as if you needed an extra amplifier to drive the bass, a 6dB loss is substantial
The best fix in my opinion is an extra woofer or a separate subwoofer
Doing the arithmetic will let you know at what frequency the -3dB point is
The easiest [ and IMO the best] solution is a powered subwoofer of sufficient power and SPL capability to match the tops
Bass is all that below 80Hz so the tens would then be classified as mid-bass.
Or just build a new cabinet reusing the drivers and XO plus a Baffle step woofer rear facing using a simple first order coil in series at the -3dB point
True Audio TechTopics: Diffraction Loss
Baffle Step Compensation
This would sound as if you needed an extra amplifier to drive the bass, a 6dB loss is substantial
The best fix in my opinion is an extra woofer or a separate subwoofer
Doing the arithmetic will let you know at what frequency the -3dB point is
The easiest [ and IMO the best] solution is a powered subwoofer of sufficient power and SPL capability to match the tops
Bass is all that below 80Hz so the tens would then be classified as mid-bass.
Or just build a new cabinet reusing the drivers and XO plus a Baffle step woofer rear facing using a simple first order coil in series at the -3dB point
I do have the original Magazine article from the 90's at home. I'll have to read up on it.
I remember seeing them at Jaycar, but apparently they didn't sell very well as the Vifa JV-60's came out at the same time and out performed them in every way. (including bass response)
I have used these particular 10" woofers in a system and as Dissi says, they do vary from batch to batch, (like most Jaycar drivers) so that would possibly explain part of the problem.
IMO they are not particularly bass heavy woofers, but I've also heard far worse.
What you do with them to fix them will depend on your budget and knowledge but if it were me, I'd connect up a new crossover from scratch (outside the enclosure) with the same values and then start tweaking them from there, with your other speakers as the reference.
I remember seeing them at Jaycar, but apparently they didn't sell very well as the Vifa JV-60's came out at the same time and out performed them in every way. (including bass response)
I have used these particular 10" woofers in a system and as Dissi says, they do vary from batch to batch, (like most Jaycar drivers) so that would possibly explain part of the problem.
IMO they are not particularly bass heavy woofers, but I've also heard far worse.
What you do with them to fix them will depend on your budget and knowledge but if it were me, I'd connect up a new crossover from scratch (outside the enclosure) with the same values and then start tweaking them from there, with your other speakers as the reference.
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