Am a complete beginner with DIY audio, with zero experience, so will probably not have supplied enough info here, but it's a start....
I have a VideoLogic Sirocco system here, on which the sub-woofer driver has disintegrated. The foam surround has fallen apart, as seems to be usual with the Audax drivers used in these VideoLogic systems. I had a pair of the mid-range drivers - also Audax - fall apart in exactly the same way several years ago. Fortunately, managed to find some good replacements units on eBay.
The subwoofer driver in question is an Audax AP170M2.
17cm unit. 6.5" paper cone, polymer chassis. 8 ohms. 45W nominal power. Spec sheet attached here.
The woofer cabinet is 39cm x 20.5cm x 34cm external, with wall thickness of 1.5cm, giving an internal volume of 19.5 litres. The cabinet has no padding inside, and a single front-facing port.
The Audax AP170M2 no longer seems to be available, and given the method of its demise I'm not sure I'd replace it with another one even if I could find one! Those foam surrounds look pretty feeble, as they were on the mid-range units.
Wondering whether anyone has any suggestions or recommendations for a suitable alternative please.
Initial searches have revealed many options, of which 2 might be:-
Visaton W 170 S - 8
https://www.soundimports.eu/en/visaton-w-170-s-8.htm
Dayton Audio DA175-8
https://www.soundimports.eu/en/dayton-audio-da175-8.html
Also found a Dynaudio Esotec MW 162, but that's £150, and probably far too good for the cabinet.
(Also have a pair of Dynaudio BM15A active monitors here, and they are wonderful, but they're not used all the time. The VideoLogic system is the everyday setup connected to my PC).
The searching has made me very aware that I have very little idea of what to look for, or how to assess the likely performance of any candidates. And have zero experience of any of them to fall back on. i.e. how do they sound, and how might they compare with the existing but dead Audax?
Have just watched this video, which I found very instructive on how to interpret speaker specs and graphs. Though he did a good job, assuming that he’s right.
How to Pick The BEST Drivers For Your DIY Speaker Project
But am still at a bit of a loss as to how to decide what to actually buy!
Can anyone chime in with any advice or pointers please?
Thank you.
I have a VideoLogic Sirocco system here, on which the sub-woofer driver has disintegrated. The foam surround has fallen apart, as seems to be usual with the Audax drivers used in these VideoLogic systems. I had a pair of the mid-range drivers - also Audax - fall apart in exactly the same way several years ago. Fortunately, managed to find some good replacements units on eBay.
The subwoofer driver in question is an Audax AP170M2.
17cm unit. 6.5" paper cone, polymer chassis. 8 ohms. 45W nominal power. Spec sheet attached here.
The woofer cabinet is 39cm x 20.5cm x 34cm external, with wall thickness of 1.5cm, giving an internal volume of 19.5 litres. The cabinet has no padding inside, and a single front-facing port.
The Audax AP170M2 no longer seems to be available, and given the method of its demise I'm not sure I'd replace it with another one even if I could find one! Those foam surrounds look pretty feeble, as they were on the mid-range units.
Wondering whether anyone has any suggestions or recommendations for a suitable alternative please.
Initial searches have revealed many options, of which 2 might be:-
Visaton W 170 S - 8
https://www.soundimports.eu/en/visaton-w-170-s-8.htm
Dayton Audio DA175-8
https://www.soundimports.eu/en/dayton-audio-da175-8.html
Also found a Dynaudio Esotec MW 162, but that's £150, and probably far too good for the cabinet.
(Also have a pair of Dynaudio BM15A active monitors here, and they are wonderful, but they're not used all the time. The VideoLogic system is the everyday setup connected to my PC).
The searching has made me very aware that I have very little idea of what to look for, or how to assess the likely performance of any candidates. And have zero experience of any of them to fall back on. i.e. how do they sound, and how might they compare with the existing but dead Audax?
Have just watched this video, which I found very instructive on how to interpret speaker specs and graphs. Though he did a good job, assuming that he’s right.
How to Pick The BEST Drivers For Your DIY Speaker Project
But am still at a bit of a loss as to how to decide what to actually buy!
Can anyone chime in with any advice or pointers please?
Thank you.
ap170m0:
Nominal impedance Z: 8 Ohm
Power：45 W
Fs: 59.7 Hz
Sd: 132.73 cm²
Qms: 3.3
Qes: 1.06
Qts: 0.8
Vas: 17.62 litres
Mean Sound Pressure Level: 87.3 dB （1w/1m）
reference efficiency n0 = (9.7822 * 10-10 * Vas * Fs3) / Qes = 0.0035 %
SPL @ 1W/1m = 112.2 + 10 * log(n0) = 87.64
Within reason we want driver specs Fs, Vas, Qes that calc to SPL @ 1W/1m, so 'do the math' to find best substitutes.
Nominal impedance Z: 8 Ohm
Power：45 W
Fs: 59.7 Hz
Sd: 132.73 cm²
Qms: 3.3
Qes: 1.06
Qts: 0.8
Vas: 17.62 litres
Mean Sound Pressure Level: 87.3 dB （1w/1m）
reference efficiency n0 = (9.7822 * 10-10 * Vas * Fs3) / Qes = 0.0035 %
SPL @ 1W/1m = 112.2 + 10 * log(n0) = 87.64
Within reason we want driver specs Fs, Vas, Qes that calc to SPL @ 1W/1m, so 'do the math' to find best substitutes.
Thank you.
Not sure I understand what all those figures mean yet (more reading to do), but looking at the spec sheet of the Dayton Audio DA175-8 (copy attached), most of them seem to be somewhere near to the Audax:-
Nominal impedance Z: 8 Ohm
Power：50 W
Fs: 39.0 Hz
Sd: 132.7 cm²
Qms: 3.31
Qes: 0.7
Qts: 0.58
Vas: 16.3 litres
Mean Sound Pressure Level: 85 dB （1w/1m）
I don't yet know how to do the math though. As above, more reading to do.
But on the face of it, the Dayton DA175-8 looks like a reasonable candidate.
Or have I mis-understood? Probably....
Not sure I understand what all those figures mean yet (more reading to do), but looking at the spec sheet of the Dayton Audio DA175-8 (copy attached), most of them seem to be somewhere near to the Audax:-
Nominal impedance Z: 8 Ohm
Power：50 W
Fs: 39.0 Hz
Sd: 132.7 cm²
Qms: 3.31
Qes: 0.7
Qts: 0.58
Vas: 16.3 litres
Mean Sound Pressure Level: 85 dB （1w/1m）
I don't yet know how to do the math though. As above, more reading to do.
But on the face of it, the Dayton DA175-8 looks like a reasonable candidate.
Or have I mis-understood? Probably....
On re-reading, I think you may have shown me how to do the maths.
reference efficiency n0 = (9.7822 * 10-10 * Vas * Fs3) / Qes = 0.0035 %
I don't understand that "10-10" term though. Isn't that zero?
If I assume that it is (but it surely can't be?) and do that calc using the Dayton figures:-
Dayton reference efficiency n0 = (9.7822 * 10-10 * 16.3 * 39^3) / 0.7 = 0.0000 %
That can't be right. Hmm.
... thinking aloud
Wonder what the Reference Efficiency equation is.....
https://speakerwizard.co.uk/η₀-eta-...ectively-a-speaker-converts-power-into-sound/
Spreadsheet....
Efficiency = 8.4906% Or 849%? Neither of those looks feasible. Or maybe the first one is?
I'm puzzled 🙂
But beginners usually are.
reference efficiency n0 = (9.7822 * 10-10 * Vas * Fs3) / Qes = 0.0035 %
I don't understand that "10-10" term though. Isn't that zero?
If I assume that it is (but it surely can't be?) and do that calc using the Dayton figures:-
Dayton reference efficiency n0 = (9.7822 * 10-10 * 16.3 * 39^3) / 0.7 = 0.0000 %
That can't be right. Hmm.
... thinking aloud
Wonder what the Reference Efficiency equation is.....
https://speakerwizard.co.uk/η₀-eta-...ectively-a-speaker-converts-power-into-sound/
Spreadsheet....
Efficiency = 8.4906% Or 849%? Neither of those looks feasible. Or maybe the first one is?
I'm puzzled 🙂
But beginners usually are.
Correction (or maybe not!) to my earlier reply.
Not sure where I got my calc of the 0% efficiency on my first go at performing your calculation, at least as I understood it.
Had another go, and again ignored the "10-10" term, which I don't understand or interpret anyway.
13.512 million?! That can't be right either!
I give in. Am obviously misunderstanding this completely.
Not sure where I got my calc of the 0% efficiency on my first go at performing your calculation, at least as I understood it.
Had another go, and again ignored the "10-10" term, which I don't understand or interpret anyway.
13.512 million?! That can't be right either!
I give in. Am obviously misunderstanding this completely.
Funnily enough, I hadn't done so until this morning, when friend emailed with that same suggestion, and some links to parts.
4-12" Speaker Surround Rubbers Woofer Edge Audio Repair Protectors
https://www.ebay.co.uk/itm/134758655000?var=434258482308
Speaker Rubber/Foam Glue
https://www.ebay.co.uk/itm/326397047818
Guess I'd assumed that this would be a professional-only job. Had never thought it would be feasible as a DIY. I should have known.
He popped over earlier and took it away, and the old foam has been stripped already. Awaiting delivery of the bits.
If it goes wrong or doesn't really work very well, can always buy a replacement driver of some kind.
Although I'm still not sure about all those calcs (and am interested to continue finding out), was coming to the conclusion that I was probably over-thinking this particular job and should just buy one of those Dayton units. It could hardly sound worse than the existing thing has been sounding for some time...!
Thank you for the thought nonetheless. It was a good one. Int'g video too. Doesn't look anything like as difficult as I'd imagined it must be.
4-12" Speaker Surround Rubbers Woofer Edge Audio Repair Protectors
https://www.ebay.co.uk/itm/134758655000?var=434258482308
Speaker Rubber/Foam Glue
https://www.ebay.co.uk/itm/326397047818
Guess I'd assumed that this would be a professional-only job. Had never thought it would be feasible as a DIY. I should have known.
He popped over earlier and took it away, and the old foam has been stripped already. Awaiting delivery of the bits.
If it goes wrong or doesn't really work very well, can always buy a replacement driver of some kind.
Although I'm still not sure about all those calcs (and am interested to continue finding out), was coming to the conclusion that I was probably over-thinking this particular job and should just buy one of those Dayton units. It could hardly sound worse than the existing thing has been sounding for some time...!
Thank you for the thought nonetheless. It was a good one. Int'g video too. Doesn't look anything like as difficult as I'd imagined it must be.
Yes, I try to provide as much info as I can since there's so many members, lurkers following that do want it, which unfortunately can overload/confuse beginners and nowadays forced to always be in a hurry, so do massive copy pasting and forgot to 'correct' the technically incorrect 10-10 from this website to 10^-10 and Fs3 = Fs^3.
Thanks for taking the trouble to clarify. Can see that it's a complicated subject, and there's the usual web forum quandary:- don't keep repeating stuff because it's tedious for the regulars, but do keep repeating stuff for the newcomers because it's very useful for them.
Just for clarity's sake, The "this website" link is actually this text -
"http://t/S Equations and how each one affects the others", and doesn't work, unfortunately.
Anyway, never mind that! Is "10^-10" saying "ten to the power of minus 10"?
I apologise for persisting with this, but I've started so I have to finish (to mis-quote the "Mastermind" quizmaster). Have tried plugging this "10^-10" term into the spreadsheet calc, and added the "minus power" term as a variable so it can be adjusted to see the results easily. And am still struggling to get a value that looks as though it might be feasible/realistic.
Have I still got this equation wrong? Here's the first go, using "-10" as the power, and showing the formula in cell C9 so you can check whether it's correct.
Cell H9 is formatted as a percentage, rather than the raw value.
If "n" is set to "-10*, this is the result: 0.135%. Is that likely?
If "n" is set to "9", obviously the decimal point in the result shifts one place to the left, giving 1.35%, which looks as though it might be more feasible, but could just as well be wrong too.
Cell H9 is highlighted this time so you can see the formula used (the same in both instances).
Am I still mis-understanding this?
Sorry for grinding on....
Just for clarity's sake, The "this website" link is actually this text -
"http://t/S Equations and how each one affects the others", and doesn't work, unfortunately.
Anyway, never mind that! Is "10^-10" saying "ten to the power of minus 10"?
I apologise for persisting with this, but I've started so I have to finish (to mis-quote the "Mastermind" quizmaster). Have tried plugging this "10^-10" term into the spreadsheet calc, and added the "minus power" term as a variable so it can be adjusted to see the results easily. And am still struggling to get a value that looks as though it might be feasible/realistic.
Have I still got this equation wrong? Here's the first go, using "-10" as the power, and showing the formula in cell C9 so you can check whether it's correct.
Cell H9 is formatted as a percentage, rather than the raw value.
If "n" is set to "-10*, this is the result: 0.135%. Is that likely?
If "n" is set to "9", obviously the decimal point in the result shifts one place to the left, giving 1.35%, which looks as though it might be more feasible, but could just as well be wrong too.
Cell H9 is highlighted this time so you can see the formula used (the same in both instances).
Am I still mis-understanding this?
Sorry for grinding on....
Erm, don't have a clue how the link got scrambled: https://audiojudgement.com/thiele-s...ydc8i*_ga*MTU0NDc0NTAyLjE2ODY3OTc2NTI.*_up*MQ and this is its associated doc: https://audiojudgement.com/thiele-small-parameters-explained/
= ( 9.7822e-10 * (Vas[L]) * (Fs^3) ) / Qes * 100
Using GM's / datasheet values (diff from yours)
=( 9.7822e-10 * (17.62) * (59.7^3) ) / 1.06 * 100
= 0.346 => 87.4 dB
Using GM's / datasheet values (diff from yours)
=( 9.7822e-10 * (17.62) * (59.7^3) ) / 1.06 * 100
= 0.346 => 87.4 dB
Honestly never noticed this seeming conflict. 
n0 = (9.7822 * 10^-10 * 16.3 * 39^3) / 0.7 = 0.00135
The SPL rating is in direct proportion to n0. Important to note is that the efficiency coefficient (n0) is highly dependent to the resonant frequency, because it’s at the power of 3. In conclusion, tweeters and mid-range drivers will be more efficient versus subwoofers.
Hopefully this concludes today's lesson. 😉 ..........or not
edit:
Hrm..... converting 0.00135*100 = 0.135
SPL @ 1W/1m = 112.2 + 10 * log(0.135) = 103.5 dB so can't be right Vs published Mean Sound Pressure Level: 85 dB （1w/1m）
n0 = (9.7822 * 10^-10 * 16.3 * 39^3) / 0.7 = 0.00135
- n0 above is a ratio, not a percentage. To make it a percentage multiply by 100.
- Vas is in liters.
- Fs in Hz.
The SPL rating is in direct proportion to n0. Important to note is that the efficiency coefficient (n0) is highly dependent to the resonant frequency, because it’s at the power of 3. In conclusion, tweeters and mid-range drivers will be more efficient versus subwoofers.
Hopefully this concludes today's lesson. 😉 ..........or not
edit:
Hrm..... converting 0.00135*100 = 0.135
SPL @ 1W/1m = 112.2 + 10 * log(0.135) = 103.5 dB so can't be right Vs published Mean Sound Pressure Level: 85 dB （1w/1m）
Last edited:
Thank you both. It's late-ish here and near bed-time (at least for this old boy), so will come back to this tomorrow morning when fresher! Just wanted to acknowledge your replies with gratitude.
I hadn't got as far as plugging the n0 value into the equation for the SPL, but just have. This is what it looks like - at least for me, using Excel. And this differs from GM's result, so mine may well be wrong. Have never done this in my life, so it could well be.
I changed the n0 figure in the first, n0 section of the spreadsheet simply by changing the format of that cell (H9) from a percentage to a plain value, giving 0.001351
Then plugged that into the SPL section (using the formula in GM's first reply above, and also in the Audio Judgement page) to get 83.5066, which is somewhere near (but perhaps not near enough, given the log nature of dB figures? Not sure) to the quoted SPL of 85 dB in the Dayton Audio spec sheet.
The Vas figure in that sheet is quoted as 16.3 litres.
Reading that Audio Judgement page on the various Thiele Small parameters, the Vas figure is the size of the cabinet in which it sits. How can Dayton know this figure? Or is this simply the size of cabinet that they recommend for this speaker? Puzzled again!
The VideoLogic Sirocco woofer cabinet in which I was considering this Dayton speaker as a possible replacement for the Audax unit with which it came has an internal volume of 19.5 litres, according to my measurements, although the Audax AP170M0 data sheet has a Vas value of 17.62.
Does this mean that VideoLogic were using a bigger cabinet than Audax were suggesting as recommended?
And does this difference in the Vas figures mean that the Dayton is not a suitable alternative speaker to put in there?
These are doubtless classic beginner-grade questions and puzzles....
I changed the n0 figure in the first, n0 section of the spreadsheet simply by changing the format of that cell (H9) from a percentage to a plain value, giving 0.001351
Then plugged that into the SPL section (using the formula in GM's first reply above, and also in the Audio Judgement page) to get 83.5066, which is somewhere near (but perhaps not near enough, given the log nature of dB figures? Not sure) to the quoted SPL of 85 dB in the Dayton Audio spec sheet.
The Vas figure in that sheet is quoted as 16.3 litres.
Reading that Audio Judgement page on the various Thiele Small parameters, the Vas figure is the size of the cabinet in which it sits. How can Dayton know this figure? Or is this simply the size of cabinet that they recommend for this speaker? Puzzled again!
The VideoLogic Sirocco woofer cabinet in which I was considering this Dayton speaker as a possible replacement for the Audax unit with which it came has an internal volume of 19.5 litres, according to my measurements, although the Audax AP170M0 data sheet has a Vas value of 17.62.
Does this mean that VideoLogic were using a bigger cabinet than Audax were suggesting as recommended?
And does this difference in the Vas figures mean that the Dayton is not a suitable alternative speaker to put in there?
These are doubtless classic beginner-grade questions and puzzles....
Keep in mind that the driver VideoLogic used was the AP170M2 and not the AP170M0. I'm guessing that these were a custom job for VL and so you can expect it to have different specs.
This is a bass only application so a longer voice coil would make sense. Then with all the other associated parameter changes would increase the required box size and go deeper.
This is a bass only application so a longer voice coil would make sense. Then with all the other associated parameter changes would increase the required box size and go deeper.
That's a good point. I couldn't find the data sheet specifically for the M2, but the datasheet available for the M2 model on this page - https://www.cadaudio.dk/audaxunits.htm - is for the M0. (Also available here - https://audax.com/archives/AP170M0.pdf)
The Audax Archive page has 3 entries for the AP170M0, but none of them mentions the M2. https://audax.com/archives.html
You may well be right - perhaps it was a custom job for VL.
Last edited: