Check plots versus tabulated data for Woofers
Hey sba,
I see discrepancy between the colour code of the plots and the colour code of the tabulated data:-
(1) - Yellow seems to be correct for both.
(2) - No Orange tabulated data, and no Blue plots, and Orange tabulated does not match Blue plots !
(3) - Purple plots do not correlate with Purple tabulated data.
(4) - Green plots do not correlate with Green tabulated data.
I think I would award you a Fail result if in an Engineering Examination !
I think I can guess which should apply to which, but please do check your files and Post the corrections, because there may be some other relevant matter there that I do not know.
Hey sba,
I see discrepancy between the colour code of the plots and the colour code of the tabulated data:-
(1) - Yellow seems to be correct for both.
(2) - No Orange tabulated data, and no Blue plots, and Orange tabulated does not match Blue plots !
(3) - Purple plots do not correlate with Purple tabulated data.
(4) - Green plots do not correlate with Green tabulated data.
I think I would award you a Fail result if in an Engineering Examination !
I think I can guess which should apply to which, but please do check your files and Post the corrections, because there may be some other relevant matter there that I do not know.
Examine tweeters physically
sba,
see the series of equally spaced humps in the Impedance plot for the yellow tweeter, and the corresponding undulations in the Phase plot for it.
These indicate a fault.
It could result from any of several possibilities, but first examine that tweeter very closely, with a magnifying glass if necessary, to see if there are any tiny holes in its dome or surround, or if any cracks or splits are starting to develop in its surround ... ?
Or, are there small wrinkles in the dome material itself ?
Then examine the Purple and Blue tweeters for similar, though lesser if any.
Orange looks to be a good quality sample.
Can you hear any difference between Orange and Yellow ? -
or between any of the samples ?
If there are no holes/cracks/splits in the fabrics, then look at the back of each chassis to see if any places where there may be an air leak through to the back of the dome.
Also, if it looks that the domes are removeable from their chassis with a simple tool, then Post that here and I'll describe what maybe can be done next ...
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Similarly, examine the domes and surrounds of the Orange and Yellow mid-domes, and their backs.
The other four mid-domes seem to not have fabric problems, but there may be small air leaks into their backs, or simply the deteriorating adhesive damping that tonedef2 described, and another member posted a photo of, earlier in this Thread.
sba,
see the series of equally spaced humps in the Impedance plot for the yellow tweeter, and the corresponding undulations in the Phase plot for it.
These indicate a fault.
It could result from any of several possibilities, but first examine that tweeter very closely, with a magnifying glass if necessary, to see if there are any tiny holes in its dome or surround, or if any cracks or splits are starting to develop in its surround ... ?
Or, are there small wrinkles in the dome material itself ?
Then examine the Purple and Blue tweeters for similar, though lesser if any.
Orange looks to be a good quality sample.
Can you hear any difference between Orange and Yellow ? -
or between any of the samples ?
If there are no holes/cracks/splits in the fabrics, then look at the back of each chassis to see if any places where there may be an air leak through to the back of the dome.
Also, if it looks that the domes are removeable from their chassis with a simple tool, then Post that here and I'll describe what maybe can be done next ...
*****************************************************************
Similarly, examine the domes and surrounds of the Orange and Yellow mid-domes, and their backs.
The other four mid-domes seem to not have fabric problems, but there may be small air leaks into their backs, or simply the deteriorating adhesive damping that tonedef2 described, and another member posted a photo of, earlier in this Thread.
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measure the inductors if possible
Hey sba,
you invite trouble for yourself !
- but it will be worth persevering as you can end up with some well matched pairs of 66s - I hope !!
Whilst you have one end of each capacitor disconnected from its circuit, then if you choose the disconnection points carefully and if you have a device to measure Inductance with, it is worth measuring some of the inductors for +/- sample variations.
(1) - the .14mH in the tweeter filter,
If one measures less than the others then use it with Purple tweeter.
If one measures larger than the others then use it with the Blue tweeter.
If you can only measure four inductors, then do these four.
And if you can measure more, then as follows:-
(2) - the .34mH/.35mH in the high mids' filter,
the lowest measured can be used with the Dark Green dome, and the highest measured can be used with the Purple or Blue domes,
and next highest with the Light Green dome,
and second lowest with the Orange dome.
I suspect the Yellow dome may be audibly faulty - can you hear a buzzing sound from it of the type tonedef2 described ?
Purple may buzz also, but at a lower frequency, but this dome may be useable when a suitable resistor is connected in parallel with it.
(3) - all the 2.2mH inductors as these can be selected between higher and lower measured values for raising the low-mids' crossover frequency for one pair of 66s.
The other pair I think can be got to work OK at the existing crossover frequency, with a parallel connected resistor trick applied to the mid-dome.
(4) - the 3.5mH inductors, for changing crossover frequency to the woofers for one pair.
Needless to say, if you do measure, then label each sample !
If I remember correctly you measured all the new capacitors when you bought them ... ? ... did you label them with their measured values ?
Hey sba,
you invite trouble for yourself !
- but it will be worth persevering as you can end up with some well matched pairs of 66s - I hope !!
Whilst you have one end of each capacitor disconnected from its circuit, then if you choose the disconnection points carefully and if you have a device to measure Inductance with, it is worth measuring some of the inductors for +/- sample variations.
(1) - the .14mH in the tweeter filter,
If one measures less than the others then use it with Purple tweeter.
If one measures larger than the others then use it with the Blue tweeter.
If you can only measure four inductors, then do these four.
And if you can measure more, then as follows:-
(2) - the .34mH/.35mH in the high mids' filter,
the lowest measured can be used with the Dark Green dome, and the highest measured can be used with the Purple or Blue domes,
and next highest with the Light Green dome,
and second lowest with the Orange dome.
I suspect the Yellow dome may be audibly faulty - can you hear a buzzing sound from it of the type tonedef2 described ?
Purple may buzz also, but at a lower frequency, but this dome may be useable when a suitable resistor is connected in parallel with it.
(3) - all the 2.2mH inductors as these can be selected between higher and lower measured values for raising the low-mids' crossover frequency for one pair of 66s.
The other pair I think can be got to work OK at the existing crossover frequency, with a parallel connected resistor trick applied to the mid-dome.
(4) - the 3.5mH inductors, for changing crossover frequency to the woofers for one pair.
Needless to say, if you do measure, then label each sample !
If I remember correctly you measured all the new capacitors when you bought them ... ? ... did you label them with their measured values ?
Thanks Alan. presently have 6.2 & 4.0uf in tweet; 4 & 24 in mid; 72's in bass. tweets are the green Eries. the rest are the Elcaps. On my planned to order sheet are:
Mills 0.5 (MRA-5)(tweet); 3.3 for the 4ufmid, 1.8 for the 24uf mid
CAPS: all Daytons- 4uf(tweet & mid), 6.2 for tweet, 25 for mid. Sonic caps are about 6 times the cost of daytons. will try and find your recommended Solen 250V 68 and 75. Not too much of a hurry as still can use spkr system B to the Minimus 7's. Do have parts on the way tho to fix phono output board of my pioneer 9500II amp. I will keep checking in to see what has transpired. thanks to all.
Mills 0.5 (MRA-5)(tweet); 3.3 for the 4ufmid, 1.8 for the 24uf mid
CAPS: all Daytons- 4uf(tweet & mid), 6.2 for tweet, 25 for mid. Sonic caps are about 6 times the cost of daytons. will try and find your recommended Solen 250V 68 and 75. Not too much of a hurry as still can use spkr system B to the Minimus 7's. Do have parts on the way tho to fix phono output board of my pioneer 9500II amp. I will keep checking in to see what has transpired. thanks to all.
Alan: re your post 182,pg 19. 15 mm between L5 & L4 present 72uf elcap is 12mm diam. pin holes are 53mm apart. distance between L1 & L3 is 45mm( where the 72 & 4 uf are). pin holes for C 6 are 60 mm. pin holes for C7 are 60mm. holes for C5 are 53mm Solen 36 caps are 34mm! 68 are 43mm, 75 is 44mm - these are diameters. the 36 are 48mm long and the 68 & 75 are 60mm long. Rather tight- if not impossible! solen electros are 16 mm diameter. considerations?
Next on my list is FR measurement, but this might be a couple of months away.
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I used the Dayton WT3 woofer tester. The graphs are composites that were made in Photoshop Elements, using a screen shot of the WT3 graph, and text that had been exported to Wordpad.
Parts-Express Woofer Tester
The problem with the woofer graph, Herr Doctor Professor, is only with the colors. The values are correct. A master column was formatted in Photoshop and used to make the remaining columns, with the values being re-entered manually…I just forgot to change the colors on a few. Good observation Alan…keep drinking that strong coffee!
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I measured all of the caps before installing them…and they were basically right on the mark. I ‘m using 25uf (15+10) in the mid section on all of my boards.
I don’t want to tear into the crossovers until we have FR measurements and a plan. Both sets are in use right now; and I need to get my other speaker project running before I can dismantle the 66’s… I can’t be without music!
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Here are some measurements of the total system. Unfortunately, the measurements were made at different addresses and on different computers. The green & purple are one set. The other set is blue & orange (and with this set I had trouble getting the tester to stabilize). So, some poor data here.
FWIW [Alan, see FWIW & IIRC ] the graph shows general trends, but the test should be redone.
*************
I used the Dayton WT3 woofer tester. The graphs are composites that were made in Photoshop Elements, using a screen shot of the WT3 graph, and text that had been exported to Wordpad.
Parts-Express Woofer Tester
The problem with the woofer graph, Herr Doctor Professor, is only with the colors. The values are correct. A master column was formatted in Photoshop and used to make the remaining columns, with the values being re-entered manually…I just forgot to change the colors on a few. Good observation Alan…keep drinking that strong coffee!
***************
I measured all of the caps before installing them…and they were basically right on the mark. I ‘m using 25uf (15+10) in the mid section on all of my boards.
I don’t want to tear into the crossovers until we have FR measurements and a plan. Both sets are in use right now; and I need to get my other speaker project running before I can dismantle the 66’s… I can’t be without music!
***************
Here are some measurements of the total system. Unfortunately, the measurements were made at different addresses and on different computers. The green & purple are one set. The other set is blue & orange (and with this set I had trouble getting the tester to stabilize). So, some poor data here.
FWIW [Alan, see FWIW & IIRC ] the graph shows general trends, but the test should be redone.
ClarityCap PX series versus Dayton caps
"Dayton" - I am presuming you are considering those +/-1% Tolerance "Dayton" branded caps.
Those are made by Bennic and selected from the general batches for close Tolerance and branded for Dayton.
Sound via them is OK, but clearer sound for very similar price can be got using ClarityCap PX series, from Madisound Speaker Components | Assisting speaker builders for more than 25 years. -{ www.madisound }-.
For the Dayton you are paying for the +/- 1% selecting.
For the ClarityCap you are paying for their carefully done low microphonic winding.
Don't worry too much about exact capacitance values - as other aspects of a capacitor's sound are more audible.
In ClarityCap PX series, 3.9uF , 6.0uF , 25uF , are all close enough to the original installed caps' values, and given the Impedance variations between samples of the drivers that sba has shown us, the very small differences in caps' values may by co-incidence match some of your drivers exactly, but in any case most will be close enough unless some of your drivers have age deteriorated a significant amount away from their original condition.
"Dayton" - I am presuming you are considering those +/-1% Tolerance "Dayton" branded caps.
Those are made by Bennic and selected from the general batches for close Tolerance and branded for Dayton.
Sound via them is OK, but clearer sound for very similar price can be got using ClarityCap PX series, from Madisound Speaker Components | Assisting speaker builders for more than 25 years. -{ www.madisound }-.
For the Dayton you are paying for the +/- 1% selecting.
For the ClarityCap you are paying for their carefully done low microphonic winding.
Don't worry too much about exact capacitance values - as other aspects of a capacitor's sound are more audible.
In ClarityCap PX series, 3.9uF , 6.0uF , 25uF , are all close enough to the original installed caps' values, and given the Impedance variations between samples of the drivers that sba has shown us, the very small differences in caps' values may by co-incidence match some of your drivers exactly, but in any case most will be close enough unless some of your drivers have age deteriorated a significant amount away from their original condition.
Fitting Solen poly caps
Solen's poly caps have fairly thick, strong leads and those will support the cap's weight sufficiently for it to not have to lie on the board.
If you think weight may be a problem, then 36uF size weighs a lot less than 68uF and 75uF.
Leave at least 1/4" -{or approximately 6mm}- of lead extending straight out of the cap's body, then bend each lead 90 degrees, then after seeing how much height above the board is needed for clearance above the inductors, bend the leads in curves towards the pin-holes' spaced distance, then bend the final section of lead straight down to go through the pin-hole in the board.
Leave sufficient space so the caps' bodies do not touch the inductors.
Never bend capacitors, or resistors, leads at sharp angles at their connection points to their bodies, as that weakens the connection.
Always leave some lead extending straight out.
Solen's poly caps have fairly thick, strong leads and those will support the cap's weight sufficiently for it to not have to lie on the board.
If you think weight may be a problem, then 36uF size weighs a lot less than 68uF and 75uF.
Leave at least 1/4" -{or approximately 6mm}- of lead extending straight out of the cap's body, then bend each lead 90 degrees, then after seeing how much height above the board is needed for clearance above the inductors, bend the leads in curves towards the pin-holes' spaced distance, then bend the final section of lead straight down to go through the pin-hole in the board.
Leave sufficient space so the caps' bodies do not touch the inductors.
Never bend capacitors, or resistors, leads at sharp angles at their connection points to their bodies, as that weakens the connection.
Always leave some lead extending straight out.
Time has run out today
Hi sba,
Thanks for the extra information, and for the Link to Acronyms - which fellows like me obviously need to see !
I have used all my spare time today and have to go now.
I will Post more soon about measuring Frequency Response, because it will have to be done in a way that allows us to see the anomolies in the drivers not affected by the reflections back to the mic from the room.
This is not difficult to do, but it is a bit time-consuming.
From the latest Impedance plots you posted, it seems that one of your 66 pairs have a different weight for their ABRs than the other pair.
Any visual differences between the ABRs ?
Post whatever you can answer of my other questions when you are able to.
I will be returning to this when I have the time available.
Hi sba,
Thanks for the extra information, and for the Link to Acronyms - which fellows like me obviously need to see !
I have used all my spare time today and have to go now.
I will Post more soon about measuring Frequency Response, because it will have to be done in a way that allows us to see the anomolies in the drivers not affected by the reflections back to the mic from the room.
This is not difficult to do, but it is a bit time-consuming.
From the latest Impedance plots you posted, it seems that one of your 66 pairs have a different weight for their ABRs than the other pair.
Any visual differences between the ABRs ?
Post whatever you can answer of my other questions when you are able to.
I will be returning to this when I have the time available.
Another good observation Alan.
They're not identical... IIRC one set has stamped metal frames, the other set has plastic frames. I'll investigate further when I find time.
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Solen's electros versus polys
Hello again DM,
Solen's electros have a 5% Dielectric Absorption specification.
That will be quite audible as fine-time smearing and dirtying the Timbre, thus I wouldn't use them except for rough types of punk and hard/heavy rock music.
They also have a Dissipation Factor of only .04% for the 68uF and 82uF values.
That is a lot lower than the likely D.F. of the old electros, even when those were new, thus the sound with Solen's electros will NOT be similar to the original 66 sound, AND to get it similar will require installation of ESR simulating resistors, thus I don't see any point in using Solen's electros, except for size and price, but both of those are somewhat irrelevant when one considers the quality of sound that can be got from the 66's woofers when better caps are used !
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For owners of PCB versions of 66s:-
To fit Solen's 36uF poly caps - continuing from my earlier Post #368 about fitting Solen poly caps - turn the PCB boards over and look at the metal deposited tracks.
Buy a new drill bit, or make sure the one you have is very sharp so as to be able to drill clean holes through the PCB.
Drill a new hole near to each old hole for both the 72uF positions.
Drill from the metal side of the board to ensure the metal stays firmly adhered to the board.
If you drill from the other side, the metal may be pushed off the board.
Connect one 36uF cap through the old holes, and connect the parallel 36uF cap through the new drilled holes.
This will give you strong enough support for each cap's weight - each supported above the inductors by its own leads, as I described in the earlier Post #368,
AND, this will give a good quality electrical connection for each capacitor to the circuit.
Hello again DM,
Solen's electros have a 5% Dielectric Absorption specification.
That will be quite audible as fine-time smearing and dirtying the Timbre, thus I wouldn't use them except for rough types of punk and hard/heavy rock music.
They also have a Dissipation Factor of only .04% for the 68uF and 82uF values.
That is a lot lower than the likely D.F. of the old electros, even when those were new, thus the sound with Solen's electros will NOT be similar to the original 66 sound, AND to get it similar will require installation of ESR simulating resistors, thus I don't see any point in using Solen's electros, except for size and price, but both of those are somewhat irrelevant when one considers the quality of sound that can be got from the 66's woofers when better caps are used !
*********************************************************
For owners of PCB versions of 66s:-
To fit Solen's 36uF poly caps - continuing from my earlier Post #368 about fitting Solen poly caps - turn the PCB boards over and look at the metal deposited tracks.
Buy a new drill bit, or make sure the one you have is very sharp so as to be able to drill clean holes through the PCB.
Drill a new hole near to each old hole for both the 72uF positions.
Drill from the metal side of the board to ensure the metal stays firmly adhered to the board.
If you drill from the other side, the metal may be pushed off the board.
Connect one 36uF cap through the old holes, and connect the parallel 36uF cap through the new drilled holes.
This will give you strong enough support for each cap's weight - each supported above the inductors by its own leads, as I described in the earlier Post #368,
AND, this will give a good quality electrical connection for each capacitor to the circuit.
Test Equipment limitations.
Some comments and questions, BUT FIRST:- thankyou to sba for posting this information to assist DIY enthusiasts.
The limitations:-
unfortunately that Behringer mic is only reliably useable up to about 2kHz,
UNLESS you have a CALIBRATED sample of it.
From about 3kHz upwards there are significant differences between production samples, and departure from flat frequency response to such degree that the measurements can be quite inaccurate.
It is OK to measure woofers and the lower mids of the mid-domes for the Celestion 66s, so we can use whatever sba may be able to Post later to refine the low mids' crossover.
That pre-amp is designed for Sound Effect and not for accurate measurements' purposes, however it can be used with a measurement mic to reasonable degree I think, if one does not drive it into distortion.
Any Distortion present will cause an inaccurate result in the measurements.
To minimise Distortion:-
Keep its Gain control at a fairly low level - so as to not be overdriving the initial gain stage.
Then, set its Output control high enough to get sufficient signal level to drive the next piece of equipment.
The Output will probably only distort when set very high, so long as the Gain is kept fairly low.
Ensure the Limiter is switched OFF.
Limiter On will cause change to the signal's waveform, even when driven at a little below its Threshold level, and thus a distortion cause, and thus not accurate measurement.
A Solid State preamp will be better for measurements' use than a 12AX7 tubed type so far as Distortion is concerned,
and if the S.S. preamp is a Low Noise design.
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Those Pink Noise plots sba,
I cannot be sure from what is on-screen.
Are they 1/9th Octave spaced, or 1/10th Octave, or ?
It may be necessary to achieve at least 1/12th Octave spaced to get sufficient detail of the Celestion woofer's behavior in the 700Hz <--> 800Hz region, and also around 1k4 <--> 1k6, and some above, if you want to re-design for a higher crossover frequency than exists.
Some comments and questions, BUT FIRST:- thankyou to sba for posting this information to assist DIY enthusiasts.
The limitations:-
unfortunately that Behringer mic is only reliably useable up to about 2kHz,
UNLESS you have a CALIBRATED sample of it.
From about 3kHz upwards there are significant differences between production samples, and departure from flat frequency response to such degree that the measurements can be quite inaccurate.
It is OK to measure woofers and the lower mids of the mid-domes for the Celestion 66s, so we can use whatever sba may be able to Post later to refine the low mids' crossover.
That pre-amp is designed for Sound Effect and not for accurate measurements' purposes, however it can be used with a measurement mic to reasonable degree I think, if one does not drive it into distortion.
Any Distortion present will cause an inaccurate result in the measurements.
To minimise Distortion:-
Keep its Gain control at a fairly low level - so as to not be overdriving the initial gain stage.
Then, set its Output control high enough to get sufficient signal level to drive the next piece of equipment.
The Output will probably only distort when set very high, so long as the Gain is kept fairly low.
Ensure the Limiter is switched OFF.
Limiter On will cause change to the signal's waveform, even when driven at a little below its Threshold level, and thus a distortion cause, and thus not accurate measurement.
A Solid State preamp will be better for measurements' use than a 12AX7 tubed type so far as Distortion is concerned,
and if the S.S. preamp is a Low Noise design.
*********************************************************
Those Pink Noise plots sba,
I cannot be sure from what is on-screen.
Are they 1/9th Octave spaced, or 1/10th Octave, or ?
It may be necessary to achieve at least 1/12th Octave spaced to get sufficient detail of the Celestion woofer's behavior in the 700Hz <--> 800Hz region, and also around 1k4 <--> 1k6, and some above, if you want to re-design for a higher crossover frequency than exists.
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Capacitors' sample variations/Tolerances
Hah sba, your original Post #147 from Page 15 !
There is sufficient differences between the samples of the 10uF caps to allow some matching to mid-drivers, and the 3.85uF cap would be best used with the highest Impedance tweeter, unless the possible faults in some of your tweeters require them to be crossed higher for better sound.
I would use the 61.3uF with the Yellow woofer, and using around 62uF plus a resistor instead of 72uF may raise the crossover frequency sufficiently for what you want to try, though the inductors should be sample chosen also for this to work properly.
What measured values did you end up with after you bought 6uF caps ?
Hah sba, your original Post #147 from Page 15 !
There is sufficient differences between the samples of the 10uF caps to allow some matching to mid-drivers, and the 3.85uF cap would be best used with the highest Impedance tweeter, unless the possible faults in some of your tweeters require them to be crossed higher for better sound.
I would use the 61.3uF with the Yellow woofer, and using around 62uF plus a resistor instead of 72uF may raise the crossover frequency sufficiently for what you want to try, though the inductors should be sample chosen also for this to work properly.
What measured values did you end up with after you bought 6uF caps ?
Measurement possibilities
I have read through most of the Manual for the WT3.
It can be used to measure not merely Resistance and Inductance, but both of those versus Frequency, and produce Plots for, thus one can see if resistors are Inductive, and if so where this becomes significant in their frequency bandwidth - useful when deciding ESR applications.
For Inductors the plots show any losses, plus the DC resistance of the coils.
Thus, when you measure your inductors sba, do use this full facility.
Doing Inductor measurements in the simpler 1kHz frequency Test is OK to compare their values for the large inductors, but doing the Test at 10kHz may give better results for the .34mH and .14mH coils, but do them at both frequencies if possible and compare results.
The "Design a Zobel" function can be used with the woofers and your 62uF caps sba - use a resistor of not less than 4.7ohm, though you may need to use a larger value in the final design, but a Plot of 4.7ohm + 62uF and a comparison plot(s) of either/both 4.7ohm + 15uF and/or 4.7ohm + 10uF would be useful to use to design for a higher crossover frequency.
5watt resistor is OK for testing, but for high volume playing in use a 10watt resistor may be better here - no there won't be 10watts through it, but after 2watts it will start to heat up significantly.
If you happen to own 5.6ohm or 6.8ohm already in 5watt, either will be OK for initial Plots, and we can then see what needs to be changed next.
Plot the same with the ESR resistor + 3.9uF cap in Parallel with a mid-dome, as that is part Zobel/part Filter.
The Light Green sample dome looks representative of an Average if you only want to do one dome, but I would plot them all, except any that have visual or audible faults - such as Yellow, and perhaps Orange ...
Which two do you have out of circuit and able to inspect currently ?
The L(e) data for ALL the drivers - did you measure that at 1kHz or 10kHz or ?
This is not clearly explained in the Manual, so far as I've currently found.
Comparing these L(e) data with the Phase Plots there is sufficient discrepancy for me to wonder whether the L(e) figures are suitable to use to re-design the crossover.
The Phase Plots, together with the Impedance Plots are more useful, BUT I may have to see each for single driver samples and with an expanded Vertical Scale to get close to exact data at the relevant frequencies to fine-tune a new crossover well.
I have read through most of the Manual for the WT3.
It can be used to measure not merely Resistance and Inductance, but both of those versus Frequency, and produce Plots for, thus one can see if resistors are Inductive, and if so where this becomes significant in their frequency bandwidth - useful when deciding ESR applications.
For Inductors the plots show any losses, plus the DC resistance of the coils.
Thus, when you measure your inductors sba, do use this full facility.
Doing Inductor measurements in the simpler 1kHz frequency Test is OK to compare their values for the large inductors, but doing the Test at 10kHz may give better results for the .34mH and .14mH coils, but do them at both frequencies if possible and compare results.
The "Design a Zobel" function can be used with the woofers and your 62uF caps sba - use a resistor of not less than 4.7ohm, though you may need to use a larger value in the final design, but a Plot of 4.7ohm + 62uF and a comparison plot(s) of either/both 4.7ohm + 15uF and/or 4.7ohm + 10uF would be useful to use to design for a higher crossover frequency.
5watt resistor is OK for testing, but for high volume playing in use a 10watt resistor may be better here - no there won't be 10watts through it, but after 2watts it will start to heat up significantly.
If you happen to own 5.6ohm or 6.8ohm already in 5watt, either will be OK for initial Plots, and we can then see what needs to be changed next.
Plot the same with the ESR resistor + 3.9uF cap in Parallel with a mid-dome, as that is part Zobel/part Filter.
The Light Green sample dome looks representative of an Average if you only want to do one dome, but I would plot them all, except any that have visual or audible faults - such as Yellow, and perhaps Orange ...
Which two do you have out of circuit and able to inspect currently ?
The L(e) data for ALL the drivers - did you measure that at 1kHz or 10kHz or ?
This is not clearly explained in the Manual, so far as I've currently found.
Comparing these L(e) data with the Phase Plots there is sufficient discrepancy for me to wonder whether the L(e) figures are suitable to use to re-design the crossover.
The Phase Plots, together with the Impedance Plots are more useful, BUT I may have to see each for single driver samples and with an expanded Vertical Scale to get close to exact data at the relevant frequencies to fine-tune a new crossover well.
Penalty !
Failed indeed, and as Penalty you are required to render to me both your pairs of 66s !
After measuring and listening I may send back to you the lesser pair ...
hey, I'll pay the Shipping both ways ... no, I didn't think you'd agree to this.
See the small hump in the centre of the large dip in the low frequency end of the Orange impedance plot - that indicates some other object is part blocking an air path in that enclosure - at least at the time you measured.
Given the significant differences in the midrange and treble between the pair for which you stated the measurements would not stabilize and the other pair, I will presume the other pair to be representative of correctly measured samples, because I very much doubt the sample variations between the drivers plus effects of the inductors and capacitors could have caused such large degree differences.
Errors for that pair as result of air-leak -{vented !}- enclosures affect only the bass region of the plots, and highly unlikely to have significant effect above about 150Hz, except for a few narrow-band resonances which can come through vents at midrange frequencies, and I do not see any evidence of such in those Plots, thus the internal sound absorbing material is probably working well enough.
The dip to below 5ohms around the 80Hz <--> 90Hz region in the Purple + Green does surprise me though !
I am not sure that such is possible for those drivers with those inductors in electrical Series with them, perhaps a measurement error there ?
- but I'm going to think more about that before I decide.
The Orange + Blue pairs' Impedances is what I would have expected to see in that frequency region, thus perhaps those plots are the accurate ones ...
What else do you have Plots for that you can Post now ?
Failed indeed, and as Penalty you are required to render to me both your pairs of 66s !
After measuring and listening I may send back to you the lesser pair ...
hey, I'll pay the Shipping both ways ... no, I didn't think you'd agree to this.
See the small hump in the centre of the large dip in the low frequency end of the Orange impedance plot - that indicates some other object is part blocking an air path in that enclosure - at least at the time you measured.
Given the significant differences in the midrange and treble between the pair for which you stated the measurements would not stabilize and the other pair, I will presume the other pair to be representative of correctly measured samples, because I very much doubt the sample variations between the drivers plus effects of the inductors and capacitors could have caused such large degree differences.
Errors for that pair as result of air-leak -{vented !}- enclosures affect only the bass region of the plots, and highly unlikely to have significant effect above about 150Hz, except for a few narrow-band resonances which can come through vents at midrange frequencies, and I do not see any evidence of such in those Plots, thus the internal sound absorbing material is probably working well enough.
The dip to below 5ohms around the 80Hz <--> 90Hz region in the Purple + Green does surprise me though !
I am not sure that such is possible for those drivers with those inductors in electrical Series with them, perhaps a measurement error there ?
- but I'm going to think more about that before I decide.
The Orange + Blue pairs' Impedances is what I would have expected to see in that frequency region, thus perhaps those plots are the accurate ones ...
What else do you have Plots for that you can Post now ?
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Alan,
Thanks for familiarizing yourself with my measurement setup and making comments, which I’ll incorporate into the FR testing. I’ve also gleaned some things about acoustic testing here--
http://www.diyaudio.com/forums/mult...lp-dr-geddes-other-experts-2.html#post2002419
and here--
Driver Measurements
I’ve downloaded HOLMImpulse, a free acoustic testing program, but haven’t tried it yet. If I can figure it out, and get it to work with my computer/soundcard/mic, then I’ll use it for the FR measurements, instead of the RTA program. There's a pdf manual on the website if you're interested.
HOLM Acoustics
So the woofers will be tested free of the x-o. What about protecting the mid-domes during testing ?
The total system impedance test was botched. I’ll redo the test and take notes.
Thanks for familiarizing yourself with my measurement setup and making comments, which I’ll incorporate into the FR testing. I’ve also gleaned some things about acoustic testing here--
http://www.diyaudio.com/forums/mult...lp-dr-geddes-other-experts-2.html#post2002419
and here--
Driver Measurements
I’ve downloaded HOLMImpulse, a free acoustic testing program, but haven’t tried it yet. If I can figure it out, and get it to work with my computer/soundcard/mic, then I’ll use it for the FR measurements, instead of the RTA program. There's a pdf manual on the website if you're interested.
HOLM Acoustics
So the woofers will be tested free of the x-o. What about protecting the mid-domes during testing ?
The total system impedance test was botched. I’ll redo the test and take notes.
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about the Measurements' Links
Hi sba,
wrt the Links in your #377 above:-
In the first Link, which opened at #14 in its Thread, #14 info is GOOD, as is #16 - both are worth keeping in mind.
In the second Link, this is all good stuff, though a little of it is not necessary for what we are doing here.
If you can do the Le(x) tests at either or both the excursion maximum + and/or - , then you can know the degree of limitations these drivers have,
BUT, it will be almost impossible to do with the tweeters, and very difficult to do well with the mid-domes, and given that it is the mid-domes that are the critical part of the 66 there may not be much point in doing the Le(x) for the woofers because I think the limitations of the mid-domes will be greater than those of the woofers, but do the test for the woofers if you are interested.
It would be more useful to know at what frequency(s) the L(e) data you did Post was done at, so that I know whether to advise incorporating it in the crossover calculations OR ignoring it ... thus do you know the frequency/s ?
Also in the second Link, the 3rd octave smoothing is really only useful to estimate the general spectrum of the soundfield from the loudspeaker in the room.
That is not much use for designing for a small change in the crossover of a loudspeaker which was designed to produce potentially good soundfield in a room - the room is the limiting factor for well working 66s ... if one likes their basic sound.
For any measurements, do as little smoothing as possible, and if anything radical shows that you don't understand I'll attempt to explain it.
The third Link, for HOLMImpulse - if you can get it to work with your equipment it seems it can be useful for what we are attempting to do.
Protecting the mid-domes during testing:-
For low voltage input level testing, such as I presume the Impedance/Phase was done at there won't be any damage done to the domes, nor would there be with the standard 2.83volts input test if used for Frequency Response,
BUT if you are worried then connect one of your 62uF caps in electrical series with the dome ... though that will cause errors in the measurement, but if all the domes are measured with the same cap we can still see relative differences between the domes.
For the tweeters, connect one of your 15uF caps in electrical series, though again there will be errors.
Can you do a Pink Noise test with a High Pass filter applied to the pink noise ?
- and if so, what are the corner frequencies you have available for the filters ?
If you have time, do the total impedance and phase tests again before you disassemble the crossovers, though I can guess the general behavior around the bass<-->mids x area from comparing both the faulty plots.
There are other tests, which your equipment can perform, that will be more useful in deciding which drivers to apply with which others and where to cross them.
I'll Post about this when I next have time available.
In lead-up to that, which two mid-domes do you have out of use that can have a test done on them now ?
Hi sba,
wrt the Links in your #377 above:-
In the first Link, which opened at #14 in its Thread, #14 info is GOOD, as is #16 - both are worth keeping in mind.
In the second Link, this is all good stuff, though a little of it is not necessary for what we are doing here.
If you can do the Le(x) tests at either or both the excursion maximum + and/or - , then you can know the degree of limitations these drivers have,
BUT, it will be almost impossible to do with the tweeters, and very difficult to do well with the mid-domes, and given that it is the mid-domes that are the critical part of the 66 there may not be much point in doing the Le(x) for the woofers because I think the limitations of the mid-domes will be greater than those of the woofers, but do the test for the woofers if you are interested.
It would be more useful to know at what frequency(s) the L(e) data you did Post was done at, so that I know whether to advise incorporating it in the crossover calculations OR ignoring it ... thus do you know the frequency/s ?
Also in the second Link, the 3rd octave smoothing is really only useful to estimate the general spectrum of the soundfield from the loudspeaker in the room.
That is not much use for designing for a small change in the crossover of a loudspeaker which was designed to produce potentially good soundfield in a room - the room is the limiting factor for well working 66s ... if one likes their basic sound.
For any measurements, do as little smoothing as possible, and if anything radical shows that you don't understand I'll attempt to explain it.
The third Link, for HOLMImpulse - if you can get it to work with your equipment it seems it can be useful for what we are attempting to do.
Protecting the mid-domes during testing:-
For low voltage input level testing, such as I presume the Impedance/Phase was done at there won't be any damage done to the domes, nor would there be with the standard 2.83volts input test if used for Frequency Response,
BUT if you are worried then connect one of your 62uF caps in electrical series with the dome ... though that will cause errors in the measurement, but if all the domes are measured with the same cap we can still see relative differences between the domes.
For the tweeters, connect one of your 15uF caps in electrical series, though again there will be errors.
Can you do a Pink Noise test with a High Pass filter applied to the pink noise ?
- and if so, what are the corner frequencies you have available for the filters ?
If you have time, do the total impedance and phase tests again before you disassemble the crossovers, though I can guess the general behavior around the bass<-->mids x area from comparing both the faulty plots.
There are other tests, which your equipment can perform, that will be more useful in deciding which drivers to apply with which others and where to cross them.
I'll Post about this when I next have time available.
In lead-up to that, which two mid-domes do you have out of use that can have a test done on them now ?
Received yest: 68 uf Solens; 3.9, 6, & 25 uf Clarities. Mill resisters not here yet. WOW- those solens are huge. think I can get one mounted vertically, the other just barely above the inductors. for those that have *upgraded* the internal spkr wire, what gauge did you go to, and how did you attach to board?? I am looking at using 16 gauge. Can I solder direct to the track or should I cut & splice into the 20/18 stuff so as to utilize the clip onto the PCB? Might try find those 5mm female connectors tomorrow that attach to the speakers. Really not sure which wqay to go. If becomes a headache, will just use the original setup. Thoughts, suggestions?
Thanks, DM
Thanks, DM
see my Post earlier
Hi DM,
I wouldn't cut and splice one wire guage into another as this can cause an audibly suspect connection, albeit more-so in treble than in bass ...
Stay with the original wire, unless it is damaged ...
Why do you want to change any of the wiring ?
See the lower section of my Post #372 for how I would attach the large caps to the PCB.
Hi DM,
I wouldn't cut and splice one wire guage into another as this can cause an audibly suspect connection, albeit more-so in treble than in bass ...
Stay with the original wire, unless it is damaged ...
Why do you want to change any of the wiring ?
See the lower section of my Post #372 for how I would attach the large caps to the PCB.
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