Altec 416-8b woofers

[Mercury3]

Update - Got my four woofers back but sadly one has voice coil rub. Box looks fine but I know they wouldn't have shipped back to me like that so something must have happened to it in shipping. Kinda turns yer stomach. Oh well I have to ship it back again.

Update again - no voice coil rub after all. They had not clipped one side of the leads which had excess wire hanging over shorting intermittently to the other lead. Caused scratchy sound on DATS test.

I clipped the excess wire from the lead now it works fine.

[Mercury3]

I have all four woofers back and everything looks good. Here is the thing - I can post the DATS results if anyone wants to see but I'm not sure it's meaningful.

I was reading at DIYAUDIO and someone said DATS just measures the impedance curve and then guesses at the TS Parms. It isn't accurate.

I think Todd had kind of hinted this in his prior reply to me here as well.

I'm just going to use them and not worry about it. I'm an old timer and kinda prefer tuning ports the old fashioned way anyway. ie frequency generator measuring the two impedance curves across a resistor & cutting ports to length.

[GM]

Yes, please.


ALL these type testers use the measured impedance and calculates all but Vas with dead on accurate math, so sure would like to see this post.


That said, there's two DATS, the original [pro] Smith & Larson: woofertester.com and PE's cheap rip-off that they may be referring to accuracy wise, though even it does fine when set up just right, the tide is out, zero noise during measuring, etc., and some say the V2 is much better, though as always YMMV.


Which do you have?


GM

[Mercury3]

Yes, please.


ALL these type testers use the measured impedance and calculates all but Vas with dead on accurate math, so sure would like to see this post.


That said, there's two DATS, the original [pro] Smith & Larson: woofertester.com and PE's cheap rip-off that they may be referring to accuracy wise, though even it does fine when set up just right, the tide is out, zero noise during measuring, etc., and some say the V2 is much better, though as always YMMV.


Which do you have?


GM

I have the V2 - I'll post the results I do have.

- - - Updated - - -

W1.jpgW2.jpgW3.jpgW4.jpg

The high FS one these do bother me. One of them is 41 hz

[GM]

Thanks! Need Vas, but before you do it, please post the instructions as I may want it done differently.

GM

[Mercury3]

Thanks! Need Vas, but before you do it, please post the instructions as I may want it done differently.

GM

Alright - It'll probably take me a while to get to that as I think I need a test box. I'll have to check for instructions on that too.

I think it's safe to assume the actual VAS will be different from spec as well.

I was thinking of something - My DATS V2 does test a 416-8c that I have right on published specs so maybe it isn't really as far off as someone over at DIYAUDIO suggested.

If accurate then the QTS on these is pretty far off too. The QTS on these almost looks good for aperodic loading although not with that high fs.

I searched around a lot and have not found anyone else posting specs after getting recones or new GPA woofers either.

[GM]

No, you don't and why I want its instructions.

[Mercury3]

No, you don't and why I want its instructions.

Oh sorry I missundersood - Copied below:

8) Measure the driver's V as.'10 20Notes:50 100 200 500 1kHz. 2k111111111111111111111111111111111111111111111111 1111V(BJ• 1? [cu7t-609 C" AddedMassMethod1209 M = ?o-- grams? C" Spedied SPL Method-160" SPL .?o-- ?,?;;m;;;Sk 10k 20k(' Specified M(md)M(md) = ?o--gramsMeasured ParametersR(e(. 173913 Ohm,F{s)=�HzQ(ts] = fo.s'13Q[e,J,fo:98,Q(m,)•[4Ts7L(e)•�k,,H(lOkJM[ms] = ?o--gramsV(as)= ?o--[cuitr Test Lead Resislance, L R(tl. � Dh'.":._JFigure 1: A Typical DATS V2 screenOnce you have measured the speaker's free air parameters the "Measure V(as)" button becomes enabled.Select one of the four methods to measure the Vas at the upper right side of the DA TS V2 screen. The fourVas measurement methods are:
1) Test Box Method - requires a suitable test box
2) Added Mass Method - requires you to add a known mass
3) Specified SPL Method - requires the SPL be known
4) Specified MMD Method - requires the MMD be known
Enter the required data and then press the "Measure V(as)" button to start the measurement procedure.

[GM]

Thanks! Huh! Not seeing any recommendations for how much mass or reduced Fs. Not good unless it tells you it needs more.

Regardless, the pioneers determined that the test box raise Fs at least 50% and more specifically 1.56x while I've often seen write-ups for only 20-25%! With added mass then, Fs ideally needs to drop by 1.56x, so will need to be evenly distributed around the Vc. Hope you have an accurate scale.

Some folks say Vas measurement can be pretty far off and have little impact on cab design, which is true, but Vas is just about everywhere in the other specs, so can be used to check the others and frankly not sure of some of them since Bill did [2] pair of 414B last year and Jeff's measurements showed all were basically identical, so surprised these are so far off by Altec standards, at least up to '75: Thiele Small parameters equations - How each one affects the others

GM

[Mercury3]

Thanks! Huh! Not seeing any recommendations for how much mass or reduced Fs. Not good unless it tells you it needs more.

Regardless, the pioneers determined that the test box raise Fs at least 50% and more specifically 1.56x while I've often seen write-ups for only 20-25%! With added mass then, Fs ideally needs to drop by 1.56x, so will need to be evenly distributed around the Vc. Hope you have an accurate scale.

Some folks say Vas measurement can be pretty far off and have little impact on cab design, which is true, but Vas is just about everywhere in the other specs, so can be used to check the others and frankly not sure of some of them since Bill did [2] pair of 414B last year and Jeff's measurements showed all were basically identical, so surprised these are so far off by Altec standards, at least up to '75: Thiele Small parameters equations - How each one affects the others

GM

Okay thanks - I'm working a string of 12 hour shifts but will try playing with this again on a day off maybe end of next week. I'll check the manual better too make sure I'm didn't miss part of it.

Mark