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post #121 of 446 Old 02-10-2020, 01:26 PM
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You guys are amazing! How great is it to have a true expert available to consult As far as the geek / nerd stuff, yes it IS interesting. That is just an added bonus to the ultimate goal of serious theater use. Yeah, I know, this is JUST a test. But it will be fun far after the testing phase is done.


Collecting empiric data like this ... just wow! Snow and all (as we are having flash flood warnings down in AL today )
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post #122 of 446 Old 02-10-2020, 03:12 PM
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@a77cj7 Do you still need close mic measurement? I don't have it save as measurement file, just the image capture. I can do a close field measurement but it will be in a room though.
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post #123 of 446 Old 02-10-2020, 03:17 PM - Thread Starter
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Originally Posted by automata21 View Post
@a77cj7 Do you still need close mic measurement? I don't have it save as measurement file, just the image capture. I can do a close field measurement but it will be in a room though.


Don’t worry about it. I was just curious if the resonance was in the same spot.
Not worth setting up the equipment and taking another measurement.

Chris
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post #124 of 446 Old 02-10-2020, 03:26 PM
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Originally Posted by a77cj7 View Post
Saturday, I quit the sweeps at 38v into mono 4 ohm. I clipped the mic at 2m, and heard what I believed to be driver distress. I later discovered it was the enclosure bouncing on the dolly.

Thanks,
Chris
After reading the statement above and reviewing your pics, you didn't make any ground plane measurements. 2pi equals enclosure on the ground. You might get a perfect overlay with the HR model if you place the enclosure on the ground.

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post #125 of 446 Old 02-10-2020, 03:33 PM - Thread Starter
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Originally Posted by BP1Fanatic View Post
After reading the statement above and reviewing your pics, you didn't make any ground plane measurements. 2pi equals enclosure on the ground. You might get a perfect overlay with the HR model if you place the enclosure on the ground.

You think the 2” it sits above the ground significantly changes response at bass wavelengths?
I tend to doubt it would make a measurable difference. After all, if I had the box sitting sideways, much of the port and horn mouth would be much farther from the ground. As are the cones in most direct-radiator designs. Yet, those are still ground-plane measurements.

I would generally try it, but snow.

Chris
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post #126 of 446 Old 02-10-2020, 03:34 PM
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Don’t worry about it. I was just curious if the resonance was in the same spot.
Not worth setting up the equipment and taking another measurement.

Chris
I believe I have mine saved on laptop. I can send it to you once I get home. Seems like you sont need it anymore though. But let me know if you do.

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post #127 of 446 Old 02-10-2020, 03:47 PM
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You think the 2” it sits above the ground significantly changes response at bass wavelengths?
I tend to doubt it would make a measurable difference. After all, if I had the box sitting sideways, much of the port and horn mouth would be much farther from the ground. As are the cones in most direct-radiator designs. Yet, those are still ground-plane measurements.

I would generally try it, but snow.

Chris
I'm quite sure a lot of enclosures are made with wheels are not measured while on their wheels. I do understand the circumstance of snow being on the ground. Still excellent work guy! I love the frequency response. You built a monster for a mancave!

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post #128 of 446 Old 02-10-2020, 04:11 PM - Thread Starter
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Originally Posted by harrisu View Post
I believe I have mine saved on laptop. I can send it to you once I get home. Seems like you sont need it anymore though. But let me know if you do.

Sent from my SM-G950U1 using Tapatalk


I’ll take it if you have the file saved. I’m not sure if it means anything, but yay more colorful lines.
I’ll pm you my email address.

Chris
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post #129 of 446 Old 02-10-2020, 04:23 PM - Thread Starter
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EXPERIMENTAL Quad JBL Devastator Build

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Originally Posted by BP1Fanatic View Post
I'm quite sure a lot of enclosures are made with wheels are not measured while on their wheels. I do understand the circumstance of snow being on the ground. Still excellent work guy! I love the frequency response. You built a monster for a mancave!


I might have a chunk of osb stashed. If I do, I’ll A-B it.
I’m still doubting a noticeable difference.

Yeah, its a bit overkill for a shop sub. But next time jbl’s are $30 I’ll probably pick up 4 more and build a second one. Why? I’ll work on that part...

Chris
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post #130 of 446 Old 02-10-2020, 04:39 PM
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LMAO...basshead 4 life!

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post #131 of 446 Old 02-10-2020, 07:25 PM - Thread Starter
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EXPERIMENTAL Quad JBL Devastator Build

In case the burning (hah) question on anyone’s mind is “What’s more fun than ground-plane testing in the snow?”, I now have an answer. Ground plane testing in the snow, in the dark, at 20*. Bonus points for it starting to snow during the first set of sweeps.



I haven’t even looked at the data yet, will work on that once I can feel my fingers again.

I did start out with the concern brought up earlier by @BP1Fanatic . Whether the dolly I had the enclosure on affected the measurement. The result surprised me by being noticeable for part of the range, but wasn’t enough to significantly alter the data.

All the other testing tonight was performed without the dolly. (I certainly wasn’t gonna fight it back on there)

Chris
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post #132 of 446 Old 02-10-2020, 07:40 PM
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Quote:
Originally Posted by a77cj7 View Post
In case the burning (hah) question on anyone’s mind is “What’s more fun than ground-plane testing in the snow?”, I now have an answer. Ground plane testing in the snow, in the dark, at 20*. Bonus points for it starting to snow during the first set of sweeps.



I haven’t even looked at the data yet, will work on that once I can feel my fingers again.

I did start out with the concern brought up earlier by @BP1Fanatic . Whether the dolly I had the enclosure on affected the measurement. The result surprised me by being noticeable for part of the range, but wasn’t enough to significantly alter the data.

All the other testing tonight was performed without the dolly. (I certainly wasn’t gonna fight it back on there)

Chris

Normally I don't like to quote posts and force the picture to reload twice, but SOMETIMES it is worth it Utterly nuts ... and worse, I get it! About a zillion lifetimes ago (30-something years) I installed a turbo in my driveway during the winter. Had some weather to deal with, but once I got going on it I didn't want to stop.


The frozen ground ought to be good for another dB or 2, rather than soft and fluffy snow (if it ices over).



As this build and testing has progressed, I find myself going back and forth about building one of these. Reason suggests that if I am going to the trouble to build a Dev, install a 21" driver and make the labor worth it. OTOH, something about the silly, inexpensive side of this just makes me smile. 8 drivers, some wood, and a used iNuke could make a lot of noise with minimum expense.


How close are the nearest neighbors? I can't wait until the cops show up to check out the noise complaint, followed in 5 min by the guys in white coats
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post #133 of 446 Old 02-10-2020, 08:14 PM
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[snip].....


How close are the nearest neighbors? I can't wait until the cops show up to check out the noise complaint, followed in 5 min by the guys in white coats
Neighbors.....ppppttt.... I have everything in my SIG in an APARTMENT!!! And it's awesome.....


Juju

Sub List: 1- Red Five Mini V1 Devastator 18" w/PA460, 1- Red Five Devastator LFE 21", 1- Red Five Devastator 21" Finalizer V2 DF , 1- BOSS platform [The Hideaway Theater], 2- 18" "Full Marty" tuned to 17Hz w/RSS460HO
Wish List: Anthology http://www.speakerdesignworks.com/Anthology_1.html

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post #134 of 446 Old 02-10-2020, 08:23 PM - Thread Starter
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About a zillion lifetimes ago (30-something years) I installed a turbo in my driveway during the winter. Had some weather to deal with, but once I got going on it I didn't want to stop.
I swapped a transmission in a snowy driveway back in college. When we were house shopping, a heatable detached garage was one of my main requirements, so I could work on projects year round.
I ended up with an amazing 30x50 heated shop.
This does not help with ground-plane speaker testing though. There’s always a catch.

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As this build and testing has progressed, I find myself going back and forth about building one of these. Reason suggests that if I am going to the trouble to build a Dev, install a 21" driver and make the labor worth it. OTOH, something about the silly, inexpensive side of this just makes me smile. 8 drivers, some wood, and a used iNuke could make a lot of noise with minimum expense.
Owning both, I agree with both sentiments. Once I finish testing and comparing... I probably still won’t have an answer other than “Yes!”


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How close are the nearest neighbors? I can't wait until the cops show up to check out the noise complaint, followed in 5 min by the guys in white coats

Pretty much straight across the road visible in the pic. Back a few hundred feet. They were shoveling their deck while I was running sweeps yesterday. No complaints yet.

Chris
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post #135 of 446 Old 02-10-2020, 08:25 PM - Thread Starter
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Neighbors.....ppppttt.... I have everything in my SIG in an APARTMENT!!! And it's awesome.....


Juju


How you’re not met with torches and pitchforks...

Chris
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post #136 of 446 Old 02-10-2020, 08:35 PM
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How you’re not met with torches and pitchforks...

Chris
I invite them over for movie nights..... Also being on the 2nd floor above the supers storage room helps....


Juju

Sub List: 1- Red Five Mini V1 Devastator 18" w/PA460, 1- Red Five Devastator LFE 21", 1- Red Five Devastator 21" Finalizer V2 DF , 1- BOSS platform [The Hideaway Theater], 2- 18" "Full Marty" tuned to 17Hz w/RSS460HO
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post #137 of 446 Old 02-10-2020, 09:02 PM
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On the topic of experiments, how could a SLAPS or two be worked into a JBL Devastator?

I’d love to see that.

Has anyone ever put a passive radiator at the end of a QWR?

I’m guessing using a SLAPS as the port for the hemholts part of the enclosure would function as predicted.

Leave it at 8 ohms and call it a day :)
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post #138 of 446 Old 02-10-2020, 09:35 PM
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I’ll take it if you have the file saved. I’m not sure if it means anything, but yay more colorful lines.
I’ll pm you my email address.

Chris
Sent to your email.
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post #139 of 446 Old 02-10-2020, 10:01 PM
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Quote:
Originally Posted by a77cj7 View Post
In case the burning (hah) question on anyone’s mind is “What’s more fun than ground-plane testing in the snow?”, I now have an answer. Ground plane testing in the snow, in the dark, at 20*. Bonus points for it starting to snow during the first set of sweeps.



I haven’t even looked at the data yet, will work on that once I can feel my fingers again.

I did start out with the concern brought up earlier by @BP1Fanatic . Whether the dolly I had the enclosure on affected the measurement. The result surprised me by being noticeable for part of the range, but wasn’t enough to significantly alter the data.

All the other testing tonight was performed without the dolly. (I certainly wasn’t gonna fight it back on there)

Chris


Dude, you’re the man. Seriously!! Thank you for all your hard work! I’ve really enjoyed reading this thread. Still don’t understand most of it

But! I have enjoyed it. And, I may have to build one or two of these bad boys to go with the horns I have now.

- Mike
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post #140 of 446 Old 02-10-2020, 10:05 PM - Thread Starter
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I used the advice from Josh, @Ricci , earlier today and performed another set of sweeps in each driver/amplifier configuration.

The box was set up in series/parallel mono, so I started there. I dragged all the gear back into the driveway again, and got it hooked up. Mic is set at 4m again.


I used the multimeter and a 60hz sinewave to set the amp at 100w for a baseline. Using 4ohm nominal impedance, that is 20v.


I ran a set of sweeps, ending at 1000w, the rating of the amp.
Voltages are recorded from DMM, wattages are calculated using the 100w baseline and the change in dB.
Ex. First sweep is -9db, 12.5w.

I checked the data by calculating the wattage using the recorded voltage. They all check within reasonable error.

Next, I popped the hatch and set it up for parallel 2ohm 2 channel operation.


I once again used the multimeter and 60hz test tone to set the baseline of 100w. In this case, I needed 50w into 2ohm per channel. This calculates to 10v.


I performed another set of sweeps, stopping at 1000w. Voltage was recorded from dmm on one channel, wattage is total calculated.

These don’t look nearly as pretty as the series/parallel, not sure what is going on.

Lets compare the 1000w sweeps from each set, and see how they match up.

Well, thats not good.

Now, let’s add in the models on 1000w.

This isn’t getting better.

The more I try to remove variables, the farther off my results are, lol. This is getting frustrating.

I do realize that I made an oversight during the parallel 2ch measurements. I intended to swap the dmm to the other channel to verify equal output, but never did. I blame being cold.

I also used Josh’s instructions to take distortion sweeps at 1000w for both configurations. I’m not sure what I’m looking at here, so I’ll just post the graphs.

Series/Parallel:


Parallel 2ch:


Chris
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post #141 of 446 Old 02-11-2020, 04:53 AM
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^^Exellent work

If you connected them internal for 2ch 2ohm operation, why don’t you just do the series connection on the outside, from the two speaker posts? No need to open hatch and reconfigure the whole thing?

In distorsion graph you need to put the marker somewhere to get numbers, say at tuning or ~ 20hz.

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post #142 of 446 Old 02-11-2020, 05:41 AM - Thread Starter
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^^Exellent work
Thanks!



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If you connected them internal for 2ch 2ohm operation, why don’t you just do the series connection on the outside, from the two speaker posts? No need to open hatch and reconfigure the whole thing?
Superstition? Or at least lack of understanding.
Since I don’t understand why parallel vs series/parallel changes the model so much, I have been sticking to wiring configurations that seem the most “balanced” to me.
Series/parallel: I series the upper and lower driver on each side, then parallel these 8ohm pairs.
Parallel 2ch: I parallel the upper and lower drivers, each side on a channel.

I like your way better for changing up in the driveway though.


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In distorsion graph you need to put the marker somewhere to
get numbers, say at tuning or ~ 20hz.

I wasn’t sure what frequency to be interested In, so I left it off.

Chry
Chris
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post #143 of 446 Old 02-11-2020, 06:31 AM
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Thanks!

Superstition? Or at least lack of understanding.
Since I don’t understand why parallel vs series/parallel changes the model so much, I have been sticking to wiring configurations that seem the most “balanced” to me.
Series/parallel: I series the upper and lower driver on each side, then parallel these 8ohm pairs.
Parallel 2ch: I parallel the upper and lower drivers, each side on a channel.

I like your way better for changing up in the driveway though.

I wasn’t sure what frequency to be interested In, so I left it off.

Chry
Chris
Yeah, the differences between how you connected it was news to me too
But if you measure it with internal and external series-parallel next time and see if it is the same, you can continue to do it external from here on The easiest would be two external 4pole speakons, and you would be set now matter what (for the life of me i can’t understand why you guys don’t use speakons??? They are soooo much easier to deal with )

Well, maybe where 2nd and 3rd harmonics maxes out would be a starting point for distorsion?? Like ~28 or ~45hz.

EDIT: maybe you should try series and parallel them sideways to? Just to see if there is a difference that way too?

Edit2: you say you use one Stewart amp here, but isn’t there two amps on that test cart?

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post #144 of 446 Old 02-11-2020, 07:22 AM - Thread Starter
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EXPERIMENTAL Quad JBL Devastator Build

Quote:
Originally Posted by Nalleh View Post
Yeah, the differences between how you connected it was news to me too

But if you measure it with internal and external series-parallel next time and see if it is the same, you can continue to do it external from here on The easiest would be two external 4pole speakons, and you would be set now matter what (for the life of me i can’t understand why you guys don’t use speakons??? They are soooo much easier to deal with )

Yeah, I can give it a shot next time I change it.
The don’t use speakons because they stick out. All my theater speakers are tight to a wall/chair.
This project would make sense with speakons, but I didn’t have any. I always keep a handful of my favorite terminal cups around. I could add another pair for wiring ease, but they’re 6 bucks each. I’ll probably just keep popping the hatch cover.


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Well, maybe where 2nd and 3rd harmonics maxes out would be a starting point for distorsion?? Like ~28 or ~45hz.


I can do that tonight. I’m not sure that it’s relevant now that I’ve shown the spl is different.

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EDIT: maybe you should try series and parallel them sideways to? Just to see if there is a difference that way too?
I could, not sure what it proves though.



Quote:
Originally Posted by Nalleh View Post
Edit2: you say you use one Stewart amp here, but isn’t there two amps on that test cart?

The second amp is not being used. It was running the full range speakers for music testing.


As of now, my next plan is to verify voltage on the second channel.
If that checks out, I’ll try to get a car amp set up thats capable of 1000w 1ohm. Try a true parallel sweep.
I have one of these sitting on the shelf:
https://www.crutchfield.com/S-SpoRbe...-T10001bd.html

This is subject to change with suggestions, of course.

Chris
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post #145 of 446 Old 02-11-2020, 07:53 AM
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^^^ Sounds good

I am just flinging out suggestions, LOL.

Maybe @Ricci or @mtg90 can advice better

About speakons, i just put these in the cart now and then:

https://www.ebay.com/itm/10SET-BLUE-...53.m2749.l2649

10pcs of each and work great

Dual AVR 13.1.8 SWAtmos - Atmos 13.1.8/DTS X 9.1.8/Auro 3D 13.1 - Denon AVCX8500H+AVRX7200WA - Klipsch+KEF - 4xSI18" - 12x12" w/6xSLAPS M12 VNF - 4x12"HB+2x18"CLHB - 6x Crowsons - 4xBK-LFE - 2x12"BB - 2x "4DX" fans- 6xNU6K - Minidsp 10x10HD-Vertex2-Oppo UDP203-XB1X-ATV4K-JVC RS600-Dreamscreen V2 120"-Samsung QE82Q60.
>>>>Nalleh’s HT<<<<
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post #146 of 446 Old 02-11-2020, 08:41 AM
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Quote:
Originally Posted by a77cj7 View Post
You think the 2” it sits above the ground significantly changes response at bass wavelengths?
I tend to doubt it would make a measurable difference. After all, if I had the box sitting sideways, much of the port and horn mouth would be much farther from the ground. As are the cones in most direct-radiator designs. Yet, those are still ground-plane measurements.
As you found out it can make a measurable difference but in most cases it would be small enough to ignore.

Also you are nuts for dragging all this gear out in the snow and cold! I was being half sarcastic earlier when I asked if this was fun...It can also be very frustrating and a lot of work!

The cold will tend to slow down the speed of sound, boost the SPL some and stiffen the speaker suspensions compared to normal room temps. Humidity and barometric pressure also will affect the measurements.

Quote:
Originally Posted by a77cj7 View Post
I used the multimeter and a 60hz sinewave to set the amp at 100w for a baseline. Using 4ohm nominal impedance, that is 20v.

I ran a set of sweeps, ending at 1000w, the rating of the amp.
Voltages are recorded from DMM, wattages are calculated using the 100w baseline and the change in dB.
Ex. First sweep is -9db, 12.5w.
I use the voltage corresponding to 100w nominal into the nominal impedance because it is well accepted as the standard voltages for sensitivity. I use 10X the voltage in order to get better SNR and also because subs get used harder than any other speaker usually so it's more representative of use than 1w nominal.

Don't worry about labeling things with power or testing at a certain power IMO. I never do. It's voltage that matters. Power is not constant at all and varies with impedance and frequency. Voltage on the other hand is constant from the amplifier. It takes a while to get this stuck in your head, since everything is marketed by power ratings and it's deeply ingrained in most of us. Power still matters of course but it's much more complicated than a single number.

If you want to calculate how much maximum power the speaker is receiving just use the dcr if you don't have an impedance measurement. It's close enough. If you have the impedance curve just use the in bandwidth minimum.

Speaking of which an impedance curve would give a lot of additional information. You already seem to have a good grasp of REW and you seem to have everything you need. Just takes a bit of wire an amp and a resistor if you don't have something like a DATS. You do have to be careful with the level to not fry your soundcard with the amp. This is something that could be done inside at low volume with 1 volt or less into the sub.

Quote:
Originally Posted by a77cj7 View Post
I performed another set of sweeps, stopping at 1000w. Voltage was recorded from dmm on one channel, wattage is total calculated.

These don’t look nearly as pretty as the series/parallel, not sure what is going on.
Background noise is much higher in this set. Any time you see random bumps and dips in the measurements that do not repeat in other measurements it is noise. Sometimes it DOES repeat too like a 60Hz ground hum for example, but if it doesn't repeat between measurements that's a dead giveaway.

Quote:
Originally Posted by a77cj7 View Post
Lets compare the 1000w sweeps from each set, and see how they match up.

Well, thats not good.
That is a BIG difference. Could be an imbalance in the amp channels, or the amp current limiting a lot more into the impedance minimums when it wasn't fully bridged. This'd be my guess. Other thoughts are some output compression going on due to drivers getting some heat buildup in the coils, mismatched excursion issue, etc but none of this would make that big of a difference.


Quote:
Originally Posted by a77cj7 View Post
Now, let’s add in the models on 1000w.

This isn’t getting better.

The more I try to remove variables, the farther off my results are, lol. This is getting frustrating.
I'm with you on this. I can see a bit extra from baffle effects and potentially a bit more from regular old variations in gear and the SPL calibration and another boost from the cold temperature and denser air. Parts of the graph show 6 to 8dB of difference though. That much of a difference is hard to account for.

How far away are you from buildings and other large objects?

Quote:
Originally Posted by a77cj7 View Post
Series/Parallel:


Parallel 2ch:


Chris
Remember when MTG90 brought up the 90Hz peak in output and we were discussing it boosting the 2nd and 3rd harmonics? The orange bump at 30Hz is the 3rd harmonic getting boosted by the output at 90Hz and the large driver excursion in this range. The 2nd harmonic of 45Hz is being boosted by 90Hz, it is the red line. As expected.

Distortion is getting pretty high on these measurements. I don't think there's too much left in the tank.
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post #147 of 446 Old 02-11-2020, 09:01 AM
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I could, not sure what it proves though.
Couple more things to add.

I checked the wiring combinations in Akabak again and it turns out that not all of the wiring options with drivers in series results in the driver behavior mismatch.
All drivers parallel = Even
All drivers in series = Uneven
2 drivers closest to the closed end in series / 2 other drivers in series and then both groups parallel = Even
Driver pairs wired in series with a closed end driver and further way driver and then in parallel = Uneven
Driver pairs wired diagonally in series and then parallel = Uneven
Directly driving each woofer should = Even

I think this is right. Going from memory here.

Can you take one of the highest output measurements and scale them back by the amount of gain added from the starting level so that it compares at the same level as the starting / quietest curve? This will show how much the response changed and if there is compression happening.

Also can you post a group delay graph from one of the louder measurements but not the loudest? You want it loud to be out of the noise floor as much as possible but not so loud that the speaker is being run ragged.

These are things you can do with the measurements you've already done without taking all this gear out again.

If you feel like it attach or send me a few of the measurements.
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post #148 of 446 Old 02-11-2020, 09:32 AM
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For the distortion graphs in REW you can go into controls and check Plot Normalized to Fundamental and make sure Distortion Figures: Percentage and that will graph the distortion on a percentage scale which is much easier to interpret. Also be sure to make the Y axis limits something like 0.01 to 200%.
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post #149 of 446 Old 02-11-2020, 10:07 AM - Thread Starter
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Thanks Josh!
Ok, I’ll answer this half first, as it is huge for my testing.

Quote:
Originally Posted by Ricci View Post
Couple more things to add.



I checked the wiring combinations in Akabak again and it turns out that not all of the wiring options with drivers in series results in the driver behavior mismatch.

All drivers parallel = Even

All drivers in series = Uneven

2 drivers closest to the closed end in series / 2 other drivers in series and then both groups parallel = Even

Driver pairs wired in series with a closed end driver and further way driver and then in parallel = Uneven

Driver pairs wired diagonally in series and then parallel = Uneven

Directly driving each woofer should = Even



I think this is right. Going from memory here.
Can you verify this for me? If so, it really opens this design up to run on 4ohm. I will test to verify.

First, lets make sure we are using the same terminology. I use top referring to how the cabinet sits. Closed end of horn is top.


How I have it wired for series-parallel now: the top driver series to the one directly below it. The two resulting vertical pairs paralleled. I believe you’re saying this is Uneven.

What you’re saying: Top two series, bottom two series, results parallel = Even.

This will allow me to perform tests with the same output from the amp, excellent. Avoids the car amp cluster&@$? I was looking forward to.

Quote:
Originally Posted by Ricci View Post
Can you take one of the highest output measurements and scale them back by the amount of gain added from the starting level so that it compares at the same level as the starting / quietest curve? This will show how much the response changed and if there is compression happening.
Standard compression sweep stuff, sure. Super easy since I know the db changes. Do you want me to use the 12.5w and 1000w sweeps, or start a little higher to avoid noise issues?



Quote:
Originally Posted by Ricci View Post
Also can you post a group delay graph from one of the louder measurements but not the loudest? You want it loud to be out of the noise floor as much as possible but not so loud that the speaker is being run ragged.
Sure, I’ll try.
I’ve had issues with trying to use REW delay before. Don’t you need a timing reference to properly measure this? I was trying to use it to integrate sealed and ported in my theater, didn’t work out.



Quote:
Originally Posted by Ricci View Post
If you feel like it attach or send me a few of the measurements.
Pm me your email and I can send ya whatever data you want. I have all sweeps saved and labeled.

Thanks again,

Chris
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post #150 of 446 Old 02-11-2020, 10:07 AM
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GREAT post fellas! I love this site!

Hey Josh,

With freezing temps, stiffer cones and surrounds, would those situation cause the enclosure to move the dolly during testing?
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