Not to derail, but...I have wanted to do the side by side but am just not dedicated enough to buy the SS version. Of course one reason is the potential NLA nature of the Peerless drivers. The double-magnet version is not listed as one of the Peerless drivers that will be back in stock at PE in May, BUT DigiKey has 715 in-stock ready to ship. So this should be a reproducible design for a while.
I was planning out a design and started based on manufacturer data. Your sim is a lot better; smaller enclosure, lower tuning and much more flat and extended low frequency response. Which is encouraging. Guess I’ll take the time tomorrrow to break them in then toss them on the DATS
Maybe not but it can be used to compare other alignments/box volumes/drivers for the same application . . .
I have found that ported woofers GD is exacerbated in-room (mine) and that sealed is the only solution without treating the room (not possible/practical for me).
No, not pick out/choose but rather how best to align/house/DSP it for use in my application, Sir.
Please carry-on - I was just inquiring out of curiosity. I have already settled upon my woofer for use with the DM7600.
Best!
The same group delay will exist with the same driver with the same extension; in both sealed + boosted or equal performing vented boxes. It's the truth.
JR and Wolf are absolutely correct concerning GD being a product of low frequency extension.
My inquiry revolves around the room modes/reinforcement of the environment and just how low is low enough for the woofer roll-off/slope in order to satisfy the frequency response required/needed for the application.
I really wanted to use one of the round GRS ribbons, but this is going to be capable of very high output and I doubt the ribbon would be able to cross low enough and still handle things. This dome has high power handling and should have no problems with things. I already have a pair in use that I plan on recycling into this design.
This woofer models very well in 2 cubic feet tuned to 28Hz with 0.5 ohms series resistance. It exceeds Xmax at 70W at 23Hz, at which point it is tickling 100db after baffle step losses. At sane listening levels, lets call it 85db peaks (it only takes 4 or 5 watts to get there) there is no exceeding of Xmax at all, all the way into infrasonic region. It is only using about 1.5mm of cone excursion above tuning at this output level, as well. So bass and lower mids should remain nice and clean.
Disregard my alignment posted above, apparently I have two different woofers, one has a much higher Fs and Vas than the other. I'll have to do some burn in on these and see what happens. As it is, they are about 1.5db different, as well. So maybe a knock against them for consistency. We shall see. So yeah, ignore what I said about their performance for now.
So apparently I am an idiot, is the problem here. I have no idea what driver I was modeling and thought was the Sig, but it was wrong. Both of my Siggies model pretty close to each other, although there are some minor differences in specs.
Higher Fs, but also several db more sensitive. Sigh. Changes nothing, will still be installed in 2 cubic feet, Fs just moves from 28 to 36.
Will still play plenty loud without breaching Xmax, so still a high potential build.
Here is the aesthetic I'm shooting for, unfortunately the kickass name of "gorilla" Telegrapher already took for these. That was my nickname iny powerlifting days.
You can buy the Gorilla for less than 10k/pr which is not bad at all considering they are large and active. One drawback that I can see is the F3 is only 61Hz. Subwoofer is absolutely mandatory with them. Mine will not necessarily require a subwoofer so there.
Comments
So started CAD work this morning. To the point of ciphering the bracing.
Not to derail, but...I have wanted to do the side by side but am just not dedicated enough to buy the SS version. Of course one reason is the potential NLA nature of the Peerless drivers. The double-magnet version is not listed as one of the Peerless drivers that will be back in stock at PE in May, BUT DigiKey has 715 in-stock ready to ship. So this should be a reproducible design for a while.
Is your WinISD sim of the Sig270 using manufacturer data or measured?
Measured.
I was planning out a design and started based on manufacturer data. Your sim is a lot better; smaller enclosure, lower tuning and much more flat and extended low frequency response. Which is encouraging. Guess I’ll take the time tomorrrow to break them in then toss them on the DATS
JR - Check your Group Delay, please?
Why? Group delay is a function of extension. Cannot avoid it.
Maybe not but it can be used to compare other alignments/box volumes/drivers for the same application . . .
I have found that ported woofers GD is exacerbated in-room (mine) and that sealed is the only solution without treating the room (not possible/practical for me).
Anyways - I'll watch from here-on-out . . .
Do you believe you can pick out a woofer based on group delay?
No, not pick out/choose but rather how best to align/house/DSP it for use in my application, Sir.
Please carry-on - I was just inquiring out of curiosity. I have already settled upon my woofer for use with the DM7600.
Best!
The same group delay will exist with the same driver with the same extension; in both sealed + boosted or equal performing vented boxes. It's the truth.
InDIYana Event Website
.
JR and Wolf are absolutely correct concerning GD being a product of low frequency extension.
My inquiry revolves around the room modes/reinforcement of the environment and just how low is low enough for the woofer roll-off/slope in order to satisfy the frequency response required/needed for the application.
Well, applying a high-pass to the woofer to limit extension increases GD . . . so, alignment, box volume seem to be where it's at . . .
I believe this is a correct CAD drawing for what I hope to do here:
Settled on a tweeter, as well:
https://www.madisoundspeakerstore.com/soft-dome-tweeters-sb-acoustics/sb-acoustics-sb26stwgc-4-fabric-dome-tweeter-with-wave-guide/
I really wanted to use one of the round GRS ribbons, but this is going to be capable of very high output and I doubt the ribbon would be able to cross low enough and still handle things. This dome has high power handling and should have no problems with things. I already have a pair in use that I plan on recycling into this design.
This woofer models very well in 2 cubic feet tuned to 28Hz with 0.5 ohms series resistance. It exceeds Xmax at 70W at 23Hz, at which point it is tickling 100db after baffle step losses. At sane listening levels, lets call it 85db peaks (it only takes 4 or 5 watts to get there) there is no exceeding of Xmax at all, all the way into infrasonic region. It is only using about 1.5mm of cone excursion above tuning at this output level, as well. So bass and lower mids should remain nice and clean.
This is a design with a lot of potential.
Disregard my alignment posted above, apparently I have two different woofers, one has a much higher Fs and Vas than the other. I'll have to do some burn in on these and see what happens. As it is, they are about 1.5db different, as well. So maybe a knock against them for consistency. We shall see. So yeah, ignore what I said about their performance for now.
Well that’s much less encouraging, LOL
So apparently I am an idiot, is the problem here. I have no idea what driver I was modeling and thought was the Sig, but it was wrong. Both of my Siggies model pretty close to each other, although there are some minor differences in specs.
Higher Fs, but also several db more sensitive. Sigh. Changes nothing, will still be installed in 2 cubic feet, Fs just moves from 28 to 36.
Will still play plenty loud without breaching Xmax, so still a high potential build.
Should be a great sounding design. I love that your new tweeter choice mimics the mid in the visual dept.
Bears a resemblance, for sure.
Here is the aesthetic I'm shooting for, unfortunately the kickass name of "gorilla" Telegrapher already took for these. That was my nickname iny powerlifting days.
I can't afford Illuminator drivers, either.
Oh yeah! Rev 22w/8857T, Illuminator 12MU, and I'm betting an OEM SS tweeter.
InDIYana Event Website
You can buy the Gorilla for less than 10k/pr which is not bad at all considering they are large and active. One drawback that I can see is the F3 is only 61Hz. Subwoofer is absolutely mandatory with them. Mine will not necessarily require a subwoofer so there.
Decided to roll the dice and buy a pair of tweeters off AliExpress.
I just found this on AliExpress:
$197.96 | A Pair 2pcs of Melodavid Be28SE 28mm beryllium Be dome tweeter Neodymium
https://a.aliexpress.com/_mtGCylz
Looks pretty good on paper. ~$100/ea puts it up against some pretty heavy hitters that's for sure.
aesthetically - perfect match for the DM7600 - nice find!
https://a.aliexpress.com/_mKDvGiR
I was checking these out, I'm sure you've probably seen them.
https://www.htguide.com/forum/forum/primetime-a-v/mission-possible-diy/driver-testing-discussion/950314-the-best-tweeter-i-ve-tested-yet
I saw that, and have reason to believe this model is an upgrade or at least uses the same motor.
Those are probably worth every penny.
Looks very promising! I hope these meet your expectations and you'll bring them to Iowa this Fall.