I did go ahead and order a quad of those Peerless 830855 little buggers. Doing some modeling in Unibox I was like "Wow! Really?". I found a pair of the Peerless DA25BG08-06 aluminum dome tweeters hiding behind some other drivers on my shelves. So it will be a small all Peerless MTM project I will name the "Farval Pees" (two dots over the second "a"). That is Swedish for farewell, goodbye, valediction. I know Peerless is not completely gone for us DIY'rs but the writing is on the wall so to speak.
@hifiside said:
I have a Case of these for sale on eBay. Great driver.
Oah gawd please someone buy this so I stop being tempted. I was up last night goofing around with a 6 woofer tower in winISD. If the drivers are running down ~2/3s of the length would that tend to null any transmission line effects? No, stop.. I need to stop. lol
@hifiside said:
I have a Case of these for sale on eBay. Great driver.
Oah gawd please someone buy this so I stop being tempted. I was up last night goofing around with a 6 woofer tower in winISD. If the drivers are running down ~2/3s of the length would that tend to null any transmission line effects? No, stop.. I need to stop. lol
Dude - go for it!
hifiside's ebay deal is too good to pass up.
I built some towers with Peerless SDS 6 inch woofers and 6 per side a few years ago, and loved the sound.
Effortless dynamics, wonderful presence.
I never modeled any transmission line effects, but what I think I heard was that any "bounce" from the floor or ceiling was minimized and filled in from the different path lengths so that the bass and mid-bass sounded very even and authoritative.
But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
Maximum butt-flattin! Cone area adds up to more than an 8" woofer/side.
I don't think MMMTMMM would be WAF approved, and even I don't care much for that look...Too tall. Just spitballing, maybe the new Dayton Sig 4" as a mid (dimensions match the 830855 just no flats) with XT25TG30. Relatively skinny tower ~1.2-1.3cf. Probably a next year project though.
And I noticed the matching PR is still available at PE for $8. Could scavenge the frame as a trim ring for a port. Or am I just being silly by this point?
But the issue with that is the listed Re is 5.6ohm. So a pair in parallel puts em 2.8ohm before you throw other parts in the way. Might be OK for the MTM, but it might get a little dicey keeping the impedance in check if they are just doing midrange duty. Especially if trying to cross the tweeter low. With 4x as woofers can put em series/parallel back to the 5.6ohm. 6x you could wire em to get 8.4ohm or 3.92ohm.
Having the "M"s doing woofer duty too makes my brain hurt too much right now. I'll have to stew on that some more lol.
A half ohm dcr on a coil is not hard to do, and easily returns Zmin to 3.3 ohms, which is my preferred minimum on a 4 ohm amp. Spread the filters to get a rise in transition at xover a bit, and you are golden.
@Wolf said:
Running the mids in series will be best, as you don't need the output there with BSC losses.
So in that case, could still potentially do MTM +4x woofers as a 2.5ish way (2.5.5??). Running each pair in series then the pairs parallel connected for typical parallel crossover design. That should keep the overall minimum Z above 4ohm after inductor dcr. Would simplify enclosure design a bit. Where I tapout though is in knowing how that would all add up response wise.
Personally I would do the MTMWWWW as a straight 3 way. Small sub chamber for the MTM portion and the rest of the tower volume for the 4 woofers. If you cross it right the WWWW (series-paralled wired for 8 ohms) covers all of the BSL. Then the two mids can either be wired in series as Ben suggested with little to no padding required, or wired in parallel with significant padding resistance up front. Either method brings the final impedance up just fine. Sounds like a fun project/speaker. I need to talk myself out of buying Brad's second case.
Alright. I'll probably stay the course with the MTM to learn on for now then.
I was playing around with PRs in WinISD just to see. 2x DSA135 or 1x DSA175 would give about identical results with little to no added mass needed. I know folks like to do two opposed, I have heard sometimes of PRs not being very well matched to each other. This much of a real issue?
I also like the idea of being a little different with just the single larger PR (would save ~$32 overall too). Is there really much issue with ~31g swinging around sideways?
Haven't forgotten about this. Just have other projects in line before it.
After looking back at Ben's measurements on the 830855, I suppose it likely is possible to cross up near 3khz and keep distortion in check.
Still flip flopping on the tweeter decision. I started warming up to the DX20BF00 again. Though now that I've seen the measurements on the $5 buyout tweeters that hifiside did.. I wonder if they would work with just a single cap + a notch to flatten the resonance peak. Theorizing it would flatten the tilted response above 3khz and provide a roughly 3rd order dropoff. Might still be fighting the distortion demon below xo though.
Hard to get the woofers to keep xmax in check much below 50hz so that might be the weak link more so than the tweeter.
I feel the 3mm is a conservative figure, or doing the xmax math, considering how far they move in the B'ships. I seem to remember seeing another xmax figure for those at some point, but I don't know what it was.
Comments
I did go ahead and order a quad of those Peerless 830855 little buggers. Doing some modeling in Unibox I was like "Wow! Really?". I found a pair of the Peerless DA25BG08-06 aluminum dome tweeters hiding behind some other drivers on my shelves. So it will be a small all Peerless MTM project I will name the "Farval Pees" (two dots over the second "a"). That is Swedish for farewell, goodbye, valediction. I know Peerless is not completely gone for us DIY'rs but the writing is on the wall so to speak.
Yeah, just needs a pretty long port but I'm thinking of trying out a PVC long bend for once.
Mini MTMs FTW!
The 830855 was marketed as a 3.5" SDS mini subwoofer, to be paired with the 830878 3.5" PRs. It's a terrier sort woofer, thinks it is much bigger.
InDIYana Event Website
I have a Case of these for sale on eBay. Great driver.
I used the DX20 in an MTM and thought it worked well. Crossover point was about 2.75 kHz. It does enable a close spacing for the woofers.
https://sites.google.com/view/sehlin-sound-solutions/manganese
Sehlin Sound Solutions
Oah gawd please someone buy this so I stop being tempted. I was up last night goofing around with a 6 woofer tower in winISD. If the drivers are running down ~2/3s of the length would that tend to null any transmission line effects? No, stop.. I need to stop. lol
Dude - go for it!
hifiside's ebay deal is too good to pass up.
I built some towers with Peerless SDS 6 inch woofers and 6 per side a few years ago, and loved the sound.
Effortless dynamics, wonderful presence.
I never modeled any transmission line effects, but what I think I heard was that any "bounce" from the floor or ceiling was minimized and filled in from the different path lengths so that the bass and mid-bass sounded very even and authoritative.
[Sigh] Well...
Maximum butt-flattin! Cone area adds up to more than an 8" woofer/side.
I don't think MMMTMMM would be WAF approved, and even I don't care much for that look...Too tall. Just spitballing, maybe the new Dayton Sig 4" as a mid (dimensions match the 830855 just no flats) with XT25TG30. Relatively skinny tower ~1.2-1.3cf. Probably a next year project though.
How about MTMWWWW?
lol or I just merge the projects together for MTMWWWWWW. Ridiculous enough?
Oah my, this is stupid.. stupid awesome!
Now we’re talking!
Need more woofers!
I'd unpack the other 4, but then I'd have 16 to pack up again.
There you go!
And I noticed the matching PR is still available at PE for $8. Could scavenge the frame as a trim ring for a port. Or am I just being silly by this point?
possibly 3 forward 3 back, or 4 forward 2 back with the backs ½ ways based upon baffle step ?
Seriously could do some opposed layouts for thrown mass distribution too.
InDIYana Event Website
I have 12 more for what Wolf said. If you need them.
Don't tell me that!
HA!!!
I was thinking traditional 3way.
But the issue with that is the listed Re is 5.6ohm. So a pair in parallel puts em 2.8ohm before you throw other parts in the way. Might be OK for the MTM, but it might get a little dicey keeping the impedance in check if they are just doing midrange duty. Especially if trying to cross the tweeter low. With 4x as woofers can put em series/parallel back to the 5.6ohm. 6x you could wire em to get 8.4ohm or 3.92ohm.
Having the "M"s doing woofer duty too makes my brain hurt too much right now. I'll have to stew on that some more lol.
A half ohm dcr on a coil is not hard to do, and easily returns Zmin to 3.3 ohms, which is my preferred minimum on a 4 ohm amp. Spread the filters to get a rise in transition at xover a bit, and you are golden.
InDIYana Event Website
Running the mids in series will be best, as you don't need the output there with BSC losses.
InDIYana Event Website
So in that case, could still potentially do MTM +4x woofers as a 2.5ish way (2.5.5??). Running each pair in series then the pairs parallel connected for typical parallel crossover design. That should keep the overall minimum Z above 4ohm after inductor dcr. Would simplify enclosure design a bit. Where I tapout though is in knowing how that would all add up response wise.
Personally I would do the MTMWWWW as a straight 3 way. Small sub chamber for the MTM portion and the rest of the tower volume for the 4 woofers. If you cross it right the WWWW (series-paralled wired for 8 ohms) covers all of the BSL. Then the two mids can either be wired in series as Ben suggested with little to no padding required, or wired in parallel with significant padding resistance up front. Either method brings the final impedance up just fine. Sounds like a fun project/speaker. I need to talk myself out of buying Brad's second case.
Alright. I'll probably stay the course with the MTM to learn on for now then.
I was playing around with PRs in WinISD just to see. 2x DSA135 or 1x DSA175 would give about identical results with little to no added mass needed. I know folks like to do two opposed, I have heard sometimes of PRs not being very well matched to each other. This much of a real issue?
I also like the idea of being a little different with just the single larger PR (would save ~$32 overall too). Is there really much issue with ~31g swinging around sideways?
I think either will work well. The DSA135 keeps up with the 830855 in the Bottleships, but it isn't without a workout.
InDIYana Event Website
Haven't forgotten about this. Just have other projects in line before it.
After looking back at Ben's measurements on the 830855, I suppose it likely is possible to cross up near 3khz and keep distortion in check.
Still flip flopping on the tweeter decision. I started warming up to the DX20BF00 again. Though now that I've seen the measurements on the $5 buyout tweeters that hifiside did.. I wonder if they would work with just a single cap + a notch to flatten the resonance peak. Theorizing it would flatten the tilted response above 3khz and provide a roughly 3rd order dropoff. Might still be fighting the distortion demon below xo though.
Hard to get the woofers to keep xmax in check much below 50hz so that might be the weak link more so than the tweeter.
I feel the 3mm is a conservative figure, or doing the xmax math, considering how far they move in the B'ships. I seem to remember seeing another xmax figure for those at some point, but I don't know what it was.
InDIYana Event Website