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DIY HT Design Bass Driver Selection

13374 Views 101 Replies 11 Participants Last post by mayhem13, Aug 5, 2009

mayhem13

Discussion Starter · Jul 28, 2009

Ok.....So here we go. It may seem a bit premature to some watching and posting in this series but all of the important details can be worked through as we go. In this thread, i'd like submissions of suitable drivers that are capable of fullfilling the goals revealed in the polling including cost. I'm starting with the bass driver(s) as these will most likely suck up the largest portion of the budget so those submitting candidates beware. Once we have a good group to choose from, i'll poll to find the consensus and move on to midrange and highs.

For those just tuning in, the requirements for the design relevant to this poll is a three way design with extension to 60hz +/-10hz ported or sealed, 12" maximum baffle width, stand mountable enclosure, average efficiency of 92-95db 2.83/1m Vrms and peak output capability of 117db per pair......or in other words pretty F#@King loud! Single unit or pairs, doesn't matter, as long as it meets the above criteria. Oveall budget for the entire 2 speaker system is $750 including XO components.

PS...Watch the min. Z on some drivers in pairs..too low means no go!

Please support your submissions with whatever documentation is available such as FR PLots, HD testing results, Box model sims, etc. Please include the retail cost of a pair and the link to the retailer. No closeout drivers please as if this design sees it's way to completion it would be nice to know that it's sustainable for future builders. As to cost, we'll let the polling decide if it's worth the cost as it effects the rest of the build.

Some points to consider.....the intended passband of the bass section. Given the practical implimentation of a three way i would consider the highest XO point ot the midrange driver(s) would be 400hz as most mid drivers of the caliber we'll be needing can easily extend that low and some much lower. The most flexible will obviously have the greatest benefit to the design. I'll start things off in the next post. Thanx for all the research and submissions in advance. The DIY community certainly thanks you as well.

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1 - 20 of 102 Posts

mayhem13

Discussion Starter · #2 · Jul 28, 2009

3

Silver Flute W20RC38-08, 8" Wool Cone

http://www.madisound.com/catalog/pro...roducts_id=848

Re 7.3 Ohms

Sensitivity 91 dB

Power 100 watts

Fs 30.8 Hz

Qms 1.30

Qes 0.28

Qts 0.23

Vas 83.3 Ltrs

Mms 20.9 g

Cms 1281.1 mM/N

Sd 0.0214 M2

BL 10.1 TM

X-max 5 mm

Le @ 1kHz 0.92 mH

Frame Ø 203 mm

Cutout Ø 183 mm

Depth 86 mm

Krm 1.65 mW

Kxm 32.793 mH

Erm 0.853

Exm 0.591

Cost per pair $73.60

Submitted alignment Ported tuned to 50hz in 1.5cuft net (43L) parallel pair.

Unibox modeled simulation of bass extension and excursion to limits in prestented volume 125w system power avearge efficiency 97.5db before BSC.

Attachment 148852

Attachment 148853

Link to MarkK's extensive testing comparison of the Silver Flute and a group of other 8" units. Great Linear and Non Linear distortion measurments.

http://www.audioheuristics.org/measu...fer%20test.htm

Summary- I've got a pair ready to go in a box for testing so everything mentioned above is purely based on sims, speculations and others non verified testing but preliminary observations are extremely positive. In a nutshell this driver has everything going for it and them some. 2" voice coil matches up with most of the Hifi 8" group, cast frame, high sensitivity with reasonable Z for a pair, good xmax and given we won't be pushing o too far up the FR ladder, low HD in our intended passband. And lets not forhet about the cost. Chinese manufacturing at it's finest. See Zaph's testing and comments on it's siblings the 5.5" and 6.5" versions. I see no reason to suspect that the similiar positives wouldn't somewhat apply but you never know!

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penngray

· #3 · Jul 28, 2009

Quote:
Great Linear and Non Linear distortion measurments.

The nonlinear distortion of the SF8 @ 60Hz didnt look good compared to the RS250, same for the tone bursts

That link really shows the RS250 is a better driver.

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Jay1

· #4 · Jul 28, 2009

2

How about the Peerless Nomex 830869 ?

I don't have measurements to post, but the line has tested very well. The motor should be superior to the SF's with shorting rings, even if they are aluminum. Sensitivity requirements would be met for a pair with 4db BSC, sealed or ported could be used. The cost of 4 would be about $100 more then the Silver Flutes.

For a single driver solution that would match the SF's in price, a Eminence DELTA-10A could be an option.

Again, I don't have any measurements, just basic performance parameters. The biggest advantage this driver has is it can easily achieve 120db spl, while meeting all the other requirements. Actual sensitivity is 96 db so it will still work with BSC, has to be ported.

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dlneubec

· #5 · Jul 28, 2009

2

Based on Brandon's (Augerpro) testing, how about the Eminence Kappalite 3012HO. It goes for $170 each. Here is a link at Parts Express:
http://www.parts-express.com/pe/show...number=290-589
http://sites.google.com/site/driverv...r-measurements

With a 60hz BW2 low pass and a 400hz LR2 high pass implemented, below is what they look like with 125watts input. This is in a ported box of 55 liters, 60hz tuning, with a 6"dia x 6.5" long port. SPl is over 117db. With 400watts, they will go up to 122db before reaching XMAX.

With 4-5 db bsc you should have about a 93-94db sensitivity. This uses up $340 of the budget. Combine this with the B&C 6md38 for a midrange (96db sensitivity, $77/each) and the SB Acoustics SB29RDC ring radiator tweeter (93db sensitivity, $50/each) and you have a sensitivity of around 93db, with $156 left over for passive crossovers. The box may have to be widened to 12.5" or so, or it could hve tapered sides so it is wider on the botom and narrower on the top for an average of 12" wide.

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zero the hero

· #6 · Jul 28, 2009

Quote:
Originally Posted by penngray /forum/post/16900483

The nonlinear distortion of the SF8 @ 60Hz didnt look good compared to the RS250, same for the tone bursts

That link really shows the RS250 is a better driver.

that'd be great if there really was one. That was a prototype. The production driver is the RS225 and it's not sensitive enough for what the mob wants here.

I second both drivers that Jay mentioned - in fact I've already mentioned them in previous threads.

I also really like the RS270s, although if you want a pair in a ported box you're going to need permits and a certificate of occupancy.

ZilchLab

· #7 · Jul 28, 2009

Quote:
Originally Posted by dlneubec /forum/post/16903944

The box may have to be widened to 12.5" or so, or it could hve tapered sides so it is wider on the botom and narrower on the top for an average of 12" wide.

I would be surprised if cheating were allowed here....

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mjg100

· #8 · Jul 28, 2009

Quote:
Originally Posted by ZilchLab /forum/post/16904376

I would be surprised if cheating were allowed here....

Zilch, you disappointed me. I saw that you had posted and I clicked on the thread to read your suggestion.

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LTD02

· #9 · Jul 29, 2009

won't the low qms result in crushed dynanamics?

augerpro

· #10 · Jul 29, 2009

Will it? You tell us.

NEO Dan

· #11 · Jul 29, 2009

Quote:
Originally Posted by LTD02 /forum/post/16904629

won't the low qms result in crushed dynanamics?

Where did this come from? That's the first I've ever heard anything like that. Maybe I've been under a rock for too long.

mjg100

· #12 · Jul 29, 2009

Looks like I can forget about building anything right now. New water heater last week and now it looks like I am going to have to get a new dishwasher this week.

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augerpro

· #13 · Jul 29, 2009

I've heard about the high Qms thing once in a thread at diyaudio, but nobody offered any support or reasoning and that was the last I've heard about it. Pro drivers tend to have higher Qms, but not always. Thing is if you start looking for drivers with Qms above say 5 or so there really are not many, including pro drivers. Yet those seem to display dynamics just fine so I don't put much import on high Qms.

mayhem13

Discussion Starter · #14 · Jul 29, 2009

Quote:
Originally Posted by zero the hero /forum/post/16904260

I also really like the RS270s, although if you want a pair in a ported box you're going to need permits and a certificate of occupancy.

Good thing is we don't need a ported box, either will do and a pair of RS270's will work in 55L sealed.

As for the Peerless Nomex, i like the driver too, and the Polycone version...BUT....the power handling concerns me.

mayhem13

Discussion Starter · #15 · Jul 29, 2009

Ok....so here's the deal. Those submitting drivers that are realy interested in this project.....help us out here. The followers of this thread need a bit more information than random musings. Cover the bases please. It's clear i've been putting a reasonable amount of effort into this and if i post driver suggestions in the same fromat as the Silver Flute it may seem like i'm leading the group.....AND DOING ALL THE DAMN WORK!

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mayhem13

Discussion Starter · #16 · Jul 29, 2009

Quote:
Originally Posted by dlneubec /forum/post/16903944

Based on Brandon's (Augerpro) testing, how about the Eminence Kappalite 3012HO. It goes for $170 each. Here is a link at Parts Express:
http://www.parts-express.com/pe/show...number=290-589
http://sites.google.com/site/driverv...r-measurements

I've considered a similiar platform with the B&C 10NW64 that still woks on our size baffle and performs quite well but on the low end of the sensitivity floorplan. I wouldn't suggest the Eminence simply because Brandon's project is centered around it. I do like the 6MD38 and SB29 for this design though. My only concern with the 6MD38 is beaming. Beyma's got a 5" mid driver that's pretty outstanding though.

penngray

· #17 · Jul 29, 2009

Quote:
I do like the 6MD38 and SB29 for this design though. My only concern with the 6MD38 is beaming. Beyma's got a 5" mid driver that's pretty outstanding though.

at what frequency is the 6md38 beaming?

mayhem13

Discussion Starter · #18 · Jul 29, 2009

Quote:
Originally Posted by penngray /forum/post/16905434

at what frequency is the 6md38 beaming?

Might beam is the statement, but given the driver diameter 2k sound about right. I'd like to push the mids to 3khz if possible.

Penn, consider some things for a minute. I've was in the Pro audio live sound industy for a looooong time and some things that were immediately apparent to me from the board was the closer to the stage i got, the more the soundstage fell apart. Even at moderate volumes, i can't listen to a horn loaded CD at 15ft listening distance, no less a horn loaded 10-12" mid, sounds like the output is being piped directly in my ear canal. If you've ever been to the legendar CBGB's and have seen where the mixing console was, you can feel my pain for sure. I'd set the mix and run to rear as fast as i could, dreading a revisit to tweak the mix. And were talking top of the line JBL stuff here.Pro drivers have a distinctive adavantage over hifi drivers in many areas, mid field listening NOT being one of them IMO. The idea of stuffing a WG or horn lens with random porosity foam seems counter productive to me in it's execution. It's mechanical attenuation any way you slice it. If i were Brandon, i'd wrap the horn or WG in layers of sheer womens hosiery and see how this compares to the foam. No glue needed and they come in colors. This is certain to start some serious flaming but hey, it might as well be my turn to start a firefight for a change!

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penngray

· #19 · Jul 29, 2009

You might have taking my question the wrong way, I was curious about your usage and where you believed it would start beaming.

I own it and the SB29 so its good too know.

btw, you have to discuss your opinions about Waveguides with someone like Geddes or Auger not me....Im just a believer so far in its functionality and I have also thought about pantyhose covering the waveguide.

augerpro

· #20 · Jul 29, 2009

Mayhem you are going to hate me for saying this but maybe selecting the mid first will help with the woofer selection. If we only need to go up to say 150hz, that opens a lot more options than if 400hz is needed. You may be able to get away with something cheaper if you don't demand too much from it. I imagine price will be big factor for the woofer after you blow the budget on a nice mid and tweeter and dont' forget the crossover! Other than being sealed you really don't know anything else that is required from the woofer because you don't know what mid you are using. Among other things.

That said I like the Silverflutes. I just decided to use three as "subs" for my updated Bose Buster project. If you can stretch just a bit farther the Dayton RS series are really a no brainer for clean bass/lower midrange at a reasonable price. Big boxes though usually. Was it decided to do standmount? If floorstander you could probably find a cheapish 12" and mount it side firing. Lots of options really.Just need to know the requirements/limits for the woofer.

PS keep at it! It will all be worth it in the end!

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