Help with bass section of tower

[willy65000]

Hello. I've been lurking on this site for quite some time and now could use a little help with driver selection for a project. I have access to a pair of Elac Db62-bk-2.0 new in the box for non much money and would like to use them for a speaker project. I'm looking to build a pair of almost full range floor standers by using the Elacs in their original configuration as a tweeter/midrange combo with the factory crossovers still in place and a lower section beneath them that consists of either 3 6 1/2" woofers or 2 8" woofers that would cover the lower frequencies. I plan to use a Mini Dsp 2X4 as a two way crossover to split the frequencies at around 250-300hz. I'm not concerned with extension as much as i am with the quality of the lower frequencies. Think Revel F208 on a budget. Ideally i would like to stay under $400 for the drivers alone. I'm thinking that 2 "8 woofers per side is probably my best bet for my budget. Any help with driver selection would be greatly appreciated.

 

[alex-z]

If you are looking for bass quality over extension, go sealed. Ported designs can sound good, but are much harder to perfect. The fact that you have DSP available makes this especially viable.


Peerless 830869 has fairly low motor inductance for an 8" woofer. I would run 2 of those per tower.

Home

Peerless by Tymphany 830869 8" Nomex Cone HDS WooferThe Peerless High Definition Sound (HDS) Series offers high-quality solutions for multi-way speaker systems employing vented box alignments. This driver utilizes the famous Peerless Nomex cone which offers neutral and accurate audio...

www.parts-express.com

Edit: You will still need a subwoofer even if you go ported. Power handling becomes extremely low if trying to make them play below 40Hz.

 

[HammerSandwich]

That's solid advice. Peerless seems to be going thru some supply issues and/or changing their commitment to DIY, but HDS drivers are highly regarded.

Tell us about your bass amp, because it might not match well with 3x drivers. When all woofers share a single volume, you want them in parallel. With 8-ohm drivers, that's a fairly demanding load but could well work. Using 4-ohm drivers, you'd need to run series with a 3-volume box, and you'd lose ~6dB of sensitivity.

IOW, 2x 8-ohm 8s in a shared box look easier than 3x 6s. OTOH, if you like a $40ish 6", going 2s2p could expand your options without making the bass base too tall, and you'd need only one extra panel per cabinet. Maybe Peerless HDS with truncated frames for that?

"$" hints you're in the US. Dayton's one of the value leaders over here, and the RS225's a popular 8". The DS(A)-215 sims pretty nicely, too, though it has a bit less Xmax. Elsewhere, perhaps Monacor or SB. Pro woofers probably don't make much sense here, since the active XO implies you won't need the sensitivity & they do cost more.

See Dibirama & Hificompass for driver test results.

 

[voodooless]

What about SB Acoustics SB23NRXS45-8?

 

[willy65000]

Thanks for the replies to my question and i will say that i wasn't as clear as i should have been with my post. When i said that i value bass quality over extension i meant that i don't need them to play flat down to 20 hz. It seems like most of the speakers that i would be interested in if i had a large budget play flat down into the mid 30s. The above mentioned Revel f208 has a 3db down point of 31 hz i believe. I didn't have any luck finding out the tuning frequency of that speaker but I'm guessing maybe around 35 hz or so. Also, i agree with the suggestion on going with two 8s in order to keep the impedance at a reasonable level. I would be curious to know how manufacturers achieve such goals when using say 3 6 1/2" drivers. The only amplifier I currently own is an Adcom gfa555 mk1 so I'll be needing another to make this setup work. I'm a bit confused about whether i should be looking at woofers or subwoofers given my planned crossover frequency of somewhere between 250 and 300 and the ability for them to play down into the mid 30s. A sealed box would surely simplify things but i definitely don't plan on using separate subwoofers so a front ported enclosure might be my only option. I say front because maximizing internal volume might mean the cabinets will be too close to the wall for rear firing ports. Yes i am in the US.

 

[willy65000]

Also, i have in the neighborhood of 3 cubic feet to work with.

 

[DVDdoug]

WinISD or similar software will allow you to enter the Thiele-Small parameters for your prospective drivers and optimize cabinet design.

The lowest note on a standard bass guitar is about 40Hz so often that's low-enough and most pro subwoofers used in clubs and for live events are "tuned" down to that range. A kick drum and low frequency effects in movies* can go lower, but generally as you go lower you sacrifice efficiency. The software will help you figure-out all of the compromises.

And I'm all for big-bigger woofers but they generally require a larger cabinet so that's another factor. (It depends on the Thiele-Small parameters so there are exceptions.)


* The "point one" LFE channel in moves requires a separate subwoofer channel as this channel is not included in the stereo downmix.

 

[HammerSandwich]

Paragraphs, please!

...flat down into the mid 30s. The above mentioned Revel f208 has a 3db down point of 31 hz i believe. I didn't have any luck finding out the tuning frequency of that speaker but I'm guessing maybe around 35 hz or so.

Stereophile's measurements showed 28Hz or so.

...impedance at a reasonable level. I would be curious to know how manufacturers achieve such goals when using say 3 6 1/2" drivers.

They use high-Z drivers in parallel. Unfortunately, there aren't so many 16-ohm drivers for DIYers, though the pro brands offer more. OEMs don't have that problem once they get past the garage-builder stage; they order what they need. The extreme example I recall is the original Paradigm sub with 6x paralleled drivers, which had something like a 70-ohm Re!

Adcom gfa555 mk1 so I'll be needing another to make this setup work. I'm a bit confused about whether i should be looking at woofers or subwoofers given my planned crossover frequency of somewhere between 250 and 300 and the ability for them to play down into the mid 30s.

Sure, no reason not to investigate sub drivers, as that amp should drive the extra excursion. IIRC, Zaph called out the RSS210HF as a possibility for higher XO than "sub" implies. Plenty of other options, obviously. That said, ASR's B6.2 review showed THD issues around 400-500Hz, so I'd choose drivers which could XO that high. You might not hear a difference, but it's free & easy to experiment with DSP, so you might as well have drivers that allow it.

A sealed box would surely simplify things but i definitely don't plan on using separate subwoofers so a front ported enclosure might be my only option. I say front because maximizing internal volume might mean the cabinets will be too close to the wall for rear firing ports. Yes i am in the US.

If you can get enough SPL to 35-40Hz from sealed, there's really no downside. Do not forget how many midrange issues we've seen from leaky ports!

 

[willy65000]

I changed my mind and decided to go with the Emotiva B1+ for slightly more money and brand new. They seem to review and measure a bit better as well. also, the 2X4HD is on the way. I still haven't made the woofer selection and for now will play around with an existing lower cabinet with two ported 5 1/4"s.

 

[willy65000]

The Mini Dsp and Emotiva's arrived and with help from a friend and a lower cabinet with 2 6" drivers on loan from the same person i've got things up and running.

What about SB Acoustics SB23NRXS45-8?

I received the 2X4 hd and the Emotiva's and have two lower bass cabinets that have been loaned to me by a friend. The system is up and running and i am still looking at woofers as i Don't want to make a hasty decision. I keep coming back to the 4 ohm version of those Sb woofers. According to the box recommendations from Madisound i can have f3s in the mid 30s from a 2.5-3 cubic foot box using two of those per side. Ideally i would like to hear from someone who has had success with them before pulling the trigger. Also watching the Directiva R2 thread cause there is talk of a bass section with 2 8s.