Driver choice

Hello guys.

I live in a small room (12 sq.m, about 130 sq.ft), and I'm not planning to move away for a long while. I want to build a nice pair of speakers, and I need help in drivers choice.

I'll build the cabinet from MDF or plywood, using the "translam" method. The speakers (because of the small size of the room) will be very close to the back and side walls. The room is about 9 ft wide (3 meters) and 13 ft long (4 meters).

I would like to build standfloor speakers, because I want a good low-end extension, a fast and articulate bass response. Also, I was planning to make it a 2 way. I want a simple crossover, so I'll have less chances to mess it up.

The woofer I was planning to use is the Scan Speak 18W/8531 G00. For the tweeter, I was considering the Vifa XT25-BG60, the SB Acoustics SB29RDC, or a Scan Speak Revelator tweeter. I would rather use a cheaper one (I find the Revelator tweeter ridiculously expensive!).

Please, from your experience, is the woofer ok? Is it too large (or small :)) for my room? Would you recommend a better woofer for a similar or smaller price, better in terms of low-end extension and midrange quality? Also, could you recommend a tweeter?
P.S.: I love the sound of paper drives and silk tweeters
P.P.S: I listen to almost every kind of music, but I'm looking for good quality in classical music, jazz, soft-rock.

Thank you!
 
Hi,

A closed box should give good results in your intended room and speaker place; the SS 18W/8531G00 is one of the best 7" available today and perfectly adapted to i.e. a 0.56 Qtc closed box of approx. 1.09 cu ft. Qtc 0.56 gives a very good compromise between maximum flat response and best pulse response. :)
 
Thank you for your answers!

I would prefer to avoid Transmission Lines, TWQT, or any other complicated constructions. They might yield better results, true, but they are difficult to work with.

What I want is to buy a couple of drivers that work very well together, to build a sealed or bass-reflex enclosure, with a minimal crossover (hopefully without any Zobel, impedance correction filters or any other complications in the crossover). Hopefully, by being forced to keep the speakers very close to the walls, I might even avoid a baffle compensation circuit.

So, the midwoofer is ok... Now could you recommend a tweeter that matches this woofer? I'm concerned about voicing. I don't want paper-sound mids and metal-sound highs... I have seen dozens of build using this woofer and a Revelator tweeter, but I'm still hoping I could save a couple of hundred euros by buying a cheaper tweeter close in performance and sound-print...

One more thing I'm still concerned about. A 1 cu.ft (28 liters) enclosure with a 7" woofer, very close to the walls, is not too much for a 12 sq.m (about 130 sq.ft) room, is it? I now have a home-made 1.75 cu.ft enclosure with 4 5" kevlar woofers, 1"tweeter, and a (not so great) multi-slope crossover, and it really seems too much for my room at medium-high levels.
 
In a small room the room gain begins at higher fr; besides the speaker place close to walls that's why I suggested a closed box which is more adapted to your config than opened boxes.
Regarding the tweeters the XT25 seems not to be a good match to a 7"; but the SB29 or a revelator are OK; one of my prefered tweeters is the SEAS 27TDFC or even more adapted to a 7" and easy to filter is the 27TBCD/GB-DXT.
 

kbgl

Member
2010-04-03 1:25 pm
Thank you for your answers!

I would prefer to avoid Transmission Lines, TWQT, or any other complicated constructions. They might yield better results, true, but they are difficult to work with.

What I want is to buy a couple of drivers that work very well together, to build a sealed or bass-reflex enclosure, with a minimal crossover (hopefully without any Zobel, impedance correction filters or any other complications in the crossover). Hopefully, by being forced to keep the speakers very close to the walls, I might even avoid a baffle compensation circuit.

So, the midwoofer is ok... Now could you recommend a tweeter that matches this woofer? I'm concerned about voicing. I don't want paper-sound mids and metal-sound highs... I have seen dozens of build using this woofer and a Revelator tweeter, but I'm still hoping I could save a couple of hundred euros by buying a cheaper tweeter close in performance and sound-print...

One more thing I'm still concerned about. A 1 cu.ft (28 liters) enclosure with a 7" woofer, very close to the walls, is not too much for a 12 sq.m (about 130 sq.ft) room, is it? I now have a home-made 1.75 cu.ft enclosure with 4 5" kevlar woofers, 1"tweeter, and a (not so great) multi-slope crossover, and it really seems too much for my room at medium-high levels.

How loud do you want to be able to play? Have you measured the bass response that you currently have? Your room may be boosting the midbass quite a bit. Have you considered EQ. A speaker that has a higher f3. (ie, a small speaker) could help. Why do you want to avoid zobels and such?
 
Crazyhub - thank you for the answer and suggestions. I was also considering the SB29 and the SEAS 27 TDFC. They would save me around 300-400 eur where I live, compared to the Revelator tweeter. :)
I think I will try a colsed box and a down-fire bass-reflex cabinet, and settle for one of them. I'm leaning towards the closed box too, but I read that the 18w revelator has a better midrange in bass-reflex or TL.
So, placing the speaker close to the wall increases my bass and midbass response. I knew that. What does it do to the midrange? And what can I do to make the midrange sound good when placing the speakers almost in the corners of the room?

Kbgl - I was hoping to get to 100-105 dB when I want to, but usually I want about 90-95 dB... I measured the response with a cheap mic, and the midbass is indeed boosted, and not only a bit (about 8-9 dB at 150-200 Hz). The speakers do sound boomy. The cabinet is a front ported bass-reflex. The EQ flattens the response a bit, but they still don't sound really good. And the mids are not really that good. It might be because of the crossover, but they are using cheap drivers, so...
I don't want a higher F3, I actually want a lower F3, if that's possible.
I want to avoid zobels, notch filters and any other complications for 2 main resons: I want as few components in the path of the sound as possible, and as good as my budget will allow, so I want to avoid using a lot of expensive components in order to get better divers. And 2, I really don't know a lot about crossovers, I don't have the equipment I need to build a good crossover, and the only friend I have that has the equipment and the knowledge has left the country...

Sdclc126 - I know the ZRT, thank you! I'm still trying to build it with a cheaper tweeter and a simpler crossover.
 

kbgl

Member
2010-04-03 1:25 pm
Crazyhub - thank you for the answer and suggestions. I was also considering the SB29 and the SEAS 27 TDFC. They would save me around 300-400 eur where I live, compared to the Revelator tweeter. :)
I think I will try a colsed box and a down-fire bass-reflex cabinet, and settle for one of them. I'm leaning towards the closed box too, but I read that the 18w revelator has a better midrange in bass-reflex or TL.
So, placing the speaker close to the wall increases my bass and midbass response. I knew that. What does it do to the midrange? And what can I do to make the midrange sound good when placing the speakers almost in the corners of the room?

Kbgl - I was hoping to get to 100-105 dB when I want to, but usually I want about 90-95 dB... I measured the response with a cheap mic, and the midbass is indeed boosted, and not only a bit (about 8-9 dB at 150-200 Hz). The speakers do sound boomy. The cabinet is a front ported bass-reflex. The EQ flattens the response a bit, but they still don't sound really good. And the mids are not really that good. It might be because of the crossover, but they are using cheap drivers, so...
I don't want a higher F3, I actually want a lower F3, if that's possible.
I want to avoid zobels, notch filters and any other complications for 2 main resons: I want as few components in the path of the sound as possible, and as good as my budget will allow, so I want to avoid using a lot of expensive components in order to get better divers. And 2, I really don't know a lot about crossovers, I don't have the equipment I need to build a good crossover, and the only friend I have that has the equipment and the knowledge has left the country...

Sdclc126 - I know the ZRT, thank you! I'm still trying to build it with a cheaper tweeter and a simpler crossover.

You have EQ to fix the bass, so the big issue is SPL, and smooth response. I've not looked at the response of the scan woofer yet, but what you want is something very flat through 3k or higher, with a smooth rolloff. For a 2-way without a sub, !00 dB in room is asking for a lot.
 

ScottG

Member
2003-02-04 12:23 am
US
..Also, I was planning to make it a 2 way.


..I want a simple crossover, so I'll have less chances to mess it up.

I would rather use a cheaper one (I find the Revelator tweeter ridiculously expensive!).

.. ..could you recommend a tweeter?

Would you recommend a better woofer for a similar or smaller price, better in terms of low-end extension and midrange quality?


Thank you!



Yes.

Because you want a simple crossover I'd suggest the Scan Speak Discovery 10F/4424G00 as your *tweeter*.

It has a very similar off-axis response when compared to standard 1.1" dome tweeters but has several additional octaves of lower freq. extension.

http://www.zaphaudio.com/temp/Scan-Speak-10F-4424G00-FR-offaxis-0-15-30-45-60.gif

Linear Decay is better than most tweeters:

http://www.zaphaudio.com/temp/Scan-Speak-10F-4424G00-CSD.gif

Perfect for a 1st order design.


I'd also suggest *2* Usher 8945A's (per loudspeaker) wired in parallel for an average 4 ohms. (..they have acceptable linear decay higher in freq., are reasonably linear, have outstanding non-linear distortion at lower freq.s, and have a low Vas allowing for a smaller enclosure overall even with 2 drivers.)


Figure around 700 Hz for the crossover. (..a WWT design. The tweeter below the two woofers, and about 25 inches off of the floor with polar tilt 15 deg.s oriented upward to the two woofers.)
 
Last edited: