recommended shielded 2-way speaker designs? - Page 2

scone · 14th November 2004, 07:46 AM

thanks for all the suggestions everyone.

Quote:

Since you have an active 2 way with 4.5" miniwoofer, I think one of the handful of 2 way standmounts 5-7" mid/woofers would be a nice start. John Krutke's XG18/27TDFC MTM is a large standmount.

Sounds like a very inviting option. I'd have to place them on shelves about 5 ft. high and 6.5-7 ft. apart. I could angle them slightly down and inward. This is so they clear my roomie's floorstanding speakers and also to stay away from the TV. They would be very close to the wall but such is life (and they're not rear-ported so it's not as bad of a problem). Unfortunately there's not as much info on Krutke's MTM as there is on the Proac clones (actually, I can't find a single account of someone having built them, other than John himself)

I noticed that the woofer in the Proac 2.5 clone is shielded but the tweeter is not. Can unshielded tweeters damage CRTs as well? I'd have to assume yes, but perhaps the magnetic field created by them is small enough that it isn't a problem?

tktran · 14th November 2004, 12:36 PM

The woofer in the original and clone ProAc are unshielded. ScanSpeak offers a shielded version of the same driver, and people who have substituted this driver have had good results. I recall someone has built a centre speaker by doing this...

The clones must be THE most popular diy speaker of all time. IMHO, this is because

a) very good website- informative and helpful, thanks to Al M.

b) ease of build and moderate cost- it's a straightforward 2 way box speaker.

c) thoroughly fine tuned by several key people, and backed up with measurements.

The fact that the commercial (using similar but customised drivers) retailed for some 2,700 GBP/USD4,500/AUD10,000 in circa 1996-2003, makes it very tempting to the prospective DIYer...

Oh, and did I mention it does sound rather good?

Some designers prefer to do their own thing, and I can understand that you are hesitant because there's not as much feedback.

But I wouldn't be surprised if they sound as good or better, or have other qualities lacking in the 2.5.

I have other projects pending for summer 04/05 (yes we're south of the Equator so it's building time!)
Tony Gee Humble Homemade Hi-Fi
John K's NaO

cjd · 15th November 2004, 02:32 AM

Quote:

Originally posted by tktran
[B]John Krutke's
XG18/27TDFC MTM is a large standmount. If you can wait awhile his smaller L18/27TBCG should be also great value.

Got to hear these yesterday.

Top notch stuff. They were one of the only speakers that stood up to one track we played with some very heavy and somewhat distorted bass, yet they handled just about everything else with the same finesse. Really a superb speaker.

I'm not sure they'd like being placed that close to a wall though. IIRC they have full baffle step built in, so they would tend to sound boomy near room boundaries.

C

tiroth · 15th November 2004, 02:53 AM

I have the normal CloneAcs with unsheilded woofer and tweeter within 12-16" of my TV, it is no problem. (Samsung CRT HDTV) I would not worry. Closer than this, you may be pushing your luck.

scone · 15th November 2004, 05:55 AM

Quote:

I'm not sure they'd like being placed that close to a wall though. IIRC they have full baffle step built in, so they would tend to sound boomy near room boundaries.

Forgive my ignorance, but I don't know what it means to have a full baffle step built in.

There's nothing i can really do about the boominess. Even floorstanding speakers would have to be placed pretty close to the rear wall, and those would have to be sandwiched in between a TV and my roomate's speakers. At least the MTM would have breathing room on both sides because I can mount it on shelves. We live in a pretty small apartment, but college living conditions are temporary and my speakers should outlast them .

tktran · 15th November 2004, 03:57 PM

cjd,

do you mean the XG18/TDFC MTM or L18/27TBFCG?

Really I should stop looking I have too many project ideas...

I feel that 2 ways should be confined to bookshelves IMHO and smaller rooms.

If I'm going to the trouble of building large floorstanders all the time/effort and MDF/veneers deserve more drivers for cleaner bass/higher sensitivity (eg MMT or MTM), or dedicated mids and larger woofers for better midrange and lower bass eg. 3 way.

scone,
The "baffle step" is the rising acoustic response (SPL of increases with increasing frequencies) of a driver once it has been placed on baffle (the front panel of the speaker). Without baffle step compensation, (compensating for this rising response by designing the crossover to tilt the reponse back to flat) speakers initially sounding "detailed in the midrange" soon reveal themselves as too prominent in midrange/low treble and fatiguing. Very harsh on your ears. You can partly counteract it by placing the speakers closer/against front wall. This elevates the low end (room gain) thus effectively tilting up the low end.

Speakers with full BSC have a flatter frequency response. But now if you place them against a wall the boosted bass will make it sound very unnatural/boomy.

Some speakers provide partial BSC compensation facilitating closer to wall placement and midrange that doesn't rip your head off when you place it clear of walls.

I hope my simple explanation of BSC made sense. Hopefully others can point out my mistakes...

cjd · 15th November 2004, 05:01 PM

Ummm...

Yes? I heard both. I got to hear the L18/27TBFCG combo from two different spots - I seem to recall it had a little trouble on the really heavy bass track (and I mean, REALLY heavy... we're not talking bass shy speakers on ANY of these, but this track was just a killer) at our standard level. Speakers were set to ~88dB from the front center (~2m back) which was actually too loud for me - I was one seat over and ended up giving it up and moving around the room 'cause my ears started hurting.

The XG18/27TDFC combo was a little more to my liking - I'm not really sure why at this point. One of my thoughts is that I'm not a fan of metal dome tweeters.

But I really liked the ribbon we heard, so who knows. Anyhow, I suspect just about any of John's projects would be a no-brainer.

C

DirkD · 16th November 2004, 06:14 AM

Thanks for everyone that suported my suggestion for the 2.5 clones. As I said in my original post, building them as a closed box design to start off with will allow for easier placement in a small room, yet give you very tight and dynamic bass. Has anyone else tried this?

D

tktran · 16th November 2004, 07:28 AM

stuffing the port kills the bass (obvious) and makes the mid-range sound shut-in (not sure why)

One of the aims of the clones is to provide good full range sound from a compact floorstander.

The tradeoff is low sensitivity. The tweeter has plenty of sparkle, and some say the midrange could be better.

So if you do it sealed, or going to use them with subwoofers, you may as well go with another design.

my 0.02dB

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14th November 2004, 12:36 PM	#12
tktran Account Disabled Join Date: Mar 2003 Location: Perth	The woofer in the original and clone ProAc are unshielded. ScanSpeak offers a shielded version of the same driver, and people who have substituted this driver have had good results. I recall someone has built a centre speaker by doing this... The clones must be THE most popular diy speaker of all time. IMHO, this is because a) very good website- informative and helpful, thanks to Al M. b) ease of build and moderate cost- it's a straightforward 2 way box speaker. c) thoroughly fine tuned by several key people, and backed up with measurements. The fact that the commercial (using similar but customised drivers) retailed for some 2,700 GBP/USD4,500/AUD10,000 in circa 1996-2003, makes it very tempting to the prospective DIYer... Oh, and did I mention it does sound rather good? Some designers prefer to do their own thing, and I can understand that you are hesitant because there's not as much feedback. But I wouldn't be surprised if they sound as good or better, or have other qualities lacking in the 2.5. I have other projects pending for summer 04/05 (yes we're south of the Equator so it's building time!) Tony Gee Humble Homemade Hi-Fi John K's NaO

15th November 2004, 02:53 AM	#14
tiroth diyAudio Member Join Date: Dec 2001 Location: Pittsburgh, PA, USA	I have the normal CloneAcs with unsheilded woofer and tweeter within 12-16" of my TV, it is no problem. (Samsung CRT HDTV) I would not worry. Closer than this, you may be pushing your luck.

15th November 2004, 03:57 PM	#16
tktran Account Disabled Join Date: Mar 2003 Location: Perth	cjd, do you mean the XG18/TDFC MTM or L18/27TBFCG? Really I should stop looking I have too many project ideas... I feel that 2 ways should be confined to bookshelves IMHO and smaller rooms. If I'm going to the trouble of building large floorstanders all the time/effort and MDF/veneers deserve more drivers for cleaner bass/higher sensitivity (eg MMT or MTM), or dedicated mids and larger woofers for better midrange and lower bass eg. 3 way. scone, The "baffle step" is the rising acoustic response (SPL of increases with increasing frequencies) of a driver once it has been placed on baffle (the front panel of the speaker). Without baffle step compensation, (compensating for this rising response by designing the crossover to tilt the reponse back to flat) speakers initially sounding "detailed in the midrange" soon reveal themselves as too prominent in midrange/low treble and fatiguing. Very harsh on your ears. You can partly counteract it by placing the speakers closer/against front wall. This elevates the low end (room gain) thus effectively tilting up the low end. Speakers with full BSC have a flatter frequency response. But now if you place them against a wall the boosted bass will make it sound very unnatural/boomy. Some speakers provide partial BSC compensation facilitating closer to wall placement and midrange that doesn't rip your head off when you place it clear of walls. I hope my simple explanation of BSC made sense. Hopefully others can point out my mistakes...

15th November 2004, 05:01 PM	#17
cjd diyAudio Member Join Date: Jun 2004 Location: Windy City	Ummm... Yes? I heard both. I got to hear the L18/27TBFCG combo from two different spots - I seem to recall it had a little trouble on the really heavy bass track (and I mean, REALLY heavy... we're not talking bass shy speakers on ANY of these, but this track was just a killer) at our standard level. Speakers were set to ~88dB from the front center (~2m back) which was actually too loud for me - I was one seat over and ended up giving it up and moving around the room 'cause my ears started hurting. The XG18/27TDFC combo was a little more to my liking - I'm not really sure why at this point. One of my thoughts is that I'm not a fan of metal dome tweeters. But I really liked the ribbon we heard, so who knows. Anyhow, I suspect just about any of John's projects would be a no-brainer. C

16th November 2004, 06:14 AM	#18
DirkD diyAudio Member Join Date: May 2004 Location: Paarl, South africa	Thanks for everyone that suported my suggestion for the 2.5 clones. As I said in my original post, building them as a closed box design to start off with will allow for easier placement in a small room, yet give you very tight and dynamic bass. Has anyone else tried this? D

16th November 2004, 07:28 AM	#19
tktran Account Disabled Join Date: Mar 2003 Location: Perth	stuffing the port kills the bass (obvious) and makes the mid-range sound shut-in (not sure why) One of the aims of the clones is to provide good full range sound from a compact floorstander. The tradeoff is low sensitivity. The tweeter has plenty of sparkle, and some say the midrange could be better. So if you do it sealed, or going to use them with subwoofers, you may as well go with another design. my 0.02dB