8'' two-way any reason why not?

[jim85iroc]

Re: 8'' two-way any reason why not?

Well I've spent a few months playing with the Audax's and all I can say is WOW. I realize now how colored the mid range was with the Dayton's. The Audax's are so much smoother up top. As for crossovers I started with the 6db set up as in the KLS9's and its sounded quite nice except when the volume was turn up. The HiVi's weren't happy so I've since put them back on a 24db @ 3K. I've been pretty happy so far, still in playing mode...

If your crossover didn't properly address the Dayton's breakup node (and when using a 4,500hz filter of any kind, it didn't), it's no wonder you thought the Dayton was colored.

The Dayton is a much lower distortion (read: Less colored) than the audax when used properly. I'd strongly suggest digging out those daytons and pairing them up to a tweeter that lets you cross it LR4 or steeper at 1500hz. Something tells me you'll have a new-found respect for the Dayton. Mark K's RS225 & RS82A 2-way would be a great place to start:

http://www.audioheuristics.org/projects_gallery/RS225_RS28A_updates/dayton_reference_rs225.htm

I think John Marsh has also used the RS225 in a 2-way design (probably also with the RS28) that uses a very steep cauer-eliptical filter.

[6thplanet]

Re: 8'' two-way any reason why not?

I definately won't get rid of the Daytons, as they are a real nice set of drivers. They just don't play up high enough to play nicley with the planars. I agree totally about pairing them up with a tweeter that'll go down to 1.5K like the RS28 in Mark K's design. Saved for another project indeed!!

[Bob Scott]

Re: 8'' two-way any reason why not?

2000Hz would be about the limit and lower will be better. I remember the AR 8" two ways from the mid 70's as being a very nice all around loudspeaker. Reasonably compact and full range. I think they were ARs hard to believe that was 30 years ago.

I took apart and analysed my 40 year old Wharfedale acoustic suspension 8" two ways, similar to your ARs. 0.75 cubic ft. boxes. I believe the crossover was 2,500Hz after measuring the coil inductances. Crossing low is not hard with those purple tweeters. The Fs of those old tweeters is 960Hz. I can't find any new ones anywhere near that low. Bass is/was boomy. Peak of 5.6dB @ 100 Hz. F3 of 63 Hz. (They seemed to sound better than those specs; "pleasing" sound for rock and roll.) I got the resonance down to 90Hz by stuffing them completely with fluffed up cotton batting.

Unfortunately there are not any budget class 8" woofers that fit the bill that I am aware of.

I found one that would make my old speakers sound better! The peak would go down to 3.8dB @ 62Hz. F3 would be 38Hz in those same sealed 0.75 cu. ft. boxes! I guess the secret is in their higher than average cone mass. That would mean less sensitivity. 84dB as opposed to the old 88.5dB

http://www.madisound.com/catalog/product_info.php?cPath=45_228_257&products_id=8445

Korean, Sammisound CWR200B50. I wish PE carried these. Low power, budget ($11) woofers for old acoustic suspension speakers. The voice coil is only one inch dia, but so are the originals. I wouldn't buy these for any new designs.

Bob

[lasse]

Re: 8'' two-way any reason why not?

Let's see-
My M8N/DX25
Your TDFC/F8
Shawn's "TBA"
Mayhem's SB29/CA22RNX MTM

Others?
Wolf

Hey,

don´t forget the RFL-21L.

8" Peerless CSX 217
1" Peerless KO 10 DT
2500 XO, perhaps 3rd tw, 2nd wo

Boxes and baffles almost ready (paint is drying)
Raw driver measurements coming....

Regards//lasse

[robert]

Re: 8'' two-way any reason why not?

If you like it - a reason why. Mine are nowhere near done yet, and not sounding like I want them. However, the size of the image, especially vertically, is larger than my ZRT's and they sound a lot bigger (not better though). Whether this is good or not is your call, I thought it was kinda cool.

Cheers / Robert

[tpremo55]

Re: 8'' two-way any reason why not?

Came across an old model Seas 8" that looks like it might be a nice contender for an 8" 2-way TL setup.



$50 ea at Zalytron right now. $88 at Madisound.

[robert]

Re: 8'' two-way any reason why not?

As the Governator says: "Do it. Do it now!" Price is definitely right. and you get to join the club!

Cheers / Robert

[DDF]

Re: 8'' two-way any reason why not?

Came across an old model Seas 8" that looks like it might be a nice contender for an 8" 2-way TL setup.



$50 ea at Zalytron right now. $88 at Madisound.

The off axis response looks like it could work. The Vifa M21 and P21 were very popular for 8" 2 ways in their day. Both could use lower order xovers, but I think the M21 was more successful IME (I tried both in 2 ways).

The challenge with this is the harder break up on the top end than the M21 had, so it might need a taller order, or a trap at the peak.

[tktran]

Re: 8'' two-way any reason why not?

I think the key is to manage the crossover region appropriately.

A woofer with a smooth upper end roll-off makes work easy, but even a hard cone unit could work if the LP filter was designed appropriately.

A few months ago I listen to the Dynaudio AIR 15, which uses a plastic coned 8" midwoofer. It sounded very nice.

There are a few good DIY candidates like the SEAS CA22RNY or the Scan-Speak Discover 22W-8534G00.

Mark K RS225/RS28A project would be great. Vented, it would be a slamming system.

[Wolf]

Re: 8'' two-way any reason why not?

There's a poster that has been AWOL for a while!
WB-tktran!
Wolf

[brianpowers27]

Re: 8'' two-way any reason why not?

I think the key is to manage the crossover region appropriately.

A woofer with a smooth upper end roll-off makes work easy, but even a hard cone unit could work if the LP filter was designed appropriately.

What do you think the key to an appropriate xo with 8" woofers is?

[robert]

Re: 8'' two-way any reason why not?

I'd guess, based on the ones I have heard that you need to:

1.) Keep the XO point as low as is reasonable, while observing tweeter power limits.

2.) On mine, I found that a flat on-axis FR (woofer and tweeter level) sounded too hot. I suspect that even though the woofer off-axis roll-off wasn't as big a deal as it everyone thought, it did have some effect. If you adjust the tweeter flat with the woofer on-axis and use MLS measurement, it is actually putting out a lot more energy in a full pattern and you hear it from wall reflections, etc. In short, pay attention to overall response and listen to your ears at the end, not the model.

3.) The woofer should be reasonably well-behaved in the passband, although Wolfie pretty much proved this to be a nice thing and not a requirement with his design - the M8 was quite well-behaved and smooth.

Anyone else?

Cheers / Robert

[brianpowers27]

Re: 8'' two-way any reason why not?

2.) On mine, I found that a flat on-axis FR (woofer and tweeter level) sounded too hot. I suspect that even though the woofer off-axis roll-off wasn't as big a deal as it everyone thought, it did have some effect. If you adjust the tweeter flat with the woofer on-axis and use MLS measurement, it is actually putting out a lot more energy in a full pattern and you hear it from wall reflections, etc. In short, pay attention to overall response and listen to your ears at the end, not the model.

I am not sure I understand what you are getting at.

When you state that the tweeter is too hot due to a an increase in total energy radiated into the room are you suggesting that you are listening off axis? When you get it right to your ears, what does the model look like?

It seems to me that Wolf's model was nearly flat but had a large dip in the power response through the xo region. I haven't heard the design so I can only guess what it sounds like.

[robert]

Re: 8'' two-way any reason why not?

If tweeter is radiating nearly 180 degrees at Fc (crossover freq) and woofer is radiating at some angle less than this, an on-axis only model will result in a tweeter that looks balanced in sim/measurements but due to wall reflections and off axis (or total power response) will sound brighter.

You have to dip/tilt down the power response a bit. I think you did the same thing on yours, and it sounds like Wolf did, too. My overall tweeter level averaged about 1dB or so down from what the woofer was doing 500-800Hz. Really surprised me, since it did this even after I fixed the top octave. Sounded right in the living room, but maybe a tad dull in the auditorium in Iowa.

I am in a hotel in VA right now, but when I get back, will place the off-axis plots and final for the XO - a pic or graph is worth 1K words.

Cheers/Robert

[Wolf]

Re: 8'' two-way any reason why not?

I am not sure I understand what you are getting at.

When you state that the tweeter is too hot due to a an increase in total energy radiated into the room are you suggesting that you are listening off axis? When you get it right to your ears, what does the model look like?

It seems to me that Wolf's model was nearly flat but had a large dip in the power response through the xo region. I haven't heard the design so I can only guess what it sounds like.

It's not THAT large:



FWIW, this is a pretty typical power response form-factor for an 8" 2-way.

I really think what is going on in Robert's is that the woofer doesn't have much off-axis response above the diameter wavelength (pistonic behavior), and therfore, the tweeter seems a lot louder with all the reflections it DOES have.
He also said the off-axis response doesn't seem as bad as one would think, and while it isn't, it's not fantastic either. There is fall-off.

You were probably thinking waaaayyy too hard about Robert's statements.
Later,
Wolf