alternative to U-baffle for this design...

[charliemouse]

Any suggestions as to a suitable way to include the following two woofers in this design? I'm still building with scrap wood:



The problem is I can't fit the two Peerless woofers (>200Hz) in the main panel and get tweeters at good listening height, but I *don't* want to rearrange panel layout. I am using entirely passive crossovers, though the subs are amped separately.

I'd be very grateful if anyone can suggest whether a W design or suchlike might be feasible. I've just been listening to these for months as they sound so nice and I can't think of resolution for woofer problem, but I really need to get on and get the design finalised.

for info, I posted a thread, mainly about the tweeters, earlier in the year.here, and with help from the wise people here, have since been enjoying this hugely :T

Summarising, I'm using all metal drivers:
Woofers: Seas Excel W22 (W22EX001 / E0022)
Mids: Visaton TI100
Tweeter: Scanspeak D2904/980000
low-woofers: Peerless 10” XXLS 830843

Thanks!

[Dennis H]

How about one above and one below? SWMTMWS.

[Hdale85]

Also could do one facing forward one facing back. Or are you looking for open baffle methods for the subs too?

[Rudolf]

This definetely is a case for a ripole. I managed to get two 10" woofers into a cube of 30*30*30 cm. You will loose some efficiency but otherwise the ripole will work almost the same as your U-frame.
I just have compared a pair of Visaton W250 drivers (much inferior to your Peerless) in a M-frame and a ripole:

Image not available

Ripole in the middle, M-frame to the right. This is the on-axis-comparison without any correction filters. Just a lowpass at 2 kHz. dB values are only relative (no calibration):

Image not available

[dlneubec]

Here's a link to more infor on ripole's.
Ripole

[JoshK]

Is the resonant peak at 300hz, here in this example?

[Rudolf]

Is the resonant peak at 300hz, here in this example?

For reasons I haven´t brought to light yet, the W250 splits into two peaks (300/400 Hz). With better drivers you would have a single peak at about 330-350 Hz.

[JoshK]

Very interesting. It seems as though you can use these higher up than say, SL's H baffle. Certainly they are quite a bit more compact.

[Dennis H]

I think it's hasty to conclude anything about the resonant peak's frequency. Ridtahler's own graphs show it as low as 200 Hz. This is basically SL's W baffle with the openings squished down to narrow slots to mass load the driver and lower its Fs. (Not really sure how Ridtahler got a patent but that's another subject. ) SL's tests showed that changing the driver in the same W frame or H frame could move the peaks quite a bit so it's a complex relationship. He basically said build it and measure it as you can't really calculate it.

http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/aka_sub_sonder_en.htm

[Rudolf]

SL's tests showed that changing the driver in the same W frame or H frame could move the peaks quite a bit so it's a complex relationship. He basically said build it and measure it as you can't really calculate it.

Ridtahler can - and does - calculate the parameters of his ripoles exactly. May be it is his better understanding of this relationship which gained him a patent. AFAIK there has been some kind of agreement with SL about the patentable aspects of Ridtahlers ripole

[Davey]

Those two measurements look surprisingly similar to me....considering the two woofer configurations are quite a bit different. Almost like they're the same measurement....just scaled.

I don't understand.

Dave.

This definetely is a case for a ripole. I managed to get two 10" woofers into a cube of 30*30*30 cm. You will loose some efficiency but otherwise the ripole will work almost the same as your U-frame.
I just have compared a pair of Visaton W250 drivers (much inferior to your Peerless) in a M-frame and a ripole:

Ripole in the middle, M-frame to the right. This is the on-axis-comparison without any correction filters. Just a lowpass at 2 kHz. dB values are only relative (no calibration):

[Rudolf]

Those two measurements look surprisingly similar to me....considering the two woofer configurations are quite a bit different. Almost like they're the same measurement....just scaled.

I don't understand.

Sorry charliemouse that I´m highjacking your thread

Dave,
after all its the same driver and the same depth of the dipole frame for both measurements. A comparison of the front/back SPL would show much more difference.
You may have recognised that the drop from 100-35 Hz is slightly less for the "ripole" than for the M-frame. By narrowing the center chamber this will be enhanced further. I´m trying to document this next weekend.

[charliemouse]

Hi guys... and no worry at all about hi-jacking thread. Work went rather silly and I've not had a minute to read this for a while!

This definetely is a case for a ripole. I managed to get two 10" woofers into a cube of 30*30*30 cm. You will loose some efficiency but otherwise the ripole will work almost the same as your U-frame.
I just have compared a pair of Visaton W250 drivers (much inferior to your Peerless) in a M-frame and a ripole...

I should play around with this...

Couple of conderns re ripoles though. One, and with reading the article you posted, is the targe they aim their ripole at
"- PC home cinema
- bass that may not be located
- bass extension for electrostatic and full range drivers.
"
I'm intending on using these purely for hi-fi.
In connection with this, I'm the U baffle is still a dipole at present, and it extends to 200Hz, therefore they will have some directionality. Whilst I'm sure the ripoles will cover up to 200Hz, I'm unsure as to how this will effect the sound qualitatively. Any thoughts, compared to your M baffle.

The M Baffle (the one on the right, anyhow!) looks a lot more promissing... that would let me keep the subs dipole, as the rest of the system. Any great negatives of Ms?

Thanks for your posts above

[charliemouse]

How about one above and one below? SWMTMWS.

Yes, I've seen one on here before, but As I need the extend side baffle which isn't present for the rest of the drivers, it would look very odd... Then again... I'm wondering if a retaining short side panels for wmtmw section, then curving out to the subs at both top and bottom would look good if done well.

It may well involve loosing the 45 degree baffle which PaulW recommended for his 'wings' design, and a shape which I do indeed prefer the sound of to 90 degree baffles.

A quick qualification here... I sound very non-technical in this. I just believe that specs mean only so much. My Quad 22Ls have a nice spec. They measure better than these project in an anechoic room, but they sound like PC speakers compared to the above. Whilst I use MMS measurements and modelling programmes at various stages, I'm doing a lot by ear. The quantitative difference between neoCD3 ribbons and these scanspeak tweeters can be modelled, the suitability of dispersion patterns considered etc, but in the end there is so much qualitative difference which the devices attached to edge of my head measure pretty well, that I'm relying on them when in doubt.

Hmmm. a SWMTMWS would also be create a spectatcular mess if toppled, that I'd almost want to bolt it to the ground :E

[charliemouse]

Also could do one facing forward one facing back. Or are you looking for open baffle methods for the subs too?

Yep, going for an open baffle for the subs if possible...
like John's or Paul's or Steve's or.... the orion by some chap called Linkwitz
Definitely passive crossovers as far as possible though... I'll consider building a purely analogue filter later. (Won't be using digital without a huge investments in another 3 Meridian DACs to match up with the one I already have)

[Rudolf]

Couple of conderns re ripoles though. One, and with reading the article you posted, is the targe they aim their ripole at
"- PC home cinema
- bass that may not be located
- bass extension for electrostatic and full range drivers.
"
I'm intending on using these purely for hi-fi.

That crazy marketing blurb again. If you feel the ripole to be too constricted you could open it up as wide as space allows. You would loose a bit of bass extension on the way though.

In connection with this, I'm the U baffle is still a dipole at present, and it extends to 200Hz, therefore they will have some directionality. Whilst I'm sure the ripoles will cover up to 200Hz, I'm unsure as to how this will effect the sound qualitatively. Any thoughts, compared to your M baffle.

The ripole definitely is more of a dipole than your U-frame. I took some measurments at 0°, 90° and 180° horizontally:




While the M frame is almost perfectly symmetrical, the ripole is a little bit more efficient to the front than to the back, but still a capable dipole up to 200 Hz.

The M Baffle (the one on the right, anyhow!) looks a lot more promissing... that would let me keep the subs dipole, as the rest of the system. Any great negatives of Ms?

Dont ask me. I prefer M frames to H frames and W frames. :B

[JoshK]

To hi-jack this thread a bit further...

Rudolf, have you experimented with the horizontal angling of woofers inside an H-frame like MFK (mfk-projects.com)? I was just curious as it might make for a nice form factor for something I was thinking about. Of Course the Ripoles might work too.

[charliemouse]

Rudlof,
the info above is very encouraging; Really appreciate your time taking the measurements.
In conclusion, I think it's probably time to saw up some more bits of scrap and made an M and ripole and audition them. The tweeter's verticle height simply can't increase: like in Paul's wings design, the scanspeak/seas drivers need a small mid to avoid over stretching either... so unless I have one XXLS below, and another doing lower frequencies in a different location (hmm, that's 5 way - no) then the design requires the XXLS drivers to be in an M or a ripole.

There were problems with a bit of a peak around 200Hz as Paul suggested there would be from a quick glance at the length of the sides on the U, so it's definitely time to try the two alternatives.

Full of festive flu, which I'm somewhat annoyed has arrived on holiday rather than work time, so I'll get to work in new year.

Thanks again.

[Paul Ebert]

Where would the acoustic center be for a ripole?

[charliemouse]

I think it's hasty to conclude anything about the resonant peak's frequency. Ridtahler's own graphs show it as low as 200 Hz. This is basically SL's W baffle with the openings squished down to narrow slots to mass load the driver and lower its Fs. (Not really sure how Ridtahler got a patent but that's another subject. ) SL's tests showed that changing the driver in the same W frame or H frame could move the peaks quite a bit so it's a complex relationship. He basically said build it and measure it as you can't really calculate it.

https://web.archive.org/web/20080610..._sonder_en.htm

Dennis, I notice you said here that ripole limits to around 100Hz.

I presume opening the ripole into more of an M will be necessary as a result, as Rudolf mentioned?

That crazy marketing blurb again. If you feel the ripole to be too constricted you could open it up as wide as space allows. You would loose a bit of bass extension on the way though.

[Dennis H]

Well, Rudolf has built both so he's the expert.

[Rudolf]

Rudolf, have you experimented with the horizontal angling of woofers inside an H-frame like MFK (mfk-projects.com)? I was just curious as it might make for a nice form factor for something I was thinking about. Of Course the Ripoles might work too.

MFK was the one I took the inspiration for my M-frame from. As you can see in my first posting in this thread, a 90° angling of the drivers will give some more efficiency than the ripole. When laying the M-frame on the floor, efficiency will rise another 1-2 dB due to better floor coupling of both drivers.

Where would the acoustic center be for a ripole?

If you look at my ripole measurments at 0°, 90° and 180°, it´s almost symmetrical up to 200 Hz. So the acoustic center will be the middle of the axis between the two drivers.

Dennis, I notice you said here that ripole limits to around 100Hz.

I presume opening the ripole into more of an M will be necessary as a result, as Rudolf mentioned?

The upper frequency limit of any W-frame mainly depends on its depth. A W-frame for 10" drivers will have a higher peak frequency than a 15" W-frame. My frames as presented (M-frame and Ripole) both peak at 400 Hz, because they feature the same inner depth. Opening the frame will not change that. What you loose is a bit of bass efficiency.