The Chr-70 could be interesting with a vertical arrangement of four drivers. Wired parallel series for an 8ohm load, sensitivity and power handling would be excellent. The response could be pushed to 80 hz using the right dsp. High pass would be required for this.
If you are using a helper woofer in close proximity then an alpair would be a nice choice such as the 10.2 but you will need to tone down the HF a lot.
As for baffle width, that depends on what kind of electronics you are using. I prefer the sound of a narrow baffle if you have a way to boost the low end at the signal level, especially if you have helper woofers and a monopole sub woofer to cover the really low stuff under 50hz.
Do you already have stereo sub woofers or are you using helper woofers on the same baffle?
If you are using a helper woofer in close proximity then an alpair would be a nice choice such as the 10.2 but you will need to tone down the HF a lot.
As for baffle width, that depends on what kind of electronics you are using. I prefer the sound of a narrow baffle if you have a way to boost the low end at the signal level, especially if you have helper woofers and a monopole sub woofer to cover the really low stuff under 50hz.
Do you already have stereo sub woofers or are you using helper woofers on the same baffle?
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I am thinking of doing something similar to the Jamo R-909. I already have 4 Alpha 15's for the bottom. I know the Alpha's are kind of ugly past 200 hz. So I was thinking of a full range driver with a helper tweeter for the top. I will be using plate amps for the subs & using my NAD for the mid/tweet combo. So other than the subs, this will be a passive crossover design.
If budget can be stretched a bit, I'd suggest you look at the Alpair6 (either metal or paper) - quite simply a more refined driver than the CHR, and when XO'd the the area under consideration should be quite capable up to "reasonable" SPL.
They make great surrounds for a 5.1 system, for which application they survive well in pretty teeny box.
You might not even need helper tweeters at all with the A6M .
As Ryan noted, there are a few different approaches to dimensions for Open Baffles, as well as XO points / methods. It would be worth experimenting at least with a line level passive HP XO on the NAD driving the smaller driver(s) - if you ultimately determine a tweeter is required, a simple 1st order cap cornered somewhere in the 10-12K range might suffice.
They make great surrounds for a 5.1 system, for which application they survive well in pretty teeny box.
You might not even need helper tweeters at all with the A6M .
As Ryan noted, there are a few different approaches to dimensions for Open Baffles, as well as XO points / methods. It would be worth experimenting at least with a line level passive HP XO on the NAD driving the smaller driver(s) - if you ultimately determine a tweeter is required, a simple 1st order cap cornered somewhere in the 10-12K range might suffice.
I did an open baffle system with an Eminence 3015LF Neo and Mark Audio Alpair 10.2 a few months ago. Actively crossed over and EQ'ed with a DBX DriveRack PA+. Open class winner at the MWAF in Dayton and the SEC speaker competition in Mobile.
Brandonnash (user name) visited my home and heard these speakers and on the AVS forum (DIY speakers) he commented:
"When we started listening to those (open baffle speakers) I brought a CD with a lot of music I was familiar with and the first thing that jumped out at me was the incredible image they threw. I know everyone has heard the phrase "it was like [insert artist name here] was in the room with us", but this was the best example I have experienced with my past with speakers. The best word I can think of describing the sound from these speakers is holographic. The sound stage was incredibly wide, the imaging was spot on, and there was depth that extended all the way back to the wall even though these speakers were 6 feet from the wall. I was very impressed hearing these speakers. Jim correct me if I mislabel the drivers, but I believe they were Mark Audio full range 10 2 and the woofers were 15" Eminence pro audio drivers using neo magnets mounted on an H baffle. The crossover was an external active that I can't remember the model, but everything worked well."
http://www.diyaudio.com/forums/full...rk-audio-alpair-10-2-open-baffle-project.html
Jim
Brandonnash (user name) visited my home and heard these speakers and on the AVS forum (DIY speakers) he commented:
"When we started listening to those (open baffle speakers) I brought a CD with a lot of music I was familiar with and the first thing that jumped out at me was the incredible image they threw. I know everyone has heard the phrase "it was like [insert artist name here] was in the room with us", but this was the best example I have experienced with my past with speakers. The best word I can think of describing the sound from these speakers is holographic. The sound stage was incredibly wide, the imaging was spot on, and there was depth that extended all the way back to the wall even though these speakers were 6 feet from the wall. I was very impressed hearing these speakers. Jim correct me if I mislabel the drivers, but I believe they were Mark Audio full range 10 2 and the woofers were 15" Eminence pro audio drivers using neo magnets mounted on an H baffle. The crossover was an external active that I can't remember the model, but everything worked well."
http://www.diyaudio.com/forums/full...rk-audio-alpair-10-2-open-baffle-project.html
Jim
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Thanks chrisb. The budget definitely will allow for Alpair 6. My concerns are of the low end roll-off of the midrange/full range driver meeting the 200 hz cut off of the 15's. I will have to experiment with baffle widths, although I really wanted to follow the wide baffle design of the 909.
Thanks Jim. I must admit that I started thinking open baffle when I read your write-up and the listener comments regarding your Openminded design. When searching for examples of open baffle designs, I came across the Jamo R-909, and loved the "look". Although the Revelators the Jamo uses are out of my budget, the Alpair 10.2 is well within. Thanks for your input.
Woof,
You are on the right track in your thinking. While I like my Kappalite 3015LF Neos, the Eminence Alpha drivers 15s will do the job at a very low cost.
I like the ability to EQ an open baffle system. But several similar projects on Martin J. King's site (Quarter Wavelength Loudspeaker Design) use passive crossovers or active crossovers without much EQ resources.
If I reworked my design, what I would do is work to reduce the width of the top baffle with the full range driver. I suspect that some work with Martin's open baffle simulations or similar capability would better optimize the top baffle.
Good luck and let us hear about your progress.
Jim
You are on the right track in your thinking. While I like my Kappalite 3015LF Neos, the Eminence Alpha drivers 15s will do the job at a very low cost.
I like the ability to EQ an open baffle system. But several similar projects on Martin J. King's site (Quarter Wavelength Loudspeaker Design) use passive crossovers or active crossovers without much EQ resources.
If I reworked my design, what I would do is work to reduce the width of the top baffle with the full range driver. I suspect that some work with Martin's open baffle simulations or similar capability would better optimize the top baffle.
Good luck and let us hear about your progress.
Jim
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The alpair 7.3 has a response way beyond 20k, that being said most people who hear my 10.2's say they have the sweetest highs they have ever heard. I think you can safely omit the tweeters if you are using MA drivers. It's all going to come down to how much control you have over the line level signal with dipole speakers. Sounds like you have the raw power. In addition to a good EQ you really need some loudness control. The ear is much less sensitive to bass at low volume levels. Some home theater recievers have the ability to compensate for this.
Does anyone know if there are any stand alone preamps that have kinds of features that home theater recievers do? It seems like you pay an arm and a leg for a good preamp and recievers get amazing preamp functionality just thrown in there for next to nothing.
Does anyone know if there are any stand alone preamps that have kinds of features that home theater recievers do? It seems like you pay an arm and a leg for a good preamp and recievers get amazing preamp functionality just thrown in there for next to nothing.
Yup, it's certainly interesting that except for the lack of discrete pre-amp outputs for all of the main and surround channels, almost any decent mainstream receiver in the $400-500 price range has a feature set that we would have been a pipe dream 10 yrs ago for less than 4-5 times that price. It's hard to believe that the power supply and 5 or 7 channels of even the lowest power output stages wouldn't contribute at least 50% of the manufacturing cost of these units, and that a no-frills processor couldn't be built to retail for less than $400, with a decent profit margin.
While there is no dearth of processors with more computing power and functions than the space shuttle, it seems few manufacturers are willing to cater to the budget conscious who may happen either have all the requisite amps lying about, or would be happy to DIY that much easier part.
rant off
Chris,
We should rant even more. If we don't DEMAND better features they will milk us over time with incremental improvements.
I would like to see built in 2 way amplification for each channel with active crossovers. Speaker building will become much easier and more fun.
Digmoda has what I want. If someone can put that into a home theater receiver and sell it cheap enough then we could all rejoice.
We should rant even more. If we don't DEMAND better features they will milk us over time with incremental improvements.
I would like to see built in 2 way amplification for each channel with active crossovers. Speaker building will become much easier and more fun.
Digmoda has what I want. If someone can put that into a home theater receiver and sell it cheap enough then we could all rejoice.
You say you have to pad down the top end of the 10.2's. How exactly are you doing that?
I have a pair of new 10.2's showing up today in the mail. I'm going to start them off in cardboard boxes just to break them in. Hopefully, in the next month or so I will have my project well under way or finished.
I'm using six 8" Peerless India woofers for each channel in a slot loaded OB (Nelson Pass design). These will be powered by a pair of GR-Research SA-1 amps which have a built-in crossover, built-in gain circuit for OB use, and a 20Hz HP filter. I will be crossing these over at the amp's max of 125Hz.
The 10.2's need to be crossed at around 200Hz 1st order, and I'm going to do everything on the 10.2's passively. I don't want to use any EQ, so will need to know what to do to pad the top end. Baffle size I want to be narrow as possible but still be able to support 100-150Hz.
Any thoughts and/or suggestions?
The implication of using even multiples of 10.2 as woofers has me a bit concerned - there are lots of other drivers well suited to the heavy lifting/excursion, most particularly in an OB application.
Maybe Mark could pipe in to the subject?
You can tune the top end by the position of the speakers and how much you are listening off-axis.
dave
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