Cheap and FAST OB, Literally

- Those SB Acoustic ceramic drivers look very much like the 6 inch version of the driver used in a very interesting speaker and some think one of the best small speakers out there - the BMR Philharmonic Audio Speaker, designed by Dennis murphy , I don't know if Dennis had some health issues or just got to busy to build them any more , but Salk Sound puts the speaker together these days, or you can by the driver kit and diy it.

https://www.salksound.com/model.php?model=BMR+Monitors

here is a great video where the reviewer talks about the drivers
 
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Hard to compare as they are totally different. This SLOB dipole (which I will call the XSD, henceforth) is much higher sensitivity and being an open baffle, the sound is very large. It just fills the room and there are no bass modes as you move around the room. It is very uniform. The dynamics of a 95dB sensitive midrange (padded down to 91dB) coupled with 8x 6.5in woofers makes for a very powerful speaker that has low distortion when played at normal (loud side) listening levels of 85dB. In general, the XSD is perhaps one of the best sounding speakers I have heard - probably in the top 2 or 3*. It has the dynamics and ability to play high and low SPL with convincing bass in either case, the wide soundstage and visceral gut punch impact unparalleled. The low distortion gives clarity and intelligibility to vocals that is amazing. I really feel that this speaker just does so many things well. One of the toughest tests is to play: speed metal, classical organ, hip hop, jazz ensembles, stand up bass, jazz piano, drum solos, large orchestral symphonies, classic rock, pop, girl and guitar, folk, country, and electronica all well. I have not found a sound that causes this speaker to collapse or falter yet.

it really makes me rethink spending $800 on a pair of Purifi woofers when $220 on 16x cheap woofers in a SLOB will do the trick much better. Of course it’s a larger floorstander and not a stand mount. Much more room presence. But the floor footprint is not bad at 12in w x 14in deep.

*other top speakers in my top 3 list:
  • Wesayso’s Two Towers line array with 50 drivers and full DSP signal processing.
  • 10F/RS225 FAST TL
  • AMT Synergy with 6MDN44 mid and front loaded bass horn below 200Hz.
 
- Hi Xrk , I really like your - ( SLOB ) - henceforth - XSD !!!!!

- How hard do you think it would be to marry the SLOB - Bass part of the Speaker to just this - Midrange / Tweeter combo below??



- It can cross over as low as 200 Hz. -- ( Normally the speaker uses the pair of Servo woofer seen below, but very expensive )

SerenitySuper7 a.png

SerenitySuper7 . b ..jpg




these are either an early prototype or maybe a diy version...

Super7 . c ..jpg






-- The reason I am really considering this Neo10 / Neo3 - combination is much higher efficiency - 97db so I can really use my new 2.3 watt Tube Amplifier that I've fallen for , and because it has been described as one of The Best sounding Midrange /Tweeter combinations that GR Research has ever designed and built, and were Danny's personal speakers - - - ( that is next to their new top of the line and very expensive Line Force speaker )


- Thank you, Dean


-- ( only 6 pair were ever built by GR Research , now I believe they are sold by Serenity Acoustics... new - $ 20,000.00 ) ... but you can get a Demo pair for just -- $ 10,800 -- :spin:
 
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Hi @xrk971, regarding the 6.5”/8” debate - It sounds like the depth of slot is the issue for upper reach? so, how about a ‘racetrack‘ driver like the SB15SFCR39?

It has a low fs and I’d guess has a slightly larger cone area then a 6.5”
X, can you just confirm as mentioned by CJ66 that in relation to the resonance that limits the upper frequency limit, it is the depth of the slot that is the critical factor ie the horizontal distance between the mouth of the slot and the back wall of the slot chamber - ?
 
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- Hi Xrk , I really like your - ( SLOB ) - henceforth - XSD !!!!!

- How hard do you think it would be to marry the SLOB - Bass part of the Speaker to just this - Midrange / Tweeter combo below??



- It can cross over as low as 200 Hz. -- ( Normally the speaker uses the pair of Servo woofer seen below, but very expensive )

View attachment 1048179
View attachment 1048180



these are either an early prototype or maybe a diy version...

View attachment 1048182





-- The reason I am really considering this Neo10 / Neo3 - combination is much higher efficiency - 97db so I can really use my new 2.3 watt Tube Amplifier that I've fallen for , and because it has been described as one of The Best sounding Midrange /Tweeter combinations that GR Research has ever designed and built, and were Danny's personal speakers - - - ( that is next to their new top of the line and very expensive Line Force speaker )


- Thank you, Dean


-- ( only 6 pair were ever built by GR Research , now I believe they are sold by Serenity Acoustics... new - $ 20,000.00 ) ... but you can get a Demo pair for just -- $ 10,800 -- :spin:
Hi Hallcon,
It would be easy and in fact, I am thinking of making just the bass part as a stand-alone “stand” to mount a top to. Like Magnepans etc. the 8in Neo’s are now made by GRS and are a great sounding mid. You do need 4 of them to go low enough but I am not sure they would have the impact of the XSD slot loaded punch plus dynamic mid. To get 97dB of bass sensitivity will require maybe 8x of the 92dB 6FE100’s as the woofers maybe. It would be insane though and you would have a 97dB open baffle dipole.
 
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X, can you just confirm as mentioned by CJ66 that in relation to the resonance that limits the upper frequency limit, it is the depth of the slot that is the critical factor ie the horizontal distance between the mouth of the slot and the back wall of the slot chamber - ?
Yes, the front to back chamber depth controls the max upper bandwidth. A 6.5in driver allows 475Hz, 8in about 350Hz. If you have a midrange that can go lower then 8in is not a problem. At some point though, the driver depth even when aligned 90deg makes it wide and not visually appealing like a conventional tall floorstander. Although flat pancake like woofers like plastic cone Boss DF10’s might work. 6 of those would be quite dramatic.
 
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That’s the LSA HyperDrive-2 preamplifier and headphone amp. It’s a hybrid design that uses NOS 6N1P (or E88CC) tube buffer and solid state circuitry with a MCU control for selecting 1 of 3 inputs and provides graceful startup and shutdown with solid state relays. It has two outputs, selectable gain of 0/6/9dB toggle, the headphone amp is based on a Class AB TPA6120A2 chip amp and capable of 2W into 32ohms. Sonic profile is dominant 2nd harmonic and overall THD is below 0.005% for reasonable loads. It sounds superb. I use it as my main preamp for everything now.

1650929555171.jpeg

1650929929712.jpeg

More info here
https://www.diyaudio.com/community/threads/hyperdrive-2-headphone-amp-preamp.383708/#post-6963831
 
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Hi Hallcon,
It would be easy and in fact, I am thinking of making just the bass part as a stand-alone “stand” to mount a top to. Like Magnepans etc. the 8in Neo’s are now made by GRS and are a great sounding mid. You do need 4 of them to go low enough but I am not sure they would have the impact of the XSD slot loaded punch plus dynamic mid. To get 97dB of bass sensitivity will require maybe 8x of the 92dB 6FE100’s as the woofers maybe. It would be insane though and you would have a 97dB open baffle dipole.


- Thanks for the reply , I went and took a look at the FaitalPRO 6FE100's -- they look clean to out past 2,000hz. .... How high into the lower midrange could the drivers operate at ?? - If we needed to could we maybe could cross them over around 400hz. to help with the upper bass/ lower midrange punch??



- Making the base stand-alone would be an Excellent Idea - !!!

- Have you tried the JBL530 on top yet??

- I have about 80 - 90 hours on mine now, and they are really sounding good but I'm sure they would really shine relieved of trying to produce low Bass out of that amazing but I'm sure beleaguered 4 inch woofer
 
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I have used the 6FE100 up to 3500Hz and it sounds very good. It has some increased distortion bump at 1kHz. But 400Hz is not a problem as a woofer. You can listen to it as a mid in my earlier videos of the XSD.


Come to think of it, 8x of the 6FE100’s in the slot loaded box would be insane sensitivity at 98dB at 2.83v (4ohms).
 
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Interesting idea to try the JBL 530 as a top on the SLOB woofers. I suppose almost any two way speaker could be used here. To get the rest benefit though they would need to be at least 90dB sensitive. Plus, a XO would have to be made for the XO circa 450Hz. But it would not be a dipole. The Heil AMT would be interesting here as a tweeter. Maybe on top of the 5MR450NDY.
 
Hi Xrk ,

- is there a page where you list the outside dimensions of the Bass Bottom of the Speaker? - - ( SLOB part of the XSD Speaker )


- Are going to post a plan for the SLOB part of the speaker, or the whole XSD speaker?


Thanks , Dean
--------

PS. - Ooops - -- Duh , I just looked closer at picture ..... since the top part of the speaker is connected to the front baffle you couldn't have tried the JBL530 on top yet - didn't have my glasses on - lol .
 
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I gave the dimensions in words and pictures earlier in this thread. Go back maybe 10 pages and do a little reading. It’s all there if you look. I don’t have CAD drawn plans posted as this was built by trial and fit by a cabinet maker from my rough hand made sketches. I have yet to draw actual plans.

Edit: Look at post # 443.