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Now a Soviet Era Drivers for the Mets

shafic

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#81
IME, all speakers interact with the room, unless set up correctly. I had the B&W 801 Matrix speakers too. Set up correctly, nothing to beat the bass of B&W 801. Which is why I guess a few Pink Floyd albums have been mastered on B&W.

For coherency and tonality nothing by to touch a single driver.

For transparency an electrostatic.

For microdynamics and presence a horn.
Prem,
What about Field coils?
I have few vintage and modern ones. planning to build cabinets like this. Acquired Baltic birch ply of various thickness. Will start the project soon.
 
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Hari Iyer

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#82
Prem,
What about Field coils?
I have few vintage and modern ones. planning to build cabinets like this. Acquired Baltic birch ply of various thickness. Will start the project soon.
Measure them first and then simulate before building the box. It will save you time and money.

My 2 paise.
 

prem

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#84
Shafic have heard the Line Magnetics once. Other than that have never heard a field coil. Sorry Shafic don’t know much about field coils to have anything meaningful to say :)
 

Hari Iyer

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#86
Some lessons learned from simulating an OB speaker,

- The ideal driver Qts should be around 1.0. Lower than 0.71 cannot give you good bottom-end.
- The position of the driver on the baffle (width & height) is crucial in getting good bottom-end and with minimum peaks & dips.
- Not all drivers (woofers & FR) are suitable for OB as its believed. The choice of drivers in FR is very minimum as most FR drivers are designed to go either in a horn loading or TL loading projects which has very low Qts not suitable for OB duty. Hence you will need a largish woofer to supplement the bottom-end which has its own issue of cross-overs and matching.

I tried simulating two Ahuja 12" woofers on an OB and found them to be not suitable for OB duty as they begin to surprisingly roll-off around 200 Hz even though it had a Qts of 0.69. So just having a 12" woofer is no qualification for and OB speaker IMHO.
 

yogibear

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#87
- Many commercial designs have successfully employed dual 10" and 12" bass driver each side in their OB speakers. I personally feel it should be 15" and up and preferably a single 18" / 21" diver each side. Goldwood 18" 1858 is one great VFM OB driver.
-One commercial design updated from 15" Qts 1.1 Fs 25Hz drivers to 15" Qts 0.7 to Fs 40Hz driver for OB bass duty and it became their highest selling speaker.
-A couple of my 12" FR Qts 0.7 drivers do well down to 100Hz in OB.
-One aspect of high Qts drivers intrigues me a lot: Qts is made up of Qes and Qms. Two very similar high Qts value drivers could have radically different (high and low) Qms values. How do these two drivers actually compare sonically in bass duty, even if their Qts is same but radically different Qms values ?
-My 0.7 Qts 15" bass drivers, with a pinch of 5dB boost on the lowest octave start making fast dynamic bass like "Diesel Locomotive Engines". You do lose the low end of bass in OB but the chest thumping lower mid bass is a thing to be experienced !
-When it comes to looking for high Qts low Fs (lower than 30Hz) drivers, it gets very difficult, else its not scarce and OB cannot be discounted. I cannot say better than to quote a well respected person in DIY community who has made valuable contributions both in OB and TL designs, theory, simulations and executions:

"Inexpensive large high Qts woofers used in a dipole speaker over a limited low frequency range is so out of the mainstream boxed woofer thinking. It is extremely difficult for long time speaker designers/builders to get their heads around the trade-offs. It is like left and right hand drive cars and going from what you have known forever into the opposite seat, mind boggling. These types of woofers in OB set-ups seem to defy logic and perform well above their price point."
 

yogibear

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#89
Very interesting thread. Thanks for sharing. Expensive drivers coz of top $$$ and the passive crossovers is another thing that still eludes me. Another one "dark secret" of making OB work is weaving the drivers into each other with some passive crossover designs, as one veteran states....
 

Hari Iyer

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#90
@ Yogibear
Do you mean to get reasonable low end from an OB the size of the driver is important? Does it have to be 10"+ to get any meaning full bass. Does driver Qts do not play a major role here? Are the Basta simulation having some major bug? Are the simulations lying me? Please educate me as i have zero experience in an OB.
 
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yogibear

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#91
Hari, If I had been at your place, would have asked the same questions.

Yes, woofers larger than 10" make life easier to produce OB bass and the bigger they are, the better they perform, given a Qts of 0.7 or higher. Qts does play a role but Qts lower than 1 has performed as well in practice.

I can at best share my little experience but cannot educate on OB. Veterans, who can, in fact, seem to have some "dark secrets" of passive network tricks already employed in some commercial designs and so would not share in details. I would be very much interested in working with someone well versed in passive network design and share whatever little I know to find out the exact DIY details and find out why passive networks in OB are preferred over active by these very people.

I dare not say Basta simulation has a bug as it was suggested by MJK himself but he was himself baffled by practical execution of OB setups and the sonic impressions he experienced. Above are his exact words that I quoted.
 

prem

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#92
Yogibear, you can write to the guy in the thread whose link I had posted. He had replied to my queries with crossover details etc.

Unfortunately I no longer have them since I dropped the idea. This was more than 5 years back.
 

Hari Iyer

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#93
Thanks Yogibear for your insights. Appreciated.

Does that mean OB speakers are designed by expriments, trail & error rather than any solid driver TS parameters. More like bigger is better (BIB) for drivers? What role does then Basta play in the whole picture? Still wondering as MJK found practical execution to be different than simulation.
 

yogibear

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#95
Thanks Prem, I will shoot him an email.

Hari, MJK insists that one must simulate OB using Basta before attempting it. I think in practice one can go easy with limits of driver specs as dictated by Basta.

I came across an interesting BLH plan for high Qts drivers. I am not sure if it could be useful to your driver or if its nothing new for you. But I will share it here:

http://www.jogis-roehrenbude.de/LS-Box/Berndt_Burghards-Viecher/Viech.htm
 

yogibear

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#96
I just had my hands on a pair of very interesting drivers, NOS, made in Japan with some beautiful paper cones and very exotic surrounds. These are 8" in size. I am yet to measure the TSP but the freq specs look like too good to be true. I played them and they sound very nice, something like 95dB and 12-13K to 100 Hz at best I presume.

I would like to call them "Poor Man's Coral Flats" !!! Here are the pics:

IMG_0867.jpg

IMG_0868.jpg

IMG_0869.jpg

IMG_0872.jpg
 

Hari Iyer

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#97
[QUOTE="yogibear, post: 765847, member: 78692"
I came across an interesting BLH plan for high Qts drivers. I am not sure if it could be useful to your driver or if its nothing new for you. But I will share it here:

http://www.jogis-roehrenbude.de/LS-Box/Berndt_Burghards-Viecher/Viech.htm[/QUOTE]

But, wont BLH require low Qts drivers to begin with? Well therotically?
 

yogibear

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#98
No idea Hari. I am clueless with BLH or FLH. But the guy used Qts 1.1 Beyma driver and executed above design.
 

Hari Iyer

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#99
I have simulated some drivers in the LA and have noted that driver with high Qts rolls of earlier in a horn or TL speaker. Low Qts driver typically less than Qts < 0.5 are good for BLH & TLs.
 

yogibear

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Hari, I am sorry if I have kind of steered your thread to a discussion on Open baffles, at times. And though I confess that here but I still cannot help it. So please bear with me for a little more on the subject.

Prem, I want to thank you again for the above reference. I have been reading it diligently. When I started my OB experiments, it was based on my "Audio Hunches" and desire to approach OB setup with my own beliefs. And I am really surprised to find similar opinions/observations by the very experienced and seasoned gentleman mentioned by Prem in the above link. I wish to quote some of his observations which had been exactly mine too and could be a great learning experience for any of DIYers interested in OB designs:

-- I lowered the woofers’ crossover point to hear more of the D9e-II’s bass potential. This is one reason why I prefer to run my fullrange drivers unfiltered.

--The life blood of all music is in the midrange.

--Open baffles are famous for producing very billowing and dimensional staging between and behind them but are not as great at the sides or in front and behind the panel. And that’s exactly how the Feastrex behaved too. No surprises there.

--I personally like the idea of the potential ultra simplicity of open baffles for evaluating almost all my full range drivers.

--I personally have found that nearly all good full range drivers sound more natural in the simple open baffle format. Some OBs require diligent tweaking of alignment and toe in/out or the addition of on-baffle woofers and tweeters to sound their best. But in the critical presence region where all of my widebanders run unfiltered, they perform remarkable in simple open-baffle platforms and without the colorations derived from horns or cabinet-based designs. As you can tell, I am a fan of the simplest most natural-sounding format possible. What fits that requirement better than open baffles? Of course not even they are perfect.

--In the end, the OB format is something even the least inclined woodworker can enjoy experimenting with at home.

P.S.: I must confess, I never studied Physics so diligently back in College as I do audio concepts of my preference.
 
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