Now a Soviet Era Drivers for the Mets

[prem]

Your wall unit there will mess up the sound completely. It’s got glass doors. Also your TV is there. As it is with a TL design you were having a huge problem. With the OB it will be a nightmare.

 

[Hari Iyer]

Your wall unit there will mess up the sound completely. It’s got glass doors. Also your TV is there. As it is with a TL design you were having a huge problem. With the OB it will be a nightmare.

OK. Did not consider those. Will putting a simple thick bed sheet on the TV screen reduce reflection? The glass door can be opened where the AV items are creating a cavity. Also they are at below 1.5 feet. Alternatively, can putting some cotton cloth like a thin bed sheet behind the OB baffle reduce the effect.

 

[prem]

Hari, with your room size, I would try to build a speaker that probably goes down to about 40-45 hz. Below that may not be required.

 

[prem]

No Hari. The back wave is quite strong. The lower frequencies will hit your wall unit and come back, messing up the complete sound. With a boxed speaker you tame the rear wave to a large extent. But what you introduce is box coloration. In your case the box will be a lesser evil

But by all means experiment with OB. It’s easy to put it together. Also pretty inexpensive.

 

[Hari Iyer]

One more simulation OB (Blue) Vs TQWT (red). The box coloration is quite obvious in the mid frequency in the TQWT. Perphaps adding some stuffing can tame this. Also the mid-bass is less in the TQWT. The OB excels in this area. The driver is the same in both cases.

Also octave-to-octave balance is very smooth in the OB compared to the TQWT;

 

[keith_correa]

Hari, if you need a cheap place to stay when your family throws you out, I have you covered.

 

[jls001]

Haha

Don't know too much about OBs except at one point I was seriously contemplating building a Manzanita.

The thing that brought me back to terra firma from my lofty dreams was the fact that the baffle is going to be one ugly monster especially since I was thinking of a driver complement of a 15" woofer with 4" wide bander. I could live with the space requirement behind the baffle (36" at the minimum) but the right drivers were rather difficult to source. What ultimately discouraged me was the horror stories of drivers crushed and destroyed on their journey from overseas sellers.

 

[Hari Iyer]

Hari, if you need a cheap place to stay when your family throws you out, I have you covered.

My wife overheard me when i was speaking with my carpenter on phone explaining him the OB design. After that, she gave me 3 choices with freedom to choose,
1 Me and the Mets stay.
2. Me and the OB stay.
3. Mets and OB stay.

If i select the 3rd option, will contact you for sure

 

[Hari Iyer]

But in third option you will lose all sound you have !!!!!

Dinner offered. BF& lunch at office.

 

[keith_correa]

My wife overheard me when i was speaking with my carpenter on phone explaining him the OB design. After that, she gave me 3 choices with freedom to choose,
1 Me and the Mets stay.
2. Me and the OB stay.
3. Mets and OB stay.

If i select the 3rd option, will contact you for sure

Hey, it's Women's Day today - whatever they say they win!

 

[venki7744]

My initial suggestion was, since your driver is high Qts, just do make a test baffle just for comparison with your TL. With space constraints OB is no good and TL would be perfect.

Some people prefer to attempt TL only if driver Qts is between 0.25 to 0.4 Though I do not know if this rule strictly applies in practice.

Is QTS the only parameter to be taken into consideration while building OB, doesn't extrusion (xmax) capabilities also matter (especially to play low end).

 

[Hari Iyer]

Is QTS the only parameter to be taken into consideration while building OB, doesn't extrusion (xmax) capabilities also matter (especially to play low end).

Qts around 1.0 to 1.1 is ideal. If its over that then there would be a peaky response in the 50Hz to 60Hz region which cannot be tamed. Lower Qts driver tends to roll-off bit earlier and you dont get good bottom end.

If you driver Qts is around 0.71, but adding a small series resistance of 0.33 ohms can lift the Qts a bit to 1.0 but with a drop of SPL. Also the speaker cable resistance can contribute to the rise in Qts. Beware.

 

[venki7744]

For low end duty, Qts on the higher side, say above 0.6 helps for flatter response. My little experience tells me, I would go for larger woofers, 15” preferably and with higher senstivity, above 95 dB. An Xmas of 3mm or above is sufficient. Consider the surface area being moved even at 3mm plus and minus. An Fs of 40hz or below is preferable. And there is no single driver which has all the cherries in it for OB low end duty starting with high Qts.

And OB dipole bass is different from sealed or ported. If done right, you can differentiate between diffferent drum beats.

Trying to wrap this OB concept around my head. Cant this be achieved with a normal sealed or ported enclosure or better TLs or horns? AFAIK the only thing unique about OB is that the speaker is not mass loaded (contained in an enclosure) probably making the speaker sound as raw as it can (- the backwave). Is there something else that makes OB special (I have only built couple of OBs (that is when I absolutely had no idea on how to design it!) so pardon me for the lack of knowledge/experience with OB)

 

[Hari Iyer]

Trying to wrap this OB concept around my head. Cant this be achieved with a normal sealed or ported enclosure or better TLs or horns? AFAIK the only thing unique about OB is that the speaker is not mass loaded (contained in an enclosure) probably making the speaker sound as raw as it can (- the backwave). Is there something else that makes OB special (I have only built couple of OBs (that is when I absolutely had no idea on how to design it!) so pardon me for the lack of knowledge/experience with OB)

You can try simulating the OB in a Basta simulator (download link in post #20 ). With that you can simulate vented, closed boxes and compare for yourself. You can try different driver Qts and check out the outcome.

 

[prem]

Yogibear, I owned the Beethoven for a few years. Yes, from a DIY perspective OB is a simpler option

 

[prem]

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 to touch a single driver.

For transparency an electrostatic.

For microdynamics and presence a horn.

 

[prem]

I replaced the Beethoven with top of the line Logans

 

[prem]

I would choose my current speakers Tekton Double Impact SE over any commercially available OB speaker. It comes very close to horns for dynamics, has transparency of an electrostatic, great bass and more or less the coherency of a single driver.

It loses out on a bit of texture and tonality to some of the other speakers I have owned. But for the price it sells, it’s a steal. It’s 99db efficient and there are people driving it from a 2 watt amp to a 300 watt amp

 

[Hari Iyer]

I am listening my reconed Fostex with the Mets without the ribbon tweeter for over 2 weeks now, and i am very much liking what i hear. The Fostex i believe was more technical sound and had a shout at the crucial midrange which requires compensation. This paper driver is silky smooth in the mids and has extension till 12KHz and has a very good low end to my taste which is tight and with good transient. For my kind of music these speakers are good enough. The paper cone are having 3 ridges to reduce cone breakup in the mids.

 

[prem]

Hari, i never knew why you added a ribbon tweeter in the first place