[studley]

I have a pair of vintage PM6As that came out of some Accoustas so I'm interested in this design.  However, I know the infamous Lowther SHOUT is not  a myth, cos I've heard it.  Does this design do anything to tame it?

[Scott F.]

studley,

If you've got a pair of 6As out of the Acousta cabinet, there is a high likelihood that those have the 'old' style whizzers and latex surrounds. If that is the case, those had a 'shout'. If the cabinets and driver are old enough, you might just have the Ticonal magnets which are pretty darned rare and sound a bit different (better some think) than the Alnicos.

The new style whizzers with the rolled edges no longer shout....at least with the A series. When it comes to the latex surrounds, owners had to rotate the drivers to keep  them from scraping, that or realign them. Again, the new foam surrounds eliminate that.

I would suggest that you send them off to Jon verHalen at Lowther America and have them reconed. I'm not sure what the charge is but as I remember, it is fairly reasonable. It will be money well spent.

...and yes, if you offset the drivers in the baffles as MerRev and myself did, it really cuts down on the baffle diffraction in that 2500Hz region where the 'shout' exists. Same goes for the LMPs though you need to cross them at a much higher frequency (around 400Hz).

[studley]

Thanks Scott.  I'm in the UK but there are people over here who do such repairs.  In fact I had the surrounds replaced a few years back with foam ones because the originals had perished.  I will look into getting new whizzers.

[jhm731]

...and yes, if you offset the drivers in the baffles as MerRev and myself did, it really cuts down on the baffle diffraction in that 2500Hz region where the 'shout' exists. Same goes for the LMPs though you need to cross them at a much higher frequency (around 400Hz).

Scott-

What HP/LP crossover frequencies/slopes are you using?

Dn

[Scott F.]

With the Pass B4 prototype I'm using a 12db slope at 150Hz. When I use my Pioneer SF850 I use 18db at 125Hz.

[JayB]

I ran across Scott's Enjoy the Music article a few weeks ago and it got me thinking about going in the Lowther OB direction. I 've owned a pair of 416s for about 20 years waiting for the right project. Scott, you really did an excellent job in your article of debunking some of the Lowther myths, all of which I have read about at one time or another. One thing I don't think you discussed thought was high frequency beaming (for lack of a better word). Are Lowthers a head-in-a-vise speaker? Also, what kind of room treatment are you all using? Scott, your room look bare-walled. Could you guys comment on your thinking here? 

[Scott F.]

I ran across Scott's Enjoy the Music article a few weeks ago and it got me thinking about going in the Lowther OB direction. I 've owned a pair of 416s for about 20 years waiting for the right project. Scott, you really did an excellent job in your article of debunking some of the Lowther myths, all of which I have read about at one time or another. One thing I don't think you discussed thought was high frequency beaming (for lack of a better word). Are Lowthers a head-in-a-vise speaker? Also, what kind of room treatment are you all using? Scott, your room look bare-walled. Could you guys comment on your thinking here?

Jay,

Thanks for the kind words.

Regarding the head in a vise thing, well, yes. The Lowthers I've played with all have that characteristic. You've got about 6" where the sweet spot exists but let me qualify that just a bit. Unlike many, I tow mine in where they are almost pointing directly at the listening seat. Since I sit so far away (about 15') it doesn't seem to be as big an issue as when I used to sit much closer (8'-9' away). When you reduce the tow angle, the sweet spot gets considerably larger (1'-2'). When you have them heavily towed in as I do, that narrow focus gives you considerably more extension and 'sparkle'. That tow position is where you reach that ~14k treble extension. Off axis the treble does roll off a bit but it isn't bad. Guessing, you still get to 10k without any issues.

As for room treatments, first let me qualify that my room is considerably larger than most at 15'x38' with stepped ceilings. As opposed to something like one of my smaller rooms (14x17 and 9x11) where I need tons of treatment, this large room is considerably more stereo friendly. I use Armstrong Dune acoustic ceiling lay in tiles in this room with an NRC rating of .5 and a CAC rating of 40. Although the ratings aren't as high as some, they do a fine job in helping attenuate and isolate. Another issue often overlooked is the fact that my floor joists run the same direction as my headwall. This helps knock down some of the primary ceiling reflections that penetrate the acoustic ceiling and try to come back through.

Next is that an open baffle speaker loads a room differently than a traditional box speaker. Since you have sound radiating and reflecting in all different directions by design, you don't want to over damp the room and eliminate the primary reflections. IMO, that is where you get that monster soundstage that I experience in my room. Just to give you an idea, MerRev (one of the local guys) and I played with the size of the decorative plants located just inside the plane of the baffles on the headwall (see pic)



Believe it or not, we ended up reducing the size of the plant by over 50% because the larger plant made the soundstage collapse. You can see the size of the plant we ended up with in this pic.



Next you can see where I used plants on the headwall corners to help diffuse some of the bass buildups in the corners. Though not as effective as a trap, it does have an affect. I do use plastic/silk plants throughout to help diffuse rather than absorb. I've found that the first sidewall reflection being diffused seems to help with focus.

So between the ceiling tiles and diffusion that pretty well takes care of the high frequency anomalies that happen in my room. Now we are left with bass nodes and nulls. That one was fairly easy. I sat myself on an office chair with rollers and played the same song over and over as I rolled back and forth until I found a place where the nodes and nulls were minimized. That said, where my listening chair is, I do get a bit of boost below 50Hz but that doesn't bother me a bit. In fact I rather prefer it that way.

Now the way I do it will not work for every room. My smaller rooms tend to be a PITA to treat properly and these are a much better example of the typical room.

[JayB]

I love your room Scott. Mine is pretty similar, 45x16 basement with view out windows, acoustic tile ceiling. Speakers (Edgar sys100) are 6' from the wall, 14' from my listening chair, so I could duplicate your high frequency results. I have a desk along an adjacent wall where I listen when I'm working, which is the reason for the "head-in-a-vice" question. Thanks for taking the time to respond with picture and all.

[MerRev]

Next is that an open baffle speaker loads a room differently than a traditional box speaker. Since you have sound radiating and reflecting in all different directions by design, you don't want to over damp the room and eliminate the primary reflections. IMO, that is where you get that monster soundstage that I experience in my room. Just to give you an idea, MerRev (one of the local guys) and I played with the size of the decorative plants located just inside the plane of the baffles on the headwall (see pic)

hi JayB and Scott- I would have never guessed it could be so dramatic a difference but Scott is right about the plants in his room.  It was an amazing difference and a real ear opener to say the least.   

[alexstl]

Hi Scott,  a voice from the past.  I am interested in doing either an open baffle, lowther on a stick or dropping in a pair of pm6a's into my cain and cain abbeys.  If you have time I would love to chat.  alexbornstein@yahoo.com

[alexstl]

Your plexiglass lowther OBs look fantastic.  I would love to hear them.