microTower bipolar ML-TL for CHR-70 or EL70

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planet10 said:
I understand that Quattro (an item of lust for me in my youth) is also caught in a time warp. That model was not available in right hand drive at the time period of the show.

dave

Right, although if you carried a big enough stick / wallet, you might (just) have been able to parallel import one of the first off the line from the factory in Germany. Not likely. Just adds a little extra sheen of (very sinister) weirdness to the proceedings.
 
Scottmoose said:

Doobie Brothers. I always liked Takin' it to the Streets myself... the CD's better than the vinyl though.


well, like I said, it was more a matter of nostalgia for the "heady" days of audio sales than the musical merits - frankly by the time Michael McD took over vocals from Simmons/Johnston/Porter, the band had already lost its charm for me. Let's just say that a little Michael goes a long way.

I was a much bigger fan of Chicago when they were still a "rock-band" ( 25 or 6 to 4), mostly Brit prog-rock (King Crimson, ELP, even the overblown Rick Wakeman operatic works), and Supertramp COTC, and Pink Flyod - WYWH - I must have worn out 2 copies of each of those.


geeze, if we're not careful this event could turn into being about the music rather than the gear - I don't know which is more dangerous


were is that Buffet guy when you really need him?
 
Did someone say Chicago???
 

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I figure the PP amp would be fine, the SE might be a little shy.

dave


BTW, I swapped out the FE108EZ Buschhorns with the EL70 "castle-top" MTs in the living room the other day, nested in room corners on a pair of 1" quartz-stone slabs, and driven by a cheap little Sony (25W?) receiver. While they're a bit too far apart (16ft) for critical listening, that's fine for this application, and holy $hit, these things can fill the room. Sure they can be overdriven, but they are less obnoxious than the FR125 when that happens.

For fun, I'll try to drag up as many of the tubed amps as possible this weekend for testing - will range from 2A3 & 300B SET to EL84 & EL34 PPT.
 
As Dave has not posted the dimensions for his cabinets, those of you who want to dive-in and build a ML-TL speaker using the EL-70 or CHR-70 can use the design in my offset bipolar ML-TL thread. This thread is at:

http://www.diyaudio.com/forums/showthread.php?t=148939

The offset bipolar consists of two twin ML-TLs in a partitioned box but can just build a single ML-TL given my dimensions if you chose.

My speakers were heard at DIY speaker events in Dayton, OH (early July), Atlanta, GA (early August) and the Nashville Bottlehead meeting. Several listeners were surprised at the amount of bass derived from these speakers and I'm sure that Dave's versions will receive good reviews where comments are available.

Jim
 
Where's the edge roundovers or bevels fellas? Are we operating on the premise that skinny baffles don't need them as much? Or that they're too much effort for the return? Or both?


Neither, actually - our first were quick proof of concept prototypes that "we" were pressed for time to complete, along with about a dozen other boxes,for the little event at Dave's last week.

Veneering or inlaying solid in the chamfered edges takes a fair bit of time, and I just took a chance that the sound would merit the resources expended on the rough finish. Since I'd already planned where I'd be using my pair (the Cinammon Cherry castle-tops) if they didn't sound hurtful, they would definitely need grilles, and the fancy edges wouldn't even be seen.


But you're right, this certainly merits building another few pairs for comparison purposes.
 
Feel free to add them. They should help. As a tribute to the original, the starting point is as faithful as possible.

dave

Shame that "snarky" doesn't come through on the internet. Tone is often lost in translation. I phrased it as a lightweight potshot in good fun. While I'm at it, why don't I make some hockey and Mountie jokes?

My point was simply that future builders should consider bevels and roundovers. Some people ignore them because "The baffle's so skinny that the driver's directional before any frequencies of concern". This is a common fallacy (the logical extension) as people often think of speaker behavior in terms of brick-wall filters, when there's no such thing. You still have diffraction artifacts in the instance of a tiny baffle, they're just suppressed by however much directionality loss the driver has at the frequency and distance. There's also the issue of ray length. On a skinny floorstander, you still have some significant path lengths from driver to edge, the further down from the driver you go, the lower in frequency this gets.

Audibility of edge diffraction problems is sometimes questionable, but I'm of the school that says that you fix known problems when you can, and certainly a bevel or roundover is easy enough for a competent maker of sawdust.
 
frugal-phile™
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Shame that "snarky" doesn't come through on the internet.

:)

My point was simply that future builders should consider bevels and roundovers.

I got that and it is a very good point. I'm trying to encourage people to have fun with mutations on these, and bevels or roundovers are a very good one.

Here is the current beta of the documents.

http://p10hifi.net/tlinespeakers/FAL/downloads/microTower-maps-130809.pdf

Comments & suggestions are encouraged... the section on bipole placement is in very early draft, pictures are missing, and i'm sure there are others.

dave
 
Dave & Bob beat me to posting link to the document - the dimensions start around page 3.

I was going to add this to my earlier post, along with the comment that the size of the document doesn't accurately portray the number of hours Dave spent on it - quite likely more than the total elapsed time for build and finishing of initial 2 pairs.

Of course, if these designs prove to be as successful as the Fonken & Spawn families, the long term aggregate build time will be much higher.



As for theoretical efficacy of small diameter radius or bevels in terms of mitigating edge diffraction artifacts, that's another issue.



let's not get started on the hockey and Mountie jokes, that could easily go both ways, and how can you make fun of us ?, we do such a fine job of it ourselves.


:snarky: - hmm, no emoticon for that, well hows snooty :snooty:

cheers
 
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