LX521, the baffle

[dewardh]

Originally Posted by john k...

Also, please recall that when I made the choice of the 10F I was designing the original Note with passive crossover for the panel and sensitivity was a big issue.

That certainly makes a difference, although it pretty much goes away when you go full active. The sensitivity of the TG9 (4 ohm) is 87 dB at 2.8V, the 10F (4 ohm) is 90 dB at 2.8V (both nominal . . . I have not measured the two side by side on the bench). That's significant in a "passive" design, not so much when active. With the same cone area and the same (nominal) xmax they are both going to make effectively the same amount of noise (plenty loud enough) in use.

[Melo theory]

Originally Posted by dewardh

That's pretty much irrevelant, because you're off both of them well above the frequency where driver "Q" matters. The distortion profiles, while different, are both admirably (and probably inaudably) low (and the different cone of the TG9 gives a different, also low, profile from the TC9). The drivers are remarkably similar in a number of ways (price excepted) . . . I'd hate to have to try to tell them apart in a "blind" test (behind active crossovers in otherwise identical speakers).

That's not to say that the Scan 10F is not a very good driver . . . it's just to say that by accident, or by luck, or by good design the Vifa (especially the TG9 version) is also a very good driver (making it a real bargain).

If you're selling a "high end" speaker (or "high end" design) the Scan name alone is probably worth the extra bucks . . . it's more pain than it's worth trying to explain why you used a "cheap TV driver".

Ps. It looks like John typed a bit faster than me this time . . .

Yes, I know the drivers are not being used at that low frequency, but the tc9 can take more abuse whilst keeping low distortion and that is important in an OB.

I agree the SS is a great driver, and when I first saw Zaph measurements...I was sure to buy it. Thank god I waited a while because he then posted the vifa measurements. I bought 52 of them.

I know name brands are important in the big leagues, but for a flat pack DIY, I would rather save 200 bucks!

[dewardh]

Originally Posted by Melo theory

but the tc9 can take more abuse whilst keeping low distortion

I wouldn't bet on that . . . although they have almost the same nominal xmax (without either defining exactly what that means) the Scan has a much larger xmech . . . you'd have to really work to break it. But I wouldn't plan on driving either of them to xmax anyway if keeping distortion low is part of the plan . . .

[LineSource]

My lunch table survey generated positive comments for the LX521 top baffle artistic Grecian Urn shape, EXCEPT for the funky base stand. A few stand-offs at the baffle corners would allow a form fitting lycra sock grill cloth.

Shock mounted swing baffles had positive threads. A top rubber O'ring suspension mounting would be interesting to preview at a Burning Amp meeting.

[natehansen66]

Not to keep with the OT but I tried the Vifa TC9 as an upper mid in my 4-way dipoles for a bit. If anyone is interested I'll see if I can dig up the graphs. I was shooting for a 4k+ upper xo to the tweeter. The TC9 directivity started narrowing more than I would have liked past 2.5k, compared to the Fountek FR88, or better yet the Neo8's I ended up with. The little Vifa did not match up well with the tweeter at 4k+ at all as far as dispersion is concerned.

[dewardh]

Originally Posted by natehansen66

The TC9 directivity started narrowing more than I would have liked past 2.5k,

Yes, the TC9, with it's 2.7" diameter cone, is starting to beam at 2.5kHz . . . as are all the 3" to 4" drivers, though not enough to be a show stopper for me. The trouble with the Neo8 is that to get slightly better horizontal axis performance you have to accept much worse vertical axis performance, along with some other issues unique to the Neo8. If you like it you like it, and nothing wrong with that, but many designers have looked at it and concluded that overall there are better choices. I really wanted to like it, but couldn't . . .

[dewardh]

Originally Posted by LineSource

EXCEPT for the funky base stand.

I agree that the bass box really needs a grill cloth . . . it will be very easy to add.

[Melo theory]

Originally Posted by natehansen66

Not to keep with the OT but I tried the Vifa TC9 as an upper mid in my 4-way dipoles for a bit. If anyone is interested I'll see if I can dig up the graphs. I was shooting for a 4k+ upper xo to the tweeter. The TC9 directivity started narrowing more than I would have liked past 2.5k, compared to the Fountek FR88, or better yet the Neo8's I ended up with. The little Vifa did not match up well with the tweeter at 4k+ at all as far as dispersion is concerned.

Yes. I would like to see the off axis graphs. do you have them up to 45 degrees?
I'm using these drivers in a line array, this would be helpful
Thank you

[natehansen66]

Out to 60 deg actually, in 15 deg steps. This is nude with no baffle, about a meter away. And back to the topic

[ivosp]

Its getting a bit of an old topic here, but anyway here it goes:

In top of the baffle the back tweeter is mounted above the front one. I always thought its crucial to mount the dipole tweeters in the same axis. When mounted higher, vertical off axis response at 90 degrees gets all messed up resulting in a bouncing up and down response straight at floor and ceiling (90 degrees top and bottom). Doesn't effect horizontal off axis behaviour offcourse BUT dont we want a nice dipole effect to eliminate unwanted reflections from floor/ceiling in a nice even spread way?

Is this effect not relevant because the tweeter is just doing >7k or has it to do with the special shaped baffle? Or am I just thinking wrong/missing something?