Beyma TPL-200H

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
The image in your post does not work, but no problem, I googled the name and found this conversation with pictures.

A not so DIY line array | Sound Forums

So basically he just put the horn versions on top of each other. That's interesting. I wonder how critical is he about the sound quality. He is doing a pa system, so of course it won't need to be the same as my non compromise system for my living foom. I certainly won't use the horn version, but I've thought about buying TPL 200s with a kind of factory? modified front panel. Google:

"BEYMA TPL-200/HR, HIGH-REVOLUTION"

They are sold in ebay for 900€/pair.

However I worry that the distance might be to great if don't put the drivers as tight as possible, which is only possible without the front panel. Or I guess I could grind the front panels to be shorter too. But that's a lot of work.

Danny Richie talks about one inch distance in this video:

YouTube

And I believe him, since I'm have that gap now and it sounds almost like a single tall driver. I'm saying almost, because there is a just a hint of separation which I can hear, barely.
 
And then there is the aspect of what happens to magnets in the long run when I force them against each other for years.

What will happen to a permanent magnet if we keep the same magnetic poles of two magnets close together for a long time? - Physics Stack Exchange

"While a pair of magnets will repel each other, they are not stable in this condition. One magnet won't simply float forever above another magnet."

Magnet Basics

Also I am not sure what happens in the magnetic gap where the membrane is. Maybe the output is not what it should be? There could be even added distortion because the ends of the gap are maybe compromised by the other, intruding magnetic field?
 
I did some more listening and tried different gaps and certainly I can say that with these rectangular tweeters, the lobing problems are much smaller than with traditional round ones, which I have used in the past in a similar configuration. No wonder round tweeters or full range drivers are not recommended at all for this purpose.

I happened to also find a good guide, which many of you already know, Design Guidelines for Practical Near Field Line Arrays, James R. Griffin:

https://audioroundtable.com/misc/nflawp.pdf

and there is written at page 7, "Active Radiation Factor for Slot (Rectangular) Drivers" should be more than 76%.
I measured, TPL 200 and 150 have a ratio of 78% with the flat front panel and without it, like I have mine now, bare and magnet to magnet, it's 83%.

But, I don't think I can keep them like this for very long and of course the looks are better with the front panel so I guess I would have to settle for the 78%...

I already tried that distance, and it seems mostly ok. For fun I also calculated the ratio when used with a horn, it's a measly 54%. So certainly won't go that route.

If anyone can give a tip for a better driver for the purpose let me know. Would be nice to have a 85% ratio, if possible.
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.