Chris Roger's DIY Transmission Lines

[Martin213]

Discuss please........

Having recently aquired a very much previously loved pair of these 'classic' TL Monitors i would very much appreciate your opinions guys.....

IMHO they still 'sing',in there own way,despite the original design now being 34 years old! (OMG,it really was that long ago!!!)

The pair i proudly own now have been constantly modified,every time a mod became available,i have all the paperwork

In the 21st century,i'm sure with a few mods,they can still excel

One thing that confuses me is that in this reincarnation,a Morel MD32S is only used between 3.5k and 10k,where it crosses over to a super-tweeter to 21k

The Morel 32S can reach to 25k,so i'm confused

Please feel free to share your views and opinions...........

Kindest Regards

Martin

[Martin213]

BTW apparently they reach down to 23hz,it certainly feels like it

(actually i very much doubt my humble Rogers Cadet gets nearly that low,but at least our pics ain't fell off the wall yet,LOL!) :d

[Scottmoose]

Is that the Hifi Answers design?

BTW, I don't pretend to be an expert on drivers / XOs, but you don't always run a driver full-bandwidth. Most drivers have a greater bandwidth capacity than is utilised in complete speaker systems, primarily because although they might notionally have a couple of extra octaves extension, that doesn't necessarily mean they'll do it with much aplomb. In this case, the supertweeter probably has a smoother response across the 10KHz+ regions than the Morel does, so it makes sense to use it, and roll the Morel off earlier.

[Richard]

Hi Martin

Yes, my q too, are these the Answers ones from Peter or the later Pro9TLs? I have both original articles and will have a look at the rationale, but what Scottmoose says is certainly true about not running domes nearer than a couple of octaves from resonance.

[Martin213]

Hi Scott,Richard,
They are PeterJ's HFN&RR examples,but what puzzles me is that Ivan Leslie rates the MDT32S highly,used full range in his S5TL's.
Surely then the supertweeter is best used above,say,20k?

[Martin213]

I say HFN&RR because that's what it says on the folder containing all the paperwork,i suppose it could be Hi-Fi Answers

[planet10]

To quote from Chris Rogers on the revised Pro9 TL

"In the three years or so since my original TL design appeared in print (HiFi Answers) there has been considerable advancement in drive unit design and, of course, we have 3 years further knowledge & understanding of the TL principal. This then is the culmination of the last 3 years presented as a new design."

In the early version the T27 was considered to not be extended enuff so a super tweeter was added. The newer version used a more extended tweeter and dropped the super-tweeter (as well as using a self-enclosed midrange)

I have attached the x-section of both, the right-most being the newer design.

In keeping with the inttentions of CR, when the more extended Morel was subbed in the super-tweeter should have been disconnected.

It is interesting to note that the modern evolution of this design...
http://www.remo.nl/rogersm.htm
is based on the original and is a 4-way



dave

I have the original article in pdf (as it happens i just made Scottmoose read it) and could assemble the revised one into a pdf as well.

[Scottmoose]

Thanks for that Dave.

That original article is an interesting read BTW. I'm still digesting parts of it for future reference / use. My only slight issue is the mounting of the two tweeters in the line itself, near the terminus, which would not be my top choice. Obviously works though, and if stuffed to aperiodic levels, shouldn't cause any problems.

[MJKing]

Dave,

I would be interested in reading the articles. Can you send me a copy or a link?

Thanks

Martin

[planet10]

http://homepage.mac.com/planet10/TLS...s/Pro9TL-1.pdf
http://homepage.mac.com/planet10/TLS...Pro9TL-Mk2.pdf

Note: the Mk II pdf is quickly put together... it could be tidier

dave