Troels Gravesen The Loudspeaker 1

I have a bit of a long-winded question here so please bear with me...

I few years ago I decided to do a home theater room/audiophile listening room. I've barely watched movies in here. I've spent countless hours listening to music, though. I setup it up originally with Klipschorns as the mains, Heresy as the center, Klipsch Chorus I's as the side surrounds and Cornwall 1's as the rear surrounds. A single REL HT/1508 subwoofer. It was very dynamic and loud.

My equipment was and still is: JBL SDP-55 Home Theater processor, Jeff Rowland Continuum 500 along with 4 Jeff Rowland monoblock amps for all the surround channels. I used an Emotiva for center channel and Atmos ceiling speakers. This is when I discovered listening to music in multichannel stereo. I would turn off the Emotiva amp and play just 6 channels. I thoroughly enjoyed this for a lot of different music. It was quite immersive.

I rebuilt and restored a Thorens TD125 MKII turntable and matched it with a GoldNote Phono preamp with separate power supply. I thoroughly enjoy this as well. The turntable setup is strickly 2 channel stereo.

So, I got the bug and decided I wanted to change out all my speakers. I think commenced to selling off all my speakers and chose to build the Troels Gravesen's The Loudspeaker 1's for my front mains. I have communicated with Troels for what he would recommend for surrounds and didn't really get a good response. He pointed me to some other speakers in his catalog. They won't be timber matched. For movies, this isn't a huge deal, but for multichannel stereo music it would be a very big deal.
I have been dragging my feet in getting the TL1's completed. I've acquired all the drivers, crossover components and the Hypex amps for the bottom end, semi-active. When I was purchasing drivers, I went ahead and bought another pair of the 18 Sound mids and 18 Sound compression drivers with horns. These are all the same drivers Troels spec'ed for the TL1's.

Would it be possible to use the 18 Sound mids and 18 Sound compression drivers w/horns to make a 2 way setup for my side and rear surrounds? A 2 way reflex setup. In otherwords, a ported cabinet tuned to 18 Sound spec's for the mid driver?
The mid driver is 10NMBA520 midrange driver model. Would this matchup well with my whole setup and the REL sub taking up the slack on the bottom end for the surrounds?

This has really been eating at me for quite a while now. Hopefully there will be plenty here with some insight.

And YES! I'm INSANE!!!
 
diyAudio Moderator
Joined 2008
Paid Member
Maybe. You'd have to consider a change in baffle step, and the naturally rising response and how far down you'd have to follow it. You'd be reducing the sensitivity considerably meaning you'll have to change the tweeter crossover too, deal with below baffle step modes near to the side walls as well as contend with a low end rolloff near the sub cross frequency. Xmax looks ok.
 
diyAudio Moderator
Joined 2008
Paid Member
It makes no difference to what I said... unless you thought I was just trying to tell you it would be difficult. I was not.

There are a number of ways I could think to answer this but perhaps what is more important is whether you get that response right.. not which woofer you use to do it.
 
diyAudio Moderator
Joined 2008
Paid Member
Yes, but only if the radiation and room interaction is the same. The tweeter waveguide plays a part there, use a different one and the bets are off.

The woofer on the other hand is largely pistonic in it's passband. Choose one of the same size and it will be quite similar. Choose one of the same construction/material/surround type etc since you'd be taking it close to breakup when crossing to a waveguide.
 
I doubt the room interaction will be the same as the mains as the surrounds are in different locations will have different reflection points.

I want to keep the voicing the same as the mains and so utilize the same drivers as the mains in my surrounds.

I do not have experience in speaker design, but am going to learn on this setup. I was hoping I could come here and gain some insights to help me go the right direction and when I make mistakes/failures I can get advice to help me get back on track.
 
I am talking about using the 18 Sound 10NMBA520 and the 18 Sound compression driver NSD1095N with the 18 Sound horn XT1086. These all are the exact same components Troels used for The Loudspeaker 1, which is what I'm using for front mains. These are the only drivers I'm considering.
 
diyAudio Moderator
Joined 2008
Paid Member
The answers to some of your questions you may have to find out yourself.

Put it this way, if designing a centre channel, the specified waveguide may be able to give a comparable performance in power smoothness and ratio, whereas the woofer is less critical as long as it is used correctly. The situation still won't be perfect regardless.. the speakers are probably best listened to off axis and you won't listen to the centre channel that way.. but this can be adjusted by all accounts.
 
I'm curious to get some insight from those that are much more knowledgeable on the subject of speaker design. I'd like to know if I'm barking up the wrong tree and need to follow a different path or can I utilize my selected drivers to achieve what I want?

Troels designed the TL-1 to have a crossover point from the midrange to the horn at 1300hz. I've been reading that below 1000hz baffle step isn't to really be much of a consideration in the design, as baffle step was mentioned earlier. Also, the location these speakers will be placed will be against the wall, which further negates the need to put much emphasis on baffle step.

18 Sound has a 2 way Reflex design utilizing their drivers, but of course its with different drivers. Is it possible to use their design as a model to start from?
 
I don't expect these to provide me with the same output as the mains. I'm only trying to keep the voicing the same as the mains. These speakers are very sensitive, so if sensitivity is reduced by the design of the 2 way, my surround channel amps are capable of producing 250 watts into an 8 ohm load. I have 4 Jeff Rowland Model 201 monoblocks to serve as my surround channels amps. Power is not an issue in any of my speakers. The only issue is I'm a kindergartner that escaped from a psycho ward.
 
How important is it to try and maintain the same sensitivity of the mains in the surround speakers?

What if, instead, I didn't use the same drivers as the mains and used the design 18 Sound already has, which uses different drivers and horn? Would that really pose a problem trying to blend with the mains?
 
diyAudio Moderator
Joined 2008
Paid Member
You seem to have the right idea about sensitivity, you can simply turn up the amp. Dirac can not do as well if you don't cross properly so don't overlook that.

Regarding the other design, I understand the compression tweeter may be overkill for the sides in it's price and it's output capability. You can try to blend a different design, it may be fine.
 
http://www.troelsgravesen.dk/TL-CENTER.htm

1706293178859.png



Matching high-spl mid just introduced. Looks like ok design, big and loud, isn't it just what many HT fans want?
2x10" woofers aperiodic tuning, 6" mid and 29mm Be-tweeter