Robins Next generation

Dedicated to those large boxes at one end of the room
Post Reply
User avatar
rowuk
Old Hand
Posts: 453
Joined: Sun Jun 01, 2014 2:50 pm
Location: Germany

#1 Robins Next generation

Post by rowuk »

There is a retired guy in Germany that is making horns at a reasonable price - which motivated me to think about the next generation of speaker. At first I am using my 2x12" Fane Neodymium woofer box with the horn to hear what it does. The first impressions are decent.
MiniDSP, 4 channels of single ended pentode and my MacMini media center with Focusrite DAC. Woofers currently crossed over at 350 and the horn at 550 Hz with the MiniDSP Bessel 12dB/octave.
IMG_1969.JPG
Everything sounds OK except counter tenors...

I am planning some 80Hz horns under these 65cm ones and separate low frequency management. The Grande Castine or Kornhent speakers pretty much are the direction that I am considering.
Whenever I feel blue, I start breathing again.
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#2 Re: Robins Next generation

Post by IslandPink »

Nice - but I understand your concern about what is needed. The region from 100 to 500H is the big problem area - I'm sure it needs horn, but how to do something successful that is not impractical ? Compromises have to be made - but will it be mouth size, length or offset/delay to compromise ?

Personally, from the work I've put in so far, I feel that mouth size can be compromised more than length, and that offset can be used, but not more than about 5ms at 300Hz, maybe only 3 or 4ms at 600Hz. If you are happy with DSP then things are easier...
"Once you find out ... the Circumstances ; then you can go out"
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#3 Re: Robins Next generation

Post by chris661 »

rowuk wrote: Wed Mar 04, 2020 8:49 pm
Everything sounds OK except counter tenors...
Looks like an interesting system. When you say the tenors sound bad, could you narrow it down at all?

I can see that you've separated the crossover points - was this done by ear, or measurements?
IMO, crossovers really need measurement equipment to get dialled in properly, especially when HF horns are involved.

Chris
User avatar
rowuk
Old Hand
Posts: 453
Joined: Sun Jun 01, 2014 2:50 pm
Location: Germany

#4 Re: Robins Next generation

Post by rowuk »

Chris, I always measure first. Holm Impulse is my tool of choice, as the room plays less of a factor during initial voicing - and I do not have to be outdoors in the wet/cold.

In this case, the 66cm horn has plenty of gain down to around 250 Hz and the 12" Fane Colossus MBN sounds great up to 800-900Hz. Being able to crossover from 250 - 800Hz gives me plenty of room to optimise. With 6dB/8va crossovers, I was able to flatten out the lower end of the horn response, reduce the load on the Faital HF146 and make a smooth transition from the 12" to the horn - and finally get rid of the honky sounding counter tenors. The original problem was a little too much at around 500Hz. Instead of notch it out, I used the crossover to solve it.

My first experiments are normally done with a MiniDSP to set the crossover points, then I build the line level passive xovers into the amplifiers. I am still at the MiniDSP stage but am VERY close.

Next step will be to acoustically dampen the horn backside and build a proper stand for it.
Whenever I feel blue, I start breathing again.
User avatar
rowuk
Old Hand
Posts: 453
Joined: Sun Jun 01, 2014 2:50 pm
Location: Germany

#5 Re: Robins Next generation

Post by rowuk »

IslandPink wrote: Wed Mar 04, 2020 9:58 pm Nice - but I understand your concern about what is needed. The region from 100 to 500H is the big problem area - I'm sure it needs horn, but how to do something successful that is not impractical ? Compromises have to be made - but will it be mouth size, length or offset/delay to compromise ?

Personally, from the work I've put in so far, I feel that mouth size can be compromised more than length, and that offset can be used, but not more than about 5ms at 300Hz, maybe only 3 or 4ms at 600Hz. If you are happy with DSP then things are easier...
I agree with the 100-500Hz being the area of concern. It is not a problem as horns are what they are, you either accept that or use something else. Any serious compromise ends up landing in the bin.
I only use DSP for the modeling stage. I do not like my analog sources being converted to digital and back. If I only had digital, it would be a no brainer.
I will be first experimenting with the Kornhent/Grande Castine 80 -300Hz solution and Bert Doppenbergs Orelo open back configuration.
Whenever I feel blue, I start breathing again.
Post Reply