Work in progress of one of the three amps that will power the LGT's:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Shin,
I know that your midrange cabinet space was carefully planned. Yet I have never heard a midrange that I liked in a closed cabinet. I would hate to see you have to cut a hole in the back of your perfect cabinets without some good experimentation first but I would bet that some Dynaudio or Scanspeak variovents would give you the sound you wanted in the midrange although they might lower the absolute power the drivers can handle. You could make a small test box of the same volume and shape as the speaker cabinet midrange volume and see how they sound in something that approaches an infinite baffle. And you could experiment with various stuffing methods.
I know that your midrange cabinet space was carefully planned. Yet I have never heard a midrange that I liked in a closed cabinet. I would hate to see you have to cut a hole in the back of your perfect cabinets without some good experimentation first but I would bet that some Dynaudio or Scanspeak variovents would give you the sound you wanted in the midrange although they might lower the absolute power the drivers can handle. You could make a small test box of the same volume and shape as the speaker cabinet midrange volume and see how they sound in something that approaches an infinite baffle. And you could experiment with various stuffing methods.
Hezz said:
Are you insane... cut a hole in them?!?
If the AT sounded like junk then I'd maybe consider it but already it sounds good if not great. I've only really had this up and running for a couple of days now so there's a million and one more things to try before resorting to such drastic measures.
float said:
Hi Mark,
The bass drivers have had no running in except for any testing or listening that been done(I guess about 50 hours). Back in Feb when the mids first arrived I let them run for 2 days using a 15hz sine wave at around 3/4" xmax so about 48 hours of good run in and then they've probably got about the same again with music content.
Next week I'll leave them playing inaudble sines whilst I'm out during the daytime to make sure they're 100%.
You are right. Somehow though I got the feeling from reading your observations on the midrange sound that it was not going to be satisfying to you but I hope that you get them dialed in to your satisfaction after all the work you have put in. They are awesome looking speakers and the project is just fantastic.
Forgive me if I am a little biased towards infinite baffle sound but to me it is the end all of good midrange and midbass timbre.
Thanks for the suggestions.
Where to begin...
I've re-worked the mid driver cutouts with a 45 degree bevel. I've also been playing with something called noisestop(or was it noisekill?) which was given to me by my father and is used in ceiling and floor voids to soundproof multistorey apartments. Its a foam of some kind and is about an inch n' half thick and very dense, its open cell as you can breath through it.
To start with I wrapped a load of this around the rear of the driver and packed all area's of basket window openings taking care not to impede cone movement. Foolish move. This stuff really does soak up a lot of rear wave and it sounded dead. Took it all out and just placed some toward the top and bottom of the basket windows as these are in close proximity to cabinet walls. Sounds much better like that and not one bit of that shouty and forward quality I was talking about before.
I also put back in the large foam section that sits at the very rear of the mid enclosure as this definitely helps the upper bass clarity. You can really tell the difference with and without.
I did try other combinations but these either made no difference or none that I could definitely pick up on or they had a negative effect. I consider what I've settled on to be optimum.
I've also been playing with a 3.5way crossover using the upper midrange upto 820hz where baffle step kicks in and the lower midrange I've been using with alsorts of crossover points because I'm no longer tied up with MTM issues. Tuesday spoke some excellent advice on the last page. The AT really does sound a lotbetter up higher but I think the real problem is that the RAAL really doesn't have the mass and weight in sound to convince at 1.2Khz, I'm pretty sure its that which was sucking some of the dynamics away. I've got a great sounding setup going where I'm using the the AT upto 2.5Khz. The sound is lot more full and dynamic. Not quite as clean as when I was running the RAAL at 1.2Khz but it has weight, soul and body in the upper mids and lower treble.
I think this has got to be a 3.5way design as it sounds so much better. I was A/Bing the 3-way vs. 3.5way and thanks to the PC XO setup you get to instantly compare the two. A massive difference where not only is everything more focused but the integration is improved and finally I have dynamics in the mids! You can also now sit closer without having that annoying two drivers working together sensation.
The overall integration between all the driver units is really spot on. Its amazing really considering the size of them and the number of driver units but I think its one of the most coherent speaker I've heard. Right from HF to where the 8's roll off to nothing its all seemless. I've been running sines from top to bottom and its almost pitch perfect.
So what a fantastic weekend! Its starting to sound like a great speaker rather than just a good one Nowhere near done yet though and I think I'm only just scratching the surface here with more to come.
Where to begin...
I've re-worked the mid driver cutouts with a 45 degree bevel. I've also been playing with something called noisestop(or was it noisekill?) which was given to me by my father and is used in ceiling and floor voids to soundproof multistorey apartments. Its a foam of some kind and is about an inch n' half thick and very dense, its open cell as you can breath through it.
To start with I wrapped a load of this around the rear of the driver and packed all area's of basket window openings taking care not to impede cone movement. Foolish move. This stuff really does soak up a lot of rear wave and it sounded dead. Took it all out and just placed some toward the top and bottom of the basket windows as these are in close proximity to cabinet walls. Sounds much better like that and not one bit of that shouty and forward quality I was talking about before.
I also put back in the large foam section that sits at the very rear of the mid enclosure as this definitely helps the upper bass clarity. You can really tell the difference with and without.
I did try other combinations but these either made no difference or none that I could definitely pick up on or they had a negative effect. I consider what I've settled on to be optimum.
I've also been playing with a 3.5way crossover using the upper midrange upto 820hz where baffle step kicks in and the lower midrange I've been using with alsorts of crossover points because I'm no longer tied up with MTM issues. Tuesday spoke some excellent advice on the last page. The AT really does sound a lotbetter up higher but I think the real problem is that the RAAL really doesn't have the mass and weight in sound to convince at 1.2Khz, I'm pretty sure its that which was sucking some of the dynamics away. I've got a great sounding setup going where I'm using the the AT upto 2.5Khz. The sound is lot more full and dynamic. Not quite as clean as when I was running the RAAL at 1.2Khz but it has weight, soul and body in the upper mids and lower treble.
I think this has got to be a 3.5way design as it sounds so much better. I was A/Bing the 3-way vs. 3.5way and thanks to the PC XO setup you get to instantly compare the two. A massive difference where not only is everything more focused but the integration is improved and finally I have dynamics in the mids! You can also now sit closer without having that annoying two drivers working together sensation.
The overall integration between all the driver units is really spot on. Its amazing really considering the size of them and the number of driver units but I think its one of the most coherent speaker I've heard. Right from HF to where the 8's roll off to nothing its all seemless. I've been running sines from top to bottom and its almost pitch perfect.
So what a fantastic weekend! Its starting to sound like a great speaker rather than just a good one
Nowhere near done yet though and I think I'm only just scratching the surface here with more to come.
Sorry I didn't explain things very well. Blame the late night post 
At the moment the setup I've been enjoying the most is as follows. This changes hourly though
Both 8's are running up to 200hz(12dB/oct LR) the lower one has a metal clad resistor to attenuate as it measures about 2db hotter than the upper one due to floor loading. Both mids cross in at 200hz(12dB/oct LR) with one running upto baffle step at 820hz(12dB/oct LR) and the other to 2.5Khz(24dB/Oct LR) where it hands over to the RAAL.
There's also a bunch of notch all pass and notch filters the smooth the overall response and in particular tame the rising top end of the mids.
I'm using Frequency Allocator at the moment but simply because it allows very fast experimentation, much quicker than generating filters. Its all IIR filter rather than FIR though. I really just want to try as much as possible to get an idea of what works and what doesn't so am less concerned about the filters and where they came from at the moment.
At the moment the setup I've been enjoying the most is as follows. This changes hourly though
Both 8's are running up to 200hz(12dB/oct LR) the lower one has a metal clad resistor to attenuate as it measures about 2db hotter than the upper one due to floor loading. Both mids cross in at 200hz(12dB/oct LR) with one running upto baffle step at 820hz(12dB/oct LR) and the other to 2.5Khz(24dB/Oct LR) where it hands over to the RAAL.
There's also a bunch of notch all pass and notch filters the smooth the overall response and in particular tame the rising top end of the mids.
I'm using Frequency Allocator at the moment but simply because it allows very fast experimentation, much quicker than generating filters. Its all IIR filter rather than FIR though. I really just want to try as much as possible to get an idea of what works and what doesn't so am less concerned about the filters and where they came from at the moment.
I see nothing wrong in the low woofer being a bit louder than the upper one, how does it sound without attenuation ?
Have you tried just 6db at the 800hz xo
I suppose that you know that its the actual acoustical slopes that really matters most
Have you tried even higher xo point than the 2500hz, with 12db LR
Have you tried just 6db at the 800hz xo
I suppose that you know that its the actual acoustical slopes that really matters most
Have you tried even higher xo point than the 2500hz, with 12db LR
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