Thanks for the response.
@mordikai, I think overexcursion is not a problem. The back chamber is there to protect the dome/diaphragm from touch
and air pressure when in box with other speakers (and its own cone).
Most dometweeters are unprotected.
@Rudios, yes that are Oberton 8CXs, LF8Ω/HF16Ω. Oberton changed the design of their coaxials to my dissappointment.
They glued a thick Kartoffelsack/dustcap on the front to hide the bad aligned horn/coilformer/cone.
The coilformer was 3-4mm protruding and I had to Dremel that down to make it as smpooth as possible.
The tlhp catalog shows an old model but on Oberton's page you see the new.
@adason, I didn't hear or measure inceased distotion. Maybe because it's already quite high.
But the listening experience is much more pleasant.
Cheers
Attila
@mordikai, I think overexcursion is not a problem. The back chamber is there to protect the dome/diaphragm from touch
and air pressure when in box with other speakers (and its own cone).
Most dometweeters are unprotected.
@Rudios, yes that are Oberton 8CXs, LF8Ω/HF16Ω. Oberton changed the design of their coaxials to my dissappointment.
They glued a thick Kartoffelsack/dustcap on the front to hide the bad aligned horn/coilformer/cone.
The coilformer was 3-4mm protruding and I had to Dremel that down to make it as smpooth as possible.
The tlhp catalog shows an old model but on Oberton's page you see the new.
@adason, I didn't hear or measure inceased distotion. Maybe because it's already quite high.
But the listening experience is much more pleasant.
Cheers
Attila
I think if you cross it low/ play it loud enough there is potential on some cd's to run in to the phase plug. ! have not done this myself so just repeating what others have mentioned. ymmv
Did you use a series inductor when doing this initial listening test? This can help to flatten the response.
Are you going to make any measurements? If not, how will you design the crossover?
I did not use any coils or capacitors, I concentrated on the bass only. An U-frame with 5 panels was satisfactory. The coaxial flat panel will be 41x39cm (16x15 inch) extended by de bass panel below. Crossover frequencies 200 and 3000hz. At the moment I'm waiting for my UMIK-1 and the crossover stuff i ordered. I will make measurements later, at the moment I'm learning how to use VituixCAD2 for the crossover. As soon as I have some results i will post them here.
Thank you for your interest.
Thank you for your interest.
I know, thank you. For the tweeter I use the same setup for the bass/mid I will try a series filter.
Well, this is probably one reason why you think the bass sounds "lean". The open baffle system loading has a response that falls at 6dB per octave, meaning lower SPL towards the low frequencies. Maybe you know this already but I am not sure. Because the response falls at 6dB per octave you often add a series inductor to it because that makes the response tilt down towards the high frequencies, and that corrects the dipole tilt.
The other factor that makes the bass sound lean is the Q of the system is much like the Qts of the driver because there is no "air spring" behind it like when it is in a closed box. The GRS 10PT woofer you use has a Qts=0.48, so the response is rolling off and will be -6dB at Fs, which is 50Hz for the GRS driver. That is really a lot of bass loss, the combination of the dipole loss and the roll off from the driver. You need to "fix" these with the crossover system, otherwise the bass will always be missing in action.
I will do this as soon as I have the coils and capacitors. The learning curve is steep. I did this in Vituixcad2:
Hi,
I'm following your progress with interest!
Perry Marshall has a project with the eminence 15a and tweeter on top in which he uses some passive crossover tricks to augment the bass.
I'm using the 12" SB Audience OB with my system. I do use DSP to bring up the bass but I find it satisfactory to my taste/constraints of apartment living.
Question:
Why did you go with the Celestion and why 10"? I'm not very experienced but am curious.
I'm following your progress with interest!
Perry Marshall has a project with the eminence 15a and tweeter on top in which he uses some passive crossover tricks to augment the bass.
I'm using the 12" SB Audience OB with my system. I do use DSP to bring up the bass but I find it satisfactory to my taste/constraints of apartment living.
Question:
Why did you go with the Celestion and why 10"? I'm not very experienced but am curious.
Size, 12" or 15" speakers would have made it a bit easier for the bass but the size was eventually too big for me.
Also, found some good feedbacks on this speaker and how "smooth" it sounded.
Also, found some good feedbacks on this speaker and how "smooth" it sounded.
I did a first batch of measurements with DATS and I do not like what I see. Configuration: 2 bass drivers in an u-frame OB, the Celestion FTX1025 in its own flat OB with the crossover (as above) and no tweeter connected. The blew line should be smooth between 70 and 500hz, or do I see this wrong? I did not finish the bass OB, so no damping materials used yet.
The GRS bass driver free air:
FTX1025 OB imp sweep (free air is the same):
The GRS bass driver free air:
FTX1025 OB imp sweep (free air is the same):
The shape of the blue line blew me away. 😉
Some bracing of the u-frame did wonders (pine wood), no damping materials used yet.
This weekend i hope to make a SPL graph in REW.
Some bracing of the u-frame did wonders (pine wood), no damping materials used yet.
This weekend i hope to make a SPL graph in REW.
Finally I got a measurement outside the house with REW. Not under optimal conditions, too close to the facade (3 meters) with some background noise. Graph looks awful, but the speaker does not sound awful at all?! I think I need active correction for the speaker (I hope it is not an audiologist I need). 🤭
The blue line is with micro in vertical position.
The blue line is with micro in vertical position.