CSS FR125S 2 way OB

Rafal · 5th October 2006, 05:39 PM

Hi Folks,

I have read that there was some interest in the 2 way OB with CSS FR125S and a bass driver (Eminnence Beta 15").

Has anyone tried it? If so, how would the crossover design look?

I was very intrigued by the Visaton Nobox but I already have the Fr125s so maybe I can use those.

Thanks,

Rafal

Rafal · 8th October 2006, 04:48 PM

Any idea on what would be amplification requirements for a 2 way OB (FR125S and 15' Eminnence Beta)? In other words, would a 20w/ch chipamp be ok to drive them?
I know this is a rather hypothetical question, but I just want to get an idea if I will be ok using my cipamp or if I will run into trouble. This chipamp just running the FR125S in OB seems to work fine.

rabbitz · 9th October 2006, 02:05 PM

Not quite your OB FR125S, but I did a hybrid with a woofer so the information here might give you some ideas.

Your chipamp should be fine as long as you don't go nuts on the volume control

I found the T-amp I have ran out of puff quickly but my chipamps have no problems and they are about 29W.

2litre · 9th October 2006, 03:06 PM

Rafal,

What baffle size / design are you lookng at with them?

Also, how are you going to drive them? Wired as a 2-way or with a seperate chip amp for them in addition to the one for the FR's.

R/

Jim

tade · 9th October 2006, 03:58 PM

I am also interested in a project such as this. I would consider active amplification with a mono sub amp for the dual bass drivers and and small tube or chip amp for the small fullrangers. crossover as low as possible at least, but i think that this would be great with those CSS FR125S above 150hz and a pair of dayton audio reference 15" for below. keep me posted!

Scottmoose · 9th October 2006, 04:11 PM

James D, an occasional contributor here, has an interesting way of crossing over two drivers like an Eminence and something else (whatever it happens to be) on OB. As I understand it, the drivers are connected in series, and have the filter components in parallel across them. Should be easy enough to alter for the CSS unit. Don't ask me how it works though -I've no details, and XOs are not my thing.

James D. · 9th October 2006, 06:51 PM

Hi Scott!

The problem with the eminence and the CCS FR is the large sensitivity difference.... fortunately its the Em that is more sensitive so you can pad it down... which has its own problems..

I would use different drivers - either different bass driver or different fullrange...

Heres a link comparing series and parallel filters x-over filters

James

Scottmoose · 9th October 2006, 06:55 PM

Cheers for that James -I really should have thought of that. Eliot Sound is a site I occasionally visit, usually to get a reality check, but I hadn't seen this article before -if it's half as good as his other work, I reckon I'm going to enjoy working my way through it.

Look forward to meeting you at Eggfest

Best
Scott

MJK · 9th October 2006, 07:18 PM

Quote:

The problem with the eminence and the CCS FR is the large sensitivity difference.... fortunately its the Em that is more sensitive so you can pad it down... which has its own problems..

If you cross over low enough, the added efficiency of the Eminence woofer could be used to extend the bass response and might even allow the baffle size to be reduced. Having the bass driver more efficient than the mid-range/full range driver can be a real advantage and traded off in the design process. It depends on the sophistication of the design process to use the added efficiency to its full advantage. A lower or equal efficency woofer in an OB reduces the variables and ties the design diown with fewer options to trade off. I would trade the CSS FR driver and keep the Eminence woofer (or maybe use the Alpha version) if I were doing the design work.

James D. · 9th October 2006, 08:20 PM

Ummm....

If the bass driver is mounted on an open baffle, either flat or U-shape (like I design) then you cannot extend the drivers frequency response downwards by adding series resistance or using an autoformer to reduce its sensitivity - you can extend the measured response of the system by reducing the higher frequencies to the same sensitivity as the rolled off low end of the bass driver ( which is what the series resistor does...) but it doesn't change the bass drivers response wrt roll off. It does cause the system effective Qes to increase so the bass response becomes peaky and the sound of the system changes - usually (always when I have tried it) for the worse... so I don't like to do this...

Also the baffle response will be strongly influencing the low end response (for any practical domestic baffle) and reducing its size will impact the bass response by lifting the system lf rolloff point in some manner...

Martin - are you suggesting using some lf EQ network, either active or passive to adjust things or is it the pulling down of the rest of the frequency range to match the lf roll off of the driver that you are suggesting?

James

5th October 2006, 05:39 PM	#1
Rafal diyAudio Member Join Date: Nov 2003 Location: London Ontario	CSS FR125S 2 way OB Hi Folks, I have read that there was some interest in the 2 way OB with CSS FR125S and a bass driver (Eminnence Beta 15"). Has anyone tried it? If so, how would the crossover design look? I was very intrigued by the Visaton Nobox but I already have the Fr125s so maybe I can use those. Thanks, Rafal

9th October 2006, 02:05 PM	#3
rabbitz diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	Not quite your OB FR125S, but I did a hybrid with a woofer so the information here might give you some ideas. Your chipamp should be fine as long as you don't go nuts on the volume control I found the T-amp I have ran out of puff quickly but my chipamps have no problems and they are about 29W. __________________ No longer DIY active

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Fr125s Bib	cangaceiro99	Full Range	16	26th August 2008 06:16 AM
My take on FR125S in OB	Rafal	Full Range	37	22nd March 2008 10:20 PM
FR125S x2 (EU,UK)	jimbo1968	Swap Meet	0	23rd November 2006 05:21 PM
css fr125s	joe perry	Full Range	5	10th May 2006 04:11 PM
FR125S in TL?	robertG	Full Range	37	27th March 2006 03:58 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

8th October 2006, 04:48 PM	#2
Rafal diyAudio Member Join Date: Nov 2003 Location: London Ontario	Any idea on what would be amplification requirements for a 2 way OB (FR125S and 15' Eminnence Beta)? In other words, would a 20w/ch chipamp be ok to drive them? I know this is a rather hypothetical question, but I just want to get an idea if I will be ok using my cipamp or if I will run into trouble. This chipamp just running the FR125S in OB seems to work fine.

9th October 2006, 03:06 PM	#4
2litre diyAudio Member Join Date: Jul 2005 Location: Bremerton, WA.	Rafal, What baffle size / design are you lookng at with them? Also, how are you going to drive them? Wired as a 2-way or with a seperate chip amp for them in addition to the one for the FR's. R/ Jim

9th October 2006, 03:58 PM	#5
tade diyAudio Member Join Date: Feb 2005 Location: Ralieigh nc	I am also interested in a project such as this. I would consider active amplification with a mono sub amp for the dual bass drivers and and small tube or chip amp for the small fullrangers. crossover as low as possible at least, but i think that this would be great with those CSS FR125S above 150hz and a pair of dayton audio reference 15" for below. keep me posted!

9th October 2006, 04:11 PM	#6
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	James D, an occasional contributor here, has an interesting way of crossing over two drivers like an Eminence and something else (whatever it happens to be) on OB. As I understand it, the drivers are connected in series, and have the filter components in parallel across them. Should be easy enough to alter for the CSS unit. Don't ask me how it works though -I've no details, and XOs are not my thing.

9th October 2006, 06:51 PM	#7
James D. diyAudio Member Join Date: Nov 2002 Location: North Herts, UK	Hi Scott! The problem with the eminence and the CCS FR is the large sensitivity difference.... fortunately its the Em that is more sensitive so you can pad it down... which has its own problems.. I would use different drivers - either different bass driver or different fullrange... Heres a link comparing series and parallel filters x-over filters James

9th October 2006, 06:55 PM	#8
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	Cheers for that James -I really should have thought of that. Eliot Sound is a site I occasionally visit, usually to get a reality check, but I hadn't seen this article before -if it's half as good as his other work, I reckon I'm going to enjoy working my way through it. Look forward to meeting you at Eggfest Best Scott

9th October 2006, 08:20 PM	#10
James D. diyAudio Member Join Date: Nov 2002 Location: North Herts, UK	Ummm.... If the bass driver is mounted on an open baffle, either flat or U-shape (like I design) then you cannot extend the drivers frequency response downwards by adding series resistance or using an autoformer to reduce its sensitivity - you can extend the measured response of the system by reducing the higher frequencies to the same sensitivity as the rolled off low end of the bass driver ( which is what the series resistor does...) but it doesn't change the bass drivers response wrt roll off. It does cause the system effective Qes to increase so the bass response becomes peaky and the sound of the system changes - usually (always when I have tried it) for the worse... so I don't like to do this... Also the baffle response will be strongly influencing the low end response (for any practical domestic baffle) and reducing its size will impact the bass response by lifting the system lf rolloff point in some manner... Martin - are you suggesting using some lf EQ network, either active or passive to adjust things or is it the pulling down of the rest of the frequency range to match the lf roll off of the driver that you are suggesting? James