CSS Driver Idea

Hello, I am new to the world of DIY audio speakers, although I did construct a pair of Jordan fullrangers.


The new CSS 4.5'' driver intriques me, and I am curious as to why - if the driver is as good as some people here are saying it is - the driver is not being used by practically everybody. I heard one guy say it was better than the Jordan JX92S, which is considerably more expensive. If it is truly better than the Jordan, I will love this driver. People are saying that it has better bass response than any other driver about it's size, although the Jordan (which is about the same size) goes down to 40Hz whereas the CSS goes down to 60Hz. Is the bass response truly better?

The most frustrating thing about building the Jordan speakers was working with the cabinet. For this reason, I have an interesting design idea. Why not just load the CSS driver into an inverted horn lense (ala nOrh, but have it be a true horn lense)?

I was thinking something like this: http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=264-315

You would mount the driver on the mouth...would it work? Does the plastic rim surroundng the driver extend the diameter to about 6 inches for the CSS driver (I have had trouble finding dimensions)?
 
Originally posted by Czilla9000
The new CSS 4.5'' driver intriques me, and I am curious as to why - if the driver is as good as some people here are saying it is - the driver is not being used by practically everybody.


It has been on the market for less than a year. People have been talking about and playing with ht Jx92 for nigh on 5 years now & it is just getting a big head of steam (not to mention that as a driver it goes back some 30 years -- i was playing with the 4" Jordan-Watts in 1975!!)

I heard one guy say it was better than the Jordan JX92S, which is considerably more expensive. If it is truly better than the Jordan, I will love this driver. People are saying that it has better bass response than any other driver about it's size, although the Jordan (which is about the same size) goes down to 40Hz whereas the CSS goes down to 60Hz. Is the bass response truly better?


The 2 drivers are in the same league (until you throw price into the equation) The CSS trades going lower for a relative lack of top end. It is a fair compromise. The CSS gives up a bit of efficiency to the Jordan -- in this case a consequnce of the XBL which means less distortion. Really the Jordan is challenged to get to 80 cycles...

[/QUOTE]I[/QUOTE] was thinking something like this: http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=264-315

You would mount the driver on the mouth...would it work? Does the plastic rim surroundng the driver extend the diameter to about 6 inches for the CSS driver (I have had trouble finding dimensions)?[/QUOTE]

Interesting though... you would probably do better to go searching for clay pots as an alternative to these thou (been done with good success with the JX92) ... there are lots of object sthat could be repurposed for use with small speakers.

dave
 
Re: Re: CSS Driver Idea

planet10 said:
The 2 drivers are in the same league (until you throw price into the equation) The CSS trades going lower for a relative lack of top end. It is a fair compromise. The CSS gives up a bit of efficiency to the Jordan -- in this case a consequnce of the XBL which means less distortion.

Dave, what tweeter would be a good match for the WR? I always liked the look of the G2Si + JX92 combo, but it seems like a WR125 + G2Si pairing would be very wastful of the tweeters 94 dB sensitivity.
 
Re: Re: Re: CSS Driver Idea

Originally posted by leadbelly
what tweeter would be a good match for the WR? I always liked the look of the G2Si + JX92 combo, but it seems like a WR125 + G2Si pairing would be very wastful of the tweeters 94 dB sensitivity.


Tim is successfully using the weird bezeled Fostex, if you just plan on letting the WR125 run full out it doesn't take much tweeter to fill in the top octave.

It may be sacriledge, but in our 1st crack at this puppy, we are going to waveguide load the ApexJr 50 cent tweeter. If we decide that doesn't cut it we will upgrade to the Audax gold dome version. In this ap, as general guidline, the smaller the tweeter the better.

I'll let you guys know how it works out when Scott brings the boxes down. (BTW i'd be happy to toss in a pr of Ts with any pair of WR125 purchased -- i note no one has mentioned the price drop in the WR125 -- at least the 8 ohm version)

dave
 
If anyone wants to try the bipole before i get prototypes done... here it is (as big as will fit on the forum -- i can provide a larger -- ie readable -- pic directly)

dave
 

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The cab volumes were calculated around the WR125ST although the WR125S should work also. I like the way the WR125ST behaves with tube power, however, an interesting side benefit of the XBL^2 motor is it's stable impedance. You could parallel a pair of WR125S and be able to call it 8 ohm nominal as the low impedance point is still well above 4 ohms.
 
Poking and proding

Good for you Dave:
A well worded poke for me to get on with the construction of the prototype.
I have been busy with the things I am told to do by "she who must be obeyed".
Right now is digging season and I have been mixing concrete and doing a lot of digging. I have learned better than to make any promises about when I will get the proto done but lets hope it is soon.
It might even be a plywood box this time!
 
Re: Poking and proding

Originally posted by SCD
I have learned better than to make any promises about when I will get the proto done but lets hope it is soon.


Some black 1354 phase plugs is on the top of your list (1 pr backordered)... speaking of phase plugs...Tim have you had a chance to try the 207?

dave
 
Re: Re: CSS Driver Idea

planet10 said:
The 2 drivers are in the same league (until you throw price into the equation) The CSS trades going lower for a relative lack of top end. It is a fair compromise.


I looked at the Jordan for a long time. The thing that kept throwing me was the rising frequency response. I know it's intended to counteract the beaming, and you're supposed to cross the driver paths in front of you. In my intended location I needed to have the driver firing straight ahead. Besides I've listened to systems where the drivers cross in front of the listening position, and I didn't like the effect.

Price wasn't a consideration in my case, nor was efficiency.
 
Performance of Jordan JX92S vs. CSS WR125S

Let me comment on Planet 10/Dave's reply from above:

"The 2 drivers are in the same league (until you throw price into the equation) The CSS trades going lower for a relative lack of top end. It is a fair compromise. The CSS gives up a bit of efficiency to the Jordan -- in this case a consequnce of the XBL which means less distortion. Really the Jordan is challenged to get to 80 cycles... "

These two drivers are very similar in their bass ability according to my BassBox models. The JX92S has an Xmax of 4.5 mm vs. the WR125S value of 6 mm. When I model them in the same size 7 liters vented box their 3 dB down points compute to be within 2 Hz of each other (the WR125S being lower) while the 7 liters sealed boxes 3 dB down points are within 1 Hz on the low end (the JX92S being lower). Now the JX92S has slightly more cone area so it makes up for its smaller Xmax vs. the WR125S. I would call it a dead heat on their bass ability.

The primarily differences between these drivers relate to the JX92S's capability to produce about 3 dB more output in SPL. This difference also shows up at the SPL level achievable at their rated Xmax values. At 1000 Hz and with 1 watts input the JX92S has a sensitivity of 89 dB while the WR125S runs 86 dB. With a 30 watts level signal signal at 50 Hz the vented JX92S can produce more than a 97 dB SPL level while the WR125S runs about 3 dB lower in its SPL level under the same conditions.

The JX92S trumps the CSS driver on the high end of the band (15 to 20 kHz) if you were trying to run them full range.

I have measured data on the JX92S at:

http://www.creativesound.ca/pdf/JX92SG2siDesignPak.pdf

Note that for this JX92S design the 7 liters sealed box measures at a 3 dB down point of 70 Hz and a vented box 3 dB down point is 51 Hz based upon these near field measurements.

Bottom line is that the JX92S has slightly more sensitivity and a 3 dB more SPL output level than the WR125S. It is up to the user to decide whether these sensitivity differences, any sound quality difference, and higher cost of the JX92S vs. the WR125S would be justified.

Dave, I should say that the JX92S or the WR125S can produce more than enough bass output below 80 Hz for many users. In fact, in MLTL boxes for the JX92S (and likely for the WR125S) both speakers would likely move their 3 dB down points into the 40's Hz range. Both of these drivers are rather remarkable for their size and output. Now if you wish to achieve pressure wave bass levels, you'll have to use a subwoofer with either driver.

Jim
 
Timn8ter said:
The volume numbers you've posted produce nearly the same F3 point however the smaller box will give you a rise approaching 100Hz before it rolls off.

I don't get it. I used this calculator http://www.mhsoft.nl/spk_calc.asp#sealed
and WinISD and specified a Q of .707 for each. How the heck do they give such a different result?

I happen to have a pair of 50L cabs with no plan, so that interests me. I'd love to stretch f3 down to 60 Hz but OTOH I'd prefer a sealed box.
 
Re: Re: Re: Re: CSS Driver Idea

planet10 said:
It may be sacriledge, but in our 1st crack at this puppy, we are going to waveguide load the ApexJr 50 cent tweeter. If we decide that doesn't cut it we will upgrade to the Audax gold dome version.dave

I think you should use the Hi-Vi RT1L round planar tweeter. It would be too cool to have both a tweeter and a mid-woof with copper phase plugs. ;~)