FR125 / Comb effect

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I am thinking of starting my first speaker project I thought full range would be a good way to go for cost and sound reasons.

I have read up on the CSS WR125 and think it sounds promising I was thinking of using two WR125st per speaker and running them full range similar to rosa plans I have seen but with out a tweeter. I have two questions

1. The last few days I have read about a FR125 with a better top end depending on price I might upgrade to the FR does any one know if a FR125st is planed? That is a 16 ohm version with a truncated surround.

2. I have heard about comb effects when largish drivers are run full range and in the same speaker is that still a problem when using only two drivers or just in larger arrays?

My room is 10 by 20 and I can only use half of it for audio – HT I am at least interested in dipole designs but could I use them is such a small space. Another limitation is SAF and they need to be toddler proof or they wont last long.

Thanks
CoryLee
 
1. They already priced the FR125 at $150/pair. I wouldn't be surprised to see the 16 ohm version follow soon after as it did with the WR125 and at a slightly higher cost.

2. I think I've also heard the same, but I don't know how prominent it would actually be with two drivers though I'd guess minimal but someone else can probably better answer that.

I'd be interested to know the answer myself.
 
Last I heard is that there would not be a 16 ohm version. The impedance curve is such that even two FR125 in parallel would still maintain a friendly load for most amps. I would still hook them to the 4 ohm taps but I know the minimum impedance would be above that. You may want to consider making it a bipole if you're not going to have a tweeter. That would eliminate pushing them up against a wall but you may only need a foot or two of space.
 
FR125 impressions

I heard this driver on the weekend @ the RAW event in Surrey BC. I was very impressed with the performance and the potential of this driver. It was a prototype driver in a small cabinet. You will have to check with others for the specifics on the cabinet. I thougfht it sounded great and for me was one of the hits of the show.
 
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you could roll off one of the drivers with a filter, but maybe you think that would ruin the purity of a single driver. Often fullranges need a baffle step filter anyway and this would be one.

Bipole addresses the baffle step and probably the full range issue wthout any filter probably, so would be a good solution also.

Myself, I was thinking about two facing forward and two back. In theory I think I would need to at least roll off one of the front drivers, but I'm not ver good on theory, and theory doesn't always predict accurately.

Or maybe you could run a WR125 next to your FR125 and the WR would roll off soon enough to reduce the problem. Its probably too wide range though.
 
I have listened to and built a few bi-poles. I think this is an incredible design and if the room is wide or large enough it can create an amazingly large sound stage. The cabinet can be adjusted back and forth from the rear wall to tune to room needs and things just seem to disappear. In a small or conjested room the rear drivers add to the sound yet they do not seem to develop into as big a sound stage. Therefore IMHO bipoles are not for every room, they sound better in a room that has a bit of space to the side.
If you amp is stable to 4ohm or below there are not too many problems to worry about. Parralel conection will bring the efficiency up a bit.
I intend to try this driver in a bi-pole TL design. I am keen and think the drivers that are designed by CSS are just begining to get noticed. As I indicated in the Northwest audio thread I was quite impressed with all the designs that Al put together and could easily live with most of them. The room we were in caused a lot of colouring and bass boom but the mid range was marvelous. The WR125 coupled with a nice tweeter and not too much crossover yeilds a very nice sound to my ears. THe lower efficiency of these drivers is the primary challenge as it tends to eliminate the low power SET options.
The FR125 prototype was great. I am very interested in getting a few and working up some designs.
Good things are happening in the FR world these days.
 
Thanks for all your input

Last I heard is that there would not be a 16 ohm version. The impedance curve is such that even two FR125 in parallel would still maintain a friendly load for most amps.

I don't have an amp yet but was hopping to use a low to mid line Denon or Yamaha receiver and I am not sure about there 4 ohm stability

Bipole addresses the baffle step and probably the full range issue wthout any filter probably, so would be a good solution also.

OK this will show all of you how new and naive I am but what is baffle step? I have read about people compensating by boosting the sound around 150 hz but I don't understand what baffle step is A link would be fine as I am sure others have asked this question


I have listened to and built a few bi-poles. I think this is an incredible design and if the room is wide or large enough it can create an amazingly large sound stage.

I am in 10 X10 ft space with one of the side or back wall (depending on furniture set up) being open to another 10X10 foot space. Is that wide or large enough?

it would be easier to put the speakers against a wall because of space issues so a dipole is a consideration but only if it would make a bigish difference in SQ


you could roll off one of the drivers with a filter, but maybe you think that would ruin the purity of a single driver.

I haven’t yet formed an opinion on this keeping additional components out is just a way to KISS (keep it simple stuxxx)

again thanks for your input!! I would like some more opinions on if comb filtering will be a problem?
 
I don't have an amp yet but was hopping to use a low to mid line Denon or Yamaha receiver and I am not sure about there 4 ohm stability

Modern receivers are built to handle 4 ohm loads but check to make sure. I'm reasonably certain Denon and Yamaha make 4 ohm stable amps.

what is baffle step?

http://www.t-linespeakers.org/tech/bafflestep/intro-bds.html

If you're only trying to fill a 10 x 10 room I don't think you'll need two FR125 per channel. The single driver in the 7 liter cabinet with 1.5" rear port can be placed very close to a wall which will take care of your space issue and the baffle step issue. If you have doubts about this we may be able to arrange an audition for you.

Also, an FYI. BI-pole typically refers to two drivers firing in phase in 2 different directions. DI-pole is typically two drivers firing in different directions but out of phase or it can be an open baffle speaker.
 
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Timn8ter has a design that has 2 125's stacked. He might have an opinion about comb effects, etc... I guess he wouldn't have posted it otherwise! In theory if it is crossed over pretty high, there should be some effect I think, but sometimes these things aren't as audible as people claim..

http://www.timn8er.com/alegria_audio_rosa_tl.htm

How about it Timn8?
 
An audition would be nice. If it will work with 1 driver that would make things a lot simpler. :D I have heard great things about this drivers midrange and that it plays low. I guess I fell for moor is better adage. I guess it would make sense to see what 1 driver can do before deciding to go with 2.
 
How about it Timn8?

I posted my FR measurments for Rosa and it was proposed that the bump at 7kHz was combing effect. I have my doubts because the same bump occurs whether in a single, double or even 3-way configuration when the WR125 is allowed to run up that high. That makes me think it's cone breakup, not combing. Even if it were, comb filtering is difficult to detect in the average listening environment, IMHO. I think Rosa sounds great and those that have heard it agree.
However, the person that purchased my Rosa prototypes has agreed to let me attempt to tweak them to see if I can attack that bump. It may be that adding a small inductor to the WR125s will take care of it.
 
CoryLee said:
An audition would be nice. If it will work with 1 driver that would make things a lot simpler. :D I have heard great things about this drivers midrange and that it plays low. I guess I fell for moor is better adage. I guess it would make sense to see what 1 driver can do before deciding to go with 2.

You're welcome to contact me.
 
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The idea of using a WR for BSC with the FR is a very good idea... Using one of the 16 ohm ones on the back was also siggested as a 3 dB BSC compensation.

Chris is busy on 2 pr of bi-pole ML-TLs (one ply, one MDF). FR125s may land next week.

I'm very excited about this driver.

I have a couple more designs up my sleeve too.

dave
 
I would like to suggest that since this is your first project, go with the simple...single driver approach for now. From there you can see how you like them, play with some BSC maybe even as a tweak.

Once you have this relatively simple project under your belt, make a decision as to whether you need or want to ahead and get more complex with dual drivers, dipole/bipole, crossovers, etc.

Shoot, from looking at your location, it seem you are right smack in the middle of WR125s/Adire land so getting an audition shouldn't be a problem for you at all I wouldn't think.

Just my thoughts...

Noidster
 
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theNoid said:
Shoot, from looking at your location, it seem you are right smack in the middle of WR125s/Adire land so getting an audition shouldn't be a problem for you at all I wouldn't think.

If Tim can't help you out, then maybe an "overseas" trip to Vancouver Island. Looks like a VI DIY-fest is shaping up for late August at the mountain and we hop to have a variety of FR125 boxes in action (as well as some of the other usual suspects -- maybe the new FE108ES horns). Chris is currently building otherwise identical MDF & plywood bi-poles (hopefully to settle some of the arguement).

I also drew up a 1st pass of an Onken-style BR last night (inspired by the Solo 103).

Sims show that the FR125 will pop into a sealed box between about 3 & 10 litres, depending on how low a Q works for you (or what size containment is handy)

dave
 
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planet10 said:
Sims show that the FR125 will pop into a sealed box between about 3 & 10 litres, depending on how low a Q works for you (or what size containment is handy)

Here is the sim... Q = 1, net volume 2.5 litres
Q= 0.7, net volume 9.5 litres.
Q = 0.64 , net volume = 18 litres


dave
 

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