Xsim crossover critique

[Dissi]

Hi Rich,

The curves in Scanspeak datasheets are very accurate IMO and are well-suited to be used in a simulation. However your results in post 1 and 3 unfortunately are wrong. I assume there's no valid phase data in your zma and frd files.

The R2604/832000 tweeter is the Scanspeak version of the well known Vifa XT25 ring radiator. Distortions rise dramatically below 2 kHz, hence a crossover at 2.5 or 3 kHz is more appropriate. But a tweeter that allows a 2 kHz crossover would be even a better solution.

 

[montana1]

Hi JReave,
I could not get SplCopy to work properly either. Fiddled with settings suggested in help menu. Finally, got it to run through. When I tried to open it in Xsim it had errors and would not open. I just downloaded FPGraphTracer and will give that one a try. I will check out Zaph's blog as you suggested.

Thanks a Million,
Rich

 

[montana1]

Dissi,
Thanks for your reply. Yea, JReave has lined me out now. I missed several steps in learning this stuff. It's a good thing I stopped and inquired on this excellent forum or it would have been less then desirable. I will keep referring back to this thread as I move forward. It contains outstanding information and links to other needed resources.

Best Regards,
Rich

 

[jReave]

Did I make an error? I've been looking at the Scan D2604/8330 and referring to it in my posts. If so, Rich, you'll need to ignore my posted info about it. My bad.

Mind you, it'll work pretty nicely in combo with a 6.5" woofer.

Thanks Dissi.

 

[montana1]

JReave,
I was looking into this one. (see attachment) But, if you have better choice; I'm all ears.


Thanks,
Rich

 

[montana1]

According to Dissi's distortion comment in post #21; there may be a better tweeter choice for a 1,600 to 1,800 khz. crossover point. JReave, I will take a look at your suggested tweeter. I really would like to stay with the Scanspeak 18W/8434G and find a tweeter to match up well. There should be a few available that will fit into my price point of approximately $60.00 or less.

Thanks,
Rich

 

[montana1]

JReave,
I may need re-evaluate my woofer choice. If you don't mind take a look at this screen shot from WinISD. This is with the Scanspeak Ts parameters from Zaph's blog. His numbers were much different then manufacturers data. I will also attached the one using Scanspeak published data. Thanks once again!


Best Regards,
Rich

 

[eriksquires]

JReave,
I was looking into this one. (see attachment) But, if you have better choice; I'm all ears.


Thanks,
Rich

The LM-1 I'm building use a nearly identical driver. It's a good choice! Low distortion, and great FR and rolloff. I have not measured compression or distortion at high volumes though.

Erik

 

[eriksquires]

According to Dissi's distortion comment in post #21; there may be a better tweeter choice for a 1,600 to 1,800 khz. crossover point. JReave, I will take a look at your suggested tweeter. I really would like to stay with the Scanspeak 18W/8434G and find a tweeter to match up well. There should be a few available that will fit into my price point of approximately $60.00 or less.

Thanks,
Rich

The distortion isn't bad, by the way, it's just not great. It is better crossed over at 2kHz than below that.

 

[eriksquires]

JReave,
I may need re-evaluate my woofer choice. If you don't mind take a look at this screen shot from WinISD. This is with the Scanspeak Ts parameters from Zaph's blog. His numbers were much different then manufacturers data. I will also attached the one using Scanspeak published data. Thanks once again!


Best Regards,
Rich

If in doubt, Madisound's recommendations seem based on real world drivers, but no guarantees.

Is it a big deal for you? I mean, have you already committed to a certain cabinet, or is it that you are afraid of building the wrong one? If the latter, I'd either go with Zaph's or measure with DATS for $99.

Now if you wanted to use the 18W/4531 that I have specs for. 🙂

Erik

 

[mbrennwa]

Don't rely on SPL tracing alone, and especially don't rely on manufacturer's T/s specs. I think ScanSpeak puts the interns on them, they're never even close.

So far, my own measurements on Scan Speak drivers always gave results that were consistent with those in the manufacturer data sheets. As far as I can tell, data measured and published by test magazines (e.g., Hobby HiFi et al.) also tend to find Thielle Small parameters that are consistent with manufacturer specs.

 

[montana1]

Erik,
Thanks for your replies. I was just trying to go through process as you and Jreave have laid out. I have built one cab already and rather not change plans in that area. My thoughts are to make a solid driver choices that fit all the while not breaking the bank. I appreciate your offer on specs for the 18W/4531 but at over $200.00 each they exceed my budget. There does seem to be a few offerings from companies like Seas, SB, Scanspeak, Dayton, etc. that have woofers/ tweeters that would make a fine 2way system. Just did not want to get locked into one manufacture without considering others or listening to a few suggestions from those with first hand knowledge.

Best Regards,
Rich

 

[eriksquires]

Here are the distortion measurements I ran on this tweeter, or rather it's shielded sibling.

 

[montana1]

Thanks mbrennwa,
I probably need to invest in some entry level test equipment like DATS that Erik suggested. I appreciate your comments.

Best Regards,
Rich

 

[eriksquires]

Here's a better chart....

 

[montana1]

Nice!
Thanks Erik. That looks like a solid performer.

Best Regards,
Rich

 

[jReave]

My understanding of the D2604/8320 is that it is indeed a good tweeter but like Dissi said, it's best used above 2000Hz.

IMO the D2604/8330 would be a better choice as well as any one of these:
sb-acoustics-sb26stac
sb-acoustics-sb29rdc
sb-acoustics-sb29rdcn
Dayton RS28

If your cabinets have an internal net volume of 24L, I don't think you have to worry about changing your woofer selection. Either set of TS parameters can be made to work in that volume but what you'll need to do is play around with the port length to get a tuning that you are satisfied with. Attached is what Unibox shows with Zaph's parameters in 24L and Fb of 42Hz with a port 2" x 4.75". F3 is 40Hz. And that also shows you the max SPL for 1 driver at 1m before xmax is exceeded with content above 40Hz.

 

[eriksquires]

So far, my own measurements on Scan Speak drivers always gave results that were consistent with those in the manufacturer data sheets. As far as I can tell, data measured and published by test magazines (e.g., Hobby HiFi et al.) also tend to find Thielle Small parameters that are consistent with manufacturer specs.

Look towards the end of this discussion and you can see Raal and my own measurements.

If you look in other threads you'll find where other DIY'er shave mentioned to me how far off the Scanspeak specs are.

I guess it varies. 🙂

Best,


Erik

 

[eriksquires]

Nice!
Thanks Erik. That looks like a solid performer.

Best Regards,
Rich

I think so, but given the distortion below 2k is mostly 2nd HD I think you could cross it below that with good results. I noticed Gravesen does just this in a couple of his designs.

This looks like a pretty versatile tweeter.

Erik

 

[montana1]

JReave,
Thanks for posting that chart. I'm going to go with the Scanspeak 18/8434 and select one of the tweeters you suggested. At this point, I rather start working with Response Modeler and refine my skills with the software. Thanks to everyone for your outstanding replies!

Best Regards,
Rich