Speakers Build

[4ey]

I'll try to build speakers with donated JBL l26 cabinets and crossovers. I have idea which drivers I'd like to use - Dayton Audio PA255-8 10" Pro Woofer and

Peerless by Tymphany D27TG35-06 1" Silk Dome Tweeter​

I settled on either reworking the crossover point from 2000hz to 1500hz or buying another crossovers.
I'm interested to learn more about both options - how to rework this crossover to get to the 1500hz point and work with those drivers and alternatively what other crossover to buy (maybe new) to make these work.
As always, all your valuable input is highly appreciated.

 

[swechsler]

The best solution would be to DIY your own crossovers. This isn't that difficult - there are guides online that can help you - and if you're ordering the drivers from Parts Express, adding on the components wouldn't cost much extra.

The reason you might want to DIY is that speaker impedance isn't a single number, it's a curve. And that means that at frequency you've chosen to cross the speaker over, the impedance at that frequency (for both woofer and tweeter) might be nowhere near the rated impedance of the driver. Since you're buying the drivers new, you have access to the impedance curves on the PE website (actually, to be 100% accurate, you'd need to measure the woofer's impedance after it's mounted in the cabinet, but almost no hobbyists do that).

But before you make any purchase, have you modeled the woofer in the L26 cabinet volume and port size? You may find that that is not an ideal match.

Also, remember that a two way crossover consists of a high pass filter for the tweeter and a low pass filter for the woofer, and they are actually completely independent.

 

[homebrew]

I wouldn't recommend using the D-27TG tweeter with that woofer. The tweeter's resonant frequency is too high. You'd have to cross it over at 2500Hz or higher. Your woofer starts to get all squirrely above around 1500Hz. In my opinion, ten inch woofers are better suited for a three-way configuration. But if you're committed to a two way with the 10", maybe consider the XT25BG60 tweeter with a 590Hz resonant frequency. Nice flat impedance curve. You could cross that one over around 1500Hz.

 

[Apreggiator]

Woofer
I'd try to find a woofer that has as similar as possible TS parameters to the JBL 125a, which the L26 cabinet is designed for.
(I did not check the Dayton you suggested.)
TS parameters according to JBL can be found here: https://www.cieri.net/Documenti/JBL/Documenti tecnici/JBL - Thiele-Small Low Frequency Driver Parameters and Definitions (2001).pdf

Tweeter
Troels Gravesen did nice (measurement) work on the original crossover here:

JBL L26 restoration and upgrade

I'd try to find a tweeter that is sympathetic to the original crossover point as stated already in this thread, and keep the observations from these measurements in mind as well.
His follow-up three way project at the bottom of the page is rather tasty by the way, but also massive overkill considering what the L26 is imho.

P.s.
If you go with another crossover my recommendation about the tweeter can be ignored, but the recommendation regarding the woofer stands.
Unless you want to adapt the cabinet itself to suit the parameters of a woofer with different specs.

 

[4ey]

The best solution would be to DIY your own crossovers. This isn't that difficult - there are guides online that can help you - and if you're ordering the drivers from Parts Express, adding on the components wouldn't cost much extra.

The reason you might want to DIY is that speaker impedance isn't a single number, it's a curve. And that means that at frequency you've chosen to cross the speaker over, the impedance at that frequency (for both woofer and tweeter) might be nowhere near the rated impedance of the driver. Since you're buying the drivers new, you have access to the impedance curves on the PE website (actually, to be 100% accurate, you'd need to measure the woofer's impedance after it's mounted in the cabinet, but almost no hobbyists do that).

But before you make any purchase, have you modeled the woofer in the L26 cabinet volume and port size? You may find that that is not an ideal match.

Also, remember that a two way crossover consists of a high pass filter for the tweeter and a low pass filter for the woofer, and they are actually completely independent.

Yes, I will have to teach myself how to do that and get all the parts I'd need. As #homebrew mentioned I will have to consider another tweeter. I hope all matches well. I will take measurements to make sure they all fit. My goal is not to rebuild them as close as possible to an original L26 speaker but rather to make something possibly better out of them. I thought of crossing them at 1500hz as I read 10 inch drivers may cause problems crossing at 2000hz - which is the original cross point. With all your help, I feel confidant I can make it work.

 

[Apreggiator]

Looking into your Dayton woofer, taming the rising response between 1.5kHz - 2kHz doesn't seem like a big challenge, the dip looks like more of an issue to me.
Manufacturer specs here: https://www.daytonaudio.com/images/resources/295-030-dayton-audio-pa255-8-specifications-46882.pdf

The Dayton DC250-8 has a much gentler response curve for instance (at the 'expense' of sensitivity).

P.s. I haven't taken the time to compare TS parameters of the Daytons and the woofer of your JBL speaker cabinet was designed for.
P.p.s You COULD not care about bass extension (ergo, not care about the fact that the cabinet is not optimally tuned to the bass driver you use) and use something like the Faital 10FE200, which plays beautifully all the way up to 3kHz.. And has really good midrange.. And will run higher up the frequency range if you care less about off-axis response.. Oh and it's also very budget friendly for what it is. The reason that cab tuning doesn't matter with a driver like this, is that it likes to be cut off between 100-150 Hz in the lower range. When cut off off properly, run a sub with it and pair it with a very efficient high frequency driver, you'll end up with a formidably 'fast' and efficient speaker. I chose the Faital as example because of it's price/performance and wide availability, many PA midbass drivers will fit this approach.

 

[J1mbo]

Or go compression driver and waveguide.

 

[70's Rockfan]

I have used many of these tweeters in
my diy builds and think they sound great.
you would not have to mess with your crossover either.

Dayton Audio DC28F-8 1-1/8" Silk Dome Tweeter

Dayton Audio DC28F-8 1-1/8" Silk Dome TweeterThe Dayton Audio DC28F-8 1-1/8" Silk Dome Tweeter is a great option for DIY speaker enthusiasts, as it offers amazing performance at an unbelievable price point. Featuring treated silk dome, this tweeter delivers smooth sound, while the damped rear...

www.parts-express.com