JBL Studio 590 Upgrade Project

[jgs5607]

I haven't been active on this forum ( I have lurked around for specific topics) but I thought members might be interested in an upgrade project I did on my JBL Studio 590's.

The link below is to AVS where I have a detailed thread on the project. Although they are a discontinued speaker ( replaced by the Studio 6 series) JBL had the various 5 series speakers at almost give away prices for over a year, so there are a lot of them around.

It is a worthwhile upgrade IMO, especially if you are using them primarily for music.

https://www.avsforum.com/threads/jbl-studio-590-upgrade-project.3322673/?post_id=63919222#post-63919222

 

[Beave]

That's some serious determination and dedication to re-engineering those speakers.

Does the actual crossover for the woofers in your speaker match the schematic JBL shows in their tech paper, or is it something different?

 

[jgs5607]

I have not pulled the stock crossover board for the low pass section out to verify what it looks like; if I pull the lower woofer out for some reason, I will take a look just for grins.

The acoustic response from ASR, Newport Labs and my own measurements tells me it isn't right.

The same model 580J woofer is used for the upper and lower driver.

You don't get a 15db notch in response without a high Q notch filter in the circuit ( see attached graph)

The text below are 2 excerpts from a lengthy response from a HARMAN Field Engineer when I asked the question about the low pass filter section


"You've hit upon a common and
frustrating issue in audio:
discrepancies between published
schematics and actual measured
behavior. It's excellent that you're
digging deep and cross-
referencing multiple sources."

"Recommendations for Your
Active Crossover Project
* Trust the Measured Data:
* Based on the ASR and
magazine reviews, it's highly likely
that the schematic is incorrect
Prioritize the measured data over
the published schematic"

Basically, the acoustic response doesn't match what is on the published schematic.
There should be an LCR notch filter depicted and there isn't.

Since I am not going to an active crossover anymore based on the performance of the passive setup with my new high pass filter ( which uses 9 less components than JBL's, which I did verify was correct) and the stock low pass filter, I will just let sleeping dogs lie.

 

[Beave]

Yep. I admittedly didn't read your entire AVS thread, but I did see that part. It certainly appears to be a notch filter for that woofer.

I've seen pics for the woofer crossovers for the 530, 570, and 580 models, and they all appeared to match what is shown in their respective schematics. I did a Google search for images of the 590 crossover but didn't find anything.