[JDUBS]

Hey guys,

Given how good these sound even with their crappy amplifiers, I'd like to investigate replacing the onboard dsp / class-d amplification with a minidsp + a good 4-channel amp (for a pair of the JBLs).

I've done something similar before....but I'm wondering what functions the onboard JBL dsp can't (if any) be duplicated with a software solution like Room EQ Wizard with individual driver measurement and correction?

I mean, honestly, the speakers sound great as is....but I love trying to make stuff "better".

-Jim

[poseidonsvoice]

Hey guys,

Given how good these sound even with their crappy amplifiers, I'd like to investigate replacing the onboard dsp / class-d amplification with a minidsp + a good 4-channel amp (for a pair of the JBLs).

I've done something similar before....but I'm wondering what functions the onboard JBL dsp can't (if any) be duplicated with a software solution like Room EQ Wizard with individual driver measurement and correction?

I mean, honestly, the speakers sound great as is....but I love trying to make stuff "better".

-Jim

Good luck.

Without an anechoic chamber and discrete detailed polars in both the horizontal, vertical and oblique axes or a polar map, you are shooting in the dark. I really think REW (which I use heavily) is perfect for in room measurements below 300 Hz (without smoothing) and only fine for confirmatory measurements above 300Hz in room with 1/6th-1/12th octave smoothing to verify that the loudspeaker performs as it should. But to use it from the ground up to design a loudspeaker that performs well from a polar standpoint above 300Hz? Sorry, even with gating, etc...I would be afraid that my data isn't real. Put the loudspeaker high up hanging upside down in a gymnasium and now we are getting somewhere. Or build an anechoic chamber. But then oops, I forgot, you need to be an audio engineer, with an EE at least for starters.

If you are able to download the DSP file and then input that into a well designed third party DSP with multiple separate amplifiers, okay, then we are getting somewhere. Others have tried, but they have failed (do a google search).

Perspective: Why not get a JBL 705i or 708i with a BSS processor and do that instead? Or just get the 705p/708p and be done. The drivers and waveguide are much improved than the 3 series.

Frankly, I'm shocked with how good the LSR305 polar measurements are and the pair matching they provide at that price.

Like you said, the speakers (LSR305) sound great as it is.

Best,
Anand.

[HAL]

You might try a set of ground plane measurements outside for the woofer.  Need about 29' of clear area around the woofer to get down to 20Hz.  Use a good omni mic on the ground plane about 1 meter from the driver(s), centered on the driver(s). A balanced output phantom powered mic with a long cable should work correctly.

Basically a pressure zone measurement and works well from comparisons data I have seen. 

[JDUBS]

Good luck.

Without an anechoic chamber and discrete detailed polars in both the horizontal, vertical and oblique axes or a polar map, you are shooting in the dark. I really think REW (which I use heavily) is perfect for in room measurements below 300 Hz (without smoothing) and only fine for confirmatory measurements above 300Hz in room with 1/6th-1/12th octave smoothing to verify that the loudspeaker performs as it should. But to use it from the ground up to design a loudspeaker that performs well from a polar standpoint above 300Hz? Sorry, even with gating, etc...I would be afraid that my data isn't real. Put the loudspeaker high up hanging upside down in a gymnasium and now we are getting somewhere. Or build an anechoic chamber. But then oops, I forgot, you need to be an audio engineer, with an EE at least for starters.

If you are able to download the DSP file and then input that into a well designed third party DSP with multiple separate amplifiers, okay, then we are getting somewhere. Others have tried, but they have failed (do a google search).

Perspective: Why not get a JBL 705i or 708i with a BSS processor and do that instead? Or just get the 705p/708p and be done. The drivers and waveguide are much improved than the 3 series.

Frankly, I'm shocked with how good the LSR305 polar measurements are and the pair matching they provide at that price.

Like you said, the speakers (LSR305) sound great as it is.

Best,
Anand.

Do you not believe in software solutions like Dirac and Audiolense then?

I mean of course I'd rather have 708i 's.  But I'd also rather have have jbl 4367's, too.

But those are obviously many multiples the price of the 308s so not terribly relevant.

-Jim

[jtwrace]

Do you not believe in software solutions like Dirac and Audiolense then?

I mean of course I'd rather have 708i 's.  But I'd also rather have have jbl 4367's, too.

But those are obviously many multiples the price of the 308s so not terribly relevant.

-Jim

I gotta tell ya Jim I've heard the 4367's and wasn't blown away.  They're definitely not on the same level as the M2's.  I'm really liking the 708P's in my home as much as I did in CA. 

[jpm]

I'm really liking the 708P's in my home as much as I did in CA.

I'd appreciate any more insight you'd care to offer on these along with comparisons to any well known benchmarks, like the LS50s.  I've been so blown away by the 308s in my temp setup, it's impossible not to contemplate what the 708Ps might sound like.

[Russell Dawkins]

Hey guys,

Given how good these sound even with their crappy amplifiers, I'd like to investigate replacing the onboard dsp / class-d amplification with a minidsp + a good 4-channel amp (for a pair of the JBLs).

I've done something similar before....but I'm wondering what functions the onboard JBL dsp can't (if any) be duplicated with a software solution like Room EQ Wizard with individual driver measurement and correction?

I mean, honestly, the speakers sound great as is....but I love trying to make stuff "better".

-Jim

I'll bet the drivers in the 305 sound about as good as they can already. Since the 305 sounds so good, and measures well, too, maybe it would be just as much fun to take another two good drivers in a box (or OB) and try to match or beat the 305 .

My guess is you would spend much more time (let's call it money) than the difference in price between a pair of 305s and a pair of 705Ps and have as a result something that falls way short of the 705P. I'd also be surprised to learn that you managed to improve upon the work of a talented team of engineers at JBL after all that work.

Also, unless the DSP in the mini DSP is of the FIR persuasion, you would immediately be at another disadvantage since I read (once, somewhere) that the 305 uses this type of DSP as do a growing number of outstanding monitors, like the JBL 705P, 708P, Presonus Sceptre S6 and S8, the new Neumann KH80 DSP, the new Dynaudio Lyd 48, the KS Digital line (all), the IK Multimedia iLoud Micromonitor and other superior speakers.

FIR DSP I believe is the way of the future in speakers—that and crossoverless, as drivers improve.

And isn't it only a presumption that the amplifiers are "crappy"?

If you were to go ahead, I think you should start with the 305P Mk IIs because they claim improvements (unidentified) in both drivers—and the cabinets look better!

[poseidonsvoice]

Do you not believe in software solutions like Dirac and Audiolense then?

I mean of course I'd rather have 708i 's.  But I'd also rather have have jbl 4367's, too.

But those are obviously many multiples the price of the 308s so not terribly relevant.

-Jim

Jim,

I didn't say that I didn't "believe" in Dirac or Audiolense. I do not believe that the ordinary diy'er like myself* has the requisite tools** that I feel are necessary, even while using REW, Dirac or Audiolense, etc... to competently replicate the polar response curves without direct access to the FIR data that is inside the DSP module of the LSR 305/308. If you have direct access, then it's easier***. But if you don't, it's like starting with a clean slate. You have to contend with the issues of removing the multitude of reflections you will get from the room you measure your new design in. The investment becomes too great and just getting the 705i/705p or 708i/708p starts looking really nice. Or being happy with the LSR305/308 as designed.

* = But then again Jim, you might be very competent from that standpoint. So have at it.
** = properly measuring the said loudspeaker in a reflection free environment (i.e. anechoic chamber, ground plane measurements, etc...)

*** = FWIW, I believe the member HAL has tried to replicate those active filters for the JBL M2 with his new design using the dspMusik LCD. Again, that information was available to him, he didn't have to re-engineer the EQ for the JBL M2.

All that being said, I'll be very curious to see what solutions you come up with the use of DIRAC, Audiolense, etc...

Best,
Anand.

[JDUBS]

Never mind.  Wrong forum.

-Jim