XPL200A vs 4315A first impressions

[johnaec]

OK - I hooked up the DBX DriveRack 260 with its calibrated mic today and ran a few curves. Unlike Zilch's Behringer, (which analyzes 1/6 octaves), the DR260 only does 1/3 octave, with 16K being the highest.

Grilles were removed for the tests, with the mic centered both vertically and horizontally in front of the respective speakers, at a distance of 1 meter. Testing level was ~ 94dB, measured with a C-weighted Radio Shack digital SPL meter.

Bear in mind that because of the environmental conditions, these curves should really only be looked at for relative differences between the speakers. Perhaps later in the year I'll take them in the backyard, laying them flat, and get some much more objective curves.

One thing obvious in all curves is that both speakers would benefit from being raised above the floor, (judging by LF output). Also, this was done in my living room, with lots of padded and also reflective surfaces, all over the place - I'm sure this had a significant impact on the readings. Also, I believe the pink noise has a crest factor of a couple dB - that's why the curves vary a little in the LF on the same speaker.

The first curve is of the 4315A, with all controls at "0". The next one is the 4315A with the UHF at -4, HF at -3, and MF at 0, as per Greg Timbers' comments - these settings appeared to yield the flattest response.

The third curve is of the XPL200A with the HF trim flat, and the following curve is with the -2 dB switch turned on.

Anyway, I'll leave the speakers with the trim settings enabled for a while, to get some closer listening comparisons in the future.

John

[johnaec]

How do you "normally" have your 4315A settings?

Normally I had all the levels at "0" and used a little outboard EQ to smooth things out.

BTW - lowering the level of the 8" MF in the 4315's took that bump at 630hz down, but added dips to both sides of it...

Also, once you realize the graphs are +/- 12 dB at full scale, the curves aren't too bad.

One thing I don't like is that the graphs are also based more on what an engineer would want to see at the outputs - green for safe, then yellow, and finally red for peaks. It doesn't make for a very natural looking graph, (although I should have raised the gain a little for a mean of "0").

John

[Robh3606]

Hello Johnaec

I would like to make a couple of suggestions on setting these up and where to take your measurements from. I always look at tunning speakers in my room from a different perspective. I don't really care what the 1 meter curves look like. Simple reason is I don't listen there. If I set-up my speakers for good on axis response I do it from my prime listening positions. The reasons for this is two fold. If you have done your speaker placement right they are set-up to have the least bit of interaction with your room modes. Same with your listening position. It's your listening position because it gives you the best overall frequency response and the best balance of direct and reflected sound. When you set-up the controls and levels on the drivers you want the best response where you listen. Measure from there not at 1 meter. Just set the Microphone up on a stand at seated ear height and see what you get there. You also have to remember that these 4 ways are not that easy to measure close in. You might want to try at least 2 meters. I find the 4344 won't "look" right at 1 meter simply becasue the distance between drivers won't allow them to integrate properly at that distance.

Rob

[johnaec]

Thanks for the replies, guys. Like I mentioned in the RTA post, I know these curves aren't representative of the sound in the room - they were simply meant to show the relative differences. And Rob - I too was concerned with the 1 meter measurement re: blending of the drivers. I'll do some more tests from a listening position when I get the chance, (hopefully later today).

Also, there was about 15" difference horizontal mic placement between the two speakers, (directly in front of each one), which also likely accounts for some of the differences, probably mainly in the LF curves, I'd guess.

John

[4313B]

It looks like Greg measured the 4315B 4W @ 2m (4.5V).

[johnaec]

It looks like Greg measured the 4315B 4W @ 2m (4.5V).

I'll try 2 meters too. I'm not sure how to measue the output voltage correctly, (I do have meters - do I just check AC voltage across the leads?), or do you know what dB SPL level that would equate to? I'll also do the XPL's this way. I'll also make sure both speakers are in the same location for the next checks.

John

[Robh3606]

"I'm not sure how to measue the output voltage correctly, (I do have meters - do I just check AC voltage across the leads?), or do you know what dB SPL level that would equate to?"

You may not want the same voltages on the terminals because that doesn't account for the sensitivity differences. That and a Whoops can ruin your whole day. You really don't need to know what the exact SPL is to do the comparisons. You can use relative measurements just as well. When you set them up just get a baseline measurement. Choose a system doesn't matter which and use it to get a snapshoot of your in room response from say 300Hz and Up. Just set the speakers to give the same relative level through this range when you make the comparisons. You can use your RTA for this. Just measure from the exact same place in your room when you do it. I have an SPL meter and the RTA and SPL meter track each other very well. Just make sure that the RTA is not on auto range. With mine it can auto range to keep the measurement centered in the RTA window. You don't want that.

Rob

[boputnam]

You really don't need to know what the exact SPL is to do the comparisons. You can use relative measurements just as well. When you set them up just get a baseline measurement.

Agreed.

But I would "baseline" each "system" (read: set-up) using Pink Noise and SPL. Get things relatively normalized, and then do your tests. Without a meaningful normalization, there are far too many variables.

[Mr. Widget]

We got a bit off topic and a bit rude as well so I deleted a few posts. With luck we can continue this very interesting and informative thread in the spirit that it was begun by John.


Widget

[oznob]

Good call, no, GREAT CALL Mr. Widget! John is passionate about this stuff and he's a great guy! We owe it to him to stay on point!

[boputnam]

Good, but difficult call.

There is an urgency in some quarters to try and winnow the wheat from the chaff here, and ensure that readers can distinguish between the two. There's all sorta combinations that might "work", but posters need to define "WORK" as in JBL parlance, and "work" as in other (read: DIY at your own risk), and parse the two. It seems to be driving quite a number to drink.

Hell, I know I wanna get hammered...

[johnaec]

Well, I finally got the XPL200A's biamped with the DX-1 crossover. For LF I borrowed a JBL 6260 from Zilch, and for HF I'm (temporarily) using a JBL 6215, (Zilch also loaned me a 6230 for HF, but one channel's out... ).

Unfortunately, I have no true pre-amp, ('looking at an Adcom, though), so right now, I've got the CD player going into a cheap DOD 1/3 octave graphic EQ, which fortunately has master level controls, and also RCA plugs, (in addition to balanced inputs), which go straight out to the DX-1.

I haven't gotten much farther than making sure it all works, (it does!), and I won't get a real chance for serious listening tests/comparisons until I get back from vacation next week. But so far, even with the little 6215 for HF, it sounds amazingly good! Lately, I've been alternating mostly between the XPL's and the 4430's, with the 4315's doing backup. Now I need to figure out how to come up with a setup that allows for meaningful comparisons between all this stuff. The hard part will be dealing with different amps, which wasn't a factor in my earlier tests.

Anyway, just wanted to update the situation. Now, I have to go mow the lawn ... 'more later.

John

[Zilch]

(Zilch also loaned me a 6230 for HF, but one channel's out... )

"You break it, you bought it!"

Naw, I'll check another one out from the dungeon for you, and swap it....