BIC EV-15 Eviction Measurements

[JohnBooty]

@Dennis Murphy Did you have any luck? Or is this "patient" perhaps beyond saving?

 

[Dennis Murphy]

@Dennis Murphy Did you have any luck? Or is this "patient" perhaps beyond saving?

I haven't given up yet. So far I've performed two transplants. I replaced the woofer with a more promising 15" from Parts Express that can work well sealed and is smoother. And I replaced the deeply flawed midrange with what seemed to be a better sealed-back 5 1/4" , also from Parts Express. The woofer may be a keeper and I will definitely use it for one of the mods. The new mid--not so much. It at least has some stuffing in the rear cavity, but it has dips that can't be fixed with a passive crossover, and it isn't really sensitive enough. So I guess I'm stuck with the stock unit, although I'll keep looking. Anyhow, tomorrow I will work up a revised crossover using the new woofer ($26 each). And then I'll do one with the old woofer and see what's what.

 

[JohnBooty]

Wow! Exciting!

 

[tomtoo]

A better 15“ woofer for 26$???

This sentence somehow sounds funny. Couse i realy dont know how to get even the worst 15“ for 26$ in germany. )

 

[JohnBooty]

A better 15“ woofer for 26$???
This sentence somehow sounds funny. Couse i realy dont know how to get even the worst 15“ for 26$ in germany. )

Haha. I've been trying to figure out which woofer it is as well. The cheapest I see is $32 (which is still shockingly cheap!) Perhaps Mr. Murphy gets volume or industry discounts. Parts Express has "pro" accounts IIRC.

https://www.parts-express.com/grs-15pf-8-15-paper-cone-foam-surround-woofer--292-415

edit: We should, of course, focus on finding a proper VISUAL successor to those stock red woofer cones. Maybe bright green or something. Let's go even uglier.

 

[Dennis Murphy]

Haha. I've been trying to figure out which woofer it is as well. The cheapest I see is $32 (which is still shockingly cheap!) Perhaps Mr. Murphy gets volume or industry discounts. Parts Express has "pro" accounts IIRC.

https://www.parts-express.com/grs-15pf-8-15-paper-cone-foam-surround-woofer--292-415

edit: We should, of course, focus on finding a proper VISUAL successor to those stock red woofer cones. Maybe bright green or something. Let's go even uglier.

No banana. That one is only has a sensitivity of 87 dB. I'm partial to lime green. It's timeless, as long as the time is 1970.

 

[Dennis Murphy]

One down. I worked up a Xover for the stock midrange and new woofer yesterday, and it smooths things out to the point where almost all of the deviations from linearity are dips and not peaks, and everything fits within a 3 dB window at a listening position of 3 meters. With a speaker this large, and with the drivers so far apart, it's impossible to design a crossover that will measure well at both one meter and 3 meters. Unfortunately, I don't have any measurement system that has enough resolution to show the anechoic response at 3 meters, so you have to pretty much take the predicted measurement on faith. Next I'll put the stock and oh-so-red woofer back in and see if I can make it work.

 

[JohnBooty]

Unfortunately, I don't have any measurement system that has enough resolution to show the anechoic response at 3 meters

When you're ready, I'll be happy to try out your upgrades and take measurements with my outdoor setup.

 

[Dennis Murphy]

Good news on the mod front. I didn't have much hope for getting the cheap midrange to produce accurate sound, and I was also concerned that the big tweeter horn was going to honk even if I couldn't see any obvious problems with the frequency response. But I diddled with the crossover some more and listened and measured and listened today, and these things sound great. I still have to compare this mod with my other speakers, but the sound is very clean. I've attached a distortion plot I took at 1 meter and at 90 dB. I don't have much confidence in the data below 200 Hz or so, but the above that point OmniMic is pretty accurate. Over most of the plot, distortion is .3% or lower, even in the midrange. I still have to try to mod the speaker using the original woofer, but at least I know what to do with the midrange and tweeter. Please note that OmniMic switches from a 5 dB grid to a 10 dB, and when you attach the file the aspect ratio gets silly--waaaay too wide. So the response isn't as smooth as it looks. Also, room effects start to show up below 500 Hz.

 

[JohnBooty]

Good news on the mod front. I didn't have much hope for getting the cheap midrange to produce accurate sound, and I was also concerned that the big tweeter horn was going to honk even if I couldn't see any obvious problems with the frequency response. But I diddled with the crossover some more and listened and measured and listened today, and these things sound great.

This is one of the coolest moments ever for me in this hobby!

I think it will be an amazing thing for audiophiles who are capable of performing their own mods. This could be a first for the hobby... a mod that gives people cheap, big-displacement, high-output speakers that actually measure well. I honestly think this could be a bit groundbreaking.

Dennis, did you have to sacrifice much (or any?) sensitivity in order to make the midrange behave?

 

[Dennis Murphy]

Given how choppy the stock response is, it's difficult to say what its sensitivity is. OmniMic doesn't allow me to measure sensitivity, at least not easily. My simulations indicate about 90 dB, but I'll have to wait until I can measure with Praxis to get an accurate read on real world sensitivity. I haven't actually built the crossover board yet. My design software has an "Emulator" function that allows you to listen to a given crossover based on the electrical transfer function. It's dead accurate, but my Praxis measuring software and my design software are on the same old klunky XP computer, so I have to actually measure the output with OmniMic, which is on my state[-of-the-art Windows 7 computer. I'll know for sure about sensitivity when I actually build the board and measure with Praxis. I hope to be able to report on my results using the the stock Big Red woofer tomorrow.

 

[JohnBooty]

My technical ability tops out at roughly "assembling a flat-pack kit from Parts Express" (unless you count software development) but if there's literally anything I can do to help, please count me in. Up to and including driving to wherever you are and lugging speakers around for outdoor measurements or remotely sending medicinal quantities of Starbucks to via UberEats.

I am on the way out of this hobby, as most of the things left I'd like to accomplish require a budget I'll never have, but this is an eminently worthy cause. If you think the modifications sound good I will promote the "Dennis Murphy BIC EV-15 Mod" like it was my actual job.

 

[A800]

Port area is severely compromised.

 

[JohnBooty]

You're severely compromised!

 

[A800]

You're severely compromised!

LOL!
How so?

 

[tomtoo]

I like this project. This will never be a highend speaker. But for the younger people that enjoy good sound and party at lower budget that could be great. I call it powerhifi.
Teufel also has powerhifi
https://www.teufel.de/stereo/power-hifi-p18764.html?extProvId=5&extPu=teufelde-gaw&extLi=24867363&extCr=59713381838-391198056875&extSi=&extTg=&keyword=teufel power hifi&extAP=&extMT=e&partner_id=sea-de..google.24867363.391198056875.&gclid=EAIaIQobChMI_satqZ6f6gIVRKQYCh2NhgHJEAAYASAAEgLG9PD_BwE

But very different budget region. For me it's realy interesting that a expert looks at it. Thats realy cool!!!

 

[tomtoo]

Port area is severely compromised.

Why?

Edit says: For me @Dennis Murphy is a expert that has proofen that he knows what he is doing. If he at least gives a try this thing can't be complete rubbish.

Edit also says:
Yes maybe some people like 5"woofers with a 0.75" dome. But hey for partys they are like a plastic knife on a gunshooting.

 

[A800]

Why?

The diameter is much too small.
You will have a shift of tuning frequency and port compression/noise at higher levels and therefore increased distortion which could have been avoided.

 

[tomtoo]

The diameter is much too small.
You will have a shift of tuning frequency and port compression/noise at higher levels and therefore increased distortion which could have been avoided.

At higher levels! How high?

Edit says: I think we both conclude this will never give a high end speaker. It's far away from that, but with a little love from @Dennis Murphy it maybe gives a good performer for younger people. Yes i think this is possible. Something between a PA speaker and a hifi speaker but on the hifi side. I think that would be great for many younger people. At this price!

 

[A800]

At higher levels! How high?

Amongst other things it depends on the enclosure volume and tuning frequency.