[JohnR]

Here are a few graphs of my OB that I thought might be of interest - I'd really like to know what you think.

This is a refinement of the same speaker I posted about here: http://www.audiocircle.com/index.php?topic=89097.0. Full writeup will be published in HifiZine in a few days.

Here is the response of the main panel at 1 meter, at 0, 30, 60 and 90 degrees. There's something funny going on at 7-8 kHz which I think is caused by the tweeter mounting structure. I'm going to see if I can fix that in the next version of the baffle. Other than that, what do you think? (The plot only makes sense down to about 200 Hz. There are some room effects in this measurement but not too much I don't think.)



This is the response at the rear of the panel, at 180, 150, 120, and (again) 90 degrees:



This is the in-room response of the full system including subs. Red is a first-order crossover, blue is 8th order (which the above plots were taken with).

[Russell Dawkins]

Congratulations! I would say that's a commendably flat in-room curve, especially given the scale of 5dB per major division - that looks to be in the order of ±1.5 dB or so from 17Hz to 7kHz!! I would be proud to have achieved that.

I am curious about the B&C 6PEV13 6-1/2" midrange speaker. The numbers on that look pretty amazing as far as power handling and efficiency goes and I read on the Parts Express site that it sounds good, too. Are you still using it?

[panomaniac]

Looking good!

[guest60106]

I certainty hope I can get a response that nice with my project. What are you using for subs?

[JohnR]

Thanks guys! Matthew: I have a pair of sealed subs using the (long-not-sold) Adire DPL-12. Anechoic f3 calculates out to be in the low 30's, which I think does make things a bit easier. However the next thing to try will be an octet of Exodus DPL-10s as subs on OB...

Michael: hey

Russell, still using the 6PEV13, at this point the only reason I would have to change it would be if I wanted to use a planar driver for the midrange - the B&C stops behaving like a dipole to the rear above 2.5 kHz. Crossover points are 800/2500 for 8th order and 800/3500 for first order. It's just loafing along, really.

[guest60106]

However the next thing to try will be an octet of Exodus DPL-10s as subs on OB...

Interesting. The design I posted utilizes DPL-10s. Be nice to hear how they turn out in both cases.

[JohnR]

Interesting. The design I posted utilizes DPL-10s. Be nice to hear how they turn out in both cases.

They're nice drivers, I used them in an earlier version of this OB, running up to 400 I think, which is probably too high for them - hard to say really, as I didn't do good measurements on that earlier version. They played down to about 30 without a problem.

[guest60106]

Nice. I bought them on a blowout deal when they were discontinued. The specs looked pretty good but I have always been a little concerned about the efficiency. At the price I couldn’t resist and figured since I was going to run them independently I would just use more of them and turn them up. My plan at this point is to cut them off around 100hz. I bought 10. 8 for my project and 2 for backup since they we discontinued. You are the first person I have talked to that has heard them.

You have some nice graphs. What are you using for measurement? I still need to buy an RTA and I like the looks of the system from Parts Express but it is a little pricy for me. I have been looking for a used RTA on eBay for cheaper but have not found one yet. I am not really sure of what I am looking for because I have never used an RTA before. I have been building speakers for 30 years and have never measured any of them. I just tuned them by ear. My BO project will be my first swing at taking it to the next level. I’m very excited.

Matthew

[JohnR]

I bought 10. 8 for my project and 2 for backup

Heh heh, so did I 

I use REW for the in-room measurement and Fuzz Measure Pro for the gated measurement. There's a bit of info on what you need here (about a third of the way down) :

http://www.hifizine.com/2010/09/subwoofer-equalization-and-integration-with-the-minidsp-2x4/

I think someone was selling a mic interface in the Trading Post just recently.

[JohnR]

The full writeup is on hifizine now - let me know what you think 

  Refining a 4-way open-baffle speaker with the miniDSP 2×4

[jtwrace]

The full writeup is on hifizine now - let me know what you think 

  Refining a 4-way open-baffle speaker with the miniDSP 2×4

Off to read it now.  Why not link under Site News? 

[JohnR]

Thanks Because I'm worn out.

[ttan98]

John,

I read your 2 articles at HI-FI Zine and learn a few things from there. I am thinking of using the Minidsp as well and your articles certainly help me.

I notice you use midrange B&C 6PEV13 6-1/2" and I think it is a very good one, however I also think you cross it too high up and also you want to act a good mid bass. You will notice John K. from Music and Design new OB uses Tweeter(Neo10), Midrange(full range scanspeak), midwoofer, midwoofer and woofer.The scanspeak can cross very high up but does not cover the mid bass freq. range hence the twin mid woofers. A suggestion to your system is to introduce a high quality mid or a full ranger(4-5") to fill in between the B&C and Neo, and let the B&C cover the mid bass freq. range. Just a suggestion.

[JohnR]

Hi ttan, thanks, you're welcome The Lambda woofer seems to sound pretty good crossed at 800 Hz... I originally had the crossover set at 400 Hz and wasn't intending to go higher but moved it up to improve the off-axis response. I didn't spend any time listening to various crossover points - perhaps in future I'll experiment with this. Moving the freq much lower than 400 Hz would start  to require more eq on the mids and in that case something like a 6nd430 might be a better choice (more xmax). I'd have to start all over again with the baffle design too.

[ttan98]

Hi,

Danny from GR Research always believes that the woofer should cross at or below 200-250Hz because above that frequency it(woofer) tends to interfere with the tonality(@200Hz ear is at its most sensitive region) of the mid range unless the woofers and mid range are of the same made(material), the sound will not integrate well.

His idea seems logical to me.

[JohnR]

Hi ttan - I think Danny must be talking about his H-frame subs in that case, as the 12" woofer on the top baffle of the Super-V is being crossed over somewhere in the 800-1000 Hz region (as I recall, please correct me if I'm wrong on that one). I'm using the Lambda up to a similar kind of frequency, and then using subs on the bottom as he does - mine are currently sealed but I'm going to be trying OB ones for the next article.