Bladesmiths' Open Baffle Project.....

bladesmith · « **on:** 18 Mar 2015, 09:15 am »

Greetings,

I have begun my OB project. I'm in the "Frankenstein" phase right now.

Starting with Aurum Cantus G1's (midrange tweeters), Morel MW-1075's (midrange bass) and Eminence Delta 15FLA's.

I'm just breaking in the speakers right now and will be experimenting with side wing/wings soon. Maybe add a back firing tweeter. Completed the crossovers and making sure those are correct before making a permanent home for them on some better looking material. Everything seems to be sounding fine. Very interesting. Really enjoying the new sound.

Vapor Audio · « **Reply #1 on:** 18 Mar 2015, 04:00 pm »

So you're crossing over from a G1 ribbon to a 10" woofer? Have you taken any measurements to see how that Morel performs? My guess is it's going to very bumpy FR from 800-2500hz, and that you'd be better off with something smaller to cover that range. It's directivity is also going to narrow significantly toward the upper end of that range.

Where did the schematic for the crossovers you say you completed come from?

My suggestion would be to take a step back before progressing further, re-evaluate the design on paper and likely make some adjustments. My first thought would be attempt something like a 3.5way, where both the Morel and Eminence have no high pass filter on them, but different low pass points. And with that use a high sensitivity midrange (of smaller diameter than the Morel). That would be a somewhat complex design however, and you would need to take measurements if you're to have any chance of success.

bladesmith · « **Reply #2 on:** 18 Mar 2015, 06:59 pm »

Quote from: Vapor Audio on 18 Mar 2015, 04:00 pm

So you're crossing over from a G1 ribbon to a 10" woofer? Have you taken any measurements to see how that Morel performs? My guess is it's going to very bumpy FR from 800-2500hz, and that you'd be better off with something smaller to cover that range. It's directivity is also going to narrow significantly toward the upper end of that range.

Where did the schematic for the crossovers you say you completed come from?

My suggestion would be to take a step back before progressing further, re-evaluate the design on paper and likely make some adjustments. My first thought would be attempt something like a 3.5way, where both the Morel and Eminence have no high pass filter on them, but different low pass points. And with that use a high sensitivity midrange (of smaller diameter than the Morel). That would be a somewhat complex design however, and you would need to take measurements if you're to have any chance of success.

Ryan,
I totally agree. You are right on with your evaluation. Looking from the outside and the data given. I did some research on a smaller diameter morel midrange driver. And with the data given, your comment is right on.
But, the actual Freq. Resp. on both of these drivers (G1/Morel) are deceiving. They both over lap and work well together, for my application. The Morels are very flexable/tough and I am experimenting with a Z eq. circuit with them, exclusively. The combination of the G1's and the Morels are more like monitor speakers, in sound, IMHO. I am making the foundation of my system/crossover with the G1's and the Morels, the Eminence drivers are just for augmenting the low end. The Morels do very well, until you get down to below 100hz, then the Morel drops off pretty hard. But, the Eminence drivers will be adjusted as required in that area.

V....

matevana · « **Reply #3 on:** 19 Mar 2015, 01:43 pm »

The top section of the Hestia V is similar in that I used the Dayton AMTPro mid/tweeter coupled to an Eminence 10" bass driver, but I could not make a successful transition w/o the use of a smaller 3" coupling driver. As mentioned, it's not just a matter of covering each driver's respective frequencies. The polar plots will likely be pretty uneven without some type of coupling driver and most 10" woofers will really start beaming when asked to play above 1k. You will probably discover this in extended listening sessions, especially when moving away from the near field. It took me quite a while to test and revise, before settling on the right combination of drivers for the build. I too use a separate bass driver to fill in below 100Hz, crossed 4th order, which I believe is the way to go.

http://www.audiocircle.com/index.php?topic=126622.msg1336327#msg1336327

bladesmith · « **Reply #4 on:** 19 Mar 2015, 05:42 pm »

Matevana,

I never thought about beaming btwn 1khz and 2khz area. I am simply cutting these (Morels) off at 2khz. Although some speaker builders are running these up to 2500hz. My Freq. Test on them ran flat up to 2600hz. The manufacturer recommends cutting them off at 1600hz. So far it hasn't been an issue with mine, personally.

I started out making a simple two way ob speaker with the G1's/Morels. And they sound really nice, even though they are not broken in yet. Everyday they sound a little more relaxed and less grainy. I like the simple idea of a two way type, speaker design.

I'll need to do some tweaking on them before I am done. I'll look into the freq. "beaming" and see what I come up with.

So far, they sound sublime and the bass is just very lifelike and full.

V....

Vapor Audio · « **Reply #5 on:** 20 Mar 2015, 05:58 am »

Welcome to speaker design, no shortage of considerations

Here are my thoughts

The 10" Morel being an older design, and knowing similar drivers, likely has no copper in the motor. That means midrange distortion will climb, and likely be significantly higher than a more modern design with copper shorting rings. And while the frequency response might measure somewhat flat up to 2500hz, I guarantee the cone is not retaining pistonic motion above 1000hz. Typically the first spot you see a blip on the FR is where pistonic motion stops, my best guess is 800hz. Above that point it can still sound good, but you are losing resolution/transparency when the cone starts flapping like a flag in the breeze. Other issues, inductance is rising pretty steeply through the upper midrange with that driver, and 3" VC drivers just aren't as good with midrange.

Those things aren't to say it can't sound good, but just be aware of what you're giving up.

Yes absolutely directivity will narrow significantly from 1000-2500hz too. Being a soft cone, you might get 1-200hz more out of it before it starts to narrow, but that's based on cone diameter primarily. So there's nothing that's going to be able to negate that issue. People do make too much out of things like Polar Plots IMO though, the first impulse (on axis response) is far more important. Power response is an important consideration of course, but at least if you get a respectable on axis response and put them in a room that isn't too reflective, you can get away with a poor power response. Being OB will contribute and fill in the power response in some areas too, but how exactly I couldn't say without data.

To sum it up, go ahead and build and enjoy as is ... but be open to the idea of adding a smaller midrange driver to bridge that gap between the ribbon and 10" woofer down the road.

bladesmith · « **Reply #6 on:** 20 Mar 2015, 01:00 pm »

Ryan,

I agree, and I am basically using this as a start up design. And I have my eye on a smaller morel driver that I will be experimenting with in the future. But, I cant resolve every issue at one time, and I am doing just as you suggested with the Morel 1075 and the Eminence driver, already, just using a simple low pass on both. Everything is working as intended and moving forward nicely. I just felt the need to get them powered up and broken in so I'm not completely without music.

I still have some testing to do. Testing that will show were my weaknesses/strengths are, at the current design. That will then lead me towards the right speaker to fill the gap, if there is one, right now the set up sounds very good. It's surprisingly full and has a very wide sweet spot. And the bass, fast, accurate and powerful.

Thanks

bladesmith · « **Reply #7 on:** 2 Apr 2015, 10:58 pm »

Okay, so I added a back firing dome tweeter. At first I wired it normal, it sounded "okay", then I reversed the polarity and now it sounds very nice.

Can anyone explain that to me ?

Thanks,

V...

JohnR · « **Reply #8 on:** 7 Apr 2015, 11:05 am »

Nominally, wiring the rear tweeter in reverse polarity means that you have dipole operation... However, the rear and front tweeters are very different...

Are you doing measurements?

jtwrace · « **Reply #9 on:** 7 Apr 2015, 06:11 pm »

Quote from: JohnR on 7 Apr 2015, 11:05 am

Are you doing measurements?

You're a funny guy.

Nah, those aren't needed.

Juhazi · « **Reply #10 on:** 7 Apr 2015, 06:11 pm »

Hi,
about rear tweeter - wavelenght in tweeters' passband is so short that physical distance between radiators propably rolls over the phase at some frequency - and so on over again and again... And this is practically impossible to be measured ritht. Just set polarity based on our listening impression and be happy with it! I recommend connecting them in series to avoid impedance problems. On the other hand, parallel connection makes it possible to attenuate the rear tweeter if that is asked for.

Happy testing!

bladesmith · « **Reply #11 on:** 7 Apr 2015, 08:22 pm »

Quote from: JohnR on 7 Apr 2015, 11:05 am

Nominally, wiring the rear tweeter in reverse polarity means that you have dipole operation... However, the rear and front tweeters are very different...

Are you doing measurements?

John,

I am actually trying to get measurements. But, my mic isn't working well with my mac mini. Not sure why, I can't find the right settings on Mac mini. And I get side tracked with other projects, but, I'll get there. Working on it tonight.

V..

(Modified: okay, I couldn't get the mac to work with my mic so I got my Windows laptop to work with the Emm6 mic and the REW software, now I got to figure out how to work this over complicated REW software. I wish there was an easier way of making a test measurment. Looks like a lot of reading.

)

bladesmith · « **Reply #12 on:** 7 Apr 2015, 10:10 pm »

Quote from: Juhazi on 7 Apr 2015, 06:11 pm

Hi,
about rear tweeter - wavelenght in tweeters' passband is so short that physical distance between radiators propably rolls over the phase at some frequency - and so on over again and again... And this is practically impossible to be measured ritht. Just set polarity based on our listening impression and be happy with it! I recommend connecting them in series to avoid impedance problems. On the other hand, parallel connection makes it possible to attenuate the rear tweeter if that is asked for.

Happy testing!

Understand, I am enjoying these speakers to a great degree so far. It's hard to explain but, they sound great...

As for the rear firing tweeters, I am not getting what I wanted from them, there is a difference in sound quality with them added. But, they just take away from the G1's too much to keep installed. If you know what I mean.

V....

bladesmith · « **Reply #13 on:** 8 Apr 2015, 07:57 pm »

Rosewood veneer finally here....

bladesmith · « **Reply #14 on:** 21 May 2015, 02:24 am »

Not great pics, but, I haven't been able to do much lately. I need a nice sunny day to get better pics but, you get the idea...I finished these some time ago, just not the time to do the things I want right now.

The Rosewood came out very nicely. And they sound very sweet. I have a variable resister on the tweeter output, so I can dial them in. Same goes with the separate amp I use for the 15" bass driver. So everything is very flexible. Both outputs of my amps are also adjustable.

Tyson · « **Reply #15 on:** 21 May 2015, 03:01 am »

VERY NICE! I rarely use all caps, but this deserves it - stellar build!

mcgsxr · « **Reply #16 on:** 21 May 2015, 10:38 am »

You're going to have to explain to people that you built those. They look commercially done - in a good way!

Love the veneer work, just gorgeous.

bladesmith · « **Reply #17 on:** 21 May 2015, 02:45 pm »

Quote from: mcgsxr on 21 May 2015, 10:38 am

You're going to have to explain to people that you built those. They look commercially done - in a good way!

Love the veneer work, just gorgeous.

mcgsxr,

It was a bit more frustrating than I anticipated. I had some thoughtful audiophiles advise me to stop and think about it a bit, before diving head first into it. Because it does take some effort to complete.

Secondly, I can see why the single driver OB projects are so sexy. Much easier to put together and the down side is probably small. Small or large coax-type drivers would be much easier to complete, and the simple design is very attractive, in sound and looks. Especially if the driver requires no x-over work or you can get the driver with a x-over already designed/built for you, IMHO.

I tried to get some help from various members of the audiophile community, but there schedule and my schedule just didn't work out, so I had to do it all on my own. But, I do have a work shop, so that does help. I was a bit confused on whether to put a cap on the top or not, but it does look better with it and seems to frame the Rosewood veneer. I'll try to get some better pics, later when I can. Taking pictures of my knives is far simpler/easy, than taking pictures of large/heavy speakers. You can trust me on that.

I might add that I do work with wood/steel, more than the average person, that has some form or function in completing the project. But, my shop is built/designed for knife making, so I had to do some adjusting. And, again, it was not an easy project. But, the rewards are very nice.

The main body is 1.5" MDF. The base is 2 1/4" thick. The rosewood is covered/finished in linseed oil, I cover all of my wood projects in linseed oil, it's old fashioned

. The rest is flat black automotive paint, to match the drivers color as much as possible. So almost everything has a soft finish. The x-overs are built on simple red plastic boards and the wires soldied on the under side for a clean finish.

Thanks for looking,
V....

I don't know why they still look a bit fuzzy, I take them with my camera and they look great, but after uploading them, not so much..

brad944911 · « **Reply #18 on:** 21 May 2015, 03:17 pm »

Simply beautiful man! You're hired!!!

The rosewood is amazing with the linseed!

ACHiPo · « **Reply #19 on:** 22 May 2015, 07:56 pm »

Really nice looking speakers. It just hit me that all the buzz about OB speakers makes me think those old consoles might have been a good idea after all