Wanted: 6.5" High-SPL Wideband Mid - diyAudio
Go Back   Home > Forums > Commercial Sector > Manufacturers > Markaudio

Markaudio Designers and builders of audiophile grade drivers

Reply
 
Thread Tools Search this Thread
Old 24th June 2011, 12:58 AM   #1
diyAudio Member
 
Taterworks's Avatar
 
Join Date: May 2007
Default Wanted: 6.5" High-SPL Wideband Mid

Hello Mark & the crowd,

I've got an idea for a niche product where MarkAudio already has the core competencies needed to be successful.

Recently, the price of Tang Band drivers with Neodymium motors has skyrocketed to the point where they no longer represent a good value. I was considering the Tang Band W5-1611, which uses a thin poly cone on a 6" frame, to use as a wideband midrange driver in my next build, a 5-driver 3-way. The Tang Band driver was attractive because it had a high sensitivity (90 dB 1w/1m, 8 ohm) and an underhung motor structure. It also had a great-looking clear-anodized aluminum phase plug. The one strike against the driver was its injection molded plastic frame, but since the motor was a lightweight Neo motor, I decided it wasn't an issue.

With the surge in price and the long back-order on the W5-1611, I went searching around for alternatives. The only driver that was close to a perfect match was the 7" glass fiber cone Scan-Speak Discovery midwoofer. The Alpair 12 was also very close, just half a dB shy of the W5-1611's sensitivity. However, not everyone (and I'm part of that 'not everyone') likes the sound of metal cones, because of the long decay time in the breakup region of the FR plot, even when the breakup doesn't manifest unacceptably on a FR plot. I believe the optimal material to use for a midrange driver is a loose-weave paper treated or coated with a flexible resin, because it dissipates energy chaotically through the material and thus damps itself very effectively.

I think MarkAudio should tackle the design of a purpose-built wideband midrange/midbass, with a paper or poly cone, in the 6.5" size class. It might be possible to take a lesson from silk-dome tweeters, where a very open-weave fabric is treated with a flexible damping compound that cures to a flexible semi-solid. I think this technique of diaphragm construction could be applied to cone diaphragms. It would seem be advantageous to use a thin, open-weave paper cone and treat it with the damping compound to produce an airtight, highly self-damping diaphragm without ending up with a cone that has high mass. The motor should be ferrite, to escape the market forces driving the high price of Neodymium, and a phase plug should be employed to eliminate dust cap resonance. Alternately, a black paper cone with a black-anodized aluminum dust cap (from the CHR-70, possibly) could be used. These are all just ideas; your experience can guide the specific design decisions.

What do you think about this idea? I realize R&D funds are tight for everybody right now, but a paper-cone Alpair 10 or 12 would be just the ticket for people like myself who are looking for a good, sensitive wideband midrange.

Best Regards,

Rory
__________________
If it works, but you don't know why it works, then you haven't done any engineering.
Taterworks Audio (nothing for sale)
  Reply With Quote
Old 24th June 2011, 01:31 AM   #2
diyAudio Member
 
markaudio's Avatar
 
Join Date: Nov 2008
Hello Rory and guys,
A quick reply from me as I'm shipping drivers and working on much overdue Markaudio web-site upgrades.

I predicted base material price hikes early-middle of last year (see my many and various old posts on this issue). Hence Markaudio drivers stayed well clear of Neo. Many of you will have seen my other posts on my measures to combat rising costs by re-deisnging many of our driver components to reduce assembly times. As a result, Markaudio's base manufacturing costs are less affected compared to others. But saving money without improving the product, in my book is a No-No. The new batch of drivers are delivering more bang for your bucks (dollars).

Coming on to Rory's suggestions, if enough guys vote on this thread for me to do a driver of the sort Rory's looking to buy, I'm happy to give it a go. One thing's for certain, its much easier for me to build a wide-bander than a full-on fullranger.

Rory, do your best to get all your audio buddies to comment on this thread. The more feedback, the better for me knowing what to make.

Cheers

Mark.

Last edited by markaudio; 24th June 2011 at 01:45 AM.
  Reply With Quote
Old 24th June 2011, 02:04 AM   #3
ra7 is offline ra7  United States
diyAudio Member
 
Join Date: Feb 2009
Blog Entries: 1
This is a great idea.
1. Wideband 100 Hz - 5kHz.
2. High eff >90 db/W.
3. Paper cone
4. Minimum number or zero resonances in the passband
5. Smooth roll off, again if possible with no resonances or break-ups.

I have a 3" vintage Coral driver that does this. But if you can make it, I'll be definitely up for it.
  Reply With Quote
Old 24th June 2011, 02:20 AM   #4
Westy37 is offline Westy37  Australia
diyAudio Member
 
Join Date: May 2010
Expression of interest. Enough said really. If this concept goes ahead I'd take a pair.
  Reply With Quote
Old 24th June 2011, 03:06 AM   #5
diyAudio Member
 
Taterworks's Avatar
 
Join Date: May 2007
Let's keep the sensitivity around 90-91 dB, I think, since that will help it mate with a wider variety of direct-radiating tweeters. Too much above that and a lot of affordable tweeters struggle to come up with the sensitivity. The true rationale for this driver is that there's far too few (IMO) drivers out there that are suitable for a wideband mid, and those that are out there are pricey.

Back to cone talk, forget about the earlier tissue-paper musings. A typical paper cone with a very light application of some doping compound either to the front or rear (preferably the front to protect against humidity/incidental wetting) and with the black-anodized aluminum dust cap would be very attractive, aesthetically. If we need to go with a phase plug, I personally really like the concave design used by Eton and by Veravox on their 5s/5x drivers, and that would complement the doped paper cone handsomely, but the more we can do with your standard parts, the better.

Now, let's talk turkey. I think the pricing sweet spot for a niche driver like this would be in the $75-$120 range. If that money goes toward buying better materials and more of them, or cool add-ons like copper in the motor to decrease Le, that's all the better. For a reasonably-damped paper cone and suspension system, a fairly powerful motor will be needed, so I don't mind paying for the extra steel, and for a cast metal basket to support it. The Alpair 10 looks like it's in the right price bracket, so we could probably build this wideband mid driver on that platform and just swap out the cone for the lightweight paper one.

Regarding the upper frequency limit for such a driver, I'd really like it if the driver could reach 6 kHz or 8 kHz comfortably. An underhung motor with between 2mm and 3mm Xmax would probably help reach that goal, with a lighter voice coil.

Oh, and... 8 ohms, plz.
__________________
If it works, but you don't know why it works, then you haven't done any engineering.
Taterworks Audio (nothing for sale)

Last edited by Taterworks; 24th June 2011 at 03:14 AM.
  Reply With Quote
Old 24th June 2011, 10:52 PM   #6
diyAudio Member
 
markaudio's Avatar
 
Join Date: Nov 2008
Quote:
Originally Posted by Taterworks View Post
Hello Mark & the crowd,

The one strike against the w5-1611 driver was its injection molded plastic frame, but since the motor was a lightweight Neo motor, I decided it wasn't an issue.
Best Regards,
Rory
Hi Rory,
Not sure why you assume plastic frames are inferior. Too many metal based frames have resonance interference characteristics, their designs are poorly damped, or have no resonance control of any description!

I won't specifically comment on TB's frame design but I'm more than happy with the progress of my work on using polymer technology for component making. From my research several years back, polymer based frames offered superior damping qualities while remaining lighter and can mould complexity to a greater accuracy with closer tolerances.

Given that polymers use less energy to form shapes, are much easier to re-cycle and and offer potential to include sustainable bio-based materials, I'll likely stick with polymer based technology. Look around on the various threads, you'll see members like Jim Griffin approving of my work on frame design.

Cheers

Mark.

Last edited by markaudio; 24th June 2011 at 11:01 PM.
  Reply With Quote
Old 24th June 2011, 11:13 PM   #7
diyAudio Member
 
markaudio's Avatar
 
Join Date: Nov 2008
Hi Chaps,
Here's a paper coned wide band prototype I made in late 2009.

Cheers

Mark.
Attached Images
File Type: jpg PWJ_1.jpg (74.6 KB, 487 views)
  Reply With Quote
Old 25th June 2011, 12:05 AM   #8
diyAudio Member
 
Taterworks's Avatar
 
Join Date: May 2007
Now, that looks like something I'd buy. Materials-wise, it looks perfect for my application. Would anything be gained in upper-midrange detail from using an aluminum dust cap with the same Bandor/Jordan-style profile?

What was the sensitivity and usable range of the Alpair 10PWJ? Also, rated power?

Your plastic frames look a lot more substantial than many of the ones I've encountered. How thick is that flange, 1/4 inch (6 mm) or more? Usually I work in 3/4" MDF, and that would be a fairly deep recess to countersink, but for the specific project where I'm trying to use a wideband mid, I'm going double-layered on the baffle. Would you recommend using T-nuts and machine screws with your plastic frames or just ordinary wood screws? (That is, has plastic cracking around the mounting screws from over-torque been a problem?)
__________________
If it works, but you don't know why it works, then you haven't done any engineering.
Taterworks Audio (nothing for sale)

Last edited by Taterworks; 25th June 2011 at 12:12 AM.
  Reply With Quote
Old 25th June 2011, 12:58 AM   #9
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally Posted by Taterworks View Post
a cast metal basket
Why go backwards?

The only downside of the Alpair baskets is getting used to tthe wide bezels... but that gives a wide stable platform and a wide-open backside.

The TB W5-1611 also has a nice frame too, a bit soviet era Russian tractor factory rough when compared to the Mark Audio, but i'd still rather have it than most of the cast Al baskets i've seen.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 25th June 2011, 01:13 AM   #10
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally Posted by Taterworks View Post
Your plastic frames look a lot more substantial than many of the ones I've encountered. How thick is that flange, 1/4 inch (6 mm) or more? Usually I work in 3/4" MDF, and that would be a fairly deep recess to countersink, but for the specific project where I'm trying to use a wideband mid, I'm going double-layered on the baffle. Would you recommend using T-nuts and machine screws with your plastic frames or just ordinary wood screws? (That is, has plastic cracking around the mounting screws from over-torque been a problem?)
Driver drawings are here: p10 hifi | Box Library / Mark Audio

You should never trust a screw in MDF.

It is important that the back of the driver's cutout be heavily champhered or at least rounded over. Even with 11-12mm rebates on the larger drivers, we use 18mm baffles and some support at the magnet.

Click the image to open in full size.

dave
Attached Images
File Type: gif driverCutout.gif (8.8 KB, 908 views)
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Active high dynamics/SPL & high performance loudspeaker system for my living room…! Robert GS Multi-Way 77 30th December 2012 10:39 AM
4" (3.5"-5") high efficiency wanted please sumaudioguy Multi-Way 131 21st October 2010 12:27 PM
High Efficiency 10" Mid Suggestions Impious Multi-Way 13 10th March 2009 08:21 AM
Wanted,wideband Front Load horn to go with I.B. mikee55 Full Range 0 10th February 2006 12:18 PM
Suggestions for high efficiency high SPL kit/design Kanga Multi-Way 50 23rd May 2003 12:52 AM


New To Site? Need Help?

All times are GMT. The time now is 04:44 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2