Mark Audio Alpair 7 application - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 22nd January 2010, 08:34 AM   #11
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 jockel77 View Post

There's another interesting design called "Torretta" by RumoH Zelfbouw Luidsprekers, postet in the CHR-70 application thread.
The CHR-70 doesn't need LCR correction in this design (the enclosure disigner says)
this is the plan: http://www.diyaudio.com/forums/attac...retta-tqwt.jpg
Torretta is a TQWT design like the needle. A bit smaller (shorter line) than the Needle and the port is on the backside of the cabinet.
It's tuned to 50 Hz and should give fine bass response with CHR-70.
My 1st look at that leads to the question of how come they say the EL70 will work with the same tuning.

And if you want bass heft, the smaller microTower goes lower (tuned to 42 Hz)

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 22nd January 2010, 08:42 AM   #12
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
No thanks necessary, it was made some months ago.

Basically what Dave said. Maximum LF extension was not the prioirity with the Pencils; the design-goal with the Pencil 7 was to produce something that is a doddle to make & tune, that is solid to 60Hz with useable output to the high 40s in-room, with reasonable power handling, well-controlled displacement & a TL-style impedance load. This is why I gave up posting graphs: without considering the specific design critera, there is a tendency to compare apples with oranges (& forget to factor other things into the equation, such as room-gain below Fp).
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com

Last edited by Scottmoose; 22nd January 2010 at 08:57 AM.
  Reply With Quote
Old 22nd January 2010, 09:00 AM   #13
diyAudio Member
 
Join Date: Feb 2006
Location: Germany
Scottmoose, I think that I've understand your aims for designing the Pensil series. I think (in theorie, regarding the sims) you did a professional job and bass enforcement in upper bass area is well done with your tuning.
Other designs (like the Needle) try to push a small speakers tuning down to the limits with the disadvantage of leaving a hole in upper bass area.
Otherwise. the ALPAIR 7 has an extraordinary xmax (4mm) that enables the driver to play even in bass area at higher levels (compared to other speakers).
So my idea is the following:
Instead of using a rectangular port - switching to a round port at the ground of the enclosure. Diameter of port around 6 cm (-> opening at all around 30 qcm). Length of port at first try 10 cm.
Advantage of round port is, I can change it by cutting it, later.
  Reply With Quote
Old 22nd January 2010, 11:03 AM   #14
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
How kind of you to say that in theory you think I did a professional job.

Re the above, it'd no longer be a Pencil, & throws all of my design goals & alignment straight out the window, so you're on your own. I did not design the Pencils for maximum extension, so if that is your priority, why not use a box designed for it? Tuning substantially below Fo might look pretty on a basic FR graph, but it tends to have consequences elsewhere -you do understand what these are, correct?
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com

Last edited by Scottmoose; 22nd January 2010 at 11:31 AM.
  Reply With Quote
Old 22nd January 2010, 11:37 AM   #15
diyAudio Member
 
Join Date: Feb 2006
Location: Germany
First of all, sorry for my remark about "theoretical" professional job.
This wasn't ment to doubt about your practical experience - more I'd like
to get some impressions of someone who had built the Pensil speakers.

As you said, everything's a compromise when implementing such small drivers for fullrange usage. If I had to choose between a deeper tuned enclosure which lacks in upper bass with LCR correction needed and a slightly higher tuned enclosure with a rising plateau between 64 Hz and 200 Hz to compensate baffle step effect I'd go for your Pensil design.

To explain, where I'm coming from. Up to now, I listened to a pair of ML TL speakers with Tangband W3-315 (link: http://coolcat.dk/bjoern/TABAQ_TL_for_TB.pdf)
These enclosures are tuned to around 50 Hz (but lacking in upper bass, indeed).
On page 7 of the linked pdf-file, the author compares the Needle design to the TABAQ design, which prooves, that Needle design is tuned to low for this driver.
Some days ago, a friend of mine and me compared my TABAQ speakers to a JORDAN JX92 (in 35 Liter bassreflex) and I got a strong impression about difference between both fullrange units. While the TABAQ's (with this nice little Tangband 3'' driver) played amazingly open in middle-hightone area, the JX92 has it's strength in overall performance. Chorus Voices and instruments had more body with JX92.
In the end I couldn't decide which of the both projects I'd prefer.

This leaded me to the ALPAIR 7 which should have the advantages of both speaker projects. Now, I read a lot of enclosure examples for CHR-70, that are much different and I'm asking myself which enclosure design to go for to get best results (compared to our W3-315 SC vs. JX92 listening impressions)
  Reply With Quote
Old 22nd January 2010, 02:06 PM   #16
diyAudio Member
 
mondogenerator's Avatar
 
Join Date: Sep 2009
Location: City Of Villans
Blog Entries: 1
Quote:
Originally Posted by Scottmoose View Post
Your BR calculator is assuming an empty cavity, with a uniform internal air particle density, no standing waves, and no damping. The exact opposite of the Pencil in other words, where the cabinet dimensions and transmission-line stuffing is critical to how it functions. The Pencil 7 is not a bass reflex enclosure, so trying to model it as such will give completely inaccurate results. As I mentioned, I even decided not to call them MLTLs, because they're such a specific alignment / have a specific design criteria.
IMHO the 'damped air coupler' design seems like another term for an aperiodically tuned TL, or or maybe an aperiodic MLTL if, in fact it is mass loaded(or a true, in an electrical sense, TL), and i agree that it is NOT an MLTL, of the convetional variety.

However no offence, but i dont believe its anything new either
__________________
Every new piece of knowledge pushes something else out of my brain - Homer.....................Simpson
  Reply With Quote
Old 22nd January 2010, 02:34 PM   #17
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Of course it's not new. I never said it was. I'm one of the people that keeps pointing out that in fact there was very little the pioneers of audio back in the 1920s - '40s didn't do. The air coupler name, implying a QW enclosure with a terminus CSA = the pistonic area of the driver dates back to at least the 1950s. This particular variation happens to have a very specific design criteria as partly above, and the Vb alignment to achieve it is of my own devising (that is new, although hardly something to write home about). Voila! a damped air coupler. Describes the function of this specific alignment almost perfectly, so that's what I called it.
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com

Last edited by Scottmoose; 22nd January 2010 at 02:37 PM.
  Reply With Quote
Old 22nd January 2010, 03:17 PM   #18
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Quote:
Originally Posted by jockel77 View Post
First of all, sorry for my remark about "theoretical" professional job.
This wasn't ment to doubt about your practical experience - more I'd like
to get some impressions of someone who had built the Pensil speakers.
No apology needed, I've got a root-canal playing up so I'm probably a little on the irritable side today. The A7 is still very new, so there hasn't been much feedback yet. I believe a substantial number also ended up in Japan, which has futher limited the feedback we get in the West. That'll change, but still early days.

Quote:
As you said, everything's a compromise when implementing such small drivers for fullrange usage. If I had to choose between a deeper tuned enclosure which lacks in upper bass with LCR correction needed and a slightly higher tuned enclosure with a rising plateau between 64 Hz and 200 Hz to compensate baffle step effect I'd go for your Pensil design.
Would that life were easy & no compromises. I suppose that'd take half the fun away though, right? We all have different solutions to design challenges; few are really better than others, it's just a case of selecting which suits your requirements as far as possible.

Quote:
To explain, where I'm coming from. Up to now, I listened to a pair of ML TL speakers with Tangband W3-315 (link: http://coolcat.dk/bjoern/TABAQ_TL_for_TB.pdf)
These enclosures are tuned to around 50 Hz (but lacking in upper bass, indeed).
On page 7 of the linked pdf-file, the author compares the Needle design to the TABAQ design, which prooves, that Needle design is tuned to low for this driver.
It is a little, although I'm not sure there's all that much difference in practice in terms of Fp.

Quote:
Some days ago, a friend of mine and me compared my TABAQ speakers to a JORDAN JX92 (in 35 Liter bassreflex) and I got a strong impression about difference between both fullrange units. While the TABAQ's (with this nice little Tangband 3'' driver) played amazingly open in middle-hightone area, the JX92 has it's strength in overall performance. Chorus Voices and instruments had more body with JX92.
In the end I couldn't decide which of the both projects I'd prefer.
I know that feeling. The Jordan is one of the better drivers around; of course it's rather larger than the little TB & has a far lower Fo, so it should have more LF weight. The little 'uns do tend to be very nice in the upper mids & HF though don't they?

Quote:
This leaded me to the ALPAIR 7 which should have the advantages of both speaker projects. Now, I read a lot of enclosure examples for CHR-70, that are much different and I'm asking myself which enclosure design to go for to get best results (compared to our W3-315 SC vs. JX92 listening impressions)
Hmm. It's probably a good compromise, falling between the two as it does, & I can certainly say it's a very nice driver indeed. I really like mine.

How big a box can you handle?
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com

Last edited by Scottmoose; 22nd January 2010 at 03:20 PM.
  Reply With Quote
Old 22nd January 2010, 04:00 PM   #19
diyAudio Member
 
mondogenerator's Avatar
 
Join Date: Sep 2009
Location: City Of Villans
Blog Entries: 1
Quote:
Originally Posted by Scottmoose View Post
Of course it's not new. I never said it was. I'm one of the people that keeps pointing out that in fact there was very little the pioneers of audio back in the 1920s - '40s didn't do. The air coupler name, implying a QW enclosure with a terminus CSA = the pistonic area of the driver dates back to at least the 1950s. This particular variation happens to have a very specific design criteria as partly above, and the Vb alignment to achieve it is of my own devising (that is new, although hardly something to write home about). Voila! a damped air coupler. Describes the function of this specific alignment almost perfectly, so that's what I called it.
Of course i have to agree with this.. i would be as fool not to.

What exactly do you mean by the Vb alignment? Vb as in box volume? or as in the Vb/Vas ratio...i say this only as i would think it wouldnt be difficult to obtain a certain Vb/Vas ratio with a constant CSA=Sd tube, unless it was merely stumbled across, or drivers picked which suit a target Sd and Vas perfectly(or near as)... THAT is if i am getting the gist of what you are saying correctly. if not please do correct me, i dont build speakers as a pro so i may be slightly slow on the uptake!

actually hang on ill have a go!!!!!!!!!
__________________
Every new piece of knowledge pushes something else out of my brain - Homer.....................Simpson

Last edited by mondogenerator; 22nd January 2010 at 04:23 PM.
  Reply With Quote
Old 22nd January 2010, 04:18 PM   #20
diyAudio Member
 
mondogenerator's Avatar
 
Join Date: Sep 2009
Location: City Of Villans
Blog Entries: 1
Default my take on it scott

eg for a woofer qts 0.35, Sd 90cm² Vas 20litres

target Qcb of 0.7:

THus: Qcb/Qts = 2

Vas/Vb would be = about 3

thus 20/3 = 6.66litres

Vb/Sd :

6660cm³/90cm² = 74cm pipe length

342/0.74 = F3 of around 115Hz

Clearly for this type of alignment, either Vas has to be huge, or Vas/Vb much nearer = 1

ie my 'perfect' TS version....(if it is lol)

Qcb/Qts = 1.5 = 0.7/0.46

giving Vas/Vb = 1(ish)

then Vb=Vas and

20000/90 = 222cm

then 342/2.22 = ¼wavelength of 38.5Hz

so ts required are then:

Qts 0.46, Vas 20litres, Sd 90cm², Fs 38Hz

clearly, my example needs tweaking but is this the general gist of your approach Scott?
And if it is not and i have stumbled across something here, then half the royalties are mine...MUAHAHAHAHA
__________________
Every new piece of knowledge pushes something else out of my brain - Homer.....................Simpson

Last edited by mondogenerator; 22nd January 2010 at 04:27 PM.
  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
Mark Audio Alpair 10 MLTL Design Jim Griffin Full Range 210 5th April 2012 01:11 AM
Mark Audio Alpair For First Build? d3ll Full Range 10 17th December 2009 07:11 PM
Mark Audio Alpair 5/CSS SDX7 DIY Chris74 Swap Meet 4 17th February 2009 02:44 PM


New To Site? Need Help?

All times are GMT. The time now is 08:59 AM.


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