Qts in OpenBaffle - How low can you go? - Page 3 - 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 8th April 2011, 05:31 AM   #21
diyAudio Member
 
Join Date: Feb 2011
Location: Seattle
Quote:
Originally Posted by ra7 View Post
Yeah, they're pretty damn cheap too. In my opinion, they wipe the floor with the competition. At their price, everyone should have one.
(Referring to the AN's.) So are we talking Standard 8 ($128/pr) or Super 8 ($158) or Super 8 cast ($188)? Is each upgrade worth the cost? I think I remember Planet10 Dave saying to stay away from the stamped frames. Do you agree? The biggest difference I could see between the standard and super is that the spl curves look smoother on the super and the impedance curves are different, but I don't know what to look for on those anyway. I imagine that the super is worth the cost, but what about the cast vs stamped?
__________________
Shrink to Patient: "Forget the Prozac, you need more Boogie!"
There are only two kinds of music. Good and Bad
  Reply With Quote
Old 8th April 2011, 05:52 AM   #22
diyAudio Member
 
Join Date: Feb 2011
Location: Seattle
Quote:
Originally Posted by Godzilla View Post
(but with less 'tone' than TB)
I'm just trying to figure out what the 'tone' quality you refer to here is and if it relates to any technical feature that can be identified. Sometimes, for example, the SE tube guys will refer to "tone" and then it seems to be related to even order harmonics at least partly. It seems like that kind of harmonic content is associated sometimes with "tone" and "richness" qualities. I wonder if different speakers generate these kind of harmonic profiles that people seem to like.

I'm new to this stuff and trying to understand some of the nuances that are commonly described. Someday I may have a garage full of projects and experience but right now I need to get my info from discussions.
__________________
Shrink to Patient: "Forget the Prozac, you need more Boogie!"
There are only two kinds of music. Good and Bad
  Reply With Quote
Old 8th April 2011, 12:29 PM   #23
MJK is offline MJK  United States
Account disabled at member's request
 
Join Date: Feb 2002
Location: Clifton Park, NY
Quote:
Originally Posted by ra7 View Post
The 'Q' of a driver is a quality factor. A high Q indicates a big peak in output near resonance (or Fs). This means the magnet is not powerful enough to damp the cone near its resonant frequency. In a sealed box, the enclosed air provides some resistance to the cone when it tries to move excessively near resonance. On a OB, there is nothing to stop this excessive motion. But the baffle roll off counters the excessive output giving an overall flat response. However, you cannot hide the fact that the magnet is not strong enough to damp the cone.

A low Q driver on the other hand has a magnet powerful enough to resist the excessive cone (somewhat) motion near resonance. Add to this the natural roll off on OB and you get less bass compared to a high Q driver. But you can always compensate this by adding more EQ. What you will get though, is a driver that can produce a bass note in music and stop the cone from moving when the note stops.
I am not sure I agree with most of what you have said above.

The Q of the system will detemine the shape of the bass SPL response, a driver with a Q of 1 or a driver with a Q of 0.3 EQ'ed to behave like a driver with a Q of 1 will produce the same bass SPL response. If you blindly measure the SPL response of the two options I am not sure how you would tell the difference.

I think your statements about the starting and stopping of the bass notes is totally off the mark. If you look at my two way OB write up, I include the SPL and transient responses of three woofers with different Q values. In the transient response plots I don't see much difference in the ring out of the three. But in the SPL plots the driver with a Q of 1 produces the deepest bass extension. Recognize that a driver with a Q of 1 is still a very well damped mechanical system. What calculations or measurements lead you to these statements?

Martin
  Reply With Quote
Old 8th April 2011, 04:17 PM   #24
ra7 is offline ra7  United States
diyAudio Member
 
Join Date: Feb 2009
Blog Entries: 1
I'm glad you chimed in MJK. I have no calculations to back up my statements. I'm not as mathematically inclined as you are. However, I don't think we are in disagreement.

Quote:
Originally Posted by MJK View Post
The Q of the system will detemine the shape of the bass SPL response, a driver with a Q of 1 or a driver with a Q of 0.3 EQ'ed to behave like a driver with a Q of 1 will produce the same bass SPL response. If you blindly measure the SPL response of the two options I am not sure how you would tell the difference.
I did EQ the low Qts driver to have a flat response. So, what you are saying is what I did. I also measured the frequency response and I don't feel the need to check the difference between the two systems' Qs.

Quote:
I think your statements about the starting and stopping of the bass notes is totally off the mark. If you look at my two way OB write up, I include the SPL and transient responses of three woofers with different Q values. In the transient response plots I don't see much difference in the ring out of the three. But in the SPL plots the driver with a Q of 1 produces the deepest bass extension.
I looked at your OB writeup and the attached picture shows the transient response of the three drivers from the writeup. The Gamma15 has a Q of 0.38. Look at how long it takes for the alpha15 to settle. It settles somewhere around 33ms in the chart. Now look at how long it takes for the Gamma15 to settle -10-12ms (in the chart, without removing the start of the impulse). I know you will argue that the alpha15 goes deeper in the bass and that is why it takes longer to settle in this chart. But this transient response matches what I'm hearing. Whether it is below the threshold of audibility, I don't know. But I can certainly hear it.

I've also tried your suggestion for the alpair 6 and crossing it to the alpha15 at 400 Hz or so. This combination sounds bad. Really bad. The alpha15 has a thick, sluggish sound and it just doesn't go with the full range drivers. Now, with my Deltalite2515, I'm happily crossing at 400 Hz for the alpair6 and the smaller fostex drivers. It may be a case of mismatched system Q with the alpha15, but then this is the best I can do.

Do you at least agree that low Qts drivers (0.3) represent an overdamped system? I guess I prefer the sound of an overdamped system to an ideally damped system.

I agree that on the same baffle, without EQ, the alpha15 will go deeper than the beta15. But with EQ applied, the beta15, according to me, should sound better than the alpha15.
Attached Images
File Type: jpg Q.JPG (56.4 KB, 460 views)

Last edited by ra7; 8th April 2011 at 04:35 PM.
  Reply With Quote
Old 8th April 2011, 04:40 PM   #25
diyAudio Member
 
Godzilla's Avatar
 
Join Date: Nov 2005
Location: New York
>>> I noticed from your pics that you have both an MJK H-frame design system and a single baffle design both employing what looks to be the same FR drivers. Could you compare the two designs?

The open baffle and H-frame sound a bit different to me in my room. I prefer the H-frame. They somehow sound more integrated with the room. I was always moving the open baffles around... a few inches this way and that. Sometimes I would notice a bloated upper bass. I never notice that with the H-frames. Both sound incredibly good but I prefer the H-frames overall. My son has the open baffles in his room and the bass sounds superb without any bloat. So I think it’s a room integration thing rather than one actually being better. He has a larger room with more space around the speakers. This might be the reason. The H-frames just sit in what looks like the correct position and sound great. I just left some space around them and never moved them since. MJK did a wonderful thing when he published his H-frame article.

Two Alpha’s sound much better to me than the 12” powered sub I have (ACI SV12 – which cost more than double the Alpha’s!). I also have a 10” Infinity sub that frankly just isn’t in the same league.

I agree, the AQ (lol) of the open baffle is VERY NICE. The shapes are elegant and they appear to take up very little space because there is so much space around them. In reality they do require a large footprint but having an attractive slice of wood in the room appears much less obtrusive than a boxy floorstanding speaker.

I’ve swapped TB, Betsy, B20 and they all sound good in either baffle. All sound different than when they are used in a box. In fact, the cheapest B20 is transformed into an amazing thing on open baffle. Imaging expands and instruments seem to pop about… which is cool and offers a bit of realism to the performances. This is just the way open baffle sounds regardless of driver used. Sound bounces off the rear wall and seems to emanate from different places. I can see why many who go open baffle never go back to boxed speakers. I don’t notice any deficient qualities like a reduction in mid bass. I think everything smoothes over and sounds great.

But I also like the way BIBs sound. They offer an immense image as well which I believe is due to the open top and how sound (the bass and mid bass) radiates from the corners and ceiling of the room, enveloping you in glorious sound. LOL, I NEED both types of speakers and have the open baffles at home and the BIBs (back horns essentially) at the office. So one solution is not the answer because both have their pros and cons… and both sound great. I see how folks who love back horns would never go back to boxed speakers either.


>>> tone...

For me it has to do with the way instruments fill the air and then decay. TB and Fostex do this the best in my experience. I haven’t heard Lowther’s for lengthy periods of time so really can’t comment on them but expect they are similar based on how people describe them. The Eminence Beta 12lta has good ‘tone’ too… but it’s a totally different driver at 12”. If a guitar is strummed, seems to hang in the air… then fade like a real instrument does (more with one driver than the other) I’d say it has better tone.
  Reply With Quote
Old 9th April 2011, 03:15 AM   #26
ra7 is offline ra7  United States
diyAudio Member
 
Join Date: Feb 2009
Blog Entries: 1
Quote:
Originally Posted by sprinter View Post
(Referring to the AN's.) So are we talking Standard 8 ($128/pr) or Super 8 ($158) or Super 8 cast ($188)? Is each upgrade worth the cost? I think I remember Planet10 Dave saying to stay away from the stamped frames. Do you agree? The biggest difference I could see between the standard and super is that the spl curves look smoother on the super and the impedance curves are different, but I don't know what to look for on those anyway. I imagine that the super is worth the cost, but what about the cast vs stamped?
Sprinter,

I would get atleast the Super 8. The phase plug upgrade will give you the most for the added cost. The cast frame would be good to have too, but I wouldn't mind skipping it. To get a pair of drivers of this quality for $150 odd bucks is beyond phenomenal. They are lowthers on the cheap.

The build quality of AN is not the best, but you don't expect it to be at this price either. At least you get a real metal frame compared to some flimsy plastic frame on some of the other full range drivers that are popular here. Also, these AN drivers are hard to destroy, unlike some other full range drivers that have to be mollycoddled during break in.
  Reply With Quote
Old 9th April 2011, 07:40 AM   #27
diyAudio Member
 
Join Date: Feb 2011
Location: Seattle
Quote:
Originally Posted by Godzilla View Post
>>>
Two Alpha’s sound much better to me than the 12” powered sub I have (ACI SV12 – which cost more than double the Alpha’s!). I also have a 10” Infinity sub that frankly just isn’t in the same league.
Yeah, I think you really have to pay through the nose for good powered subs. I have one that came with my projector and it is really only good for Schwarzenegger movies. It actually makes music sound worse than without it.

Thanks a lot for your critiques and comparisons. They really help. The choice on FR is still a tough one because there are several in the same price range, but I've been eyeing the AN8 for awhile now and I think I'll go that route. If not, I've been very curious about the Besty as well. "She" doesn't get as much play as the others but I kind of like that for some reason. I think I mentioned that I have put some $12.50 GRS 8" in service temporarily and I'm anxious to see the difference in a better driver. They were supposed to give me an idea of OB and I like that aspect of it enough to go on. To my inexperienced ears they are pretty lacking even accounting for no augmentation yet. Of course, I can only compare it with my EV 12TRXB's in a BR and that's hardly apples and apples. I've been playing them plus the GRS directly in parallel with nice sound result. When I get the new woofers and FR's and build a baffle, I'll be able to go to town. I have a speaker switch to make it easy to A/B.

Quote:
I would get atleast the Super 8. The phase plug upgrade will give you the most for the added cost. The cast frame would be good to have too, but I wouldn't mind skipping it. To get a pair of drivers of this quality for $150 odd bucks is beyond phenomenal. They are lowthers on the cheap.
ra7, Thanks for the advice. I'll probably go for the stamped basket Super. The phase plugs apparently are a worthwhile addition. "Lowthers on the cheap?" 'I'll probably never know...but it sure sounds good. Funny thing about audio is that you can go for years listening to mediocrity and never know what you're missing. My experience. Now I'm afraid I'll never stop trying for that little bit better. BTW, I'm not including the 12TRXB's as mediocre. They were actually my first decent speakers, but one is going bad and I don't know what it is.
__________________
Shrink to Patient: "Forget the Prozac, you need more Boogie!"
There are only two kinds of music. Good and Bad
  Reply With Quote
Old 9th April 2011, 09:03 AM   #28
diyAudio Member
 
Join Date: Aug 2009
Location: Sacramento
Hello,
Depending on the dimensions of the baffle and driver to get high SPL at the bottom end.
I like a pair of 12 inch Peerless SLS’s in a W frame.
Peerless 830669 12" Paper Cone SLS Subwoofer
Retaining the dipole effect into the low Hz’s is a good thigh.
I opine, the bandwidth where a 8-inch works well is above 125-150 Hz which places the resonance frequency, the frequency where QTS lives, well outside the bandwidth being served. The 8-inch (Vifa P21W0-02) is kind of a mid bass and the importance of the resonance / QTS frequency is removed from the picture.
Where the dual 12-inch dipole beings falling off I use a sealed sub. In a small room a sealed sub is not needed.
DT
All just for fun!
  Reply With Quote
Old 9th April 2011, 09:40 AM   #29
diyAudio Member
 
Join Date: Feb 2011
Location: Seattle
Quote:
Originally Posted by DualTriode View Post
Hello,
Depending on the dimensions of the baffle and driver to get high SPL at the bottom end.
I like a pair of 12 inch Peerless SLS’s in a W frame.
Peerless 830669 12" Paper Cone SLS Subwoofer
Retaining the dipole effect into the low Hz’s is a good thigh.
I opine, the bandwidth where a 8-inch works well is above 125-150 Hz which places the resonance frequency, the frequency where QTS lives, well outside the bandwidth being served. The 8-inch (Vifa P21W0-02) is kind of a mid bass and the importance of the resonance / QTS frequency is removed from the picture.
Where the dual 12-inch dipole beings falling off I use a sealed sub. In a small room a sealed sub is not needed.
DT
All just for fun!
Crossing to the 8" at around 150 seems to be what most folks here agree is best. I'm hoping I can get my 8" down that far with an OB arrangement that I'm hoping to get as small as possible with a good AQ (new term coined here "Aesthetic Quality" - gotta love those acronyms). I'm going to experiment with a miniDSP and REW to determine the best technical arrangement before I commit a final design to expensive wood. Nice thing about OB is that it's easy to do that.

Just curious. It sounds like you have a 3-way going. Have you found an extended range driver like we've been discussing lacking? I think a lot of guys find the high extension inadequate from most of them. For me, my hearing precludes me from "enjoying" anything past 11K anyway.
__________________
Shrink to Patient: "Forget the Prozac, you need more Boogie!"
There are only two kinds of music. Good and Bad

Last edited by sprinter; 9th April 2011 at 09:46 AM.
  Reply With Quote
Old 9th April 2011, 11:13 AM   #30
diyAudio Member
 
Join Date: Aug 2009
Location: Sacramento
Quote:
Originally Posted by sprinter View Post
<snip>
...before I commit a final design to expensive wood. Nice thing about OB is that it's easy to do that.

Just curious. It sounds like you have a 3-way going. Have you found an extended range driver like we've been discussing lacking? I think a lot of guys find the high extension inadequate from most of them. For me, my hearing precludes me from "enjoying" anything past 11K anyway.
Hello,

First, in my mind there is no final design. I did stain and lacquer my last one.

Single drivers on open baffles have a large following, I have no aversion.

A couple of Burning Amp gatherings ago Papa Nelson demonstrated a couple of varieties of very expensive ~ 8 inch full range drivers on OB’s. He had Beta 15’s playing a supporting role. I was drawn in by the sound. Mr. Linkwitz was sitting 2nd row center.

Since I have built various incarnations. Currently I am enjoying a PHOENIX (MTM) clone made with Vifa PL18W009-04’s, two drivers less than 8 inch.
I have not yet tried a FR on an OB. These MTM’s have no bottom end below ~ 125 HZ, this is where a sub or real dipole woofer comes in.

In my small listening room I much prefer the dipoles to Headphones. The dipoles fill the room with sound stage.


DT
All just for fun!
  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
Possible use of a very low QTS driver? giralfino Multi-Way 7 10th January 2011 04:12 PM
what sounds best . . . Low Qts in small cab or higher Qts in bigger cab mikelm Subwoofers 18 15th July 2009 10:46 AM
Long voicecoil, low Qts drivers TwangBar Multi-Way 0 12th October 2006 12:47 AM
Need 8" sub - low Qts, low Fs??? geolemon Subwoofers 14 19th June 2005 12:38 AM
Low Qts woofer bigwill Subwoofers 19 15th March 2005 07:45 PM


New To Site? Need Help?

All times are GMT. The time now is 03:42 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