Beyond the Ariel - Page 1220 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

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 24th November 2014, 10:59 PM   #12191
fas42 is offline fas42  Australia
Banned
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 13
I found the explanation here, Compression driver - Wikipedia, the free encyclopedia, immediately made sense.
Quote:
In 1924 Hanna, C. R. and Slepian, J. [1] were the first to discuss the benefits of using a large radiating diaphragm with a horn of smaller throat area as a means of increasing the efficiency of horn loudspeaker drivers. They correctly surmised that this arrangement results in a significant increase in the radiation resistance (and therefore increased efficiency), because the loading mismatch between the vibrating transducer surface and air is largely corrected, thus allowing for much better energy transfer.
  Reply With Quote
Old 1st December 2014, 08:03 PM   #12192
JoshK is offline JoshK  Canada
diyAudio Member
 
Join Date: May 2004
Location: Toronto, ON
Just a thought Lynn, but have you consider these knock-down boxes (3cuft each) so that you could get a prototype up and running before committing to a permanent arrangement of the system?

Audio Knock-Down MDF 3.0 cu. ft. Subwoofer Cabinet for Dayton Audio 15" Ultimax Subwoofer

You could stack two each side for the dual GPA driver arrangement and place the subs elsewhere for the time being.

I like the prototype idea, especially since you have spent so much time contemplating various tradeoffs. This would allow you to atleast build and start measuring.
  Reply With Quote
Old 2nd December 2014, 01:52 PM   #12193
Rewind is offline Rewind  Sweden
diyAudio Member
 
Rewind's Avatar
 
Join Date: Jan 2009
Location: Oslo
I am not sure using a 15" for mids is right anymore. Not more than to 200Hz.
  Reply With Quote
Old 3rd December 2014, 01:28 AM   #12194
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Quote:
Originally Posted by JoshK View Post
Just a thought Lynn, but have you consider these knock-down boxes (3cuft each) so that you could get a prototype up and running before committing to a permanent arrangement of the system?

Audio Knock-Down MDF 3.0 cu. ft. Subwoofer Cabinet for Dayton Audio 15" Ultimax Subwoofer
A pair of these might do fine for closed-box Altec/GPA 416's on the floor, and the upper driver in a to-be-determined format ... open-baffle, short horn (180~700 Hz), or whatever. I have a stash of four GPA 416 Alnico's (16 ohms), and a pair of GPA 515 Alnico's (16 ohms), so I have plenty to experiment with. The existing REL Strata II subwoofer will do just fine for evaluation purposes.

As for timing ... Karna and I have been deluged with offspring staying in our house, and it may be a while until we can induce them to move out. Our garage and basement are filled up with their junk (well, I think it's junk, but treasures to them). After the big move-out, Karna and I need to do some house updates ... it's getting on 10 years old, and the inevitable repairs and replacements await. New windows here and there, new washer/dryer, that kind of thing.

My Christmas present is a Marantz UD-7007, suggested by Gary Dahl, that serves as a CD/DVD-A (S/PDIF) transport for the 2-channel system, a direct analog-output source for 2-channel SACD's and high-res Blu-Ray discs, and an HDMI source for multichannel SACD's, DVD-A's, and Blu-Rays into the Marantz AV-8003 (which supports SACD over HDMI). It also has two HDMI outputs, so I can feed the Panasonic plasma display directly, and reserve the other output for the Marantz AV8003.

Since Blu-Ray is probably the end of the line for optical media, this should take of all physical-media digital sources. As for computer downloads, an Audio-GD DI-2014 takes care of translation chores from USB to S/PDIF, as well as reclocking S/PDIF to S/PDIF. A phonograph also awaits ... either the Technics SL-1210 I own already, or maybe the new turntable that my neighbor, Thom Mackris, is working on.

Last edited by Lynn Olson; 3rd December 2014 at 01:38 AM.
  Reply With Quote
Old 3rd December 2014, 04:49 AM   #12195
oltos is offline oltos  United States
diyAudio Member
 
Join Date: Mar 2012
Location: Long Island, NY
Blog Entries: 1
Default “DACless” Stereo Bass Management?


First, can someone completely define what is meant by stereo bass management?
Obviously, it’s not quite the same as the much more often discussed home theatre bass management (i.e. LFE), since home theatre implies movies, which implies multi-channel audio. My system build will be two channel stereo for music only, as follows:

My desktop pc will feed my DAC. Speakers are a pair of HF and MF direct radiator drivers, run by a First Watt J2 amp; and a pair of midbass drivers run by a First Watt F4 amp. The F4 amp is a voltage follower so a line stage with stereo attenuators must go between it and my DAC’s unbalanced outputs. And a passive stereo attenuator must go between the input of the J2 amp and my DAC’s other pair of unbalanced outputs. Because I’m not tri-amping my mains, I can’t use an active or passive line level crossover, so it has to be a speaker level type like this XM47 passive crossover for loudspeaker drivers Stereo balance for the mains is obviously achieved by adjusting the attenuators between the DAC and both amplifiers. When done, volume/mute control is had by the DAC’s wireless remote.

The sealed boxes for my GPA Altec 414 midbass drivers will cut their low end off below ~ 70Hz. Below this a pair of Rythmik 12 or 15” active servo subs take over. The subs’ plate amps have balanced differential I/Os for master/slave daisy chaining; the master sub’s plate amp’s unbalanced inputs are then connected to the line stage’s outputs. The input impedance of the plate amp and F4 are 30K ohms and 47k ohms, so I wouldn’t expect them to excessively load the line stage. Yes?

Thanks to the midbass drivers’ 2 or 3 cu. ft. (interior) sealed boxes, no crossover is needed between them and the subs. Instead, with the help of two others-one person at the controls of each sub’s plate amp-the sub’s low pass filters are adjusted to blend it with the midbass drivers. Thus, so achieved is one of the three (or more?) goals needed to successfully integrate the subs with the mains.

Time Alignment: If the subs are placed directly under the mains (and assuming their wiring relative to the amplifiers’ outputs are in phase), then all drivers should be time-aligned?

However, as the two subs will be placed where they ought to work best against room modes-nearly as well as four subs-regardless of listener position (
( http://www.harman.com/EN-US/OurCompa...s/multsubs.pdf , figures 48 & 50 ), delay adjustment between the subs and the mains is required. And that can be done with me listening, while two people adjust the sub’s delay (phase control)? http://www.rythmikaudio.com/images/XLR2.jpg


And the third obvious integration goal is to balance the volume of the two subs with that of the mains. Again, with the two people helping to set the volume between two identical subs and the mains shouldn’t be too difficult.

Please correct any misconceptions and/or omissions in my understanding.

This whole process may or not be a trivial pursuit, but what I want to know is if can I accomplish good “stereo bass management” or “bass integration” by using the above “manual” techniques and the subs’
plate amp’s analog control circuitry, instead of a DSP device-or at
least without leaving it running in my system. My music source DAC
will definitely exceed $4.5K. Therefore, I’d prefer to avoid having any further digital conversion in my system if at all possible.


  Reply With Quote
Old 3rd December 2014, 10:21 AM   #12196
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Signal manipulation of any kind ... equalization, crossover high or lowpass, or time delay ... implies digital processing, or DSP. As used in the home theater world, "bass management" uses all of these techniques. If the HT receiver or pre/pro has bass management engaged, or Audyssey EQ, you will be hearing the sound of the built-in DACs. If the receiver or pre/pro is fed a 2 or 5-channel analog signal, it will be digitized through an inexpensive ADC (not studio grade), processed by the on-board DSP (with on-chip algorithms that are not studio quality), and converted back to analog with the built-in DACs.

Some receivers offer a "Pure Direct" mode that claims to bypass all bass management and EQ functions, and offers an all-analog signal path through the receiver. If that's really true, there will be no tone controls, no Audyssey, no bass management, and no subwoofer output. All you get is a volume control, and the same number of channels going in and out.

I should mention that is not possible to manipulate SACD or DSD signals; you can't even level-shift, much less the functions mentioned above. Professionals convert the 1-bit DSD signal to DXD (352.8/32 PCM) or DSD-Wide (2.8 or 5.6 MHz at 8-bit resolution) to apply the usual range of studio modifications, and then convert it back to 1-bit DSD for commercial release. This level of conversion is beyond the capabilities of consumer-grade home theater receivers; they automatically convert 1-bit DSD content to 176.4/24 PCM, apply the DSP processing, and leave it in PCM format for conversion with the inbuilt DACs.

So ... if you want to hear what an expensive external DAC sounds like, or hear SACD or DSD in native format, all signal processing by the receiver or pre/pro must be disabled, and hope that internal ADCs and digital signal processing have been removed from the signal path. If you have test gear, sending a 50 kHz square wave through the receiver should reveal the truth, since that will not survive the brickwall lowpass filter that an internal ADC requires.

Referring back to my previous post, when I listen to multichannel SACD's transmitted through HDMI to the receiver, I use "Pure Direct" mode to (hopefully) bypass all the PCM-based signal processing. As for the DACs inside the receiver, it's a good question whether the signal remains in 1-bit DSD format. Delta-sigma DACs live in a world halfway between straight PCM and low-bit, high-speed DSD signals.

Last edited by Lynn Olson; 3rd December 2014 at 10:38 AM.
  Reply With Quote
Old 3rd December 2014, 10:54 AM   #12197
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
With reference to "oltos" post, yes, what you want can be done with passive line-level methods (with RC filters). I would be careful not to load down the output of the DAC too badly; it'll tolerate 10K without trouble, maybe even 5K if it's a good solid-state design. The passive-filter approach also means you have to watch cable lengths; audiophile cables in particular have substantial capacitance with long cable runs. Even good solid-state gear becomes unhappy when it has to drive 500 pF or more of cable capacitance.

Gary Pimm found that low-quality electrolytics used for AC-coupling the inputs of mid-fi studio gear (like plate amps or EQs) also affected sound of the main channel, even though they were not in the direct signal path. A good-quality direct-coupled buffer stage (between the mid-fi and good system) takes care of the problem.

Last edited by Lynn Olson; 3rd December 2014 at 10:58 AM.
  Reply With Quote
Old 3rd December 2014, 01:38 PM   #12198
pooge is offline pooge  United States
diyAudio Member
 
Join Date: May 2003
Location: Northern Va.
Quote:
Originally Posted by Lynn Olson View Post
A pair of these might do fine for closed-box Altec/GPA 416's on the floor, and the upper driver in a to-be-determined format ... open-baffle, short horn (180~700 Hz), or whatever. I have a stash of four GPA 416 Alnico's (16 ohms), and a pair of GPA 515 Alnico's (16 ohms), so I have plenty to experiment with. The existing REL Strata II subwoofer will do just fine for evaluation purposes.
Don't know if this horn is short enough for you, but John Inlow just introduced a 135Hz midbass horn design that might work for you.

inlowsound.com
  Reply With Quote
Old 3rd December 2014, 06:32 PM   #12199
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Beautiful sim results, but the 34" length for the 135 Hz midbass horn is a show-stopper.

The time-alignment of the current system puts the mouth of the AH425 is about 1/2" in front of the 416 frame (as shown in the drawing). Adding another 34" to the depth of the current system makes the total depth of a time-aligned version about 46" deep; no possible way can that fit anywhere in my house. Not interested in DSP processing.

If I go with the direct-radiator version, here's a drawing of what I've been thinking of, using a bentwood bass enclosure:
Attached Images
File Type: jpg Aspen_Ellipse.jpg (155.6 KB, 538 views)

Last edited by Lynn Olson; 3rd December 2014 at 06:50 PM.
  Reply With Quote
Old 3rd December 2014, 06:59 PM   #12200
pooge is offline pooge  United States
diyAudio Member
 
Join Date: May 2003
Location: Northern Va.
Quote:
Originally Posted by Lynn Olson View Post

If I go with the direct-radiator version, here's a drawing of what I've been thinking of, using a bentwood bass enclosure:
At one time I had designs to do an enclosure very similar to that using a double wall of Sonotubes injected with insulating type foam or sand.
  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



New To Site? Need Help?

All times are GMT. The time now is 03:21 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki