Add a Sub to my Saburos? - 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 15th August 2012, 09:10 AM   #11
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
Quote:
Originally Posted by Wha' DIYa know? View Post

Yet, any way, so nows a time to build big!
A 15"er or two per side would be fun.

Give them lots of power, eq to go very low.
If she asks why you've suddenly got subwoofers, put a movie on.
  Reply With Quote
Old 15th August 2012, 09:50 AM   #12
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Quote:
Originally Posted by chris661 View Post
Called isobaric configuration.

IMHO, a bit of a waste of drivers - if you're dedicating some space for subwoofers, might as well make use of all the cone area they have to offer.
As Dave mentions, isobaric loading is useful for freeing up space since theoretically it only requires 1/2 the volume. In practice, a bit more than that due to the volume taken up by the internal driver & coupling chamber, so work on a basis of a box approx. 2/3 the size of the original. Notionally, it offers reduced distortion relative to a single unit. In practice, it doesn't necessarily work that way since the isobaric term isn't strictly accurate, and there is also differential VC heating. It does work to an extent, but it's generally more trouble than it's worth.

Quote:
IIRC (to use as many acronyms as possible), Sabs go to ~70Hz
40Hz actually. That was the point.
  Reply With Quote
Old 15th August 2012, 09:56 AM   #13
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Quote:
Originally Posted by doubtingthomas View Post
I've just hooked up a cheap sub (Kef PSW2000) to my Vulcans which I've fitted with Fostex Fe203en-s's. I did it more for fun then anything else, expecting to prove to myself that it was a bad idea, but frankly I'm amazed at the improvement. Next step is a really good subwoofer, I'm thinking of the 12" Morel kit on Wilmslow Audio. Any suggestions?
Since the 203 has a lower Q than Vulcan was designed for, it will have slightly reduced LF gain -Vulcan is also a 40Hz horn, so if you want something below that, a couple of subs are a good idea. I'm not a huge fan of Morel drivers, although they're certainly interesting looking devices, and after rubbish experiences with Wilmslow I cannot possibly recommend them. Do your own -have a look through some of the projects in the sub. section & see what you like.
  Reply With Quote
Old 15th August 2012, 10:07 AM   #14
diyAudio Member
 
Join Date: Aug 2011
What bass driver do you like? I'm intrigued by Altec 416. The Vulcans definitely had a bit more LF with 206's, but I have more detail and HF which is also less directional with 203's.I'm between the devil and the deep blue sea. How might Krishima work with 203's?
I did actually build a pair and they sounded very nice but they were in an enormous room so it's hard to compare. What would theory say?
  Reply With Quote
Old 15th August 2012, 11:15 AM   #15
diyAudio Member
 
Join Date: Aug 2011
Also, why a couple of subs? My understanding is that LF is not really directional.
  Reply With Quote
Old 15th August 2012, 11:27 AM   #16
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Who said anything about directionality?

Inherently that is true, but the XO frequency and slope has to be factored in. Multiple subs. entail a reduction of distortion & carefully placed should either excite room modes in a more even fashion, or reduce the excitation itself. http://www.harman.com/EN-US/OurCompa...s/multsubs.pdf

Since I essentially bleed Altec, the 416 is a unit I like. Just make sure it's got a big box.

As for the 203, I don't much like dropping drivers into enclosures that weren't designed for them, so can't really pass comment. They'll go in & work; how well they'd work is a case of YMMV.
  Reply With Quote
Old 15th August 2012, 12:36 PM   #17
diyAudio Member
 
Join Date: Aug 2011
I just thought that if you can tell me why 203 is no good in Vulcans, (low Q), then you might be able to suggest whether Krishima's might be better, and I have inquired about a bespoke design for the 203 in the past, but never mind, the quest continues.
  Reply With Quote
Old 15th August 2012, 03:05 PM   #18
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
I didn't say it's no good. I said it won't have as much gain as with the driver it was designed for.

With little in the way of hard data for the 203, design is largely a case of winging it. From the minimal information Fostx provide, with a mass corner of over 600Hz it is not ideal for any kind of unsupported back-load, unless used with a high output impedance amplifier, Eq, or some form of series resistance, be it a ceramic or resistive speaker wire, when it becomes more viable. In the absense of a reasonable amount of information I'm in the realms of conjecture, especially when working purely on paper (or the electronic equivalent thereof). Sorry, but that isn't my fault.

I could fake up a set of specs. based on educated guesswork extrapolated from what Fostex have done in the past, & design something optimised as far as possible to these and the amplifier output impedance / series resistance necessary. That isn't in itself a problem, but it would still be guesswork, and I could be wrong. The question is whether you regard that as an acceptable risk or not. If you want advice then frankly, I suggest that if you're really serious about using these drivers, you should to get them measured, so you know what you're dealing with. In the meantime, you could try experimenting with some resistive speaker wire. It might help.

Last edited by Scottmoose; 15th August 2012 at 03:08 PM.
  Reply With Quote
Old 15th August 2012, 03:34 PM   #19
diyAudio Member
 
Join Date: Mar 2009
15" drivers in a pair of sub woofers! Muwah-hah-hah-harrrrrr!

Saburos already dominate the neighborhood, according to she who must (eventually but not yet) be obeyed. She exaggerates so! No point sparing a few bucks while i have the option of building big, for the time being.

I guess its time to think about the particulars, then. I've always scoffed at the idea of subwoofers in the past, But I realize its because I was only ever exposed to cheapos deployed poorly in mass market stereo stores.

As a result, 'm completely ignorant about such things as amplification needed, cross over stuff, etc. along these lines, I was given a suggestion (repeated here for confirmation) that sub amplifiers dont need to be as hi fi-ish as my dynaco, thanks to the poor resolution of our hearing way down low. What they need to be is powerful. So it was recommended to get some inexpensive solid state amps capable of a couple hundred watts.

Thanks in advance for thoughts about this.
  Reply With Quote
Old 15th August 2012, 09:30 PM   #20
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
Definitely active crossovers - for subwoofer crossovers, the passive components become hugely expensive (similar expense to an amplifier), and will interact with the impedance peaks of the cabinet, giving results that are unpredictable at best.

A SS amp with a couple of hundred watts per channel would be useful - you'd be able to sacrifice efficiency (compared to the Sabs, which I assume are being driven with a lower power amplifier) to get more bass extension (Hoffman's Iron Law comes into play).

Which drivers/cabinet to choose will be dictated by...
budget
volume requirements
LF extension requirements
maximum size of the cabinet
(to a lesser extent) the amplifier with which you'll drive the sub(s)
the frequency at which you want to cross over to the Sabs.

With regards to the crossover frequency, higher would give the FR driver an easier time, but you begin to lose the benefit of horn loading.
For example, I have my FE126s in small sealed cabinets (2L a piece) and use stereo woofers with a 500Hz crossover. No point in horn loading the Fostexes, so I didn't.
If you do cross over that high, the woofers have to be in the same cabinet as the FR driver - this isn't optimal for getting an even in-room bass response: distributed subwoofers rule here.
To keep the subwoofers unlocatable (by ear), its advisable to keep the crossover reasonably steep, and at 100Hz or below.
That way, you can place the subs optimally, while keeping the FR speakers where they sound best. The link Scott posted further up the page will be of use to you.

Here's some more reading.

HTH
Chris
  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
Optical Add-on? markusA Twisted Pear 10 23rd March 2012 09:18 PM
Another pair of Saburos finished bamph Full Range 14 3rd November 2010 07:58 PM
Folded Saburos? ilewis33 Full Range 3 19th April 2008 03:08 AM
add gain jaudio Chip Amps 0 16th January 2005 12:33 PM
How to add the subwoofer ? Flavius Solid State 3 29th May 2003 06:14 AM


New To Site? Need Help?

All times are GMT. The time now is 10:19 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