Newbie Amp & Enclosure Advice Needed - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

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 27th January 2002, 08:01 PM   #1
Ron is offline Ron
diyAudio Member
 
Join Date: Jan 2002
Location: Bremerton, WA
Default Newbie Amp & Enclosure Advice Needed

Hello,

This is my first post here. I'am a complete novice when it comes to what I'am learning is the 'science' of audio reproduction.

Has any one had any experience with a subwoofer plate amp from KLH Audio, model #119117? This amp comes with the KLH 10 inch ASW 10-120 subwoofer. It has 120 watt output, manufactured by Dong Guan Wei Phon Electronic Co. in China. I can find no specs on the web regarding this amp.

I have just acquired a Shiva Mk III from Adire Audio. I want to build a down firing Sealed box for this driver. As it has dual voice coils, I would like to wire it in parallel as such, and drive it at a nominal 4 ohms. I don't know if this amp can handle that type of load.

Is there a way of testing the amp with meters or anything that would tell me? If I try it wired in parallel, and the amp can't handle it, do I lose the amp only, or worse, both the amp and the driver?

I'am leaning towards a sealed box low Q alignment of .5 as I appreciate musical fidelity, a little more than DVD effects such as the depth charge scene in U 571. Although I may be looking too low here. Any thoughts or cautions would be greatly appreciated.

This is my first attempt at building a box, or any of this, and definately could use all the advice I can get. Should I care about golden ratio aspects in a subwoofer enclosure or not?

I'am using a Denon AVR 2700, with Polk RTi 35 mains, Polk center, with Polk R10 surrounds.

It will be a bit before I can afford to upgrade the plate amp, and was hoping to hear the box and driver first.

Thanks in advance for any advice or experiences you can share.

Regards,
__________________
Ron
  Reply With Quote
Old 28th January 2002, 12:52 AM   #2
diyAudio Member
 
Join Date: Jan 2002
Location: California
There's really no way to tell if an amp is 4-ohm stable by measuring it with a multimeter. Any decent amplifier can safely handle 4-ohm loads, so just go with it and use the warranty if you need to (which you shouldn't =). Check and make sure it doesn't get too hot (i.e. you can't hold your hand on the heatsink).

If the amp fails, it could blow a fuse (hopefully), sound really bad, or possibly take out the speaker if there is no protection relay built into it and the fuses don't blow (which is usually the case).

I recently noticed a funny smell in my living room, and followed it to one of my Polk RT25i 's. The woofer was completely toast, because of my lack of any protection relays on my amp! =( Since the fault was caused by a cold solder, it somehow fixed itself and it took me weeks to find the problem. I doubt most cheaper subwoofer amps have relays due to the added cost of manufacturing, and the fact that it is not "their" speakers that will be toasted!
  Reply With Quote
Old 28th January 2002, 01:01 AM   #3
Warp Engineer
On Holiday
 
AudioFreak's Avatar
 
Join Date: Oct 2001
Location: Queensland, Australia
most decent subwoofer plate amps can handle a 4ohm load... just go slow and use it @ a very low volume initially... after a while if it doesnt get unpleasently hot you should be able to safely turn up the volume a little... if @ any stage it gets very hot then turn it down and dont exceed that point or you'll probably be risking killing the amp and maybe the driver as well....
  Reply With Quote
Old 28th January 2002, 01:12 AM   #4
Warp Engineer
On Holiday
 
AudioFreak's Avatar
 
Join Date: Oct 2001
Location: Queensland, Australia
I just checked the specs for the shiva ... given the power of the amp, you can use just a single voice coil from the shiva and leave the other one disconnected ... the amp will then get an 8ohm load... problem solved.
  Reply With Quote
Old 29th January 2002, 08:13 AM   #5
diyAudio Member
 
Join Date: Jan 2002
Location: Wellington, New Zealand
Regarding the enclosure.....

I'm going to build a Shiva sub like you - but make it a "dual vented / sealed' design.

Basically - with a Qtc of about 0.5 - which equates to approx. 130 litres with a shiva - you can run the box in both vented or sealed modes

Basically build the box - tuning the desired Fb - as a vented box with a port. When you want to play movies and want low frequency response - use it as a vented. When you want to play music and want th best transient response - plug the port (the hard part).

I thought about having a threaded port - which sticks out of the box by about 1" - allowing a rubber sealed cap to be screwed on when wanting to run it in sealed mode (I think any other sorts of plugs could get blown out at higher SPL).

If you just build a sealed box - I don't think you'll get an F3 below about 38 Hz. Not that this is high - it just might not be low enough- not knowing what music you play (ie. pipe organ lowest note is 16Hz, bass guitar or double bass is in the low 40s (or possibly high 30s???)). As far as electronic anything goes....

Dave.
  Reply With Quote
Old 29th January 2002, 02:10 PM   #6
Keld is offline Keld  Sweden
diyAudio Member
 
Keld's Avatar
 
Join Date: Jan 2002
Location: Borås, Sweden, Tellus
Default Golden Ratio

Quote:
Should I care about golden ratio aspects in a subwoofer enclosure or not?
No ! you can even build a cube-shaped enclosure, but I would brace it asymetricly to keep sides from flexing in the same frequens.

Keld
  Reply With Quote
Old 29th January 2002, 03:25 PM   #7
subwo1 is offline subwo1  United States
diyAudio Member
 
subwo1's Avatar
 
Join Date: Jan 2002
Location: North American Continent
Yes, I agree, the stiffer and more solid, the better. A cube may actually be better, as it causes more even forces on the woofer cone.
  Reply With Quote
Old 30th January 2002, 07:07 AM   #8
diyAudio Member
 
Join Date: Dec 2001
Location: California
Lightbulb plug

To Dave Bullet:

Just an idea for plugging your port....

If you don't want to have the port tube sticking out of your sub, and you are concerned about the plug "popping-out" during high spl moments... say "Dark Side of the Moon"...

Go to Home Depot, Lowes. etc. And look in the plumbing dept for a "pipe plug" or a "test cap". They are usually an ugly yellow plastic (safety yellow). But they have a wing-nut in the center that will expand the plug to fit the pipe and hold it there temporarily (usually used for temp blocking pipes or for pressure testing purposes.) They are temporary and assuming you are using PVC for the port tube they would work great.

Hey... maybe you'll find a black one.
  Reply With Quote
Old 30th January 2002, 07:57 AM   #9
diyAudio Member
 
Join Date: Jan 2002
Location: Wellington, New Zealand
Thanks mikeatfhc. I'll keep my eye out for one (just make sure I choose a PVC diameter with a pipe plug that fits).

Pity I wasn't using Focal drivers - the nice yellow cones might look good with a yellow pipe plug - especially when playing yello.
  Reply With Quote
Old 30th January 2002, 12:24 PM   #10
Super is offline Super  United States
diyAudio Member
 
Join Date: May 2001
Location: Connecticut
Send a message via AIM to Super
You may be correct, but 38hz as the f3 for a sealed Shiva seems too high. If I recall correctly, you should be able to go down to the mid 20's or so. Somebody please correct me if I'm wrong.
__________________
Bryan
  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
Need enclosure advice... gruni Subwoofers 7 15th May 2009 12:36 PM
Ported Enclosure Advice JakeDN Subwoofers 36 22nd April 2008 09:24 PM
Newbie question - Enclosure jgedde Parts 3 22nd December 2006 11:07 PM
Advice (Newbie) -=PLuKE=- Multi-Way 1 11th August 2006 04:03 PM
Newbie advice needed on books/programs Ericd2281 Digital Source 2 27th August 2002 05:16 PM


New To Site? Need Help?

All times are GMT. The time now is 12:11 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