I want to use 4 ohm Vifa XT25 tweeters with 8 ohm amp - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

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 9th September 2013, 11:28 PM   #1
diyAudio Member
 
Jimmy154's Avatar
 
Join Date: Jun 2002
Location: NH, USA
Default I want to use 4 ohm Vifa XT25 tweeters with 8 ohm amp

I want to use some 4 ohm XT25 tweeters ( http://www.troelsgravesen.dk/PL18XT_files/XT25TG.pdf ) in an active setup with a Elan Z-660 amp, but the amp is rated for 8 ohms min.
How strict is this? Most 8 ohm drivers dip below 8 ohms.
Should I use resistors to make the impedance higher or just use an 8 ohm Wavecor tweeter instead?
http://solen.ca/pdf/wavecor/TW030WA05_06_07_08.pdf

I kind of hate the thought of using resistors on an active setup.
__________________
I give up lol
  Reply With Quote
Old 10th September 2013, 12:15 AM   #2
Banned
 
Join Date: Jun 2013
Location: Melbourne
http://rickgratz.com/examples/z-im-z660.pdf
This is the link to the operating manual. It does state repeatedly that there must be 8 ohms minimum at all times on every connected output. As you say, very few speakers or drivers are actually 8 ohms or stay above 8 ohms. Even stranger is the ability to bridge outputs into 8 ohms which infers that 4 ohms is alright.

Very odd.
  Reply With Quote
Old 10th September 2013, 12:28 AM   #3
DUG is offline DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
Jimmy154: Put two 4ohm tweeters in series to get 8 ohms.

Absconditus: They may have paralleled amps to bridge and keep each amp at 8R...there are only 3 bridged circuits available for 6 amps...makes sense?
__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 10th September 2013, 01:00 AM   #4
Banned
 
Join Date: Jun 2013
Location: Melbourne
Quote:
there are only 3 bridged circuits available for 6 amps...makes sense?
Aren't you forgetting that you need six amps in order to have three bridged circuits?
  Reply With Quote
Old 10th September 2013, 01:34 AM   #5
DUG is offline DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
I looked at the manual again in more detail.

For some reason I thought it used 12 amplifiers and each pair formed a channel.

The more I look at it the more I'm not so sure.

But it might still be so.

Look at all of the speaker configurations and see what you think.

__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 10th September 2013, 02:37 AM   #6
diyAudio Member
 
Jimmy154's Avatar
 
Join Date: Jun 2002
Location: NH, USA
I need to use all 6 channels, I think.
I could use another amp for the woofers but I want just the one amp for two 3-way speakers.
I really wanted to use the Vifa tweeter, but without resistors I don't see how.
The Wavecor might be better anyway.
I need really good off-axis response from this system, so an x-over point of 2 KHz would be good even though I'm using a 50 cm^2 midrange.
__________________
I give up lol
  Reply With Quote
Old 10th September 2013, 02:38 AM   #7
diyAudio Member
 
Join Date: Feb 2004
Location: Los Angeles
Music varely rarely hits peak power in the treble region. So, if you wanted to use a 4 ohm tweeter in a fullrange speaker connected to an 8 ohm amp, I'd say "sure, don't worry about it"

In an active setup, it's a little trickier. Now, the amp can't really know how many ohms the load is. A 4 ohm load will just draw more current, and it will be like an 8 ohm load at a higher volume setting. Yawn, no biggie...until you get near clipping.

So you'd have to guesstimate if you will be driving the treble channels anywhere near clipping. If not, the 4 ohms will be fine. If you're not sure how to guesstimate, post more details about the whole system and we can try and figure that out.
  Reply With Quote
Old 10th September 2013, 02:38 AM   #8
Banned
 
Join Date: Jun 2013
Location: Melbourne
Six speaker outs on the back looks like six amps to me.
  Reply With Quote
Old 10th September 2013, 02:42 AM   #9
Banned
 
Join Date: Jun 2013
Location: Melbourne
Jimmy,
Since the tweeter is 4 ohms, it will draw more current and for the same volume setting use more power, ie, play louder. I suggest turning down the amp used for the tweeter when first hooked up, play white and pink noise and turn up the volume until tweeter output equals that of the mid and woofer.

Alternatively, you might want to post in the Solid State forum, asking specifically about using that amp with 4 ohms.
  Reply With Quote
Old 10th September 2013, 02:59 AM   #10
DUG is offline DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
Quote:
Originally Posted by Absconditus View Post
Six speaker outs on the back looks like six amps to me.
Took a very close look

I now agree.

They can drive 4R but the manual warns about shutdown.

I don't know what they do about bridging...maybe a lower supply tap.
__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  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
Matching my 8 ohm amp to 16 ohm speakers. DocJDG Solid State 9 21st April 2013 12:57 PM
6 Ohm Woofer & 8 Ohm Tweeter stoodood Multi-Way 14 28th November 2012 11:45 AM
4-ohm Speakers on 6-ohm Amp? (newbie question) diesel_88 Multi-Way 23 25th October 2007 08:54 AM
WTB: Vifa XT25 Tweeters Goldenboy Swap Meet 1 30th March 2007 04:53 PM
Single Ended Amp 8 Ohm To 4 Ohm Conversion jsaults Parts 11 21st February 2007 01:00 PM


New To Site? Need Help?

All times are GMT. The time now is 04:36 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