Decreasing speaker efficiency? - 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 22nd May 2011, 02:09 PM   #1
diyAudio Member
 
Join Date: May 2011
Location: Portland Oregon
Default Decreasing speaker efficiency?

My question is......

Can you DECREASE a fullrange drivers efficiency level? In theory I want to take a 91db efficient speaker and bring it down to 88db or so.
  Reply With Quote
Old 22nd May 2011, 02:20 PM   #2
diyAudio Member
 
Join Date: Oct 2005
I first thought you could put a resistor in series, (this will also change the behaviour in the low frequencies, if I am not mistaken), but then I thought about the following.
Now I may be making huge errors as I am far from the theoretical speaker guru, feel free to disagree with my reasoning:
You want to decrease with 3db, which in essence means that it should be half as loud.
To me this would mean that you need to put an 8 ohm resistor (when using an 8 ohm speaker) of ample wattage in series with the speaker to have this effect. Then (depending on the frequency) around half of the power would go to the speaker, the other half would warm up the resistor.
This is not efficient. I think it would be better to reduce this volume at the pre-amplifier side.
As I said, there may be big errors in my reasoning...
  Reply With Quote
Old 22nd May 2011, 03:24 PM   #3
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
It's easy enough to pick up an L pad from Parts Express for a few bucks
and give it a try.

  Reply With Quote
Old 22nd May 2011, 05:49 PM   #4
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Why are you trying to decrease the efficiency? We usually strive for more not less.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 22nd May 2011, 06:16 PM   #5
diyAudio Member
 
Join Date: May 2011
Location: Portland Oregon
First I need to lay out that I am new at all this so my "theories" may be worthless but here goes. My system is at my computer desk and is fed to a USB DAC to a DIY tube pre and DIY 6V6 PP amp, my speaker cables are DIY CAT5 and WireLogic Audio 500 interconnects all hooked to Fostex FE127E's in a small ported bookshelf cabinet on stands. My speakers are about 7' apart and I sit about 2' in front of them with a slight toe in.

The Fostex are a bit bright for me so taming that would be nice but foremost it seems as my amp opens up a bit at a higher volume......so if I decrease the sensitivity I was hoping to hit that "sweet spot" on my amp. As it is to hit the sweet spot is far to loud......I'm not sure if any of that makes sense.
  Reply With Quote
Old 22nd May 2011, 06:24 PM   #6
18Hurts is offline 18Hurts  United States
diyAudio Member
 
Join Date: Nov 2010
Guitarists do that with power resistors hooked up to their tube amps

They like the sound of tubes distorting at high levels so the resistor trick works well. They call them hot plates or dummy loads. Here is a link that goes through all the different ways to load down tube amps.

Grail Tone - Low Volume, Fat Tone
  Reply With Quote
Old 22nd May 2011, 07:04 PM   #7
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
The FE127e is actually more like 90 dB measured. Perhaps a bit of BSC is what you need, would allow you to shelve down the mid/Highs without affecting the bass alignment.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 22nd May 2011, 07:49 PM   #8
diyAudio Member
 
Join Date: Jun 2004
Location: central Pennsylvania, USA
"foremost it seems as my amp opens up a bit at a higher volume......so if I decrease the sensitivity I was hoping to hit that "sweet spot" on my amp. As it is to hit the sweet spot is far to loud......"

Your class AB (?) PP amp should be running in class A to well over 90db in the near field with the 127e's.

It sounds like you are experiencing the improved sound quality that comes with spl's above about 80db, allowing you to hear bass in-balance with the mids and highs (see: Fletcher?Munson curves - Wikipedia, the free encyclopedia). The best solution is line-level 'loudness' compensation. Baffle step compensation would also help.

BTW, nice computer room system!

Regards,

Bob
  Reply With Quote
Old 22nd May 2011, 08:59 PM   #9
diyAudio Member
 
Join Date: May 2011
Location: Portland Oregon
Thanks guys! I think I'll look into BSC......could be just what the doctor ordered.
  Reply With Quote
Old 23rd May 2011, 05:35 AM   #10
diyAudio Member
 
Join Date: Oct 2005
Perhaps try using the equalizer in itunes (or similar), based on the resulting curve you could design a filter, or simply use itunes as the filter.
  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
Speaker efficiency vs sensitivity Vaughan Full Range 30 14th September 2013 05:44 PM
Speaker Efficiency lumstar Full Range 14 19th February 2009 09:00 AM
Speaker Efficiency cm961 Multi-Way 11 5th August 2002 08:18 PM
Speaker Efficiency Oz_Audio Multi-Way 1 6th July 2002 11:52 AM


New To Site? Need Help?

All times are GMT. The time now is 11:59 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