CHR-70 bass reflex - Page 3 - diyAudio
Go Back   Home > Forums > Commercial Sector > Manufacturers > Markaudio

Markaudio Designers and builders of audiophile grade drivers

Reply
 
Thread Tools Search this Thread
Old 13th April 2012, 03:26 PM   #21
Andy17 is offline Andy17  Germany
diyAudio Member
 
Join Date: Feb 2012
Quote:
Originally Posted by Spec View Post
Im planning to build a pair of these for monitors for my computer.

Would you suggest lowing the port freq from 59hz to something a little lower? say 40 to 45?...
That is more than a "little" lower!
In simulation you won't gain much bass with lower Fb in a 7l enclosure.
For 47Hz you need ~14l. But it is only a small driver with 50cm2 cone an 4mm Xmax. So you have to take care with the power!
  Reply With Quote
Old 13th April 2012, 09:49 PM   #22
diyAudio Member
 
Join Date: Aug 2009
Location: North Texas, USA
As others have said, lowering the tuing that much won't work. Here's what will happen:

In the Microtowers (~21 Liters) a 54.5 Hz tuning gives F3/F10 of 47/41. Tuned to 40 Hz give F3/F10 73/31. Anything below low 50's causes the knee to droop very badly.


Quote:
Originally Posted by Spec View Post
Im planning to build a pair of these for monitors for my computer.

Would you suggest lowing the port freq from 59hz to something a little lower? say 40 to 45?

Any idea how long the port would have to be then?
__________________
I was so much older then, I'm younger than that now.
  Reply With Quote
Old 13th April 2012, 10:10 PM   #23
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally Posted by fastbike1 View Post
In the Microtowers (~21 Liters) a 54.5 Hz tuning gives F3/F10 of 47/41. Tuned to 40 Hz give F3/F10 73/31.
microTowers ia not a good example. It is an ML-TL not a BR.

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 11th June 2012, 06:54 AM   #24
Andy17 is offline Andy17  Germany
diyAudio Member
 
Join Date: Feb 2012
Hi all,
a little update to my ShoeBox 70.3.
I wasn't entirely satisfied with sound when it stand "free" and was driven with the normal amplifier.
Ok, not the application I use it, but some other may use the Box "free" without any active correction.
So I build up a cheap measurement equipment. A mic with MCE-4500, a mic-preamp with NE5532 and s small amp
with TDA1516. As I have to learn a bit more about ARTA and the mic is not calibrated I will not post any measurement charts.
I think the measurement equipment is good enough to make comparison measurements

I end up with a Filter 1.5mH||6.8Ohm.
(According to the placement of the speaker try 1mH .. 1.5mH)
(If you want more highs try 1 .. 2.2uF in parallel)
  Reply With Quote
Old 6th July 2012, 02:20 PM   #25
rongon is offline rongon  United States
diyAudio Member
 
rongon's Avatar
 
Join Date: Jul 2009
Location: Across the river from Rip's big old tree...
Re: subsonic filters to protect little full-rangers:

Why not put the filter at the input of the power amp? A simple RC filter can be made with a -3dB point below 20 Hz. Assuming the input impedance of the following (solid state) amp is let's say 10k ohms, 1uF in series with the signal should give you a high pass filter with -3dB point at 16 Hz. That will be a slow rolloff -6dB/octave filter, but should help. You could make the capacitor smaller to change the -3dB point. 470nF would give you -3dB @ 34 Hz.

If you're using a tube or FET amp with a high input impedance, you can do this much better, using smaller value capacitors (which work better than larger value caps). 100k ohms and 100nF would get you that same -3dB point at 16 Hz.

An RC filter at line level should be much less damaging to the final sound than a large-value LC between the amp output and the speaker driver. Right?

--
  Reply With Quote
Old 6th July 2012, 03:00 PM   #26
chrisb is offline chrisb  Canada
diyAudio Member
 
Join Date: Aug 2002
Location: victoria BC
Quote:
Originally Posted by rongon View Post
Re: subsonic filters to protect little full-rangers:

Why not put the filter at the input of the power amp? A simple RC filter can be made with a -3dB point below 20 Hz. Assuming the input impedance of the following (solid state) amp is let's say 10k ohms, 1uF in series with the signal should give you a high pass filter with -3dB point at 16 Hz. That will be a slow rolloff -6dB/octave filter, but should help. You could make the capacitor smaller to change the -3dB point. 470nF would give you -3dB @ 34 Hz.

If you're using a tube or FET amp with a high input impedance, you can do this much better, using smaller value capacitors (which work better than larger value caps). 100k ohms and 100nF would get you that same -3dB point at 16 Hz.

An RC filter at line leel should be much less damaging to the final sound than a large-value LC between the amp output and the speaker driver. Right?

--

+1 - you'd still wanna do some math to set values for the particular application
__________________
you don't really believe everything you think, do you?
community sites t-linespeakers.org, frugal-horn.com commercial site planet10-HiFi
  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
chr-70 vs. chp-70? Sonogasm Full Range 10 26th November 2011 05:02 PM
CHR-70, CHP-70, Alpair 7 Desktops - Japan markaudio Full Range 4 1st February 2010 01:42 AM
F.A.S.T. Project: Tangband W3-315 vs. MARK AUDIO CHR-70, CSS EL-70 or Alpair jockel77 Full Range 13 11th January 2010 11:20 PM


New To Site? Need Help?

All times are GMT. The time now is 08:10 AM.


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