Anyone using an FIR digital crossover? - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

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 17th February 2002, 04:04 PM   #1
diyAudio Member
 
Join Date: Feb 2002
Question Anyone using an FIR digital crossover?

Anyone using, or know of anyone, using an FIR digital crossover. What are the benefits, or disadvantages of this? An example is here: http://www.klein-hummel.com/e/produk...ml/o500c_e.htm

thanks ---- jazzius
  Reply With Quote
Old 22nd February 2002, 05:11 PM   #2
diyAudio Member
 
Join Date: Feb 2002
Location: Belgium
Well, the benefits are those of active speakers with in addition:
- not dependent on passive components
- more filter functions available and can be made very steep
- can be made phase linear
- no noise
Problems:
- expensive!
- only as good as the programming

Look also at things like:
http://www.labgruppen.se/lab.dsp.html
http://www.bss.co.uk/388spec.htm
http://www.klarkteknik.com/pages/set_products.html
  Reply With Quote
Old 23rd February 2002, 07:56 AM   #3
hifiZen is offline hifiZen  Canada
diyAudio Member
 
hifiZen's Avatar
 
Join Date: May 2001
Location: Mountain View, CA
yep. i agree. The hardware to do this can be expensive. I am in fact working on such a project right now. Acutally, it will be a general purpose audio DSP box, but digital crossovers and room acoustic corrections are the two most obvious and important applications.

Like Havoc says, the quality will only be as good as the programming, and let's not forget that real FIR filters are VERY computationally intensive, requiring powerful processors to do the math. Manufacturers might be tempted to take shortcuts by using other algorithms (eg IIR filters or DCT/IDCT transforms), potentially degrading the ideal quality that can potentially acheived.

With digital you are making very few trade-offs from analog. If you're starting from digital source material, then the only real sacrifice is perhaps cost, and maybe a short processing latency for very large FIR filters. What you're gaining is a peice of equipment which can potentially deliver carefully controlled and custom-tailored frequency and phase responses. You can do things which are simply not possible in the analog world. Furthermore, digital crossovers are not subject to component tolerances and ageing, nor any unwanted component interactions or non-idealities. Oh, and perhaps one of the nicest features - reprogrammability! Just change the code, and presto! ...it does something completely different! In the digital world, it's all just math, and nothing more. Your only real limitations are the bit-width of your processing, the amount of computational power you have available, and the quality of your algorithms.
__________________
- Chad.
  Reply With Quote
Old 24th February 2002, 06:39 PM   #4
dc is offline dc
diyAudio Member
 
Join Date: Dec 2001
Location: NYC
Chad-

I've been lurking around a variety of sites looking for a digital crossover with room correction. I'd like to use it with phoenix speakers (www.linkwitzlab.com) that i'd like to build for HT. So, how is your project coming along? Would you be willing to share what you've learned? Is it something that a novice might be able to replicate? Can you give me an idea of the total cost? Will it be able to handle 9 channels across the front plus an LFE and 2 rear channels? Will there be a delay in the audio path that is long enough to require video delay as well?

Thanks.

Brad
  Reply With Quote
Old 22nd March 2002, 08:34 AM   #5
hifiZen is offline hifiZen  Canada
diyAudio Member
 
hifiZen's Avatar
 
Join Date: May 2001
Location: Mountain View, CA
Brad:

I've been eyeballing the Phoenix loudspeakers myself... my only speaker projects to date have been very limited experiments with ESL panels (not counting all the subwoofer enclosures I built for friends in high school... but that was years ago). I find the Linkwitz designs really appealing, and the analogue crossover could be very easily implemented in a DSP... So, i think the Phoenix is a perfect project for me to start with. Now I just have to figure out where I'm going to build these things... hmm

But, I digress... my DSP project is still moving slowly ahead, though the actual hardware has not yet materialized. At the moment, i have a bunch of other stuff to get out of the way so that i will have the time to sit down and finish off the PCB layout and have it fabbed. The cost is going to be pretty steep, at least for the prototype units, and there are lots of small SMD components (including the 208-pin QFP processor... in a 0.5mm pitch package!). I anticipate about $1500-$2000 per finished unit (for my first run of 2). With all the tiny parts, only a proficient hobbyist is likely to assemble one successfully. As far as I/O, the ADSP-21065L processor I'm using is limited to 8 channels in and 8 channels out... a bit limited for home-theatre and multi-channel applications if you intend to use it for digital crossovers as well...

Rest assured, I'll be posting more as my design nears completion over the coming months.
__________________
- Chad.
  Reply With Quote
Old 26th October 2003, 02:58 AM   #6
diyAudio Member
 
LineSource's Avatar
 
Join Date: Sep 2003
Location: SiliconValley
Default FIR crossover for TI TAS5015 digital amp

Having just completed a digital amps basded upon the TAS5015 chip, I started looking forward to a digital crossover using FIR filter technology and hoped reviving this old tread would generate some new interest.


Has anyone built a DIY DSP with enough MIPs for a 2 way FIR filter crossover with complex boost and room compensation?
  Reply With Quote
Old 27th October 2003, 03:21 PM   #7
magnus is offline magnus  Sweden
diyAudio Member
 
Join Date: Feb 2003
Location: Gothenburg
Default BruteFIR

This is probably what you want. I guess it's not a standalone box but you could build a small dedicated box that resembles a hifi component.

Give the development time spent on this you are not likely to ever catch up if you choose to do it all yourself.

I have had similar thoughts myself and I think this might be the best solution both from a cost and a time-to-market (well, market of one ) POV.

BruteFIR

Oh, and how does your digital amp sound? Do you have any pictures or project descriptions? Great accomplishment.

Best,
Magnus
  Reply With Quote
Old 27th October 2003, 03:34 PM   #8
MWP is offline MWP  Australia
diyAudio Member
 
Join Date: Oct 2002
Location: Adelaide, South Australia
Default Re: BruteFIR

Quote:
Originally posted by LineSource
Having just completed a digital amps basded upon the TAS5015 chip, I started looking forward to a digital crossover using FIR filter technology and hoped reviving this old tread would generate some new interest.

Quote:
Originally posted by magnus
Oh, and how does your digital amp sound? Do you have any pictures or project descriptions? Great accomplishment.
Agreed.
How does it sound?
Any chance of seeing some schematics for it?
I would also like to build one (well maybe quite a few), but am a little scared of them sounding bad after putting all the design/building effort in.
  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
Programmable digital crossover diypole Multi-Way 5 19th June 2009 07:21 PM
Progress report - digital crossover as a DAC - digital all the way to the amps Ken L Multi-Way 0 26th November 2006 11:42 PM
digital crossover w/digital output? ezkcdude Multi-Way 30 3rd August 2006 01:01 AM
TMM 2.5 way with digital crossover sqlkev Multi-Way 7 10th May 2006 10:53 PM


New To Site? Need Help?

All times are GMT. The time now is 11:09 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