2. pc-audio
  3. 1110221460

Foobar Convolver Plugin

Been checking out a friends Windows Media Center for a while now. Decided to start my venture into the PC audio arena by resurrecting an old desktop system as a music server for my garage/shop office.

A little about the equipment - I totally believe in isolation from desktop internals for my gear so with that, for ripping audio I have an external Plextor Premium-U (USB 2) CD writer and use Plextools Professional (error logging) for the DAE process to PCM format. The sound card is integral to the motherboard - NFG. My Media Center buddy went on vacation this week so he was nice enough to loan me his Waveterminal U24 USB sound card and a DIY TDA1543 non-oversampling DAC for me to play with (sounds great by the way in his system). So here's the rig:

PCM files > WMP9 > Waveterminal > SPDIF > DAC > Hafler SE120/100 amp/pre > Ohm H speakers

Sound is very good, but at times a little bright. I tried fiddling with the U24 control panel but any changes I made left me with either polluted or no sound at all. Decided to try a different player. I kept reading about Foobar and it's exceptional playback qualities and decided to give it a try. Big mistake - I like to tweak. Anyhow, I didn't realize any difference whatsoever between WMP9 and Foobar to my ears. Tried Foobar in waveout, kernel streaming and direct sound modes ( I did find an ASIO plugin that I haven't tried yet). I do like the open source and clean/low overhead aspects of Foobar though. Got to poking around and noticed the DSP manager and started looking into that when I came across the "convolver" plugin. Apparently with this plugin you can use "impulse" samples (waveform signatures?) to model other waveforms to it. Poking around some more I found impulses which model rooms, halls, cathedrals, auditoriums, guitar amps, microphones, etc. Found a great number of them here . More searching led me to a download of analogue_impulses.zip which contains a number of "tube-like" impulses. This one caught my attention. I installed the convolver plugin and started playing with the samples. Interesting effects on the sound to say the least! Of all the ones I have tried the "SPL GoldMike Impulse" has had the most pleasing effect on the sound - with no apparant degredation. I may be on to something.

Interesting little find (for me anyway). Considering the concept, one would believe that perhaps impulses of extremely high-end reference equipment could be created and applied in this manner. I'm sure you could never replicate the purity of good gear but by utilizing this method one could almost stumble upon an excellent sounding setup. Not quite sure that I have done things completely right in my testing. Seems to me that in order to do PC Audio right, there is initially some considerable investment in an external sound card and DAC. Seems absurd that I would have to ultimately "fix" the sound with software.

Of course, I am very new to the PC Audio concept. Would appreciate input from some of the veterans to critique my setup. Also some thoughts and opinions if any of you have spent any time with the convolver plugin, which in my opinion is the most intriguing element of my experimenting so far.
slothman
vdeakin
5 posts
 
Slothman, have you tried the U24's inner DAC by simply taking the analog outs from the U24 into the preamp without SPDIF conversion? I'd really like to know, if you did, how it compares to the current SPDIF set-up - I'm looking to buy a Waveterminal and was lead to believe that it sounds reasonably good by itself.
slothman OP
311 posts
 
Vdeakin -
I'll pickup some adapter plugs, 1/4" phone to RCA at the Shack today and try it out. Looks like this U24 is more of a musicians item.
slothman OP
311 posts
 
Gotta like snowdays in the great Northeast!

OK, picked up the adapter plugs at RS. Stopped by my local PC boneyard and what do I find? A bloated, scotch-taped box containing a Xitel Pro HiFi-Link (and cables!) for $10. Excuse me while I finish laughing. Anyhow, time to get serious about this little exercise. I felt I really needed to do some sound comparisons with these "magic boxes" so I decided to move the show back into the house and use my home system CD player as my reference, utilizing what I consider my better gear and cabling as well as the convenience of my laptop.

First thing I did was hookup the Plextor and ripped three cuts that I thought would be the most challenging and convincing for the test:

• Cassandra Wilson - New Moon Daughter - Track 1, Strange Fruit
Vocals, challenging bass and my man Chris Whitley's raunchy and exclamatory National Steel riffs

• Pat Travers - Crash and Burn - Track 4, Born Under a Bad Sign
The drums are well recorded on this cut, nice, tight bass punch and well defined cymbals. I chose this cut primarily because of this.

• Jorma Kaukonen - Blue Country Heart - Track 4, Red River Blues
Acoustic - bass, guitars, banjos, mandolins - all kinds of stuff going on here - some crisp and taxing highs

Here's the setup. Far from reference equipment. This is a very recent system (except for the speakers) and I am extremely pleased with it. The amps are running in triode mode and connected to the passive outputs of the preamp - no tone controls. In keeping with the subject of the thread, I evaluated using the Foobar player only. I also decided to take the external DAC out of the equation and just evaluate the U24/Xitel on its own. To demo, I would cue up the track in the CDP and the corresponding PCM track in Foobar. I would start the CDP and then 10 seconds later, start the track in Foobar, listening to the "reference" first and then switch over and listen to the same passage through Foobar and the device being tested.

PCM files > Foobar2000 > Waveterminal/Xitel/Adcom GCD-700 CDP > Adcom GFP-565 Pre-amp > Rogue M-120 Monoblocks > JBL L100T Speakers (1986 vintage)

I started the tests initially without the Foobar convolver plugin initialized. I spent some time determining which output mode was best for each device. Long story short, I found that the Xitel worked best with DirectSound v2. I then installed the ASIO plugin and used the ASIO drivers for the U24 to get it out of Windows control. Determined that ASIO output was best for the U24. I also had to raise the replay gain in the playback settings 3 db to match the level of my CDP.

• Xitel - I was amazed at the sound I was getting through this inexpensive device. Compared to the Adcom the sound was on the bright side with the highs a little washed out and the mids a little grainy. Bass was slightly muddied and lacked the punch of the Adcom. Although the differences were noticable, I spent a good hour with the Xitel listening to the test tracks and did not find it too fatiguing. My overall summary is that it was just a little too bright.

• U24 - This device kept right up with the Adcom. Very good sound. The bass was solid and the highs were crisp and contained however it was slightly less dynamic in the mids, especially with vocals.

Now, on to the convolver plugin. I found a number of these impulse files at http://www.noisevault.com. The ones that I used most were:

manley_massive_passive.zip collection located at http://www.memi.com/echochamber/responses/

analogue_impulses.zip collection located at http://sjeng.org/ftp/fb2k/

Of all the impulses I played with so far, the ones that I found had the most pleasing and noticeable effect on the sound were:

• neutral.wav
• SPL TubeVitalizer Impulse Soft 2xLCFilter.wav
• SPL GoldMike Impulse.wav

I tested these three impulses on each device with excellent results. Again, playback levels had to be matched to the Adcom with each impulse installed. Only this time the levels were raised 3 db by adjusting the plugin parameters and checking the "auto level adjust" box as well.

• neutral.wav - this impulse had very little effect with the U24. If anything, it tightened up on everything ever so slightly - sort of brought the ceiling down just a bit. Effectively rolled the highs back and reduced the graininess on the Xitel, however did nothing to help the bass.

• SPL TubeVitalizer Impulse Soft 2xLCFilter.wav - this impulse rolled the highs back a bit and boosted the bass on both cards with the greatest difference being observed on the Xitel. I found this impulse to be the best for use with the Xitel.

• SPL GoldMike Impulse.wav - this impulse proved to be the dynamics equalizer for the U24. Head to head with the Adcom, I could notice absolutely no difference with the U24 playing the same track - across the board. Improved dynamics with the Xitel as well, however I found the previous impulse to be better suited for this device.

Conclusions. The U24 Waveterminal proves to me that the possibility of using a PC-based "transport" is certainly a sonically acceptable option with my home system. With a little software tweaking, it sounds as good as my Adcom player. Of course there are many CD players out there that would blow my Adcom away. From what I have seen on the net, some $70 dvd players could do that as well. Perhaps I haven't proved very much to myself. I do know that for $10, this little Xitel gets me into the game quite "good enough" for my shop system. Meanwhile, I'll sit back and maybe stumble upon a U24 cheap while the advancements continue.

The neat thing is that in the realm of PC audio, some excellent "tweaks" can be made at a software level - much better than throwing a couple hundred bucks at a cable or something that might gain you similar improvement. Anyhow, I'll stick with my cheap Xitel and free Foobar software and plugins for now and see how things develop. Even though I'm new to this and have done limited experimenting, I thought I might just as well share my experience so far with the group. Would be interested in hearing of other experiences with the convolver plugin should anyone else try these impulses. Have fun!
More to discover