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08-21-2021 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,173
Joined on 05-28-2004
Post #: 1
Post ID: 26287
Reply to: 26287
Some thoughts about bass in high-end audio.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-22-2021 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 454
Joined on 07-05-2012
Post #: 2
Post ID: 26288
Reply to: 26287
The video thoughts have brought questions to mind
The idea of high quality delay makes me wonder if the delay effectively increases the virtual length of the room - allowing longer wavelengths before the room Schroeder frequency is reached. This would be a "softer" bass without the room compression.

I also wonder if the tube/SS "amplification problem" is also related here - at bass frequency XX, the room is smaller than the wavelength and turns into a compression chamber - articulating harder and with uncontrolled decay. 

Certain large scale recordings have more cloudlike bass when I open all of the doors in my listening room, effectively diffusing the "compression chamber". Other, more primitive music very much benefits from the doors closed pressure chamber (like bass in a car).

The video format is getting easier for me. Keep them coming!

Whenever I feel blue, I start breathing again.
08-22-2021 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,173
Joined on 05-28-2004
Post #: 3
Post ID: 26289
Reply to: 26288
A common practice.
 rowuk wrote:
The idea of high quality delay makes me wonder if the delay effectively increases the virtual length of the room - allowing longer wavelengths before the room Schroeder frequency is reached. This would be a "softer" bass without the room compression.

This is not a question but a fact. The key here how to understand properly “high quality delay”, In audio generally we understand “high quality” as better sound in terms reverberations there is no better sound (as the reelections with 10-30 ms delay are very much sound quality compromised. The higher quality reflection injection means better mathematical algorithm that synthesizes reflection. This is why the synthesizes of reflections typically happens at 14bit processor and requires very primitive amplifiers and speakers. Yes, it is increases the virtual size of the room but with the typical problems the large rooms come with. It is very easy for you to get evidence. Play any Henry Purcell’s pieces for organ and trumpet in a typical listening room and it will sound line Apollo is blasting engine in shoebox. If you add Church or one of the Concert Halls reverberation mode to back channels then I promise you  that you will laughing for 30 minutes and will be asking yourself  what the hell you were doing in audio for all those years.
 
BTW, in pro would there is long tradition to virtualize size recording avenues by adding multiple reverberation parameters.  I personally learned a lot by reading the manual for Behringer Virtualizer 3D FX2000 and Sony DRE-S777. It is not a revolutionary subject in recording world and I have no idea why this practice never made to High-End

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-23-2021 Post does not mapped to Knowledge Tree
anthony
Posts 338
Joined on 08-18-2014
Post #: 4
Post ID: 26290
Reply to: 26289
Good one
Thanks for this one Romy, very interesting...it sorta ties together several things that I have been thinking about lately.  

I guess I am lucky that the Bass Cannons can be run off 9w from the DSET bottom channel and from memory I get about 115dB at 18Hz once room reinforcement does its magic.  One of the few benefits of a small room.

A couple of weeks ago I had a 6C33C fail on startup and short the filament which caused the filament transformer to try to do a bit of welding which melted some wires (not sure if you have ever had one fail this way - I think I should fuse that circuit).  One DSET is out of commission until the transformer is replaced so I have been listening to my surround speakers as mains.  This has been quite educational.

The surrounds are JBL708P which are a Class D DSP bi-amplified two-way with compression driver/waveguide and 8" front ported woofer.  In terms of what they are I think they are a decent speaker and are marketed as "master reference monitors" by JBL.  I purchased these because they are an all-in-one box and I did not want to be tempted to build fullrange Melquiades for surrounds:  just put them on the wall and plug in the power cable and interconnect.  Since the valve failure I did a bit of searching and apparently they are the "perfect speaker" according to some reviews (literally says that on one forum where they are measured) but needless to say that after Macondo/Melquiades I feel I am truly slumming it with the JBL's.  Even though this speaker is more capable than most similarly sized speakers in terms of power response, directivity and spl, all metrics that the research says leads to better sound, they are still missing a lot compared to Macondo.  One thing I will say about them is that it sounds more or less the same wherever you are in the room...that even power response really does a good job of making the reflections sound like the direct sound, which may be a benefit when used as reverb injection.

Anyway,  all this makes me wonder about speaker quality for the revereration injection and whether there may be something to gain with larger speakers at the rear, not that I can fit them, and not that I have trialled anything yet.   
08-23-2021 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,173
Joined on 05-28-2004
Post #: 5
Post ID: 26291
Reply to: 26290
...however....
 anthony wrote:
I guess I am lucky that the Bass Cannons can be run off 9w from the DSET bottom channel and from memory I get about 115dB at 18Hz once room reinforcement does its magic.  One of the few benefits of a small room.

That was the whole idea of Sunspeak woofer array: to have multiple divers with sub 20H FS to boost sensitivity and to drive it with the same DSET topology as the rest of the channels. For small rooms it is very elegant solution.

 anthony wrote:
A couple of weeks ago I had a 6C33C fail on startup and short the filament which caused the filament transformer to try to do a bit of welding which melted some wires (not sure if you have ever had one fail this way - I think I should fuse that circuit).  One DSET is out of commission until the transformer is replaced so I have been listening to my surround speakers as mains. 
Hm. I never had any problems with 6C33C heaters.

 anthony wrote:
Anyway, all this makes me wonder about speaker quality for the revereration injection and whether there may be something to gain with larger speakers at the rear, not that I can fit them, and not that I have trialled anything yet. 
My conclusion that the quality of revereration injector is not truly important. Of you use fast responding reverberations patterns, like Disco, Rock and etc… then speaker quality does play role but then you are listening crap and I care less how it sound. In case you are with reverberation pattern over let say 20-30ms then the quality of speaker not truly important.
 
HOWEVER
 
This is what I have learned, is soon the bass of reverberation channel begin to impact the bass of the main channel at a desirable level of reverberation volume then you need to go to ether smaller speakers, or high pass them or mover them around to get less bass. The sound from reverberation channels should not talk to sound from the main channels. This is how I feel, now.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
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