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View Full Version : the DBX 4800 Auto Warmth feature.



1audiohack
01-25-2012, 09:05 AM
Hi All;

I have a DBX 4800 in my home main system and have been digging deeper and working to learn and exploit it's capabilities to the fullest extent. My speaker system is fairly well developed meaning that changes in delay, cross-over points, slopes and EQ bring more negatives than posatives after long term evaluation. This system is taylored to my tastes and I realize that it may not be reference correct in many/any way(s), but it is after all mine, and I am very happy with it. Being however that nothing is perfect, the single largest issue would be that I have two EQ settings for low and high level listening, basically a loudness function to bring up the VLF/LF at low levels, even with two GTI1800's for subs.

Enter the Auto Warmth insert. This is a threshold adjustable, curve adjustable insert that when properly integrated has absolutely no artificial sounding artifacts, at all. I can't find the words to describe how much of a posative difference this has made in my low level listening enjoyment, this insert alone is worth the price of admission of the 4800. Now, at any level, with any source material, the sound is full. It does not jump in and out, it's invisible and it's just,,plain,,, perfect. Sorry to gush!:o: You just gotta try this thing!

There are at least two others here with 4800's, are you utilizing the Auto Warmth insert?

Alll the best,
Barry

bubbleboy76
08-07-2015, 02:06 AM
I have an dbx 4820 incoming, and I can't wait to try this feature. If it works, this is exactly what I have been missing.
Barry, what settings do you recommend for it?

1audiohack
08-07-2015, 07:34 AM
I still love this feature as much now as I did three years ago!

The 4800 is now in use with my 4350 system and even with woofers as capable as the 1501-1Al's this feature is phenomenal. I am away from home for two more days but when I get back I will report it's current settings.

I wish they would build this into their other processors including BSS and I-TECH. The DBX Zone-Pro's have a version with less adjustability that I haven't yet used.


All the best,
Barry.

bubbleboy76
08-07-2015, 12:35 PM
Ok, thanks.

grumpy
08-08-2015, 11:00 PM
was thinking about how to do this and then found...:

http://harman-hsp-web-assets.s3.amazonaws.com/site_elements/executables/156_1364847298/creating-a-bass-lift-volume-control_original.pdf

1audiohack
08-09-2015, 06:18 PM
Thank you Grumpy;

That is sensible.

I was trying to figure out how to accomplish this via limiting without being destructive to the overall sound quality and gave up.

Explore this I will.

Thanks again,
Barry.

bubbleboy76
08-17-2015, 01:51 AM
What values do you use for "Threshold" and "Amount" in the AutoWarmth-settings Barry?

bubbleboy76
08-17-2015, 01:53 AM
From the Manual:

Threshold fader
The Threshold sets the level at which AutoWarmth begins to work. Signals below the Threshold are pro-cessed to increase the Bass response in proportion to the overall volume of the signal. Above the Thresholdthere is no processing. The Threshold meter will light green when the threshold has been crossed andAutoWarmth is active. The Threshold range is between -60 and 0 dBFS. To set the Threshold, turnAutoWarmth off and adjust the Master Gain to the desired listening level. Turn AutoWarmth on andadjust the Threshold until the Threshold Meter is toggling on and off. Now as the volume decreases belowthe Threshold, the bass will gradually increase. Be careful when using AutoWarmth followed by an AGC.The AGC can add gain when the signal is below the AutoWarmth threshold resulting in overcompensatedBass.
Amount fader
The Amount parameter controls how much bass is added. A setting of 1.00:1 compensates for the per-ceived loss of bass by inversely matching the Fletcher-Munson Equal Loudness curves. Higher settings(greater that 1.00) cause more bass compensation; lower settings result is less bass compensation. TheAmount parameter is adjustable between 0.25:1 and 4.00:1.

bubbleboy76
08-17-2015, 01:57 AM
I wonder how high up in the frequencies it is working? Should I add autowarmth to both woofer and horn channels (800Hz crossover), or only woofer?

1audiohack
08-17-2015, 08:30 AM
What values do you use for "Threshold" and "Amount" in the AutoWarmth-settings Barry?

I will get you these values today, sorry to have forgotten.

Barry.

1audiohack
08-18-2015, 11:29 PM
I wrote it all down and left my note at home, but here is what I think I remember:

Just a note, this 4800 is on the 4350's so there are four 15's.

Ratio is 1:1

The channels for the 1200Fe's are at -50dB

The channels for the 1501Al-1s are at -45dB

Absolutely magic.

All the best,
Barry.

P.S. If I find my note contradicts my memory, I will revise this post.

bubbleboy76
08-19-2015, 03:42 AM
Thanks, it was the ratio I was most interested in. The treshold is very specific to the gain structure of the system. I am at -24dB now after setting it up according to the instructions in the manual.
My initial tests are very promising :)

bubbleboy76
08-19-2015, 02:30 PM
You have 4350's with 1200fe's and 1501Al-1s? That is far down the rabbithole!
Do you have a thread describing your systems?

1audiohack
08-20-2015, 11:29 PM
Yeah I took the red pill and am still going in.

I don't think I ever started a thread on that project. It kindof evolved over the plight of a pair of forlorn empty cabinets for sale in Cananda. I will see if I can find it. The story on them is not finished.

They are going to loose their -1's for a pair of plain old 1500Al's though pretty soon. They have a new home in a pair of those beautiful Maple Everest cabinetes from Hornslet. :D

Barry.

bubbleboy76
08-21-2015, 01:42 AM
Haha.
I would love to see a pic from your part of the Hifi-Matrix.

pos
08-21-2015, 01:47 AM
They are going to loose their -1's for a pair of plain old 1500Al's though pretty soon.

Hi Barry

What are you going to do with those -1's ?

1audiohack
08-21-2015, 07:22 AM
Hi Barry
What are you going to do with those -1's ?

Hi Thomas!

The 1501-1's are going in the Everest cabinets.

Barry.

1audiohack
08-21-2015, 07:27 AM
Haha.
I would love to see a pic from your part of the Hifi-Matrix.

:) I will reload and return.

Barry.

pos
08-21-2015, 08:52 AM
Hi Thomas!

The 1501-1's are going in the Everest cabinets.

Barry.

Drop me a line if you ever replace them with -2's down the road ;)

bubbleboy76
08-24-2015, 10:38 AM
Why do not more stuff have this function in them?? Adaptive loudness. It's so simple and so right.

What is the catch?

Is it a patent?

1audiohack
08-24-2015, 11:42 AM
Isn't it amazing? It can be down right transformational. It works so well and sounds so natural one would think it would be widely available. If I were a systems designer it would be one of my best kept secrets.

They did it right for sure. I am glad you like it.

Barry.

bubbleboy76
08-24-2015, 12:31 PM
They should skip all the gimmicks in the HT receivers and add this one instead.
Reportedly, Trinnov, ADA, Audessey Pro etc has some kind of adaptive loudness.
But this should be for the masses.

dr_gallup
08-24-2015, 12:46 PM
I remember older Yamaha receivers having a similar function although it may have had a simpler implementation. You set the gain with the volume control to the maximum listening level you needed and then used a variable loudness control to turn down the system when you wanted to listen at reduced volumes. It basically gave you control over the bass boost to match the Fletcher-Munson curves rather than an all or nothing loudness button that was common in the day.

I see DBX 4800's have been discontinued for nearly a decade, surprising to see they are still going for over $2000 on ebay. I thought if they were cheap I might pick one up to play with.

bubbleboy76
08-24-2015, 02:14 PM
Discontinued for some months, not a decade.
And the 4820 is the same thing, without all the external buttons and knobs.

1audiohack
08-24-2015, 02:18 PM
HI Dr;

The DBX4800 was discontinued at the end of 2014. The 4820 is the no front panel access version. it costs about $700 less than the 4800. I hazard the guess that since most of these get loaded in a rack, set up once and forgotten about that the 4820 sells better than the 4800.

The least expensive way to get this (DBX Auto Warmth) is with a DBX Zone Controller. You have to do your homework on these though, some are configured with mic inputs, or not and some other little things that might be a deal breaker for a home rig but, they have do have RCA inputs and remote input selection and volume control. They are not as powerful or as flexible as a DR260 and a long way from the 48XX series.

As a side note, the new DR360 is made in China. I don't know if all DBX manufacturing has been moved there or what will become of the factory in Salt Lake City, Utah. Just another sad page in a still unfolding story.

All the best,
Barry.