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"Dolby Volume" sound level processor...DIY?

I was trying to make my own sound level control circuit (which I did) and in the process discovered that Dolby has a very good sounding sound processor

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that is often incorporated into several digital media control units, and is also built into some CirrusLogic audio DSP chips (CS48DV2A-CQZ,CS48DV2B-CQZ,CS48DV6B-CQZ,CS48DV2A-DQZ). There are also evaluation boards (CRD48DV2-USB 2ch., CDB48DV6-USB 6ch.). The evaluation boards looked very interesting, since they had analog inputs and outputs. The ADC and DAC functions were built into the evaluation boards. The other chips above, accept digital I/O. Apart from the rather high cost for the evaluation boards ($250-300) they seem difficult to obtain, it looks like these are special factory orders, with minimum 26 week delivery times. The chips aren't all that costly 10-20$, but require orders of 2000 min, with poor delivery dates. The chips seem a messy solution, since they require a lot of supporting hardware and software. I was looking for an analog box to go between a digital cable box and a TV set. The inconsistencies of loudness between channels and programs was driving me nuts - I couldn't hear soft conversations in movies, and was blasted out of my chair by commercials. Even though the cable box provided some degree of compression, it was not enough to overcome the "mucking about" some channels have done to their audio. My home-made kludge allows me to apply a +10db extra gain for low levels, and a 10db attenuation for loud levels. Both have threshold levels that I can set from -60dbv to +20dbv. This doesn't have any of the whizzy frequency bands and masking compensation that the Dolby Volume processor has. It does finally let me watch the old movies without waking up half the neighborhood. I'm intrigued by the Dolby Volume..... has anyone tried one of these? It's being added to some of the more recent AV products (i.e., Arcam AVR600, Harmon Kardon AVR1600). I don't see any products that are cheap and simple, something that you could buy for less than $50 and stick it between your sound source and stereo in analog form. There is probably a reasonable market for such a thing, I have heard many complaints about the excessive variation in sound levels from TV stations. I did find this unit available in the UK for 60 pounds:
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but it seems impossibly small to house all the circuitry required! There is other competition to Dolby Volume, that is: "SRS Truvolume", and "Audyssey Dynamic Volume". All use DSP. I couldn't find any sources that would allow me to do a DIY circuit using them, other than purchasing another impossibly small unit like the above one, but using "Truvolume", from the same manufacturer. Grrr..... electronic technician's dilemma.... pay $100-150 for pre-packaged unit, or build it myself for about 1/2 the cost in parts, several hundred hours of fiddling, months of delivery delays..... How difficult are these audio DSP's to use and breadboard?

Paul G.

Reply to
Paul G.
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There are TAS3002/TAS3004 from TI, with the integrated audio CODECs. Very cheap and simple to use; ideal for the applications like tone/volume controls, DRC and equalization. Unfortunately NRND. The only problem with breadboarding is QFP with 0.5mm pitch.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

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Vladimir Vassilevsky

DIP adapters seem to be a lot cheaper now than some years ago...I found these:

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QFP48pin

0.5mm pitch, $8.75 each. I was expecting prices around 50-100$. Soldering them isn't all that hard, especially if you have some thin solder-wick. The physical part of the circuit is a bit awkward, but I'm concerned about the software. The Cirruslogic chips with "Dolby Volume" (CS48DV2B) require software to be run at each powerup, I wonder how co-operative Cirrus is with the DIY crowd.... The last thing I want is to be writing my own code for one of those beasts. I've done older PLD's before, I'm not so sure about the DSP's. Paul G.
Reply to
Paul G.

Why did you expect such high prices? It is just a small PCB. If you create the layout yourself and order it from

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or other PCB companies, it would be the same low price.

You can even get multi-adpaters for QFP, TQFP, for 0.5 mm and 0.65 mm pitch, from 16 to 80 leads, all in one adapter, for $1,99 from eBay:

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Frank Buss

On a sunny day (Thu, 29 Oct 2009 01:20:45 GMT) it happened Paul G. wrote in :

In the old day you could make a nice audio AGC with some J-FET and detector. Or you could send the audio via a Linux PC and use my xpequ audio processor:

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It has an AGC function. BUT is has latency of course, so the audio will be a little late :-) The analog J-FET system looks better for you, you could improve linearity by using some Gilbert cell or whatever it is called (controlled diff ammp). Use silicon transistors LOL. hehe

Reply to
Jan Panteltje

The "gotcha" is (I believe) that if you want to use their DSP software which incorporates patented/licensed technology, they won't provide it to you unless you can prove that you have a valid license from the patentholder (Dolby).

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Reply to
Dave Platt

On Thu, 29 Oct 2009 11:54:04 GMT, Jan Panteltje wrote:

It was kinda interesting to see if you can actually buy a simple box (analog in/out) that employs "Dolby Volume", or "SRS Truvolume", or any of the decent DSP based volume regulators. I can only find one, that is a "DCT-6S (newer number is AU-D6S)", manufactured by Cypress Technology.

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Cost is around 130$, and the box is amazingly small. It needs an external 5v supply. What I find unusual, is that you can't seem to get this product in North America! Oversees companies won't ship it here. Some of Cypress technology's products are available in U.S.A., but not their line of "CYP" products which include the sound processor, analog-digital converters, etc, all in their tiny little boxes. It seems that Dolby and SRS are licensing their technologies to large companies (not the DIY crowd), and if you want to have the features of Dolby Volume or SRS Truvolume, you need to buy a very expensive TV or media control center. In order to buy chips from Freescale, CirrusLogic that have Dolby Volume or Truvolume, it seems you need to be a licensee. So all this hoopla about the great volume processing is of little use to the guy who does stuff on the cheap, or by DIY. My paranoia says its a conspiracy to fleece customers or high-end buyers, my rational thinking says there isn't a sufficient market in North America for a cheap and simple TV volume adjuster that uses Truvolume, Dolby Volume, or Audyssey Dynamic Volume. There is a product called "Terk VR1 Automatic TV Volume Controller" which has a similiar function, but it doesn't use a well known methodology for controlling volume. It costs $25-40, and it's available from amazon.com. It claims to use DSP, but I couldn't find any details about it. The lack of internet discussion or comparisons on the above units suggests to me that very few people seem to care - there isn't a big market for this stuff, and the folks who make TV commercials have an incredible arsenal of techniques that can outwit any effort to control the volume.

Paul G.

Reply to
Paul G.

On Fri, 30 Oct 2009 01:51:15 GMT, Paul G. wrote: [snip]

I bought that unit, found that it was poor for TV content, due to the "long" pauses that exist in ordinary dialog, in movies in particular.

However, when hooking up my Roku Soundbridge for Internet Radio, I found that it is fabulous for equalizing different streaming sites so that I'm not constantly on the volume control... probably because the sources are "radio" and probably already using companding at the source.

I have a mind that goes totally blank during commercials ;-) Years ago I used to get calls, "We're conducting a survey. Are you watching TV show...?" "Yes." "Can you tell us who is the sponsor?" "No." ;-) ...Jim Thompson

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Reply to
Jim Thompson

On a sunny day (Fri, 30 Oct 2009 01:51:15 GMT) it happened Paul G. wrote in :

I think there is more to it, I will give an example: I used to make multi language DVDs, with for example 11 languages, in sync with background sound, using AC3 encoding. I use one language front left, one front right, one rear left, one rear right, and that x 8 channels (the maximum for a DVD). This is for providing people with translation via headsets in an event. To test those, I needed a DVD player with *analog* outputs (sure the PC sound card has those too, but there are other issues that need to be tested on a real player, such as menus, subtitles, what not). So I finally found a DVD player with 5.1 analog outputs: a Cyberhome CH-DVD 405. Very nice sound output, great for testing DVD+R (not +RW). Now you think all is well, but no, it seems Hollywood does *not like* the analog outputs, so they got pissed with Cyberhome, and added that model (or make) to the blacklist on their new DVDs. Result: It wont play my latest startrek DVDs, black screen. I think Cyberhome then went belly up. So this is all about "closing the analog loophole" (type it in google without the quotes), preventing people from making high quality recordings via analog outputs.

That is why you can only buy those things with integrated sound processor. It is insane, because anyone with just the tiniest bit of electronics knowledge can tap the analog sound from the speakers, but this is the world we live in. They do it with the video part too, that is why we have HDMI, not because that gives a better picture, it does not.

So, anyways, tap the sound that goes to the speaker amps, use a simple analog AGC, for 5.1 surround audio 5 J-FETS? and be done with it. Do not dance to Hollywood's tune.

Reply to
Jan Panteltje

On Fri, 30 Oct 2009 11:30:40 GMT, Jan Panteltje wrote:

.....[stuff deleted].......

the quotes),

can tap

gives a better picture, it does not.

AGC, for 5.1 surround audio 5 J-FETS?

Did some digging around, following your lead. It appears to be as you say.... a vast "conspiracy" to do away with analog, presumably to put a damper on piracy. Once you get away from North America, it seems that it is much easier to get your hands on devices that can deal with the analog signals. As media processing matures, I can see that the necessity for control, security, interactive programming, etc., is going to lead to complex media streams. It will probably turn into another "digital tower of Babel" like Windows. In the future, media hacking may a field day, and listening to a song could make your digital house fall apart! Luckily, it's going to be a while before speakers can only run on a digital data stream! In the meantime, I'm still working on an all analog solution. Setting attack & release times seems to be very much an artform. the range of audio from various TV stations and programs is SO variant, it becomes very difficult to design a one-size-fits-all solution that doesn't have wierd artifacts like "noise breathing". Some stations have expanded the audio range, some have applied squelch at low volumes, some have already compressed the hell out of the signals, all kinds of crazy stuff. Some have applied some very artful processing that keeps the levels reasonable, but has sounds specially designed to be disturbing i.e., baby squalling, shrill wife sounds, male buddy talk, fast talking insane car salesmen, etc. There are those supposedly lucky people who claim to be able to ignore things like commercials. But commercials are a form of propaganda, human beings CANNOT avoid being influenced by them, no matter how much the victims claim to say otherwise. You throw enogh crap at a wall, it will eventually stick. The science of propaganda was refined during the course of two world wars and a cold war..... and advertising (and of course, politics) has made good use of those techniques. A number of those techniques make use of audio processing to enhance "suggestibility". No amount of digital, analog, or mental processing will reduce those techniques.... I need to hit the "off" button. My paranoia has run off-scale!

Paul G.

Reply to
Paul G.

On a sunny day (Sun, 01 Nov 2009 02:22:40 GMT) it happened Paul G. wrote in :

Well, I usually watch from digital satellite, mainly movies, some special programs, and record on the PC, and watch time shifted at the same time. that means if commercial starts, I fast-forward the viewer :-) If I catch up with the the program, so it becomes real time, then I just stop it, and go and do something else.....

Works 100% percent, have no clue what they are advertising these days :-) But Hollyworld figured out the trick, now they want a special bit that prevents fast forward in recorded material. Do you believe it? Writing a filter for that bit is easier than taking candy from a baby. But then I have an digital satellite PCI card in the PC... the poor guy who buys a settop box will have no output.. My TV cards may one day be worth a lot of money, if PCI still exists then...

Internet, in a way, allows you to select what you are exposed too. My Usenet news reader has filters too, and they work, I wrote them: file://localhost/mnt/sda3/emit/panteltje/newsflex/index.html

Reply to
Jan Panteltje

same time.

Since about 20 years ago, I have no TV in my house. This is what I think about TV in general:

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VLV

Reply to
Vladimir Vassilevsky

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