C-24 Monitor section

[Rollerex]

Am I the only one who thinks the monitor section should have alot more gain.
I have a Bryston 4B and the C24 at fill up with the stereo bus in the Red is at about 1/4 of the Bryston output.
I havent taken any measurements to see what the output level is coming out of the C24 nor does the Bryston have meters. Just two leds a green for signal present and red for outta headroom. What Amp Speakers do you guys use?
Will the C24 power them to full?

[Sergent Pepper]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Rollerex:
Am I the only one who thinks the monitor section should have alot more gain.
I have a Bryston 4B and the C24 at fill up with the stereo bus in the Red is at about 1/4 of the Bryston output.
I havent taken any measurements to see what the output level is coming out of the C24 nor does the Bryston have meters. Just two leds a green for signal present and red for outta headroom. What Amp Speakers do you guys use?
Will the C24 power them to full?<HR></BLOCKQUOTE>

I have a NAD on ALT monitor and Alesis Matica 900 (2*250) on main, and this is OK for me.
I saw a post from a guy having the same trouble as you about 2 weeks ago "Specs not as advertised" or something like this.

BTW, is your Mono button working normaly ?

[masaudio]

Hi!
I tryed mine today and went direct to my Paradim speakers (self amp.)and everything was O.K.

[PTstress]

Please see my post C24 Not as advertised spec. You are not alone and this problem is SERIOUS. I am still awaiting a response from Digi on this matter.

[PTstress]

Dear Mas

Please try comparing the output from your control 24 with the output from an 888 if you have one, and let me know the results? Im pretty certain there will be a major difference. The 888 being true +4db and the C24 being nowhere near.

[8bit]

i noticed the difference, it was quite considerable. i am running dynaudio BM15a's and straight out of the interface they are much louder.

[PTstress]

thanks for the info 8bit.

I would recomend that all C24 users do the simple test as outlined above and read my previous mail on this subject as I am sure Digi would have us believe that its not important. In my opinion it is a huge error on Digis part allowing this console to go into production with an output as low as -15db (or 19db down on an 888s output). Its like being sold a 30 ips multitrack and finding out that it only records at 15 ips and being told that its ok by the dealer!!!.

Come on Digi - over to you

[davemc]

The couple of things that annoy me about the control24 are
1) The lower level of the outputs
2) The noise that seems to come and go from the outputs. This has been mentioned a few times a digital clock sound.
3) The terrible finish. It looks as though I have had it for years.

Of course we will not get any answers and will have to pay an upgrade to fix it later like the pro control users had to.

Come on it is +4db or -10db or switchable not whatever the output is????

[PTstress]

Dear Dave

I sincerely hope you are wrong about Digi not taking this seriously. If this is the case they will receive a substantial bill from me as my whole room was built around a console that I cant currently utilise in the manner intended.

As for the finish issue as Im not using mine its not a prob for me as yet but there have been so many comments about it you can be sure I'll be keeping a close eye on it.

Re your last comment, if the C24 was +4 or -10 that would be rectifyable. The problem is its neither.

All I can suggest is that if we keep bringing this up Digi will have to start talking to us. I for one, am not impressed by their continued silence on this issue.

[Rollerex]

My guess is that to fix this would require a new monitor section circuit board.

I haven't opened up the C24 but I assume surface mount integrated circuits for the monitor section.

Not like the old days where you could change some components for more gain.

As it is I might need to modify mt Bryston amp
or have an external "gain box" made to give the monitor outs a boost.

No you didn't "hijack" my post this is where we share information to make things better!

[darla]

Yeah, the monitor output on my C24 is definately way down. Prior to getting the C24 I was monitoring off the 888's dig out to my PSX100's D/A's. Even then my Hafler P7000 was way too loud because minimum output on it is 15 db. I can crank the C24's monitor pot all the way up & it's just barely too loud. images/icons/confused.gif Perhaps a simple resistor change? I ain't getting in there to find out images/icons/shocked.gif

[davemc]

Funny since these problems have come up we have had only one response from digi to say they are looking at the finish problem and will get back to us from the 25th of June.
Nothing to say they are looking at other problems. A few have seen to be fixed by returning the unit.

I wonder if it is just a QA as these things are made in China.

Although the output problem seems to be consistant with everyone who has one.

I can understand that digi does not want to confirm anything until they have it resolved. Otherwise buyers would wait for the fixed version before purchasing.(lost sales for digi)
It is a great console.

I just hope we get our old models fixed. Before this forum was split I read about the pro control owners paying for an upgrade that is basically a design fault to start with. http://duc.digidesign.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=29&t=000287

[Rollerex]

I tried the little test.

888 to amp all the gain I'd ever want.

C24 monitor out to amp -19db ouch!

Anyone form Digidesgn engineering care to comment about this design.

Maybe the guys who think the monitor level from the C24 is OK have powered speakers set to -10 rather than +4

[PTstress]

Dear Rollerex

I hope you dont feel that I've hi-jacked your thread, but Im sure you agree with me that we need some answers and a firm commitment from Digidesign as to what they propose to do about this issue.

[PTstress]

I have been informed by Digi that this problem requires a firmware update to resolve. What I havent been told is when we can expect it. It does not seem reasonable to me given the misinformation on their spec sheet that they could possibly charge us for fixing this problem. If you think about it Monitoring is the most important aspect of recording/mixing. As its not a case of +4 or -10 a gain make up device would have to be variable in order to put out the correct output. In my opinion they made a mistake underestimating their customers. I believe they honestly thought we wouldn't notice! I made sure they were aware of this very early on.

It is definately time to hear from Digi on this issue. Time for some old fashioned honesty.

[PTstress]

Just to add to my previous post...

If you crank the monitor pot on the console to the last third distortion starts to creep into the signal so its not a good idea to be fooring that pot. If the console was outputing correctly you wouldnt need to. I bought this console to monitor 5.1 and at present im not using this part of the board at all and sticking with the 888s output which is a far from satisfactory state of affairs.

[MIXER500]

I have to sound off about this also. I've been a PT user for a looong time now and the Control 24, while a good solution, has a finish that is MELTING away and the output is simoly not even close. I had a HUI before picking up a C24 two months ago and it looks in better shape. Please, Digi, let us know what we can so about this.

[McMasters]

Rollerex,
Did DIGI provide any schematics with the control surface?
Are schematics available?

[Rollerex]

No I don't have a schematic for the C-24.

This brings up another sticky issue.
Digidesign is now in the console buisness.
A C24 requires special shipping.
I think they are too big/heavy to send via UPS.

How about some local service?

[McMasters]

images/icons/confused.gif HELLO, DIGI?? HELLO. images/icons/rolleyes.gif
This is your customer base calling.
What is up the monitor section? I just sold my 2" machine and got a line of credit to purchase a Mix cubed and Control 24. (setting up for 5.1 mixing)
I personally go to the big speakers often, so I can feel where the low end is. I need volume.
When I demoed the C24 at my audio retailer, I just figured they had the trim pots turned down on the speakers they were hooked up to. I am surprised to here that the problem may lie with the C24 monitor section.
Now my last service tech modified my Amek control room monitor pot with a resistor for a smoother taper. Now I am not a tech, but I have learned a little by watching and helping out the techs I hire. So I would tend to believe that the problem is with the pot itself. Does the pot have too much resistance or is there an overly aggressive resistor in the monitor path? (ANY TECHS OUT THERE??)
Since DIGI IS STONE WALLING everybody. Maybe they are waiting for one of you guys to pay a tech to fix it. Then let them know how it was done.
By the way DIGI are the schematics available for people that do need them for in house service? It would be helpful and certainly save you some headaches not to mention you would find some guys who do have good techs or the funds to pay good techs to fix these bugs.
I have bought enough pro gear, cars and motorcycles to know that when you get a newly designed product in its first year of production, there will be bugs. Whether it be a monitor pot or a poorly designed rear linkage. That's the price for the "I need the newest and best now."
My problem is not that the monitor section outputs are low. My problem is that you are not addressing the problem in a timely manner. The finish is one thing (cosmetic) but this monitor problem is very serious. I will hold off purchasing this unit until I talk to my DIGI rep from NY.
I need to know if I can at least get a schematic of the monitor section before I purchase this thing. If this is your beta console give me some schematics so I can find someone to fix this.
Or better yet, instead of us having to pay a guy to sit and read the schematics, to figure out which wire trace(s) to cut and what value resistor(s) to put where. At least have your techs figure that stuff out and send us a schematic with the new design.
I know that is not what the people on this thread want to hear. However it is a solution, and it is one that keeps your console in house and only down for a couple of hours. (OK, that sessions' profit went to pay the tech, however your control 24 will monitor properly.) That is a good thing.

FYI My other board is an Amek Big which I paid $22,500 for. I did have to modify it because of a poorly designed buss structure. Go figure. However the finish did last about 2 1/2 years, until wear started to show around the control room monitor pot.
I figure for the price of this control 24 I can throw it out after 3 years and get the NEW even better SUPER DUPER surface that does even more and costs even less.

DIGI I just want to deal with a company that is straight up. If your products have problems please address them and let us know what you are thinking about doing to fix them. That's all. Bad news is better than no news in this case. And good news is better than bad news. (incase you were wondering) images/icons/tongue.gif

PROFESSIONAL GEAR MANUFACTURERS ALWAYS PROVIDE SCHEMATICS. i.e. AMEK, OTARI, NEVE, SSL. That way we can fix things in the field.
And who ever at DIGI is reading this. Talk to whoever you need to talk to about providing schematics.
I know the schematics were not included when DIGI determined the list price of the unit. I would be willing to pay a couple extra bucks for the security that only a schematic can provide. images/icons/cool.gif

[darla]

McMasters wrote: So I would tend to believe that the problem is with the pot itself. Does the pot have too much resistance or is there an overly aggressive resistor in the monitor path? (ANY TECHS OUT THERE??)
Since DIGI IS STONE WALLING everybody.
McMasters-Have you spoke with Digi on this? (I'm NOT taking sides!!) I did yesterday & they were straight up with me about the problem. it's not a simple pot (I believe it digitally controlled, you can hear it "step" thru volume changes quite easily). I initially thought it might be a simple change of resistor somewhere in that section. As I understand it, an EEPROM fix is needed & is "on the way" whenever that is. I was asked to check back in a few weeks. But they are aware of it & they know we are images/icons/grin.gif

[Rollerex]

Ok well it's been about a week now that Digidesign has not responded to this thread.

So digi i'll put it to ya point blank.

Do you think this monitor section is properly designed?

If not what will it take to make it work properly?


Many potential buyers read these message boards.
You lack of resoponse is a statment in itself.

I mean when it gets to the point where there is a actual name for this problem (LOS) or low output syndrome.
I think you (and me) have a problem

[McMasters]

ummmm images/icons/shocked.gif

[McMasters]

If the eeprom is the problem. Hopefully it will be field programable, or field replaceable.

--- EEPROM --- Electrically Erasable Programmable Read-Only Memory

Some clues to how eeproms work:

Analog audio output level calibration
A 1000-Hz sine wave at –18dBFS (+4dBu) is generated by the analog audio outputs and then fed to the calibrated audio inputs. An output gain compensation is applied by software to make sure the grabbed signal corresponds to a –18dBFS amplitude signal in memory. This step is repeated for each of the four analog audio outputs. The values of the output gain compensation are stored in the DigiSuite card's calibration EEPROM.

The same procedure is repeated with a 600-ohm load present on the analog audio outputs. The output gain compensation values using a 600-ohm load are stored in the DigiSuite card's calibration EEPROM.

Taken from http://www.matrox.com/videoweb/support/ds/specifications/le_audio/le_prep_audio_tests.htm

If anybody knows more about eeprom technology. Please post.





Analog audio output level calibration http://www.matrox.com/videoweb/support/ds/specifications/le_audio/le_prep_audio_t ests.htm (http://www.matrox.com/videoweb/support/ds/specifications/le_audio/le_prep_audio_tests.htm)If anybody knows more about eeprom technology. Please post.calibration EEPROMcalibration EEPROM

[McMasters]

Just read about the 18db of headroom the 888's have.

Would it be possible to calibrate the outputs hotter? (temp fix)

Just curious. My system should be in by the end of next week. I would like to get a handle on this problem.

[DigiCS]

Control|24 Monitor Section Output Level

Some customers are experiencing lower than desired output level from Control|24's monitor section. Control|24 uses a digitally controlled analog gain circuit. This allows us to set the output "taper" of the pot to whatever we want because it's actually smoothly switching with 0.5 dB gain steps. This also allows us to maintain a matched output level with 0.1 dB matching between channels throughout the adjustment range. The gain and control taper were chosen based on empirical listening tests done during the design phase of the product. This allows the monitor pot to remain positioned within the "sweet spot" between nine and two o'clock. The levels were selected to accommodate a wide variety of powered monitors and power amplifiers at a broad range of listening levels.
The output pot levels were tested with a wide range of powered monitors and amps including Mackie 824s, Genelec 1029s and 1031s, Meyer HD-1s and Anchor monitors. Crown, Bryston, Yamaha, Hafler and JBL power amps were also tested. We chose a nominal operating level that would allow this group of products to operate within a normal range of adjustment (avoiding the need to turn their input trims way down while letting the monitor pot sit in the "sweet spot.")
Note that not all powered monitors and power amps have input level trims (the Meyer HD-1s are a good example). Most of you should have no problem with the output level of your Control|24. However, a select group of products (JBL LSR speakers are one example) cannot be driven to full level. (These speakers do not conform to the de facto level standard used by most powered monitor and amplifier manufacturers.)
In conclusion, most of you should not encounter problems with the operating level of the monitor section of your Control|24. You may have to adjust the input level controls for a power amplifier, but usually not your powered monitors (with the exception of the JBL LSR series).
If you are experiencing problems that cannot be rectified by adjusting your equipment, please contact Digidesign Customer Support. A firmware update is available that will add 10 dB of gain. (However, this update does require the unit to be returned to Digidesign.) As already mentioned, most of you should not require this at all to get good results.

Bob Langlie
Director of Customer Service
Digidesign

[PTstress]

Well at last a response.

Digi, if I read your response acurately, you are saying you set the output level of C24 based on what sounded ok to you and not based on a +4db spec as claimed in your C24 spec sheet. Your comments based on certain amps not performing are absolute drivel and somewhat insulting to those of us who can measure what the C24 actually puts out. This has no bearing on what monitors the C24 is connected to post output so please do not try to ******** us. It is a fact that the C24 puts out 19db less than an 888 regardless of anything taking place outside your board. A +4db balanced amp expects a +4db balanced signal - end of story.

It looks to me that your efforts were concentrated on the assumption that most people use powered monitors. We all know that those monitors are often a law to themselves as far as what kind of signal they expect, however that is a purchase decision for the customer. You should have the courage to admit the error rather than try and assert that only a few of us will be unhappy about this when it is clear that all C24s have been not been built according to the spec claimed.

Having said that, I am of course pleased that a solution has been found and you can be assured that I will be talking to tech support in the uk about getting things sorted.I do question wether a 10db hike is enough to achieve true +4db operation though.

For me this has been a costly exercise and it has further confirmed the need not to take a manufactures word for even the most basic claims on a spec sheet in future.

[ July 21, 2001: Message edited by: PTstress ]

[Dave Lebolt]

There is certainly no intent to be untruthful here. We stand by the point that most customers will not need to change update their units. I'll take each of your points in turn and try to respond:
<UL TYPE=SQUARE>

<LI>Control|24's monitor section was set up not just for powered monitors, but also for professional power amplifiers. The input sensitivities for most of these products consistently fall in about the same range: between 1 volt and 3 volts AC will yield full power output (driving the power amp or powered monitor to clip).

I think some of the perceptions about this issue stem from confusion about the difference between "operating level" vs. "input sensitivity."

When a manufacturer specifies the operating level for a piece of gear, they are generally talking about the "nominal" (read "normal") level for the device, not the "maximum input level before clip." "Nominal" in most cases on pro audio gear is the "+4 dBu" level standard that we are all familiar with. It represents a reference voltage level of 1.23 VAC. For example, this is what is what the "zero" level on a VU meter (not a digital peak meter) on a pro tape machine represents. However, the peak transients the input circuit will deal with on a device (or what the output circuit will supply) are often over 20 dB higher than the nominal level. Thus it is normal for professional audio equipment to handle peak levels at +24 dBu or higher (which is far closer to 10 volts than 1). The ability to accommodate these peaks represents the headroom of the device before clip.

Professional audio power amps and powered monitors generally do not use this input sensitivity standard. Instead, they can be driven to clip by what would be the nominal level on most pro audio line level devices because they generally clip their outputs at below 2 volts (which is far below the +24 dBu I described earlier). This is why most any console on the market does not offer gain above unity on the output... it would just clip the power amplifier or powered monitor following it, and you'd have to keep the level control turned way down all of the time.

The output level as supplied on the C|24s shipped up until now had been -10 dB below unity. This means that when the level control is turned fully clockwise, most power amps or monitors can be driven to full clip (putting out their full level). As we said in the original post, the output level was optimized so that at most "loud" listening levels (SPLs in the mid 90s), you could position the control at around "2 o'clock."

<LI>The post that claims that C|24s put out -19 dB should be incorrect (unless there is something additionally wrong with that unit). Consider that C|24s original silkscreened markings for the monitor level control have a "0" mark at around the 2 o'clock position. This level does not represent "full output" (the silk screening is not correct, and will be updated on future units). At maximum output (with the control turned up fully to around 5 o'clock), level should be -10 dB below the input device's level, not -19 dB.

<LI>As to the question about whether the +10 dB level change is adequate: with the addition of the firmware PROM change, the output level of the monitor section will pass unity gain (level in = level out).

<LI>It is true that the specification sheet should have been updated on the internet (or in printed materials) to reflect the newer specs. We're sorry that this has not occurred sooner. But this is one of the reasons that manufacturers place the text "Specifications subject to change without notice" on their data sheets. It's not an attempt by the manufacturer to deceive a customer, but it's a fact of life that many times as products are brought to market (and the rushing that occurs to get it all done), these materials are created prior to the final changes that occur when releasing a product to production.
[/list]As we stated in the original post, most pro power amps or powered monitors can be adjusted (or left at the levels delivered from the factory) and work well with the C|24 with its original firmware. We're offering an update for all customers who have a problem, but most of you should not have the problem... For those of you who do, we'll update the unit, but we'd like you to contact Digidesign Customer Service first to make sure it's not a setup problem.

Dave Lebolt
VP, Product Strategy
Digidesign

[ July 21, 2001: Message edited by: Dave Lebolt ]

[ July 23, 2001: Message edited by: Dave Lebolt ]

[Rollerex]

Hey ,
thanks for your response in this matter.

I use a pro-control as well and it seems to have the proper amount of gain in the monitor section. I agree with PT stress that it should be unity gain. You bet I want this upgrade.

This brings up another sticky point.

Do any of you want local service for Digidesign?
I live in Los Angeles and Its long overdue here

[Monumental]

Hi there,
I recently changed from my digidesign cable harnesses to a shorter and cheaper DSUB harness for my monitors. Guess what, the monitor level on my system dropped approximately 19 db. Is the monitor section of the C24 using standard DSUB wiring? Could this be the problem?

[ashdot]

Hi,

Just got my replacement C24 and the monitor section sounds SO MUCH BETTER.
It's not only the level that is now right, but the sound seems more open and the low end goes lower and is tighter.

Izhar