[akuan99]

Originally Posted by BentZero

So what you're saying is that I must disable ASD and get a new exhaust when I upgrade the audio. I'll be sure to let my wife/accountant know.

if you really want to get new exhaust then I guess it is a "must" to disable ASD

On the other hand if you are on a budget you could choose right amp with right setting and not have ASD effect be more noticeable or unbearable.

[Viffermike]

Originally Posted by BentZero

Ah, that's good to know. I have the base US audio and assumed that I'd need to replace amp and speakers at the same time.

I'm in pz619's camp as well. To date I have just upgraded the speakers, but I was very careful to select speakers with relatively high sensitivity and that weren't too harsh up top (hence why I avoided Focals) so that any issues with ASD being louder were minimized. In my car, ASD is actually less noticeable than OEM -- but that could be as much a function of my fader setting than anything else.

If I upgrade the amp (probably in the next 2-3 months; I'm debating between that and a Dinan axleback), it'll either be a JL Audio 600/6v2 (gain controls for each channel) or a Bimmertech/Match (Yes. Shocking, I know. We'll see.). But speakers only is at least tolerable, particularly with hi-res programming. Barely, but tolerable.

[simoneves]

Originally Posted by akuan99

There are two factors that affect ASD volume after an amp swap.
New amp's gain and input sensitivity.
Amp gain is usually fixed and higher powered amp tend to have higher gain.
Input sensitivity is the only parameter that can be adjusted.
Setting this parameter at lowest setting for rear channels (or setting that will allow highest input voltage setting) will reduce the effect of ASD.
Amp with DSP is little bit more trickier as amp gain adjusted and increased rear channel outputs and increased ASD effect.

I've seen several discussions about this, and it still doesn't entirely make sense to me.

If ASD is to be a consistent volume, and not vary with the head-unit volume control, then obviously its signal must be being mixed in with the output of the head-unit (post-volume-control) and then into the amp, which has a constant gain and sensitivity (it's just on or off). The ASD module therefore presumably takes the four (?) channels of audio from the head unit and provides four (?) output channels to the amp, which in turn produces seven powered outputs to the speakers (LR front, LR rear, LR sub, center) from a combination of those four inputs.

If you swap the amp for one with more gain and/or sensitivity, then the music will be louder for any given setting of the head-unit volume control, and the ASD sound will presumably be louder by the same amount (assuming all channels are set to the same gain/sensitivity, or at least the same per channel as the original amp).

If ASD is mixed into the rear speakers only, then lowering the sensitivities for the rear pair of inputs on that amp will presumably lower both the music and the ASD sound in the rear speakers, without affecting the music in any of the others.

So, first question... why does the Bimmertech amp have a problem doing this which others (JL 600/6 etc.) apparently do not? Is it because the sensitivity adjustment on the Bimmertech just can't be turned down low enough to reduce the ASD sound back to an acceptable level? Obviously even if it was, you'd lose music from the rear too, but surely that would also be the case with the other amps?

Second question... the ASD sound sounds beefy enough that I'm pretty sure it's coming from the subs as well, so surely you'd have to reduce the gain on the sub channels too, which you couldn't do without compromising the music (since they're pre-mixed), so again why does the Bimmertech not handle this but other amps allegedly do.

Obviously, the best solution is to either code it off or use Technic's bypass harness (and I'm assuming the latter avoids any further degradation of the music signal by not even routing it through the ASD module mixer, even if that is now mixing in "nothing").

I just still don't understand why the Bimmertech amp requires it more than others.

Yours confused...

[akuan99]

Originally Posted by simoneves

I've seen several discussions about this, and it still doesn't entirely make sense to me.


If you swap the amp for one with more gain and/or sensitivity, then the music will be louder for any given setting of the head-unit volume control, and the ASD sound will presumably be louder by the same amount (assuming all channels are set to the same gain/sensitivity, or at least the same per channel as the original amp).

If ASD is mixed into the rear speakers only, then lowering the sensitivities for the rear pair of inputs on that amp will presumably lower both the music and the ASD sound in the rear speakers, without affecting the music in any of the others.

..

If the amp has more sensitivity and gain then music will be louder at the same volume setting than stock setup.
This will also mean that ASD will be louder and cannot be turned down with volume control.
The aim is really to obtain same volume sensitivity for music (and ASD) as before.
This will be harder to achieve with more powerful amp so one way to compensate this is to set rear channel gain as low as possible since ASD sound is biased toward the rear.
This will result in lower volume for rear channels but you can use fader control to balance sound level with front without increasing ASD effect.
This is what I did on my JL audio amp setup and the volume sensitivity is very close to stock setup and ASD effect is just a little louder than before.

[bladeomatic]

Originally Posted by BentZero

I'd start with the amp. Crappy amp pushing better speakers is still crappy.

Not necessarily. Whatever is weakest is where you should start. And all things being equally weak, starting with the speakers will usually yield the best results. More here:

http://www.2addicts.com/forums/showp...&postcount=129

[simoneves]

Originally Posted by akuan99

If the amp has more sensitivity and gain then music will be louder at the same volume setting than stock setup.
This will also mean that ASD will be louder and cannot be turned down with volume control.
The aim is really to obtain same volume sensitivity for music (and ASD) as before.
This will be harder to achieve with more powerful amp so one way to compensate this is to set rear channel gain as low as possible since ASD sound is biased toward the rear.
This will result in lower volume for rear channels but you can use fader control to balance sound level with front without increasing ASD effect.
This is what I did on my JL audio amp setup and the volume sensitivity is very close to stock setup and ASD effect is just a little louder than before.

Thank you, and I understand all that, but it still doesn't answer my question.

I don't understand why the same isn't possible on the Bimmer-Tech amp. The channel gain controls in the programming software are individually adjustable, and go down to -30dB, when most of the tune files have rear channel gains at -2dB or 0dB.

I accept that it's not possible to adjust the rear music level independently of the ASD sound, since the ASD is mixed in after the HU volume/fade controls, but surely it's possible with ANY amp to bring the overall rear output back down to original levels, if you don't care about music from the rear (which I don't).

[Viffermike]

Originally Posted by simoneves

Thank you, and I understand all that, but it still doesn't answer my question.

I don't understand why the same isn't possible on the Bimmer-Tech amp. The channel gain controls in the programming software are individually adjustable, and go down to -30dB, when most of the tune files have rear channel gains at -2dB or 0dB.

I accept that it's not possible to adjust the rear music level independently of the ASD sound, since the ASD is mixed in after the HU volume/fade controls, but surely it's possible with ANY amp to bring the overall rear output back down to original levels, if you don't care about music from the rear (which I don't).

Correct me if I'm wrong, but according to this setup guide, the A-F PC-Tool software that comes with the Bimmertech amp doesn't have gain control for individual channels.

Yes, you can adjust individual channels for time correction, EQ, channel volume balance, etc. but those are all tuning parameters, NOT power-stage gain parameters. There's a big difference between the two.

Basically, it the difference between sliding a fader control all the way forward to make the front speakers louder instead of turning up a main volume control -- which is fundamentally (but not always) a master gain control -- to get the same volume level.

Another way to put it: Musical instrument amplifiers often have as many as three volume controls:
1). The master volume (which increases power-stage gain)
2). The channel volume control (which increases gain between the preamplifier and the power amplifier)
3). The gain control (which increases gain before the preamplifier)

Basically, the A-F software acts as 3). Individual channel gain on a audio power amp is almost always 2). And overall volume set at the HU is 1).

[akuan99]

Originally Posted by simoneves

I don't understand why the same isn't possible on the Bimmer-Tech amp. The channel gain controls in the programming software are individually adjustable, and go down to -30dB, when most of the tune files have rear channel gains at -2dB or 0dB.

I'm not familiar with Bimmer-Tech amp but I'm assuming the gain you are mentioning is DSP portion.
-2dB or 0dB is close to gain of 1 which will mean total gain including the power output section will be equivalent to the amp section gain.
This may be higher than stock amp gain.
You can try override rear gain and decrease it to near -30dB if you want to minimize ASD.

[simoneves]

Originally Posted by Viffermike

Correct me if I'm wrong, but according to this setup guide, the A-F PC-Tool software that comes with the Bimmertech amp doesn't have gain control for individual channels.

It certainly does have those controls, at least in v3.x I just downloaded.



Like I said, the tunes I've downloaded so far all have those channel gains set up around zero (plus or minus a few dB for balancing), so presumably they are "louder" by default and intended to allow the system to go louder than the OEM.

However, those gains go down to -30dB so surely that is enough range to reduce the overall gain (including ASD) back to acceptable levels, assuming there are no other effects introduced due to (say) distortion in the audio chain prior to the amp at high HU volume settings, which surely would be evident even with the OEM amp.

If the overall gain of the new amp (from it's line-level input to my ears) is naturally (say) 10dB more than that of the OEM one, with those channel gain set to zero, then surely pulling them all down by 10dB will result in the same volume as the OEM amp for the same HU volume settings (ignoring any other effect due to EQ or whatever) and hence ASD and gongs etc. will also come down to original level.

This would also have the (beneficial) effect of reducing any noise coming into the amp from upstream, which maybe accounts for some of the well-documented "hiss" (some is probably from the crappy OEM amp itself, but hopefully the Bimmer-Tech is much quieter).

So, @Viffermike, now you have no excuse for not getting the Bimmer-Tech!

[Viffermike]

Originally Posted by simoneves

It certainly does have those controls, at least in v3.x I just downloaded.

Like I said, the tunes I've downloaded so far all have those channel gains set up around zero (plus or minus a few dB for balancing), so presumably they are "louder" by default and intended to allow the system to go louder than the OEM.

However, those gains go down to -30dB so surely that is enough range to reduce the overall gain (including ASD) back to acceptable levels, assuming there are no other effects introduced due to (say) distortion in the audio chain prior to the amp at high HU volume settings, which surely would be evident even with the OEM amp.

If the overall gain of the new amp (from it's line-level input to my ears) is naturally (say) 10dB more than that of the OEM one, with those channel gain set to zero, then surely pulling them all down by 10dB will result in the same volume as the OEM amp for the same HU volume settings (ignoring any other effect due to EQ or whatever) and hence ASD and gongs etc. will also come down to original level.

This would also have the (beneficial) effect of reducing any noise coming into the amp from upstream, which maybe accounts for some of the well-documented "hiss" (some is probably from the crappy OEM amp itself, but hopefully the Bimmer-Tech is much quieter).

Question: what is the range of gain adjustment in the software? Look to me, if that slider posititon is correct in representing 0db (unity), that it's mostly a cut function?

Second question (and this would be one for Audiotec-Fischer): is this gain control pre-DSP, post-DSP, or actually part of the DSP? It matters. A lot. I suspect it is pre-DSP, which means it is an input adjustment, not an output adjustment -- and that means it's not a power-related gain control. It increases gain at the input from the HU, not at the output to the speakers -- which would explain why there's not much upward adjustment because you'd fry your speakers -- and potentially the amp itself -- with too much input gain.

I'll agree with you that since that slider allows one to cut frequencies to the rear speakers, it could work to keep ASD at reasonable levels. But the tradeoff -- and this is important because of the type of gain likely used (input gain) -- is that the responsiveness of your rear speakers would not be linear with the others in the system. If you cut too much, in fact, they won't work well sonically with the other speakers at all. That may not matter to some who don't dig the four-channel setup, however.

Originally Posted by simoneves

So, @Viffermike, now you have no excuse for not getting the Bimmer-Tech!

Oh yes I do ... but that doesn't mean I'm not tempted. It's just at this point if I order one, I'd be afraid that it'd be a bomb instead of an amp!

[simoneves]

Originally Posted by Viffermike

Question: what is the range of gain adjustment in the software? Look to me, if that slider posititon is correct in representing 0db (unity), that it's mostly a cut function?

-30 to +5, so yes, mostly cut.

Originally Posted by Viffermike

Second question (and this would be one for Audiotec-Fischer): is this gain control pre-DSP, post-DSP, or actually part of the DSP?

Good question, although since the DSP doesn't perform any kind of dynamics adjustment (compression etc.) then if the DSP is transparent enough then surely it doesn't really matter. Yes, if it's being applied digitally, with a fixed analog sensitivity into the ADC, then it won't help with the digital noise floor, but who worries about those these days.

Originally Posted by Viffermike

I'll agree with you that since that slider allows one to cut frequencies to the rear speakers, it could work to keep ASD at reasonable levels.

Hurrah!

Originally Posted by Viffermike

But the tradeoff -- and this is important because of the type of gain likely used (input gain) -- is that the responsiveness of your rear speakers would not be linear with the others in the system. If you cut too much, in fact, they won't work well sonically with the other speakers at all. That may not matter to some who don't dig the four-channel setup, however.

That's a fair point. Technically it's not a linear adjustment, but making the same assumption as above that the line-level and DSP aspects of the amp are linear (enough) then I would say that most non-linearity with volume comes from the power stage and especially the speakers themselves.

While I agree that such non-linearity might introduce a tonal difference between the speakers if their channels have different sensitivities, that's really no different from the effect of the HU fader control, and I would hope it's very minor, especially, as you say, for those (like me) who don't really care about rear sound.

Originally Posted by Viffermike

Oh yes I do ... but that doesn't mean I'm not tempted. It's just at this point if I order one, I'd be afraid that it'd be a bomb instead of an amp!

LOL