DSP1124P performance???

[vince]

O.K. not to ask the same question over again, but I have just finished my electronic x-over prodject and was wondering if one did not require a x-over, or many many filters, is there a problem using the 1124 for full range EQing? Already have one unit on sub and center, and it has made a great difference! I was thinking of putting one on the surrounds and mains now that "all speakers" in system is electroniclly crossed over.. I don't really feel that I need more than 12 filters per channel, so is there a problem with using this unit as oppossed to other Behringer units??? Sorry if it seems I am asking the same question as before. It just seems some people say go with this unit because it has better specs. Not being smart, but like what in particular? just numbers of filters perhaps?, noise?,what?
Thanks,
Vince Dallaire

[brucek]

is there a problem using the 1124 for full range EQing?

I suppose it comes down to the quality of your system. I know I tested the unit on my mains for fun one day and it was quite poor. The best way to test this is to insert the BFD between the preamp and amplifier on one channel. This would allow you to listen to a channel without the unit and another with the unit. For myself, the noise floor was so high, I find it hard to believe anyone uses this for anything but the subwoofer channel.

The spec shows a 94dB noise figure with crosstalk of 76dB. Not too good compared to many systems today.

I would look to a higher quality device for my full range mains duty..

brucek

[vince]

Thanks for the reply. I have noticed that when my system is off, 1124 on, amp in stand by mode, there is a strange sound coming from the center channel. I have spoke of this before on this forum. when I have time I was going to try and eliminate the noise, it of course is not audible when content is playing only when system is quite. I guess I will look for a parametric EQ more geared to home listening enviroments, "not so pro use". And as you said, on sub use this seems to be just fine!
Thanks,
Vince

[Wayne A. Pflughaupt]

brucek wrote:

I suppose it comes down to the quality of your system. I know I tested the unit on my mains for fun one day and it was quite poor. The best way to test this is to insert the BFD between the preamp and amplifier on one channel. This would allow you to listen to a channel without the unit and another with the unit. For myself, the noise floor was so high, I find it hard to believe anyone uses this for anything but the subwoofer channel.

The spec shows a 94dB noise figure with crosstalk of 76dB. Not too good compared to many systems today.

The 1124’s 94 dB S/N spec is an unweighted figure, while most receivers use an A-weighted figure in the 100 dB range. For more of an “apples to apples” comparison you can subtract ~10 dB from an A-weighted figure, which puts the BFD comparable or a little better than the average receiver in the noise floor department (excluding Bryston gear, which has specs far surpassing the average receiver ).

That said, if you were able to audibly hear the noise floor, that suggests the BFD’s stated spec is highly optimistic...

Regards,
Wayne

[Ilkka]

brucek wrote:

I suppose it comes down to the quality of your system. I know I tested the unit on my mains for fun one day and it was quite poor. The best way to test this is to insert the BFD between the preamp and amplifier on one channel. This would allow you to listen to a channel without the unit and another with the unit. For myself, the noise floor was so high, I find it hard to believe anyone uses this for anything but the subwoofer channel.

The spec shows a 94dB noise figure with crosstalk of 76dB. Not too good compared to many systems today.

I would look to a higher quality device for my full range mains duty..

brucek

I doubt it was the actual "noise floor" you were hearing. Did you try to lift the ground? Usually most Behringer units give all sorts of hums and hisses unless the ground is lifted. I run my LCR+sub(s) channels through the DCX2496 and I can't hear the noise floor (hiss) unless I put my ear less than ~10" from the tweeter.

[brucek]

I run my LCR+sub(s) channels through the DCX2496 and I can't hear the noise

hehehe, and well you shouldn't hear any noise. Have you looked at the specs of the DCX2496. The 1124P isn't even in the same league.

brucek

[Ilkka]

brucek wrote:

hehehe, and well you shouldn't hear any noise. Have you looked at the specs of the DCX2496. The 1124P isn't even in the same league.

brucek

What do you mean? Both input/output noise levels are -90 dBu for the DCX2496. Only at +22 dBu input signal it lowers to 112 dB, but I'm not using that kind of levels. I'm driving it with a consumer level signal.

[brucek]

What do you mean? Both input/output noise levels are -90 dBu for the DCX2496. Only at +22 dBu input signal it lowers to 112 dB, but I'm not using that kind of levels. I'm driving it with a consumer level signal.

No, the noise spec for the DCX is stated as a value with a derived reference. It's a rather nice way of providing both the actual noise floor and (the classic spec) signal to noise ratio in one statement. Stated as -90dBu (@+22dBu>112dB)

The spec says -90dBu as a noise floor value, which calculates to a noise floor of ~24.5 uvoltsRMS (0.775 antilog(-90/20).

This value of noise floor is then referenced to a maximum input level of +22dBu (which calculates to ~9.75 voltsRMS).

The ratio (derived in decibels) between 24.7uvRMS and 9.75vRMS calculates to -112dB = [(20log (.0000247/9.75)]. That's one nice piece of equipment for the price. The clue that it's good is in the THD+N ratio.

On the other hand, the 1124 offers its noise spec in the classic dB down format of decibel only at -94dB. Not too good.

brucek

Holy smokes do I feel ignorant...........



I'm actually looking into getting a BFD of some type....looks like I have alot of reading to do here.

[Wayne A. Pflughaupt]

brucek wrote:

No, the noise spec for the DCX is stated as a value with a derived reference. It's a rather nice way of providing both the actual noise floor and (the classic spec) signal to noise ratio in one statement. Stated as -90dBu (@+22dBu>112dB)

On the other hand, the 1124 offers its noise spec in the classic dB down format of decibel only at -94dB. Not too good.

Since Behringer uses different methods for stating S/N for the 1124 and 2496, it’s difficult to make a meaningful comparison between the two. According to Rane's Audio Specifications guide, a S/N spec should include measurement bandwidth, any weighting filters and the reference signal level. The 1124 spec does not include the reference level info.

Rane also suggests that using a high input signal as a reference for a S/N spec, like the DCX2496 does, instead of a more standard +4 dBu reference, can make a noise spec look better than it really is:

“...if one product references S/N to their maximum output level of, say, +20 dBu, and another product has the same stated 90 dB S/N, but their reference level is + 4 dBu, then the second product is, in fact, 16 dB quieter.”

A couple of lines above the input/output noise spec, the 2496 manual notes a (unqualified) dynamic range spec of 109 dB. The 1124 doesn’t show a dynamic range spec, but its maximum input/out spec references +16 dBu at a +4 dB nominal level (probably a typo that it wasn’t given as +4 dBu), suggests a dynamic range of 110 dB.

Which only goes to show, comparing specs between two pieces of gear can be tricky.

Regards,
Wayne

[Ilkka]

brucek wrote:

No, the noise spec for the DCX is stated as a value with a derived reference. It's a rather nice way of providing both the actual noise floor and (the classic spec) signal to noise ratio in one statement. Stated as -90dBu (@+22dBu>112dB)

The spec says -90dBu as a noise floor value, which calculates to a noise floor of ~24.5 uvoltsRMS (0.775 antilog(-90/20).

This value of noise floor is then referenced to a maximum input level of +22dBu (which calculates to ~9.75 voltsRMS).

The ratio (derived in decibels) between 24.7uvRMS and 9.75vRMS calculates to -112dB = [(20log (.0000247/9.75)]. That's one nice piece of equipment for the price. The clue that it's good is in the THD+N ratio.

On the other hand, the 1124 offers its noise spec in the classic dB down format of decibel only at -94dB. Not too good.

brucek

Yeah but doesn't that mean that unless one uses a very high signal level like 22 dBu, one won't get 112 dB S/N ratio? So in fact they do have very similar specs.

I'm still saying that one should be able to use the BFD for mains too. If you're hearing some noise, it's not the actual noise level that you are hearing.

[brucek]

Yeah but doesn't that mean that unless one uses a very high signal level like 22 dBu, one won't get 112 dB S/N ratio? So in fact they do have very similar specs.

No, they don't really have similar specs. Unless specified otherwise, as you point out, most noise figures are calculated against a maximum input level, in an attempt to shed the nicest light on the product.

The DCX noise spec calculates to a noise voltage level of 24.5 uvoltsRMS with a noise figure of -112dB using a maximum input level of +22dBu.
Now examine the 1124 noise spec of 94dB. We can assume they used maximum input level to obtain the best figure here. The maximum input level of the 1124 is +16dBu (~4.9vRMS). Calculating 94dB noise results in a noise voltage level of ~100uvoltsRMS. This is over 4 times higher noise than the DCX. I can't really say the units are similar. Believe me (or not), I can hear that noise floor in my system in the form of hisssssssssssssssssssss.

The reasonable assumption that the 94dB noise figure was taken at maximum input level also sheds light on the fact that the dynamic range then cannot be over 94dB. That's a bit over 15 bits of resolution. Not bad, but not great. A lot of bits are hidden in the noise. If a 24 bit A/D convertor is used with a +16dBu input level, then the LSB voltage is about (0.826 uvolts pk.pk). So there is a lot of signal lost in that ~100 uvoltsRMS noise.

brucek