BillFitzmaurice.info

Tom Smit wrote:
+1 that's what Bill has been suggesting for yeeaaaarrrsss.

And should be one of the sayings of the forum IMO . Also just did some more testing with the onboard EQ and band-pass gain almost as high as it can go and found the limiter lets even more peak voltage through with that setup. The 61volt peak @-3dB limit might get closer to explaining blown 3015lf driver's

Could you also test with adding the "sub synth" engaged? I have a feeling that will also push the voltage higher.

DJPhatman wrote:Could you also test with adding the "sub synth" engaged? I have a feeling that will also push the voltage higher.

I'll test it as soon as I get the multimeter back, I can say that the sub synth causes approximately twice the amount of excursion on my monitors at home when set to +15dB, but it will be interesting to see if the onboard limiter can keep being pushed to higher voltages with more DSP settings adding gain to the signal

DJ Terrabass wrote:I'll test it as soon as I get the multimeter back, I can say that the sub synth causes approximately twice the amount of excursion on my monitors at home when set to +15dB, but it will be interesting to see if the onboard limiter can keep being pushed to higher voltages with more DSP settings adding gain to the signal

Exactly my thoughts. I don't have access to my XTi amps, as they are buried in winter storage. I know they will cause over-excursion in cabs not meant to reproduce sub bass, and I have tried it outdoors with my T39s, but I didn't like the sound of it. Just sounded phony to me. After hearing the T39s, everything else sounds "off". I am so spoiled!

DJ Terrabass wrote:
I'll test it as soon as I get the multimeter back, I can say that the sub synth causes approximately twice the amount of excursion on my monitors

The only thing 'sub synths' are good for is blowing drivers. Don't use it.

Bill Fitzmaurice wrote:

DJ Terrabass wrote:
I'll test it as soon as I get the multimeter back, I can say that the sub synth causes approximately twice the amount of excursion on my monitors

The only thing 'sub synths' are good for is blowing drivers. Don't use it.

And, you know, some people just have to do things "Their way"



because they can. My curiosity ends at whether the limiters squash the spikes from the built in sub synth or not. Purely a learning cycle. I am a prolific pooh-pooh-er of "sound enhancers" other than a quality EQ or DSP. Since DJ Terrabass is going to do the test anyways, I'm curious about the reliability of the limiter. I wonder if there is a way to use an oscilloscope at the outputs, I would love to know what the bass synth actually introduces into the signal. What would be the proper way to test the output signal?

DJPhatman wrote:

DJ Terrabass wrote:I'll test it as soon as I get the multimeter back, I can say that the sub synth causes approximately twice the amount of excursion on my monitors at home when set to +15dB, but it will be interesting to see if the onboard limiter can keep being pushed to higher voltages with more DSP settings adding gain to the signal

Exactly my thoughts. I don't have access to my XTi amps, as they are buried in winter storage. I know they will cause over-excursion in cabs not meant to reproduce sub bass, and I have tried it outdoors with my T39s, but I didn't like the sound of it. Just sounded phony to me. After hearing the T39s, everything else sounds "off". I am so spoiled!

As long as your HPF and limiters are after the the "sub synth" or whatever, it would work fine and not cause any more excursion than normal since the max voltage is set by the limiter and the HPF kills anything below that frequency anyway. This is only assuming you are using them though. It probably won't sound good to have the sub synth squashed by the limiter though.

I too like the natural sound of the T39 without eq or synth, just only limiting and a crossover.

The real question here is why are your xti amps in winter storage? I would have those ready and willing to be test subjects

DJ Terrabass wrote: And should be one of the sayings of the forum IMO . Also just did some more testing with the onboard EQ and band-pass gain almost as high as it can go and found the limiter lets even more peak voltage through with that setup. The 61volt peak @-3dB limit might get closer to explaining blown 3015lf driver's

If its letting through more voltage its either not a real limiter or its in the wrong place in the signal chain.

ryan222h wrote:As long as your HPF and limiters are after the the "sub synth" or whatever, it would work fine and not cause any more excursion than normal since the max voltage is set by the limiter and the HPF kills anything below that frequency anyway.

This is why I want to know. DJ Terrabass has already shown that the limiter does NOT provide brick-wall limiting. I would like to know what else effects the limiter.

ryan222h wrote:The real question here is why are your xti amps in winter storage? I would have those ready and willing to be test subjects

Because they haven't been used in over 2 years due to my poor health. I am currently unable to gig, so all my audio equipement is in storage.

ryan222h wrote:If its letting through more voltage its ... or its in the wrong place in the signal chain.

DING, DING, DING! We 'ave a winna!!

Just tested with the Xti2000's limiter set to -3dB and there wasn't any noticeable increase in voltage using the subsynth gen until about +5dB. The +15dB setting raised the peak voltages to just under 64V max, so I think if every stage in the signal chain used maximum possible gain, the voltages could reach ~65V Max

DJ Terrabass wrote:Just tested with the Xti2000's limiter set to -3dB and there wasn't any noticeable increase in voltage using the subsynth gen until about +5dB. The +15dB setting raised the peak voltages to just under 64V max, so I think if every stage in the signal chain used maximum possible gain, the voltages could reach ~65V Max

What about changing the limiter settings? Were the input gains wide open, and the input signal just below clipping? This is great information, DJ Terrabass! Thanks for doing and posting your experiment.

DJPhatman wrote: What about changing the limiter settings? Were the input gains wide open, and the input signal just below clipping? This is great information, DJ Terrabass! Thanks for doing and posting your experiment.

Hi again

Just finished testing the sub-synth generator @+15dB with the -6dB and -12dB limiter settings, the results from the -6dB setting are 48V peaks and the -12dB just under 35V peaks.

The signal chain details are as follows: 'Foobar2000' audio file player on the PC, running as much gain as possible before clipping, which is approx +2dB hotter than the line-level signal Windows Media Player provides before clipping (I think Foobar does this by ducking the level of lower volume frequencies to provide more headroom for higher volume frequencies, providing the +1 or 2dB gain before clipping.) The signal from foobar is then run straight into the Crown XTi2000 amplifier, which has +10dB gain from the on-board EQ, +15dB gain from the crossover gain and +15dB from the sub-synth generator. This represents a signal chain that I think would be at a higher gain setting than what most users would use, since there is not really any more gain possible in the signal chain unless a mixer is added in.
Will also be interested to see how the new limiters on the Xti2002 compare with the legacy XTi series limiter if I get my hands on one at some stage

Thanks for doing all this. It fills in gaps in the knowledge.

Can I trouble you to measure the output volts from your sources as well please?

Reason I ask is various dj mixers clip and redline higher than 1.4v zero dB. I trust you are using sinewave signal?

DJ Terrabass wrote:

DJPhatman wrote:
Will also be interested to see how the new limiters on the Xti2002 compare with the legacy XTi series limiter

the 2002 series limits via voltage.

netwerks wrote:

DJ Terrabass wrote:

DJPhatman wrote:
Will also be interested to see how the new limiters on the Xti2002 compare with the legacy XTi series limiter

the 2002 series limits via voltage.

They all limit via voltage, but I understand that you can select the voltage on the XTi xx02 models. But, do they limit before or after all the EQ, Synthbass, etc. Seeing as the legacy XTi is after the limiter, it's reasonable to expect the new model will work the same way.

There is no block diagram on the Xti2 manual
but if the follow the setup diagram listed on page 10 the limiters are the last in the chain
assuming the block diagram is the same as the setup layout

http://www.crownaudio.com/media/pdf/amps/143060.pdf