John Curl's Blowtorch preamplifier part II - Page 547

john curl · 5th August 2010, 01:48 AM

Anyone else who has worked with Vu meters.

johnferrier · 02:57 AM

I use SPL meters in an attempt to set playback levels to record levels. As I understand them, VU meters measure decibels of the electrical signals (post electro-mechanical transducer in the case of recording, and pre, in the case of playback). VU meters are an aid to adjust record levels to prevent clipping (distortion).

-

Using time-averaged levels, I'd like to find a means to correlate VU readings (or the like) to SPL readings. Of course, transducer response and room acoustics are large factors.

.

johnferrier · 03:04 AM

The Blowtorch does not have a power switch to avoid using signal switch/relay contacts for power on mute?

.

Melon Head · 5th August 2010, 03:46 AM

Hi John
I think I understand what you are implying here with your your Vu meter analogy and I agree with it entirely based on what I read at the TNT website.

However I have some experience with dither that is used in controlling servo-hydraulic machines for fatigue testing of materials. In this application it has the complete opposite effect. I wish I knew (it looks like I have something to read about now) exactly what the dither is doing to improve the response of the machine so I could comment further. However I could probably post some pictures to demonstrate how it improves the response. I don't know if this could be applied to audio in the same way it used in the servo hydraulic machine, but if it can, it definitely is worth looking into.

Steve Eddy · 5th August 2010, 05:12 AM

Quote:

Originally Posted by thanh1973

Hi John
I think I understand what you are implying here with your your Vu meter analogy and I agree with it entirely based on what I read at the TNT website.

What VU meter analogy was that? I don't see where John made any sort of analogy to a VU meter.

I made an impromptu "cognitive dissonance" meter in response to one of SY's posts and then John asked if anyone had ever seen or used a VU meter.

Where exactly was the analogy?

se

Melon Head · 05:45 AM

I read his mind. He hasn't shared the analogy yet.
I could be way off track with what he is trying to say here.

john curl · 5th August 2010, 05:42 AM

Well, I noted that a continuous +3 on a Vu meter shows somebody not knowing how to make a proper recording. It looked silly to me, even though it meant something else. Nothing really hidden or that important.

Steve Eddy · 5th August 2010, 05:52 AM

Quote:

Originally Posted by thanh1973

I read his mind. He hasn't shared the analogy yet.
I could be way off track with what he is trying to say here.

I haven't seen any evidence that he's trying to say anything with regard to VU meters.

What TNT article are you referring to?

se

Melon Head · 5th August 2010, 08:15 AM

Dither article
That Dither Thing - [English]

Yes it works well if the intended signal is a sine wave.
What if the intended signal was a stepped sine wave as pictured would it still smooth the signal to a sine wave

Werner · 5th August 2010, 08:28 AM

It works with her voice, too.

I can testify that said voice, while sinuous, is not a sine.

5th August 2010, 02:44 AM	#5462
johnferrier diyAudio Member Join Date: Sep 2003 Location: WA	I use SPL meters in an attempt to set playback levels to record levels. As I understand them, VU meters measure decibels of the electrical signals (post electro-mechanical transducer in the case of recording, and pre, in the case of playback). VU meters are an aid to adjust record levels to prevent clipping (distortion). - Using time-averaged levels, I'd like to find a means to correlate VU readings (or the like) to SPL readings. Of course, transducer response and room acoustics are large factors. . __________________ Michael Gazzaniga - "The arts are not frosting but baking soda." Last edited by johnferrier; 5th August 2010 at 02:57 AM.

5th August 2010, 03:00 AM	#5463
johnferrier diyAudio Member Join Date: Sep 2003 Location: WA	The Blowtorch does not have a power switch to avoid using signal switch/relay contacts for power on mute? . __________________ Michael Gazzaniga - "The arts are not frosting but baking soda." Last edited by johnferrier; 5th August 2010 at 03:04 AM.

5th August 2010, 05:38 AM	#5466
Melon Head Banned Join Date: Nov 2006	I read his mind. He hasn't shared the analogy yet. I could be way off track with what he is trying to say here. Last edited by Melon Head; 5th August 2010 at 05:45 AM.

5th August 2010, 08:28 AM	#5470
Werner diyAudio Member Join Date: Jan 2002 Location: Belgium	It works with her voice, too. I can testify that said voice, while sinuous, is not a sine. __________________ bring back dynamic range

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5th August 2010, 01:48 AM	#5461
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Anyone else who has worked with Vu meters.

5th August 2010, 03:46 AM	#5464
Melon Head Banned Join Date: Nov 2006	Hi John I think I understand what you are implying here with your your Vu meter analogy and I agree with it entirely based on what I read at the TNT website. However I have some experience with dither that is used in controlling servo-hydraulic machines for fatigue testing of materials. In this application it has the complete opposite effect. I wish I knew (it looks like I have something to read about now) exactly what the dither is doing to improve the response of the machine so I could comment further. However I could probably post some pictures to demonstrate how it improves the response. I don't know if this could be applied to audio in the same way it used in the servo hydraulic machine, but if it can, it definitely is worth looking into.

5th August 2010, 05:42 AM	#5467
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Well, I noted that a continuous +3 on a Vu meter shows somebody not knowing how to make a proper recording. It looked silly to me, even though it meant something else. Nothing really hidden or that important.

5th August 2010, 08:15 AM	#5469
Melon Head Banned Join Date: Nov 2006	Dither article That Dither Thing - [English] Yes it works well if the intended signal is a sine wave. What if the intended signal was a stepped sine wave as pictured would it still smooth the signal to a sine wave

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