Radio Shack analogue SPL meter circuit diagram

EC8010 · 16th May 2006, 08:06 PM

Does anyone have a diagram for the Radio Shack analogue SPL meter? I've done the mods to flatten the electronics but now I want to interpose a (switchable) +40dB low-noise amplifier between the microphone and existing preamplifier so as to be able to use the meter for cheaply comparing environmental noise between locations. It would help if I knew what the existing diagram was...

RogerGustavsson · 16th May 2006, 08:12 PM

You can find one here: http://mysite.verizon.net/tammie_eri...50/rs_spla.gif

EC8010 · 16th May 2006, 08:14 PM

Roger, you are a hero! Thank you. I wasted far longer than the six minutes it took you to respond searching the web for a diagram.

jleaman · 16th May 2006, 08:23 PM

I have one of these that workes 100% BUt the only thing is i dont have the numbers on the knob the sticker fell off s i dont know what each reading is

EC8010 · 16th May 2006, 08:34 PM

The settings are:

OFF
BATT
120dB
110dB
100dB
90dB
80dB
70dB
60dB

I've got to go away and think about it, but it looks rather as if that single stage amplifier could be replaced by a two or three-stage feedback amplifier with a single on/off switch to select the extra +40dB gain.

jleaman · 16th May 2006, 08:35 PM

Quote:

Originally posted by EC8010
The settings are:

OFF
BATT
120dB
110dB
100dB
90dB
80dB
70dB
60dB

Thank's Dood!

anatech · 16th May 2006, 08:37 PM

Hi,
I have one of these meters as well for PA work.

RogerGustavsson, thank you (I saw this by chance).

EC8010, what modification did you do?

-Chris

EC8010 · 16th May 2006, 08:41 PM

The one for flattening the LF and HF response of the electronics. As I've lost my original paperwork for it, I'm guessing that it was the Eric Wallin mods. I also took the capsule out of the horrible lump on the front and machined a proper slim stem for it that mounted on the front.

SY · 16th May 2006, 08:45 PM

This has been a fabulously useful device for me. I have demonstrated with scientific accuracy that I do NOT turn my stereo up to a volume as loud as my wife's TV. Not that she believes the meter, but still, I know I proved a point.

I wonder when I'll be allowed back in the bedroom.

jleaman · 16th May 2006, 08:51 PM

Quote:

Originally posted by SY
This has been a fabulously useful device for me. I have demonstrated with scientific accuracy that I do NOT turn my stereo up to a volume as loud as my wife's TV. Not that she believes the meter, but still, I know I proved a point.

I wonder when I'll be allowed back in the bedroom.

Right after yuo tell her she is right and you are wrong. Might be a long wait

16th May 2006, 08:06 PM	#1
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Radio Shack analogue SPL meter circuit diagram Does anyone have a diagram for the Radio Shack analogue SPL meter? I've done the mods to flatten the electronics but now I want to interpose a (switchable) +40dB low-noise amplifier between the microphone and existing preamplifier so as to be able to use the meter for cheaply comparing environmental noise between locations. It would help if I knew what the existing diagram was... __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

16th May 2006, 08:14 PM	#3
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Roger, you are a hero! Thank you. I wasted far longer than the six minutes it took you to respond searching the web for a diagram. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

16th May 2006, 08:34 PM	#5
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	The settings are: OFF BATT 120dB 110dB 100dB 90dB 80dB 70dB 60dB I've got to go away and think about it, but it looks rather as if that single stage amplifier could be replaced by a two or three-stage feedback amplifier with a single on/off switch to select the extra +40dB gain. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

16th May 2006, 08:41 PM	#8
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	The one for flattening the LF and HF response of the electronics. As I've lost my original paperwork for it, I'm guessing that it was the Eric Wallin mods. I also took the capsule out of the horrible lump on the front and machined a proper slim stem for it that mounted on the front. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

16th May 2006, 08:45 PM	#9
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	This has been a fabulously useful device for me. I have demonstrated with scientific accuracy that I do NOT turn my stereo up to a volume as loud as my wife's TV. Not that she believes the meter, but still, I know I proved a point. I wonder when I'll be allowed back in the bedroom. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache


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16th May 2006, 08:12 PM	#2
RogerGustavsson diyAudio Member Join Date: Aug 2004 Location: Huskvarna	You can find one here: http://mysite.verizon.net/tammie_eri...50/rs_spla.gif

16th May 2006, 08:23 PM	#4
jleaman Banned Join Date: Apr 2002	I have one of these that workes 100% BUt the only thing is i dont have the numbers on the knob the sticker fell off s i dont know what each reading is

16th May 2006, 08:37 PM	#7
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi, I have one of these meters as well for PA work. RogerGustavsson, thank you (I saw this by chance). EC8010, what modification did you do? -Chris

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