#### Voltage at volume control of bitx40??

John Cardoso

Hi folks
Would a kind soul tell me, please, what is/are the peak-to-peak voltage/s I should expect at the high terminal of the bitx40's volume control.
Sorry, but I do not have a way to measure it. :(
Thanks
-John-

Curt

John

I think you are asking how high is the sky. It depends how strong the signal received is as there is no agc. The rig is not known for robust audio. Start with headphones.  some folk use amplified external speakers or add an audio power amplifier.

Curt

John Cardoso

Thanks Curt, I kinda left it undefined by asking for "voltage/s" but I should have added for an "average/comfortable listening volume". (May be? )
It's a toughie I know but I am still curious...
I'll take the sky height, tough. :)
Take care.

 Virus-free. www.avast.com

On Fri, Jul 19, 2019 at 9:27 PM Curt via Groups.Io <wb8yyy=yahoo.com@groups.io> wrote:
John

I think you are asking how high is the sky. It depends how strong the signal received is as there is no agc. The rig is not known for robust audio. Start with headphones.  some folk use amplified external speakers or add an audio power amplifier.

Curt

Hi John,

The lm386 often states a common output power of 125mW.  This is actually a pretty strong volume level, but looking at it will give you an idea of what type of voltage you may see.  Po = V^2/R so 0.125W = V^2/8ohms so V^2 = 1 and V=1  This is an RMS value so peak would be 1.4V and peak to peak 2.8V.

Recall though that we need a doubling or halving of power to notice a  difference in volume, so you could actually be seeing voltages much less than this.

73,

Mark.

Don, ND6T

John,

In the vicinity of 10 millivolts for a readable signal at moderate volume. Consider it comparable to "line" levels for your stereo amplifier. 73, Don

Jim Sky

On 7/20/2019 3:25 AM, Mark - N7EKU wrote:
Recall though that we need a doubling or halving of power to notice a  difference in volume, so you could actually be seeing voltages much less than this.

Mark, I don't think that is correct. I believe 1 dB is discernible to most listeners.

73s
Jim

It was just from early morning memory,

But as a reference I quickly saw this:

https://www.abdengineering.com/blog/perception-vs-reality/

They confirm a doubling/halving needed.

But I found a test site too:

https://www.audiocheck.net/blindtests_index.php

And for me, a 1dB difference was reliably detectable, so I would go by the 1dB figure if their recordings were correct (dB and not dBV or dBA).  Anyway, mainly I meant that one can hear power levels at the speaker a lot less than 125mW.  Of course it all depends too on background noise in the room environment, the speaker, etc. as  125mW in a  car going down the road won't get you far!

And if you want to get depressed (or impressed) by how much hearing loss you have or don't have:

https://www.audiocheck.net/audiotests_frequencycheckhigh.php

73,

Mark.

Jim Sky

Hi Mark,

Thanks for digging into that minimal detectable increase question.

And yes on the frequency response of the ear, I may have sacrificed a few octaves to 60s music.

73s
Jim

On 7/20/2019 7:16 PM, Mark - N7EKU wrote:

It was just from early morning memory,

But as a reference I quickly saw this:

https://www.abdengineering.com/blog/perception-vs-reality/

They confirm a doubling/halving needed.

But I found a test site too:

https://www.audiocheck.net/blindtests_index.php

And for me, a 1dB difference was reliably detectable, so I would go by the 1dB figure if their recordings were correct (dB and not dBV or dBA).  Anyway, mainly I meant that one can hear power levels at the speaker a lot less than 125mW.  Of course it all depends too on background noise in the room environment, the speaker, etc. as  125mW in a  car going down the road won't get you far!

And if you want to get depressed (or impressed) by how much hearing loss you have or don't have:

https://www.audiocheck.net/audiotests_frequencycheckhigh.php

73,

Mark.