Mic volume slider doesn't work if ACC is selected as the Mic input.

Mark K1LSB

The ACC port on the rear panel (specifically  pin #1, the Line In tap) is the only option available on a 6300 to capture the Line Out audio coming from the mic preamp I'm using to power my AT2035 condenser mic.

However, the Mic volume slider in SSDR v2.1.33 has no effect if ACC is selected as the audio source.

Why is that?  The slider works if either Mic or PC are selected, but not ACC.

Thanks,

Mark  K1LSB

Buford, W4HVW

If its like other radios this is a one volt output not controlled by  the radios volume control.

Mark K1LSB

It's not an output, it's a Line In.  My computer has a volume slider on its Line In, why doesn't the 6300?  The Line In should be considered as  just another audio input to the 6300, and should have all of the audio adjustments (EQ, PROC, etc.) available to it.  In fact, the EQ and PROC are available, just not the volume slider.

Bob - W7KWS -

That's what makes horse races, difference of opinion. Line-In was a "fixed" input on many devices. Then computers came along and went the other way but what "should be" is a matter of opinion and ultimately up to the designer. As you can see at the link below, the guidelines are wide open.

https://www.bing.com/search?q=%22line...

Tim - W4TME

This works as designed.  The ACC line in gain (volume) is fixed at line level intentionally so that the output device can adjust to a fixed level.  Two variable always make for a more complex problem.

Bob - W7KWS -

Tim, This thread reminds me of somithing I forgot to ask earlier. I found that pin 5 on my 6300 ACC connector is grounded and is not Line-Out as shown in the latest manual download.

Is this a change from my early 6300 or a short in my radio?

Thanks!

Mark K1LSB

Tim,

Then the operation of the RX EQ is not consistent with that logic, as I can easily boost the mic audio to an unacceptably high level using only the RX EQ, thereby creating a need to reduce the overall strength of the audio prior to transmitting, to avoid IM distortion.  That's normally done with the Mic Volume slider, at least in the case where MIC or PC are selected as the audio source.  But if ACC is selected I have no way to reduce the audio prior to transmitting (after applying TX EQ) unless I physically reach over to my mic preamp and turn down its output, which shouldn't be required.   If I can increase (or decrease) any portion of the AF spectrum with the TX EQ, then necessity dictates that I should also have the ability to adjust the final strength of the audio, prior to transmit, from within SSDR.

Michael Coslo

If I'm going to run a line in, I'm going to do the audio massaging before I'm at line levels. So I don't want to have multiple adjustment points like Tim noted. Normal  mic inputs, normal adjustments. Line inputs to me indicate a finished equalized signal, not one that needs further adjustments. 

Mark K1LSB

Michael,

You've sure got a lot of presumptions there.

Firstly, you presume that everyone else has your same druthers, and operates the same way you do.  They (and I) don't.

Secondly, you presume that line inputs indicate a finished audio product.  Why do you make such presumptions about my mic audio signal, simply because of which Flex input port I'm using?

Thirdly, if as you say, there shouldn't be any adjustments necessary on the Line In audio stream, then why does the SSDR make the TX EQ available to that stream (but not the Mic Volume slider)?

Fourthly, you presume that just because you don't need or want any internal adjustability on your Line In audio, that no one else should either.  I'll not bother replying to that, as I don't care to waste time on such arguments.

Tim's statement that "multiple variables always make for more complexity" doesn't wash in this case, as he (or rather, Flex) gives me sufficient credit to know what I'm doing such that they have no problem giving me control over a multi-band TX EQ, but he (Flex) doesn't think I'm competent to operate a volume slider.  Give me a break!

Tim - W4TME

It has nothing to do with whether or not you are competent or not.  The ACC connector input is intended to be used with outboard audio devices like voice keyers or modems (PACTOR, TNC, etc) and that is how we engineered it.  We decided to fix the master volume of the input so that it was at line level.  Depending on the mode you are using, some of the downstream DSP processing may or may not be enabled so you still have to perform gain management of the audio signal path if you use those capabilities. 

If you are wanting to feed audio into the radio from a mic preamp, I recommend that you use the pseudo balanced input on the 8-pin Foster connector rather than the unbalanced line in because I assume the output of the mic preamp is balanced.  Turn off the Mic preamp and you may need an isolation transformer (like the W2IHY iBox) on the input of the radio to electrically isolate the radio from the rest of the audio processing gear to prevent ground loops.

Mark K1LSB

Tim,

Thank you for the reply.  I do value your posts, and have Liked your posts in the past.

1)  If any downstream DSP processing is enabled, then gain control is prima facie required (as you concede) and so should be enabled via the volume slider.  To permit any processing at all and yet deny gain control is operationally unjustifiable.

2)  I will consider your suggestion regarding feeding the Foster port with a W2IHY iBox, if I can sell the added cost (plus custom cabling) to Miss Moneypenny. 

3)  I don't understand why you said to "turn off the mic preamp", as the mic needs the preamp's 48V phantom supply to work at all (and there's no on/off switch on the preamp anyway).

Tim - W4TME

#3 - turn off the mic preamp in SmartSDR.  You do not need the extra analog gain added to the signal path because it is being provided by your external mic preamp.

Mark K1LSB

Got it, thanks.

Cecil- W4CM