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Topic: Resistors In-Line: What Are The Effects? (Read 2905 times) previous topic - next topic
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Resistors In-Line: What Are The Effects?

My PC Audio setup has been driving me crazy for months. Here's how it goes:
DAC-> Fiio K5-> Line Out to Klipsch Promedia 2.1 speakers

The problem is, in short, that an appropriate signal volume for the K5 is much louder than for the Klipsch. I had a compromise in which I was using the highest gain setting on the K5 and the bottom quarter of the Klipsch's volume control. I ordered a simple 3.5mm volume control to put in-line between the K5 and the Klipsch, but that broke literally within 24 hours. I didn't want to order another one, so last night I got frustrated and wired up a 3.5mm cable with a 4.6k resistor on each channel.

I've certainly resolved the problem, but now I'm feeling like highs are rolled off. This could be because I'm using a different range of the amp, or it could be psychology, or it could be because I've jacked up the resistance of the wire without creating a true voltage divider (which would be more complex to wire reliably and in a small space). Since I can't measure anything, I was wondering what the theoretical effects of my neanderthal solution are.

Thanks
nintendoeats

Re: Resistors In-Line: What Are The Effects?

Reply #1 –
Are you using the fiio as the DAC?

Re: Resistors In-Line: What Are The Effects?

Reply #3 –
It's unlikely that your getting high-frequency roll-off but it's theoretically possible that there's a parallel capacitor across the input and you're making a low-pass filter.

But if there  is a capacitor, it's probably a small-value capacitor and a 4.7K resistor probably wouldn't make a filter in the audio range.

Re: Resistors In-Line: What Are The Effects?

Reply #4 –
Interesting, I wasn't even thinking about what might be directly on the other end. In any case my suspicion of psychological skullduggery is strengthened, thanks.

Re: Resistors In-Line: What Are The Effects?

Reply #5 –
Quote from: nintendoeats on
My PC Audio setup has been driving me crazy for months. Here's how it goes:
DAC-> Fiio K5-> Line Out to Klipsch Promedia 2.1 speakers

The problem is, in short, that an appropriate signal volume for the K5 is much louder than for the Klipsch. I had a compromise in which I was using the highest gain setting on the K5 and the bottom quarter of the Klipsch's volume control. I ordered a simple 3.5mm volume control to put in-line between the K5 and the Klipsch, but that broke literally within 24 hours. I didn't want to order another one, so last night I got frustrated and wired up a 3.5mm cable with a 4.6k resistor on each channel.

I've certainly resolved the problem, but now I'm feeling like highs are rolled off. This could be because I'm using a different range of the amp, or it could be psychology, or it could be because I've jacked up the resistance of the wire without creating a true voltage divider (which would be more complex to wire reliably and in a small space). Since I can't measure anything, I was wondering what the theoretical effects of my neanderthal solution are.

First thing to do is to fix your absence of measurement gear. I know that one of the laws of audiophilia is to spend zillions of dollars on audio gear, but never spend a penny on test gear, but many should just set their minds of growing past that.

For example, if you are working with headphone amps and the like, it is likely that  the signal levels won't be troublesome for the inputs of many audio interfaces.  To conduct a reliable measurement only about 40 dB of dynamic range at the measurement's signal level is requried.  It is likely that if you loop back the analog output of your DAC into your computer's audio interface's line level input, that you will be able to set levels for a reliable measurement. If your computer lacks a line level input, a $30 Behrning UCA 202 will address that need.

As I understand it, you've set up a series volage divider with the 4.6 K resistor and the input impedance of your amplfier. The input impedance of your amplifier is probably in the range of 5,000 to 10,000 ohms, which means that the source impedance of your voltage divider is on the order of 2-3 K.  It might act like a low pass filter as DVD Doug advises, the only real question whether the corner frequency of that  low pass filter is audible. 

One of the well known effects of reducing volume is decreased audibility of high frequencies so it is likely (but not certain) that this is what you are hearing, in which case the voltage divider is OK, and you need to address any reservations you have with sound quality elsewhere. If the sound source is a modern  Windows PC then the freeware Peace UI for the equalizer that is built into your PC's sound system (but usuall hidden( is probably the tool of choice.

Re: Resistors In-Line: What Are The Effects?

Reply #6 –
Thank you for the in-depth response Arnold. I do occasionally think that it would be interesting to invest in some test gear, but I don't see much point until I'm fiddling with room acoustics (not something you can do meaningfully with no budget in a tiny apartment that you rent). That said, in this case I could probably wire it into my Scarlette 2i2 and work this out. Perhaps I might.

I should be clear though, I am not actually listening at a reduced volume. The point is that I need a quieter signal going into the speaker amp , but a louder one into the K5. Otherwise I am cranking the K5 all the way and using the very bottom of the dial on the speaker pre-amp.