Ok, I misunderstood the schematic and confused bias with overall output.
So if I want to reduce gain, I think I increase the size of the resistors at r39/40, right?
Can someone help me to understand how to calculate what those should/could be? I’ve been reading up on voltage dividers to learn more, but I think I’m missing the input voltage to the pot to make a calculation.
Many thanks. Any help is appreciated.
So if I want to reduce gain, I think I increase the size of the resistors at r39/40, right?
Can someone help me to understand how to calculate what those should/could be? I’ve been reading up on voltage dividers to learn more, but I think I’m missing the input voltage to the pot to make a calculation.
Many thanks. Any help is appreciated.
Should be getting all my parts tomorrow. But..
4304.6090 Schurter | Mouser
Does this not include the fuse? I didn't order one. Arg. Maybe I can use a penny?
4304.6090 Schurter | Mouser
Does this not include the fuse? I didn't order one. Arg. Maybe I can use a penny?
Okay, this may be a silly question.
I'm using my Logitech transporter as a DAC and preamp. RCA connectors then go to the amp section of my Sony ta 4650. Can I just connect the headphone amp in series between the transporter and the Sony? I'm putting in two pairs of RCA connectors on the whammy.
I'm using my Logitech transporter as a DAC and preamp. RCA connectors then go to the amp section of my Sony ta 4650. Can I just connect the headphone amp in series between the transporter and the Sony? I'm putting in two pairs of RCA connectors on the whammy.
Well, now it has been repeatedly stated that, in order to get RCA outputs, it's best to have 25 to 100 Ohm resistors between the switched headphone jack and the outputs.
I have not yet done so (this was not as clear when I built my kit). I have it straight to the ACA inputs. I have not noticed or heard any oscillations: is there a way I could know or measure such oscillations? If I can't hear any clear issues, could there be really high frequency oscillations that are beyond hearing ranges that are harmful?
So, basic question: would it merit to take things apart and solder those resistors or, if things are sounding good, am I ok leaving the output with a much lower impedance?
Thanks as always (really enjoying the Whammy!)
Rafa.
I have not yet done so (this was not as clear when I built my kit). I have it straight to the ACA inputs. I have not noticed or heard any oscillations: is there a way I could know or measure such oscillations? If I can't hear any clear issues, could there be really high frequency oscillations that are beyond hearing ranges that are harmful?
So, basic question: would it merit to take things apart and solder those resistors or, if things are sounding good, am I ok leaving the output with a much lower impedance?
Thanks as always (really enjoying the Whammy!)
Rafa.
There is an expectation that the line out will be relatively high impedance. It probably won't cause problems, though, simply supply more current than is necessary
Where you could run into problems is if the line out is too hot, which is more likely to cause problems. Too hot could cause clipping.
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Well, another WHAMMY has become a WHAMMM. It took most of the day, but I'm happy with the results. It's dead silent even at full volume (oh, wait, it was off...that's better. No, still silent). The biggest change to the music is that the bass is much, much more defined. Before there was often a bass-cloud that bled into everything. Now the bass is tighter, and you get more of a sense of an instrument playing it. I think there is also more dynamics overall, but I need time to listen more.
Thanks, Wayne, and everyone here who chipped in with ideas.
Gotta go listen to music...
An externally hosted image should be here but it was not working when we last tested it.
Thanks, Wayne, and everyone here who chipped in with ideas.
Gotta go listen to music...
Hmm...if I'm checking the DC offset right--measuring right/left headphone terminals and headphone ground, then I'm getting 23mV. That's high, right? Is there something I can do about that?
Also, checking the input the same way I got 0mV. Assuming I'm doing it correctly, does that mean that I could take out C1 and C5? Wouldn't that clean up the signal path a bit?
I'm worried about that 23 mV.
Also, checking the input the same way I got 0mV. Assuming I'm doing it correctly, does that mean that I could take out C1 and C5? Wouldn't that clean up the signal path a bit?
I'm worried about that 23 mV.
Don't be.
Assuming you had really low resistance headphones like my Denons at 25ohm, your 0.023v of a volt will give a standing DC current of 0.00092A (0.92 milliamp), loading your headphones with a dissipation of 0.00002W
(Go back and count the zeroes after the decimals)
With higher impedance, there's even less to worry about.