Sorry George,
But those won't work. They are log taper pots. You need linear pots.
Terry,
If your PCB is marked v1.2 and not v1.2c you were inadvertently shipped a first generation PCB. I had not intended to do that, but it's no big deal if that is the case. The first PCB had two resistors (R47 & R48) that were decided to not be needed. Other than that the PCBs are identical. The fix is easy. Put a jumper in place of R48R & R48L and don't put anything in the R47R & R47L locations.
The details are shown here ...
You want to end up with only R49R & R49L resistors south of the A8 op amps.
Another one bites the dust
And there I thought I had a solution... so far I have not been able to find a linear version of the quad motorised 10k pot...any suggestions..non-Alps...?
George
And there I thought I had a solution... so far I have not been able to find a linear version of the quad motorised 10k pot...any suggestions..non-Alps...?
George
Moving on .. the 10k pot vs. the 5K pot
Jan Didden was kind enough to put me in touch with Hans Polak, who performed some analysis on the likely results of using a 10K pot instead of a 5K. (Remember, this question arises when trying to include a motorised pot for remote volume control. 5K linear are very hard to find). Hans wrote "Setup for the volume control chosen by DS, magnifies the equivalent noise at the taper of the pot (generated by the op-amps and the volume pot) by a factor 3.
This makes this circuit very sensitive for the value of the pot as far as noise is concerned.
Most noise will be generated with the pot in the middle position, in this position giving the volume-control some -4 dB of gain.
The equivalent noise generated by the op-amps calculated as being completely at the taper of the pot is ca 5,1 nV/rtHz.
When using a 5k pot its equivalent noise at the taper in mid position is 7.1 nV/rtHz, giving an increase in total noise of 4.6 dB.
Now when using a 10K pot instead, its equivalent noise at the taper in the mid position is 10 nV/rtHz, increasing the total noise with 6.8 dB.
So the difference between the two pots in mid position is an increase of 2.2 dB in total noise, not something to become very nervous, and hardly noticeable.
However all stages before the volume-control are also generating noise adding up to this, so in practice when using a 10K pot noise increase will most likely be below a human’s level of discrimination of ca 1.4 dB.
To conclude: using a 10K instead of a 5K stereo pot is not a problem at all, forget about a quad version."
So, this means that any of the 10K-based remote control systems can be considered for inclusion in the build. And with that, I shall return to my bathroom renovation
My thanks to Hans and to Jan for providing this analysis.
George
Jan Didden was kind enough to put me in touch with Hans Polak, who performed some analysis on the likely results of using a 10K pot instead of a 5K. (Remember, this question arises when trying to include a motorised pot for remote volume control. 5K linear are very hard to find). Hans wrote "Setup for the volume control chosen by DS, magnifies the equivalent noise at the taper of the pot (generated by the op-amps and the volume pot) by a factor 3.
This makes this circuit very sensitive for the value of the pot as far as noise is concerned.
Most noise will be generated with the pot in the middle position, in this position giving the volume-control some -4 dB of gain.
The equivalent noise generated by the op-amps calculated as being completely at the taper of the pot is ca 5,1 nV/rtHz.
When using a 5k pot its equivalent noise at the taper in mid position is 7.1 nV/rtHz, giving an increase in total noise of 4.6 dB.
Now when using a 10K pot instead, its equivalent noise at the taper in the mid position is 10 nV/rtHz, increasing the total noise with 6.8 dB.
So the difference between the two pots in mid position is an increase of 2.2 dB in total noise, not something to become very nervous, and hardly noticeable.
However all stages before the volume-control are also generating noise adding up to this, so in practice when using a 10K pot noise increase will most likely be below a human’s level of discrimination of ca 1.4 dB.
To conclude: using a 10K instead of a 5K stereo pot is not a problem at all, forget about a quad version."
So, this means that any of the 10K-based remote control systems can be considered for inclusion in the build. And with that, I shall return to my bathroom renovation
My thanks to Hans and to Jan for providing this analysis.
George
It Sings!! Thank You Carl for putting this together. It sounds Great & i assume it can only get better as the caps wear in.
Now for some kind of cabinet, & more I/O choices.
Rick
Great!
I think you are the first to have completed a build.
Doug Self did a great job. I find the tone controls to be addictive and very listenable. I am curious to hear the thoughts and impressions of others. Congratulations!
It Sings!! Thank You Carl for putting this together. It sounds Great & i assume it can only get better as the caps wear in.
Now for some kind of cabinet, & more I/O choices.
Rick
Great job Rick!
I have my main board populated. As you can see I built most of it from my parts bin and only ordered what I needed so I don't have all those pretty green caps. As soon as the I/O boards arrive I be testing mine too.
Blessings, Terry
Attachments
Carl,
you are correct re: tone controls. Maybe THEY should get Motorized! jumping up & back tweaking them is tiresome. haha
Couple Questions.
PSU heatsinks are 53C for neg & 51C for pos. Neg V=-16.88 and Pos = 16.36 These measurements made while playing over 1.5hrs now. That more or less normal?
Rick
you are correct re: tone controls. Maybe THEY should get Motorized! jumping up & back tweaking them is tiresome. haha
Couple Questions.
PSU heatsinks are 53C for neg & 51C for pos. Neg V=-16.88 and Pos = 16.36 These measurements made while playing over 1.5hrs now. That more or less normal?
Rick
Looking at both Mouser and Digikey, the LM4562NA is really not available in quantity 15
Is the NJM4562 a drop in replacement? They are available at Mouser in the quantity we need.
This part is mentioned earlier in the thread, but it was not crystal clear to me if it is truly "drop in and work"
thanks
Dave
Is the NJM4562 a drop in replacement? They are available at Mouser in the quantity we need.
This part is mentioned earlier in the thread, but it was not crystal clear to me if it is truly "drop in and work"
thanks
Dave
There are a few distributors that seem to have them in stock.
lm4562n Stock and Price by Distributor
lm4562n Stock and Price by Distributor
OK it is singing!
Scared me at first when I didn't have an output. A little searching with the scope probe revealed it was the little relays. I didn't realize I needed to jumper the 12v SW. Once I did that all is well. Kind of fun playing around with the tone controls. I'm not sure about the ref points. Almost seems backward acting but might just be the material I'm listening to. It was a fun project. I will likely fit a chassis for this since I don't need big heatsinks. This is my 5th DIY preamp but the first to have tone controls.
I running it on +-15V right now because my 20V transformer hasn't arrived yet. The little PSU I built is putting out +-15v using a 12.6V-0-12.6v 2A transformer. Working fine from what I can tell so far. It's driving a Slewmaster mini OPS and Vertical IPS that I just finished last week. Sounds lovely.
Blessings, Terry
Scared me at first when I didn't have an output. A little searching with the scope probe revealed it was the little relays. I didn't realize I needed to jumper the 12v SW. Once I did that all is well. Kind of fun playing around with the tone controls. I'm not sure about the ref points. Almost seems backward acting but might just be the material I'm listening to. It was a fun project. I will likely fit a chassis for this since I don't need big heatsinks. This is my 5th DIY preamp but the first to have tone controls.
I running it on +-15V right now because my 20V transformer hasn't arrived yet. The little PSU I built is putting out +-15v using a 12.6V-0-12.6v 2A transformer. Working fine from what I can tell so far. It's driving a Slewmaster mini OPS and Vertical IPS that I just finished last week. Sounds lovely.
Blessings, Terry
