I have hotrodded a couple of those Denon avr units for friends over the years. I just bypass most of the interstage coupling caps, and replace the last ones with nichicon muse bp, replace some of the power supply caps, and the filter caps in the phono stage if they’re using that.
Definitely not a bad way to go for next to nothing. The direct mode without the dsp is nice, along with a remote for the volume.
I actually donated my Dynaco tube amps along with the Scott almost thirty years ago, started over about ten years later with the worst of silicon and have worked my way back to a good setup.
Most often cheap is best, that dac is a great bargain for sure.
Definitely not a bad way to go for next to nothing. The direct mode without the dsp is nice, along with a remote for the volume.
I actually donated my Dynaco tube amps along with the Scott almost thirty years ago, started over about ten years later with the worst of silicon and have worked my way back to a good setup.
Most often cheap is best, that dac is a great bargain for sure.
Curiosity and a few spare minutes got the best of me. A metric hex driver is required to get the back plate off. Good thing I just happen to have a set of those from hobby/model projects. After removing the back plate and the volume knob and nut, a gentle push of the volume pot shaft to coax the stuck board out caused it to shoot out and across the table. Oops.
So we have B10k molded onto the pot. 10k linear I suppose when I see that given the B designation.
So on with the meter. I cannot find any connection between the pot and the RCA output jacks except the ground. It looks like the circuit board traces from the pot do not run to the back. Here is a crude drawing with the pot in place on the board. Do I have the pin numbers correct? Bottom view of the board looking at the solder joints.
I have a huge assortment of 1/4 watt metal film resistors in various values. Is the quick and dirty fix to use a 1kΩ? It looks like they are using the lead-free solder. All I have is rosin core 60/40 and rosin core 62/36/2. Is that a problem? I have read not to try to mix them.
Like this?
So we have B10k molded onto the pot. 10k linear I suppose when I see that given the B designation.
So on with the meter. I cannot find any connection between the pot and the RCA output jacks except the ground. It looks like the circuit board traces from the pot do not run to the back. Here is a crude drawing with the pot in place on the board. Do I have the pin numbers correct? Bottom view of the board looking at the solder joints.
I have a huge assortment of 1/4 watt metal film resistors in various values. Is the quick and dirty fix to use a 1kΩ? It looks like they are using the lead-free solder. All I have is rosin core 60/40 and rosin core 62/36/2. Is that a problem? I have read not to try to mix them.
Like this?
I found a replacement pot on Mouser ... for about $50 delivered. Not an option for a $70 DAC. It's one of the new Chinese tiny 9mm pots with a 6mm shaft. Not replaceable with 99% of available pots.
Just try the resistor. Use the 62/36 solder.
Goal is to have the pot set at about the middle for normal listening levels.
You can change the 1k up or down as needed to achieve this.
Goal is to have the pot set at about the middle for normal listening levels.
You can change the 1k up or down as needed to achieve this.
1) Is my diagram correct?
2) Can I use my 60/40 rosin-core solder or 62/36/2 rosin core solder when the board was made with lead-free? I am out of desoldering braid.
2) Can I use my 60/40 rosin-core solder or 62/36/2 rosin core solder when the board was made with lead-free? I am out of desoldering braid.
Yes, diagram is ok, and keep the resistor leads short to avoid shorting out.
You can certainly use the solder you have.
You can certainly use the solder you have.
I finally found an A10k pot on AliExpress if I want to wait 3-4 weeks. Only $10 for 5 of them including shipping. Apparently, they are almost nonexistent. 99.9% of them on AliExpress are linear B10k so that's what they all seem to use.
We have music with a pair of 1k metal film resistors! I HATE lead-free solder. The 60/40 I used didn't want to work at all and it took multiple attempts. Still not sure how good the connection is.
I will post details later or tomorrow after a lot more testing to see if this modification has had any other effects.
I will post details later or tomorrow after a lot more testing to see if this modification has had any other effects.
I can verify that. It has been running 24/7 since I got it - except for the mod today - and improving in quality over time. Now has to warm up again after the modification. It doesn't run hot, just faintly warm. I have always left DACs on all the time as they don't use much power. Tube amps ... well that's a different matter!
Caps are labeled WIMA and Nichicon. Who knows if that's accurate or fakes ... no way to tell.
Highest chance for succes it to focus on this little job, replace the potentiometer for a good quality logarithmic one and use known good quality 60/40 solder. Less words on side thoughts would help 🙂
The resistor trick like you did can be done too but best would be to analyse and draw the circuit beforehand.
Tip: often they are difficult to remove with possibly PCB damage. Careful total demolition with a 160 side cutter is recommended if you take care not to put force on the pins. Then the pins can be removed easily in seconds.
Like in many cheap devices one never knows parts are original or fake but chances are high for fake Wima caps and fake electrolytic caps.
The resistor trick like you did can be done too but best would be to analyse and draw the circuit beforehand.
Tip: often they are difficult to remove with possibly PCB damage. Careful total demolition with a 160 side cutter is recommended if you take care not to put force on the pins. Then the pins can be removed easily in seconds.
Like in many cheap devices one never knows parts are original or fake but chances are high for fake Wima caps and fake electrolytic caps.
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The result: the 1k resistors moved normal listening position from about 9 o'clock to about 10 o'clock. That's not much difference, but it helps. I have located 9mm logarithmic pots that I hope will work. I ordered five for $4.75 from AliExpress. When they arrive, I'll test them to see if they really are logarithmic and if so which one tracks the most accurately.
Removing the old pot won't be a problem I don't think. Not sure of the best way to remove all traces of the lead-free solder from the 6 pads though. The solder on the board and my 60/40 solder don't work well together at all.
Removing the old pot won't be a problem I don't think. Not sure of the best way to remove all traces of the lead-free solder from the 6 pads though. The solder on the board and my 60/40 solder don't work well together at all.
Oh that is a pity. Please make a schematic. It can be that the potentiometer is in the feedback of an opamp.
To avoid we are busy correcting expected/normal behavior:
- please check maximum output line level of the DAC to be 2Vrms like the standard is for decades already.
- please check the input sensitivity of the following power amplifier to be 1…2Vrms for full output. Some odd devices may have ridiculous high input sensitivity and gain. In that case the DAC is not to blame and changing the non standard input sensitivity of the power amplifier would be optimal.
To avoid we are busy correcting expected/normal behavior:
- please check maximum output line level of the DAC to be 2Vrms like the standard is for decades already.
- please check the input sensitivity of the following power amplifier to be 1…2Vrms for full output. Some odd devices may have ridiculous high input sensitivity and gain. In that case the DAC is not to blame and changing the non standard input sensitivity of the power amplifier would be optimal.
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I suspect that you are correct. I can not find any direct connection between the potentiometer and the RCA output jacks as with a passive attenuator. The circuit traces from the pot run somewhere into the middle of the board. I can't make a schematic myself, and the seller and manufacturer refused to provide one when I asked them. They said they would not disclose that information.
It can also be that the design is OK and that the potentiometer is followed by an opamp to buffer.
It seems you have homework to do 😉 My suspicion is that the power amplifier is non standardized with regards to input sensitivity and modding the perfectly fine working DAC will be correcting an error with an error. You can test this by operating the DAC at full volume and add a cheap potentiometer (for testing) between DAC and power amplifier to control volume. If the symptoms are the same you will know what the culprit is.
After solving that you may want to have a better quality potentiometer which is likely larger than the one used in the DAC. You could think of the pretty standard Alps RK27 10 or 20 kOhm (or better stuff) in the now standardized power amplifier. Volume control where it is supposed to be too with probably a better “feel” and better tracking.
It seems you have homework to do 😉 My suspicion is that the power amplifier is non standardized with regards to input sensitivity and modding the perfectly fine working DAC will be correcting an error with an error. You can test this by operating the DAC at full volume and add a cheap potentiometer (for testing) between DAC and power amplifier to control volume. If the symptoms are the same you will know what the culprit is.
After solving that you may want to have a better quality potentiometer which is likely larger than the one used in the DAC. You could think of the pretty standard Alps RK27 10 or 20 kOhm (or better stuff) in the now standardized power amplifier. Volume control where it is supposed to be too with probably a better “feel” and better tracking.
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The amplifier is normal. I have used it for 30 years with various preamplifiers with no problem. It is a Dynaco ST-70 series ii from about 1992.
Out of curiosity, I tested the high range of the volume after adding the 1k resistors. The maximum output of the amplifier is achieved at about 3 o'clock on the potentiometer. Normal listening is now about 10 o'clock instead of 9 o'clock.
I have ordered 10k logarithmic pots from AliExpress as I said earlier. No idea if they will improve the situation. About $1 each for 5 of them.
You probably will not achieve best results with 1$ potentiometers.
My conclusion is that the DAC is working as it should but with unpleasant volume control. The amplifier worked fine with preamplifiers adapted to the power amplifier I guess!? Is the power amplifier unmodded and working correctly with other 2V rms sources?
Anyway, you have enough information to test/check if things are OK on the DAC side. To exclude the power amplifier you could test with another amplifier. BTW I understood the volume to be too loud at nine o’clock being “jumpy” in level which seems like linear potentiometer behavior when used for volume control combined with a too sensitive amplifier.
My conclusion is that the DAC is working as it should but with unpleasant volume control. The amplifier worked fine with preamplifiers adapted to the power amplifier I guess!? Is the power amplifier unmodded and working correctly with other 2V rms sources?
Anyway, you have enough information to test/check if things are OK on the DAC side. To exclude the power amplifier you could test with another amplifier. BTW I understood the volume to be too loud at nine o’clock being “jumpy” in level which seems like linear potentiometer behavior when used for volume control combined with a too sensitive amplifier.
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