There is a relatively high value resistor connected in series with the headphone jack in order to lower the volume with low impedance dynamic headphones. Most of the phones in the last two decades were designed with the assumption that they will be driven from low output impedance solid state amps and do not sound their best when the amp's output impedance exceeds their own rated impedance.
Changing the volume pot to lower value does not make any difference in loudness provided the source is able to drive that, which is the case with most solid state CD/DAC etc. units.
The 8200R has configurable level attenuation at the headphone output, which does not exist in the original model.
Changing the volume pot to lower value does not make any difference in loudness provided the source is able to drive that, which is the case with most solid state CD/DAC etc. units.
The 8200R has configurable level attenuation at the headphone output, which does not exist in the original model.
paczeltf,
Thanks for reply. I understand that resistors there used to reduce output level. My question is what can I do with this to reduce output impedance for the headphones. Just bypass the resistors is the best idea to reach it? Maybe I can use speaker output for my low impedance headphones and 6.3 jack for high impedance headphones? Are there any problems that I can face with?
Regarding the potentiometer, if the middle position of the knob with 50kOm is 25kOm, than the middle position of 20kOm will be 10kOm? So it will not be so loud at 8:30, and give me more space to change the volume? Right?
Sorry for stupid questions, I am not good on this topic.
Thanks for reply. I understand that resistors there used to reduce output level. My question is what can I do with this to reduce output impedance for the headphones. Just bypass the resistors is the best idea to reach it? Maybe I can use speaker output for my low impedance headphones and 6.3 jack for high impedance headphones? Are there any problems that I can face with?
Regarding the potentiometer, if the middle position of the knob with 50kOm is 25kOm, than the middle position of 20kOm will be 10kOm? So it will not be so loud at 8:30, and give me more space to change the volume? Right?
Sorry for stupid questions, I am not good on this topic.
Unfortunately it does not not resolve the high output impedance and noise floor problems with sensitive phones. You won't get deaf if you incidentally crank up the volume on the 8200, which is very important, but not a full solution.
I bypassed the resistors and try to be careful with volume. I do not use very sensitive phones though. Do not use the speaker terminals as the jack output uses a 15 Ohm parallel load that is required for these tube amps.
Potentiometers are variable voltage dividers and the resistance ratio is what matters, not the absolute value. See Kirchhoff's voltage law. Also note that these pots are semi-logarithmic so the middle position of an 50k pot is about 5-10 kOhms.
Has anyone tried replacing the resistors with different values rather than just bypassing them all together? A friend of mine actually replaced all the resistors on his 8600 to get a more manageable configuration that works with modern headphones.
https://www.diyaudio.com/forums/ele...600s-available-july-2020-a-4.html#post6443860
Also, I'm considering a pot upgrade. Is there a pot that can just replace the R27 without having to mod or will all upgrades need to break off the PCB for it to fit?
https://www.diyaudio.com/forums/ele...600s-available-july-2020-a-4.html#post6443860
Also, I'm considering a pot upgrade. Is there a pot that can just replace the R27 without having to mod or will all upgrades need to break off the PCB for it to fit?
The original question was related to the TU-8200, which does not have a configurable headphone output. TU-8200x resistor bypassing was discussed a few months ago on a different thread, you should be able to find it.
The stock pot is very small so practically all upgrades require breaking off that central part of the PCB. I was a bit scared initially but it is pre-drilled and it was easy to take it off.
I believe it's this thread that the resistor bypassing was discussed. I see some discussion on page 5. It seems like bypassing and setting it to the lowest Z is what people have done while possibly adding a preamp. I'd like to be able to use the headphone out as a regular headphone out so changing the resistors rather than bypassing seems like a more sophisticated approach to fixing the issue.
That kind of stinks with the stock pot being so small. I was hoping the CP 2511 would fit without having to mod but I guess i'll have to look at it once I get it.
OK. So you are saying that you are not happy with your headphone output, but you do not even want to try the change that others made, because it was not sophisticated enough.
It's not that I don't want to try it but it seems like there might be a better solution considering it requires one to "be careful with volume" or use a preamp. Wouldn't it be similar to just plugging the headphones straight into the speaker taps? What happens if you have a high sensitivity headphone? Is there enough volume range for it to be useable?
I'm mostly asking to see if anyone else has had experience or have tried replacing the resistors rather than just bypassing. No need to get defensive.
Hello,
I’m also looking for help with an Elekit 8200R which I have recently built with upgraded capacitors, resistors, output transformers and an Alps pot. When I power it up, the LED illuminates, the tubes warm up, but there is NO SOUND OUTPUT! I’ve checked all the solder joints and I think there aren’t any missing/bridged. My current guess is that there’s something wrong with the volume pot, but I don’t know enough about electronics to really have a clue. Any help would be really appreciated.
Kind regards,
Andy.
I’m also looking for help with an Elekit 8200R which I have recently built with upgraded capacitors, resistors, output transformers and an Alps pot. When I power it up, the LED illuminates, the tubes warm up, but there is NO SOUND OUTPUT! I’ve checked all the solder joints and I think there aren’t any missing/bridged. My current guess is that there’s something wrong with the volume pot, but I don’t know enough about electronics to really have a clue. Any help would be really appreciated.
Kind regards,
Andy.
Hello,
I have this amp and quite enjoy it, but would now like to try some different tubes than the ones that came with it.
Do I need to buy a matched pair for the 12au7 ?
I read that it is not necessary for the power tubes because of the automatic bias, but haven't been able to find any mention of whether this also applies to the 12au7s as well.
Best,
Mads
I have this amp and quite enjoy it, but would now like to try some different tubes than the ones that came with it.
Do I need to buy a matched pair for the 12au7 ?
I read that it is not necessary for the power tubes because of the automatic bias, but haven't been able to find any mention of whether this also applies to the 12au7s as well.
Best,
Mads
Just another question from someone who has the original TU8200 and has done the resistor bypass mod for the headphone output covered in the earlier pages of this thread. Would it be a feasible solution to use the Rothwell inline attenuators before the line inputs of the amp to reduce the gain and get more usable volume range from the pot? Would be interested to hear if anyone has opinions on the Rothwell attenuators.
Cheers
Cheers