Can anyone tell me if the jumpers to change the headphone settings on the 8200R are on the top or the bottom plate?
Does changing these actually change the impedance of the headphone socket or just the gain of the headphone stage?
And lastly are there any options to extend this jumper setup to the back of the amp for quick changes when the amp is turned off?
Thankyou
Does changing these actually change the impedance of the headphone socket or just the gain of the headphone stage?
And lastly are there any options to extend this jumper setup to the back of the amp for quick changes when the amp is turned off?
Thankyou
The 8200R does not have any headphone specific stage. The phones are connected to the speaker output, and different jumper settings give you different signal attenuation (full level, 3/4, 1/2, 1/4, respectively).
The output impedance is very high (>220 Ohms) at every setting, I suspect it was chosen for ear protection.
Elekit does not support direct availability of jumpers in any of their amps, Victor will confirm that for sure. (The risk with the headphone output jumpers is not that they are connected to some high voltage, but potential insulation problems with not properly carried out custom mods. ) My not very EH&S-friendly suggestion is that test the sound with every setting, and assemble the amp fully with the setting that you like the most.
The output impedance is very high (>220 Ohms) at every setting, I suspect it was chosen for ear protection.
Elekit does not support direct availability of jumpers in any of their amps, Victor will confirm that for sure. (The risk with the headphone output jumpers is not that they are connected to some high voltage, but potential insulation problems with not properly carried out custom mods. ) My not very EH&S-friendly suggestion is that test the sound with every setting, and assemble the amp fully with the setting that you like the most.
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Thankyou - would you happen to know the output impedance of the TU-8200? Was it also 220 ohm or is that a new additional with the R model.
Ill be looking to drive both 13 ohm and 300 ohm headphones with this or that was the plan...
Ill be looking to drive both 13 ohm and 300 ohm headphones with this or that was the plan...
Thankyou, seems like a big change not to mention it in the change log for the newer R model.
Does the 1/8 impedance rule still apply here? I have one of these in order but now a bit worried about compatibility with 13 and 32 ohm headphones, I also have a 300 ohm model which should be fine.
Thankyou
Does the 1/8 impedance rule still apply here? I have one of these in order but now a bit worried about compatibility with 13 and 32 ohm headphones, I also have a 300 ohm model which should be fine.
Thankyou
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Picking up interference with my new 8200R
Just finished an 8200R with Lundahl transformers (thank you so much Victor) and am blown away with the quality - transparency - of the sound - through Frugalhorns.
However I am picking up interference, the worst from from a simple RPi DAC that is a couple of feet away. I have already taken the advice to twist the mains to switch lead and the mains side of the mains transformer leads. That greatly reduced mains hum.
But I am left with a high pitched continuous whine at highest volume with the DAC turned off, and every instruction audible when the DAC is turned on.
What to do??
Jamie
Just finished an 8200R with Lundahl transformers (thank you so much Victor) and am blown away with the quality - transparency - of the sound - through Frugalhorns.
However I am picking up interference, the worst from from a simple RPi DAC that is a couple of feet away. I have already taken the advice to twist the mains to switch lead and the mains side of the mains transformer leads. That greatly reduced mains hum.
But I am left with a high pitched continuous whine at highest volume with the DAC turned off, and every instruction audible when the DAC is turned on.
What to do??
Jamie
There is no strict 1/8 impedance rule, but most of today's phones were designed to be driven from low impedance, simply because this is what most solid state amps provide. In the old days, the standard output impedance was 120 Ohms for 600 Ohm studio headphones but there are no common standards anymore.
You should be able to optimize the jumper settings for two phones (12/32 or 32/300) reasonably well, but not for all 3 at the same time. On the other hand, are you sure you will want to use all these phones with the 8200 for longer term? I have two pairs of high quality headphones but use only one except for testing changes.
btw, I bypassed the output resistors in my original version of the amp.
Interesting. I've got a Khadas Tone Board and a RPi right next to my 8200R, and my router is about three feet away and the 8200R is dead quiet. Sorry you're having problems.
Jamie
Instead of using RPI DAC, please consider to use Elekit USB-DAC. I change the op-amp to 2777P. This DAc can install inside TU-8200 no interference
Instead of using RPI DAC, please consider to use Elekit USB-DAC. I change the op-amp to 2777P. This DAc can install inside TU-8200 no interference
Hi everyone,
I've just built the TU-8200R kit to review on my YouTube channel. The 220 ohm output impedance is a problem though and bypassing the 220 ohm resistors seems like a problem too in terms of too much output power for most headphones.
My plan is to replace the 220 ohm resistors with an L-pad to drop the output without increasing output impedance too high. Are there any reasons not to do this or other things I should be aware of with this plan?
I've just built the TU-8200R kit to review on my YouTube channel. The 220 ohm output impedance is a problem though and bypassing the 220 ohm resistors seems like a problem too in terms of too much output power for most headphones.
My plan is to replace the 220 ohm resistors with an L-pad to drop the output without increasing output impedance too high. Are there any reasons not to do this or other things I should be aware of with this plan?
The issue is that, if I remove the 220 ohm resistors to reduce the output impedance for lower impedance cans, the output will get too hot. I need to reduce the OI while also managing the increase in output, hence the L-pad idea.
Also, I'm already finding the low output jumper to be plenty
Also, I'm already finding the low output jumper to be plenty
You must have some very sensitive headphones if the 1/4 volume setting is still too high. I use HD600s with bypassed serial resistors at full output without problems.
Oh really? That's great news! I read earlier in this thread that building those resistors resulted in unusable volume range. I'm glad to hear that might not be the case. Thank you!
I haven't tried the bypass yet. I was waiting until of confirmed how I would manage the higher output, but now I'll go give it a try.
I haven't tried the bypass yet. I was waiting until of confirmed how I would manage the higher output, but now I'll go give it a try.
The lowest output setting will give you about 1.5 - 2V RMS voltage depending on the speaker impedance setting. That is not a lot more than the 1V that you usually get from portable devices.
I bypassed the resistors and levels are fine with HE4XX, HD800 etc. I wouldn’t worry about complicating things with a variable resistor - just bypass.
That's correct. I'm just confirming that those who have talked about bypassing the resistors are referring to the 8200R and not the slightly different 8200 original version