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YAHA headphone tube amp - no sound?

post #1 of 9
3/7/11 at 12:50am
Thread Starter 

Hello! So i've built two YAHA headphone amps, and I cannot get neither one to make music/sound.

 

Here are some project details:

- I am using a 2 amp, regulated 12 volt power supply.

- - The tube is a 6N1P tube, supposedly the equivalent to a ECC88.

(I purchased the tube from this eBay page: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330381082733#ht_2064wt_1042 )

 

At one point, I got the tube to glow bright as soon as power was applied, but I now know this isn't good for tubes. The tube was getting roughly 9v from the LM317 regulator, and the sound was very broken up, intermittent, and distorted sounding. only coming from one headphone.

 

- I have a pack of OPA2132 op-amps, so I know the op-amp isn't the problem

- There is no volume pot in between source and the YAHA

 

I am beginning to think the design might require a little modification because of the 6N1P tube. Should I just try to get ahold of a actual ECC88 for this project, or just hack the board up?

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post #2 of 9
3/7/11 at 5:14am

The tube require 6.3 volts at 600 mA for the heater.

If you put 9 volts into the heater, it is probably

blown.

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post #3 of 9
3/7/11 at 5:20am

Did you follow the instruction here?

There is plenty of information there for troubleshooting.

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post #4 of 9
3/7/11 at 7:28am

How long was 9V being applied to that heater?

 

Did you fix the voltage regular circuit?

The tube doesn't heat up anymore?

 

Your post isn't nearly descriptive enough.


Edited by nullstring - 3/7/11 at 7:30am
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post #5 of 9
3/7/11 at 8:44am

6n1p and 6dj8 have very different heater currents. You should be able to switch between the 2 with a switch, but since the YAHA uses a current regulator to feed the tube (as opposed to a voltage regulator) care must be taken when rolling tubes.

 

If your interested in good guesses:

The LM317 is wired wrong, and something else is too. 

 

The LM317 has a dropout voltage of right around 3V, 12V-3V=9V Did you take your output current from the correct side of the sense resistor? If Im wiring point-to-point I normally spend several minutes thinking about how to wire these little buggers, or screw it up. I would not be overly concerned about the health of the tube as long as it lights up properly once you fix the heaters.

 

As for only 1 channel working. I dunno. Fix the heater first. Lucky guesses for that are that the tube for that channel is hooked up wrong, or that the opamp is. What do the voltages around the circuit tell you?

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post #6 of 9
3/7/11 at 10:13am
Thread Starter 

How would I implement a switch?

 

I will check voltages later.

 

One other thing I forgot to mention is that the 47k resistors on either side of the tube don't reduce the power to 12 volts. They only lower it down to 11.7 volts. 

 

This is my first headphone amp project. If the YAHA doesn't work out, I can just use existing parts to build a CMOY pocket amp instead.

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post #7 of 9
3/7/11 at 10:29am

If there is no current flowing though the tube the the 47k resistor will not drop much voltage.

Another indication the heaters are blown...

 

 

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post #8 of 9
3/7/11 at 5:12pm
Thread Starter 

Would the heater glow if there was power being applied to it?

 

 

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post #9 of 9
3/7/11 at 5:44pm

If the heaters are still good, they will glow with the proper voltage applied.

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