Topic: Amp's right channel is not balanced with the left.

[Bogsle]

With the SPL meter lying around after re-calibrating the HT setup I decided to play around with it.

I wanted to see if the speaker channels/outputs from my tube intergrated amp were equal.

First, I placed the SPL meter directly in front of the right speaker at exactly 2 feet away and played pink noise from the CDP. I turned the volume up until the SPL meter showed 70dB.

Next, without changing the volume control of the tube integrated amp, I move the SPL meter directly infront of the left speaker, also at exactly 2 feet away. I noticed that the SPL meter showed 69dB, and sometimes goes down to 68dB.

I tried reversing the speaker cables between left and right speakers, reversed the left and right interconnects, and even reversed the position of the tubes. But all the time I get the same readings from the SPL meter, which shows that the right channel is 1 to 2 dB louder that the left channel.

Based on the things that I have already done, it is neither the speakers nor the output from the CDP that is "unbalanced". It must be the tube amp then.

Is this normal or is there something wrong with the integrated amp?

Which components should I check or do I need to bring the tube integtrated amp for servicing already?

[JojoD818]

Hi,

Have you tried swapping the signal tubes too?

[Bogsle]

Hi,

Have you tried swapping the signal tubes too?

Yes, I did that as well.

[JojoD818]

Bro,

Provided they share the same B+ supply (not dual mono, not monoblocks), and they have near identical plate resistor values for the voltage amplifier/driver stage then the only thing left is the tube amp's output transformers not being identical... (or am I missing something else?  )

[Bogsle]

Bro,

Provided they share the same B+ supply (not dual mono, not monoblocks), and they have near identical plate resistor values for the voltage amplifier/driver stage then the only thing left is the tube amp's output transformers not being identical... (or am I missing something else?  )

Yes, correct in all your assumptions.

If its the OPTs, and assuming that both were identical from the start when the int. amp was new, is it possible the one of the OPTs could have deteriorated overtime? This is not normal, right? 

Your suggestion, please.

Thank you very much for the inputs.

[JojoD818]

Yes, correct in all your assumptions.

If its the OPTs, and assuming that both were identical from the start when the int. amp was new, is it possible the one of the OPTs could have deteriorated overtime? This is not normal, right? 

Your suggestion, please.

Assuming the output trannies are truly identical from the start then something must have gone wrong and it's not normal, but I wouldn't go there just yet.

As of now, all we can do is speculate and that is not fair, so I would suggest that you continue to monitor the difference between the two channels with your spl meter to really see if it does change under normal use.

Another speculation is that your amp may have started it's life already "unbalanced". 

[ATJr.]

With the SPL meter lying around after re-calibrating the HT setup I decided to play around with it.

I wanted to see if the speaker channels/outputs from my tube intergrated amp were equal.

First, I placed the SPL meter directly in front of the right speaker at exactly 2 feet away and played pink noise from the CDP. I turned the volume up until the SPL meter showed 70dB.

Next, without changing the volume control of the tube integrated amp, I move the SPL meter directly infront of the left speaker, also at exactly 2 feet away. I noticed that the SPL meter showed 69dB, and sometimes goes down to 68dB.

I tried reversing the speaker cables between left and right speakers, reversed the left and right interconnects, and even reversed the position of the tubes. But all the time I get the same readings from the SPL meter, which shows that the right channel is 1 to 2 dB louder that the left channel.

Based on the things that I have already done, it is neither the speakers nor the output from the CDP that is "unbalanced". It must be the tube amp then.

Is this normal or is there something wrong with the integrated amp?

Which components should I check or do I need to bring the tube integtrated amp for servicing already?

we live in an imperfect world! sometimes your left foot can be slightly bigger than your right foot....

question is, how does it affect your listening? can you hear that the right channel plays softer than the left?

if the answer is no, then the meter readings are more of an annoyance.....

and like they say, if it ain't broke, don't fix it. enjoy the music.....

[qguy]

have you tried swapping loudspeakers ?  It could also be the room.

is your room perfect ? I mean left side is equal to the right side ?

[odyopayl]

Nolan you really have Dog ears! 1 - 2dB difference is negligible! Don't mind it we are listening on a Stereo sound....
But now that you check it, it bothers you! Time to change SET Amp!
Happy New Year Bro!

[JojoD818]

Jun, masyado yata drastic yan SARS mo bro... 

baby steps muna and let's help Nolan diagnose the imbalance... 

[nizmo]

brader nolan

kumusta? buo na pala yang tube amp mo.

i think its the spl meter...

regards.

[JoeyGS]

With Nolan's test wherein the SPL meter is placed 2 feet in front of every speaker, will the room configuration have an effect on the imbalance?

Another area to look into is the tubes performance.  Are they exactly matched?

Lastly,  How does it sound in the sweetspot without the use of the SPL meter?

[JojoD818]

With Nolan's test wherein the SPL meter is placed 2 feet in front of every speaker, will the room configuration have an effect on the imbalance?

Another area to look into is the tubes performance.  Are they exactly matched?

Lastly,  How does it sound in the sweetspot without the use of the SPL meter?

Thought of this as well, reflections can cause erratic readings but knowing Nolan's knowledge in tinkering with gears I'm sure he has taken this into account.

[Bogsle]

Assuming the output trannies are truly identical from the start then something must have gone wrong and it's not normal, but I wouldn't go there just yet.

As of now, all we can do is speculate and that is not fair, so I would suggest that you continue to monitor the difference between the two channels with your spl meter to really see if it does change under normal use.

Another speculation is that your amp may have started it's life already "unbalanced". 

Maybe so. Hmmmm....

Thanks.

[Bogsle]

we live in an imperfect world! sometimes your left foot can be slightly bigger than your right foot....

question is, how does it affect your listening? can you hear that the right channel plays softer than the left?

if the answer is no, then the meter readings are more of an annoyance.....

and like they say, if it ain't broke, don't fix it. enjoy the music.....

Yeah, I guess maybe I'm getting just too anal about this.

I just have to breath in and breath out....relax. 

Thank you.

[Bogsle]

have you tried swapping loudspeakers ?  It could also be the room.

is your room perfect ? I mean left side is equal to the right side ?

Yes, did so.

I thought I tried removing the effects of the room already by placing the SPL meter at very close proximity directly in front of the speakers one at a time. Is 2 feet away still not enough?

Thanks.

[Bogsle]

Nolan you really have Dog ears! 1 - 2dB difference is negligible! Don't mind it we are listening on a Stereo sound....
But now that you check it, it bothers you! Time to change SET Amp!
Happy New Year Bro!

Ayos bro. The best suggestion....hehehe 

Nooooo, not the AMX 845, nooooo.

[Bogsle]

brader nolan

kumusta? buo na pala yang tube amp mo.

i think its the spl meter...

regards.

Senor,

Funny ha, very funny...

[Bogsle]

With Nolan's test wherein the SPL meter is placed 2 feet in front of every speaker, will the room configuration have an effect on the imbalance?

Another area to look into is the tubes performance.  Are they exactly matched?

Lastly,  How does it sound in the sweetspot without the use of the SPL meter?

Yeah, is two feet away not enough to remove the room effects from the equation?

No, they are not perfectly matched. But is it not that the autobiasing will take care of that.

I remember also swaping the tubes between left and right channels but the left one still gave a lower dB measurement.

Regarding the sweetspot....hmmm.... gitna naman ang image ng kumakanta.

Baka nga ako lang sir talaga ang may problem, hehehe.

Thanks.

[Bogsle]

Anyway, thanks to all.

I certainly did not expect all these responses. I was not sure if my inquiry was valid or a bit silly to be taken seriously. I'm really moved.  :'(

As a final act siguro, I will try changing all the tubes, the power tubes and the two peanut tubes.

I'll share my findings again.

But if the situation will be the same, I will just have to live with it and follow Tony's suggestion, enjoy the music. 

Cheers.

[qguy]

Another possiblity is the  components within the amp, capacitors and resistors which can drift from the original specs. Also this is why those exotics components are more expensive,  their tolerances are smaller . Yung mga +/- 5 percent compared to +/- 1 percent sa mga exotic parts. Imagine on the extreme you could have a difference of 10 percent between left and right channel for a particular part....

try mo na rin pa clean yung mga switches specially the potentiometer ng volume and balance, treble and bass controls, if any


You should test each resistor and capacitor if its still within specs....para pantay ang tunog ng left and right channels, otherwise di ka matatahimik knowing you have 1 DB difference..hahaha   Qguy.. now playing with your mind 

[AudioAmplified]

Sir,

Many variables might come into play.  Busted resistor, leaking caps, weak tubes, bad wire connection...

You can bring your amp in and we are more than happy to give you a free diagnosis.

www.audioamplified.com

[ATJr.]

You should test each resistor and capacitor if its still within specs....para pantay ang tunog ng left and right channels, otherwise di ka matatahimik knowing you have 1 DB difference..hahaha 

today's parts like resistors and caps are better than yesteryear's, today we have the Kiwames, holcos, polypropylene caps, tefloncaps, etc.,etc......whereas tube equipment of the olden days used paper caps, and +/-20% tolerance resistors, today we see film type not less than 5%.....

i wouldn't be bothered by a mere 1db. difference, not worth the time and effort....

[Bogsle]

today's parts like resistors and caps are better than yesteryear's, today we have the Kiwames, holcos, polypropylene caps, tefloncaps, etc.,etc......whereas tube equipment of the olden days used paper caps, and +/-20% tolerance resistors, today we see film type not less than 5%.....

i wouldn't be bothered by a mere 1db. difference, not worth the time and effort....

Thanks for your thoughts on this matter, sir.

As for qguy and AudioAmplified, I will think about your suggestions as well. Thanks for the offer.

Regds.

[Adam Warlock]

How about your room reflection sir? Why dont you measure the current coming from the amp. I mean the speaker output.

[ding45]

I have the same problem with my tube amp and when I checked the innards I saw a couple of black cylindrical thingies na parang nag leak at ng matuyo ay naging white stain. Leaking capacitor po ba ito and another thing I noticed ay parang numipis yung tunog nya. Its a 50wpc 6550 PP int. amp. Cant bring to Manila for servicing dahil ang bigat baka mabali likod ko (taga laguna kasi ako)

[Bogsle]

How about your room reflection sir? Why dont you measure the current coming from the amp. I mean the speaker output.

I don't think room reflection was an included factor.

I was hoping it will not be the case anymore since I placed the SPL meter 2 feet directly in flont of the each of the speakers.

Regarding them current measurement, I may have to call you one of these days.

Thanks.

[Bogsle]

I have the same problem with my tube amp and when I checked the innards I saw a couple of black cylindrical thingies na parang nag leak at ng matuyo ay naging white stain. Leaking capacitor po ba ito and another thing I noticed ay parang numipis yung tunog nya. Its a 50wpc 6550 PP int. amp. Cant bring to Manila for servicing dahil ang bigat baka mabali likod ko (taga laguna kasi ako)

I'm guessing you are describing a capacitor there.

I don't think the capacitors are the culprit. I just had all capacitors upgraded last year from Audio Amplified (Mundorf) as shown here:



The auto bias resitors have been replaced also with new ones. The picture hasn't been updated. The white ceramic type resistors in the middle of the main board have been changed to wirewound enamel types.

[ATJr.]

I have the same problem with my tube amp and when I checked the innards I saw a couple of black cylindrical thingies na parang nag leak at ng matuyo ay naging white stain. Leaking capacitor po ba ito and another thing I noticed ay parang numipis yung tunog nya. Its a 50wpc 6550 PP int. amp. Cant bring to Manila for servicing dahil ang bigat baka mabali likod ko (taga laguna kasi ako)

in your case that capacitor is easy to replace, just get another one with simmilar specs and solder it in, if that was an axial type, you can still replace it with a radial type of same value, all you need are soldering skills to do it.

in order to avoid mistakes, do not remove the leaky cap just yet, solder in the repalcement in parallel then cut off the leaky cap after, you can tell your tech to do this..

[alexg]

I have the same problem with my tube amp and when I checked the innards I saw a couple of black cylindrical thingies na parang nag leak at ng matuyo ay naging white stain. Leaking capacitor po ba ito and another thing I noticed ay parang numipis yung tunog nya. Its a 50wpc 6550 PP int. amp. Cant bring to Manila for servicing dahil ang bigat baka mabali likod ko (taga laguna kasi ako)

Hi Ding,

I took a look at your 6550 PP amp about an hour ago, the white stain things on the bypass caps are the glue that hold the wrapper on the polypropylene caps, the caps are intact, the labels are not. On your left channel, both the cathode bypass caps are gone and bulging.

For the life of me, I cannot believe that the designer of the amp placed 50Volt capacitors on the cathode of the 6550! (cathode biased) The voltage on the cathode hovers at around 48 to 50VDC. He even used Rubycon caps for the cathode bypass! This guy is suicidal. 

This is the second amp that he designed and built that I am fixing, both are PP amp one is KT88 and this one is 6550.

I will text you with other things that I will see on your amp.