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alexg wrote:If I were you, I would ask Andrew of AMX how hot he biased his amp and if he would recommend using the Tung Sol 6550 with lower max plate dissipation.
I have used the Tung Sol 6550 reissues on my KT88 SE amp, but my amp is biased very conservatively. The Tung Sol 6550s are quite nice sounding, quite similar to the GE 6550.
muypogi wrote:Just to update, I decided to go with a quad of SED Winged C 6550C tubes. Reviews on the internet show it's the best value for sound quality and durability. Also, my tube seller recommended it for bass, next to the more expensive Gold Lion reissue. Boss Andrew noted that the Tung Sol may not like being in a KT88 amp.
Hoping this solves my bass problem. . .
muypogi wrote:....Hoping this solves my bass problem. . .
alexg wrote:muypogi wrote:....Hoping this solves my bass problem. . .
KT88 and variants are supposed to have very good bass, is your AMX amp lacking in bass?
Maybe your input/driver tubes is the problem.
arnoldc wrote:Without the tone control, now you know how it sounds like. Have it re-designed, even change the output transformer, or even the entire power supply.
muypogi wrote:
All this happened when I removed my amp's tone controls. Andrew said the thin bass may have been due to: 1) tone controls adding just a bit of bass even in the 12 o clock position and 2) my power tubes are growing old, since they've been there for 2 years and have seen some fairly good use (the amp is for audio and video playback).
I don't think it's the driver tubes since they were changed to Sovtek 6N1p and Mullard 12AT7 equivalents just before I sent the amp for repair.
In any case, removing the tone controls made the amp's highs and mids noticeably clearer, but at the expense of bass. . .
arnoldc wrote:Without the tone control, now you know how it sounds like. Have it re-designed, even change the output transformer, or even the entire power supply.
tony wrote:a lot depends on how you listen, do you play loud or soft?
our ears percieve loudness in a logarithmic manner...you will notice that at low levels, music may not be as enjoyable as when the volume is at say 11'oclock...
this is the reason for tone controls......some even put loudness circuits to accentuate the lows and highs at low volume levels...
a simple tweak you can do is to up the power supply capacity, that is if your rectifiers can handle the inrush currents that added capacitance in the power supply brings.
muypogi wrote:tony wrote:a lot depends on how you listen, do you play loud or soft?
our ears percieve loudness in a logarithmic manner...you will notice that at low levels, music may not be as enjoyable as when the volume is at say 11'oclock...
this is the reason for tone controls......some even put loudness circuits to accentuate the lows and highs at low volume levels...
a simple tweak you can do is to up the power supply capacity, that is if your rectifiers can handle the inrush currents that added capacitance in the power supply brings.
I play between 9-11 o clock usually, since any higher and the neighbors will likely complain. . .
I removed the tone controls since I found out that after 2 years of ownership, I barely touched them beyond the 12 o clock position. I had not known that even when flat tone controls could add color to your amp's sound. I had a NAD amp before and the best sound I got really was when you either put the tine controls at the 12 o clock position or when I pressed the tone defeat button - both methods produced roughly the same effect, as far as I can remember.
How would you propose to increase the power supply capacity? Bigger transformers? How much would they cost nowadays? I had asked if moving to toroids would be beneficial, and I was told that the conventional transformers would be the best, as toroids would offer no sonic advantages and are prone o current surges.
qguy wrote:hmmm....
Your amp seems to have gone through several changes / fixes and may require more to get it to sound right to your ears..
Might be cheaper in the long run to get a new amp that fit your needs.
alexg wrote:muypogi wrote:tony wrote:a lot depends on how you listen, do you play loud or soft?
our ears percieve loudness in a logarithmic manner...you will notice that at low levels, music may not be as enjoyable as when the volume is at say 11'oclock...
this is the reason for tone controls......some even put loudness circuits to accentuate the lows and highs at low volume levels...
a simple tweak you can do is to up the power supply capacity, that is if your rectifiers can handle the inrush currents that added capacitance in the power supply brings.
I play between 9-11 o clock usually, since any higher and the neighbors will likely complain. . .
I removed the tone controls since I found out that after 2 years of ownership, I barely touched them beyond the 12 o clock position. I had not known that even when flat tone controls could add color to your amp's sound. I had a NAD amp before and the best sound I got really was when you either put the tine controls at the 12 o clock position or when I pressed the tone defeat button - both methods produced roughly the same effect, as far as I can remember.
How would you propose to increase the power supply capacity? Bigger transformers? How much would they cost nowadays? I had asked if moving to toroids would be beneficial, and I was told that the conventional transformers would be the best, as toroids would offer no sonic advantages and are prone o current surges.
You can up PSU capacitance by adding capacitors to it, or replacing capacitors with higher capacitance once. Audio Amplified carries some nice mundorf PSU caps that will not break your bank.
If I own your amp, I will check the operating points of the driver tubes. I found that on some driver tubes, higher plate voltage with higher current results in a bit of a sibilance, putting good quality bypass capacitor on the cathode of the drivers and power tubes seems to increase bass too.
I have seen some locally made amps with transformers constructed out of cores that are not suited for audio, and usually, these irons gets so hot that you can fry egg on it.
Like most tube gurus say, the quality of tubed equipment relies heavily on the quality of the transformers...
How would you propose to increase the power supply capacity?
arnoldc wrote:Without the tone control, now you know how it sounds like. Have it re-designed, even change the output transformer, or even the entire power supply.
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