Definitely better! More power, better definition in the mid range. Although I changed the coupling caps as well, therefore I cannot distinguish the reciprocal contributions to the final result.
I have just received my replacement Gold lion valve, it appears to be working fine but will give it a week to make sure.
I don't have any confidence in the Gold lion valves lasting for a long time so it's either JJ or Cossor valves in the future.
My next upgrade was to replace my speakers with something more sensitive than my current 86db speakers but the amp still sounds good so that can wait.
I don't have any confidence in the Gold lion valves lasting for a long time so it's either JJ or Cossor valves in the future.
My next upgrade was to replace my speakers with something more sensitive than my current 86db speakers but the amp still sounds good so that can wait.
Hi Victor, thanks for the advice. I will take the amp apart and check all the joints again but I found the problem with the crackling sound would follow the valve that I believe to be faulty when swapping it around. Do you think it could still be a solder joints ?
I don't have a problem with the 300B when powering on, but the filaments in the 3 preamp tubes glow very bright for a second or two before dimming after powering on. The 300B would start glowing slowly after a few more seconds.
It looks like there is a current surge into the filaments during power on. It makes me nervous as I worry that the filaments would burn out after a few more power cycles.
The 12AX7 filament supply is DC regulated but the 12AU7 filaments are fed by the raw AC from the power transformer. The fact that the same phenomenon occurs in the 12AU7 means that it is not a problem of the regulator.
Has anyone seen the same problem? I'm using Northern Electric 12AX7 and 12AU7 tubes.
Otherwise the amp works and sounds very nice. By the way, I just took some measurements with my scope. With a 5 ohm load, we could only get around 5W before significant clipping. At 1W output, we get around 2.5% distortion (2nd harmonic).
It looks like there is a current surge into the filaments during power on. It makes me nervous as I worry that the filaments would burn out after a few more power cycles.
The 12AX7 filament supply is DC regulated but the 12AU7 filaments are fed by the raw AC from the power transformer. The fact that the same phenomenon occurs in the 12AU7 means that it is not a problem of the regulator.
Has anyone seen the same problem? I'm using Northern Electric 12AX7 and 12AU7 tubes.
Otherwise the amp works and sounds very nice. By the way, I just took some measurements with my scope. With a 5 ohm load, we could only get around 5W before significant clipping. At 1W output, we get around 2.5% distortion (2nd harmonic).
I just googled it. Turned out that tube flash is quite common among some manufacturers. I've owned and built a few tube amps, but this is the first time seeing a tube flash. Anyway it is not a problem of the amp itself.
I'm at the end of my tether. I received my 3rd replacement Gold lion 300b valve last weekend it seemed OK at first but turning on the amp today I got a brief crackling noise through a speaker.
This is now things started last time.
This is now things started last time.
I use Gold Lion 300B’s. I have about 20 hours of use and 6 power on/off cycles. No issue so far.
I am having the same issue. I have tried two sets of EH 300b without fixing the problem. The same tubes work in my older TU-8600. I have also tried it with Telefunken and EH ECC82 tubes.
I am not sure if the TU-8600S has a design issue, whether we all made the same construction error, or if the TU-8600S only works with certain tube brands.
Any further info from people who have fixed this problem would be helpful.
I am not sure if the TU-8600S has a design issue, whether we all made the same construction error, or if the TU-8600S only works with certain tube brands.
Any further info from people who have fixed this problem would be helpful.
I've have not got to the bottom of this problem so I have given my amp to a technical guy with an oscilloscope.
I checked all my solder joints several times and found no visible dry joints or components in the wrong place.
I believe EH 300b tubes are made in the same factory as the Gold lions I have been having problems with.
One thing that was mentioned is that it could be an issue with the auto bias circuit, if the valves are to far out of speck it can't correct the current.
I will let you know when he gets back to me.
I checked all my solder joints several times and found no visible dry joints or components in the wrong place.
I believe EH 300b tubes are made in the same factory as the Gold lions I have been having problems with.
One thing that was mentioned is that it could be an issue with the auto bias circuit, if the valves are to far out of speck it can't correct the current.
I will let you know when he gets back to me.
TU-8600S is the best version of TU-8600 series.
Both EH and Gold Lion have the same construction(made in the same factory).They are basically identical. The only different is Gold Lion has a higher reading (my assumption).
I stopped to offer EH since 2019. EH 300B IS CHEAP TO BUY BUT EXPENSIVE TO USE.
The only advantage of EH300B is inexpensive but... there are too many disadvantages .. etc. not durable.. not sound good..
Gold Lion make good ECC83/B759...
Both EH and Gold Lion have the same construction(made in the same factory).They are basically identical. The only different is Gold Lion has a higher reading (my assumption).
I stopped to offer EH since 2019. EH 300B IS CHEAP TO BUY BUT EXPENSIVE TO USE.
The only advantage of EH300B is inexpensive but... there are too many disadvantages .. etc. not durable.. not sound good..
Gold Lion make good ECC83/B759...
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What happens when "protection" kicks in? Do the 300B filaments still light up? Is the protection for the B+ power? I just looked at the schematic. There is no protection around the 300B filament regulator. The EN pin of the regulator is hard wired to the IN pin, so what JAMA described earlier in this thread should not occur in the 8600S. I use Gold Lion 300B's, and have no issue so far.
There is a circuit to protect the amp. When there is an issue with your amp, the B+will not start .
I stopped to offer EH or Gold Lion 300B since 2019. They both are the same.
The sound of Gold Lion is too far away from Cossor WE300b/Psavne WE300B
Technically, both Psavne WE 300B and Cossor/LinLai WE300B are the same
I stopped to offer EH or Gold Lion 300B since 2019. They both are the same.
The sound of Gold Lion is too far away from Cossor WE300b/Psavne WE300B
Technically, both Psavne WE 300B and Cossor/LinLai WE300B are the same
Paul the painter
If you send me the reference voltage, I could probably tell you the issue of your amp.
Besides the tube set issue, 99% of the problem tend to be cold joints or bad soldering. The reference voltages will tell you what the problem is.
CentralCoast
I am not sure if the TU-8600S has a design issue, whether we all made the same construction error, or if the TU-8600S only works with certain tube brands.
There is no issue with TU-8600S' design. Mr. Fujita is one of the top tube amp designers in Japan. Sorry, not his design issue. No design is absolutely perfect, but Mr. Fujita is approaching perfect. We sold more than 500 PCS of TU-8600. Only a few people had issues. The issues were not the amp. 99% was soldering issue or using a bad tube set.
TU-8600S can use different types of 300B, but it must be a reliable 300B.
If you send me the reference voltage, I could probably tell you the issue of your amp.
Besides the tube set issue, 99% of the problem tend to be cold joints or bad soldering. The reference voltages will tell you what the problem is.
CentralCoast
I am not sure if the TU-8600S has a design issue, whether we all made the same construction error, or if the TU-8600S only works with certain tube brands.
There is no issue with TU-8600S' design. Mr. Fujita is one of the top tube amp designers in Japan. Sorry, not his design issue. No design is absolutely perfect, but Mr. Fujita is approaching perfect. We sold more than 500 PCS of TU-8600. Only a few people had issues. The issues were not the amp. 99% was soldering issue or using a bad tube set.
TU-8600S can use different types of 300B, but it must be a reliable 300B.
Hi Victor, thanks for the offer of help ,i have given all my voltage information to the technician looking at my amp. I will let you know when I hear back.