Hi wishmasterX
I have the Boyuu A10 EL34 SE amplifier. This is point-to-point wired with 'Japanese' uprated power and output transformers. It would be easy to modify, but I have not had time or requirement to do so yet.
I have owned this for 18 months now, having bought fully assembled. It came stock with EL34 Shuguang tubes and 6N2 chinese double triodes and stock rectifier.
I am in the UK and the voltage is very stable, although I've not measured it at primary or outgoing of rectifier valve.
Without any modifications I have just dropped in EL34, EL34B, 6CA7, Shuguang 350C, 6P3P, KT77 and finally 6N3C-E and they have all 'worked' but I have not measured their performance.
I have also tried two different types of solid-state drop-in rectifiers with various valve combinations. When I have time I will check the o/p valve bias currents and also the various B+ and other voltages for each combination.
The power and output transformers have not got overly hot at all in any of the above configurations. They are warm to the touch after a few hours but that's all.
Hope this helps.
I have the Boyuu A10 EL34 SE amplifier. This is point-to-point wired with 'Japanese' uprated power and output transformers. It would be easy to modify, but I have not had time or requirement to do so yet.
I have owned this for 18 months now, having bought fully assembled. It came stock with EL34 Shuguang tubes and 6N2 chinese double triodes and stock rectifier.
I am in the UK and the voltage is very stable, although I've not measured it at primary or outgoing of rectifier valve.
Without any modifications I have just dropped in EL34, EL34B, 6CA7, Shuguang 350C, 6P3P, KT77 and finally 6N3C-E and they have all 'worked' but I have not measured their performance.
I have also tried two different types of solid-state drop-in rectifiers with various valve combinations. When I have time I will check the o/p valve bias currents and also the various B+ and other voltages for each combination.
The power and output transformers have not got overly hot at all in any of the above configurations. They are warm to the touch after a few hours but that's all.
Hope this helps.
Boyuu A9 Builder Looking For Help
Hi All
After Watching All The Fun You Are all Having Building The Kit, I Took The Plunge And Bought One.
Now All Went Well Until I Came To Test It, (apart from pins 1 & 4 on the input tubes not shown as linked on the schematic, Picked that up from your forum)
First I Had A Very Loud Hum/Buzz On Both Channels, After Checking Everything And Moving The Heater Supplies Away From Any Input Wires/Pins, It Did Reduce.
My Problem Is That I Still Have Quite A Loud Hum/Buzz But As Soon
as Any input signal is connected, the amp plays it at full volume, regardless of the volume position.
almost as if i have built a super sensitive amp?
I have checked the volume control and it's working as it should, (checked with my calibrated fluke).
Has anyone got any ideas?
Anything Considered.
I'm Confident with electronics and have built many electronic kits but this is my first valve project.
Thanks,
John.
Hi All
After Watching All The Fun You Are all Having Building The Kit, I Took The Plunge And Bought One.
Now All Went Well Until I Came To Test It, (apart from pins 1 & 4 on the input tubes not shown as linked on the schematic, Picked that up from your forum)
First I Had A Very Loud Hum/Buzz On Both Channels, After Checking Everything And Moving The Heater Supplies Away From Any Input Wires/Pins, It Did Reduce.
My Problem Is That I Still Have Quite A Loud Hum/Buzz But As Soon
as Any input signal is connected, the amp plays it at full volume, regardless of the volume position.
almost as if i have built a super sensitive amp?
I have checked the volume control and it's working as it should, (checked with my calibrated fluke).
Has anyone got any ideas?
Anything Considered.
I'm Confident with electronics and have built many electronic kits but this is my first valve project.
Thanks,
John.
Hi 6A3sUMMER.
Thanks For Quick Reply, You Were Spot On.
After Checking Out The Volume/RCA input lines, Found A Dry Joint At The RCA Circuit Board Ground To RCA Socket Grounds.
Only Found It By Measuring Between Ground on RCA Circuit Board And RCA Sockets Outers On Rear Panel.
Looks Like I Made The Joint Good When I Pressed The Probe Of My Meter On It, While Testing It?
Anyway Now My Amp Is Working Almost Perfectly.
I Do Have A Slight Buzz You Can Only Hear At Very Low Volume Or Quite Sections in-between Tracks.
I'll Have Another Go After Its Settled In Awhile.
Thanks Again, Your Help Is Greatly Appreciated.
John
Thanks For Quick Reply, You Were Spot On.
After Checking Out The Volume/RCA input lines, Found A Dry Joint At The RCA Circuit Board Ground To RCA Socket Grounds.
Only Found It By Measuring Between Ground on RCA Circuit Board And RCA Sockets Outers On Rear Panel.
Looks Like I Made The Joint Good When I Pressed The Probe Of My Meter On It, While Testing It?
Anyway Now My Amp Is Working Almost Perfectly.
I Do Have A Slight Buzz You Can Only Hear At Very Low Volume Or Quite Sections in-between Tracks.
I'll Have Another Go After Its Settled In Awhile.
Thanks Again, Your Help Is Greatly Appreciated.
John
Hello All,
After reading and re-reading this thread (very informative but soooo long), many thanks for all the valuable info and knowledge thats been contributed. I'm just about to start a build on an A9. I want to incorporate the mods by Geek Stuff. Does anyone have an opinion of what order to follow for the build? I'm thinking that I would wire in the components on the PCB first then the coax, followed by the transformer, AC, B+ etc. and finally the components from the valves to the PCB. Any help would be gratefully accepted. If I've missed this somewhere in the thread please forgive me.
After reading and re-reading this thread (very informative but soooo long), many thanks for all the valuable info and knowledge thats been contributed. I'm just about to start a build on an A9. I want to incorporate the mods by Geek Stuff. Does anyone have an opinion of what order to follow for the build? I'm thinking that I would wire in the components on the PCB first then the coax, followed by the transformer, AC, B+ etc. and finally the components from the valves to the PCB. Any help would be gratefully accepted. If I've missed this somewhere in the thread please forgive me.
Can anyone help me?
I finished my Boyuu A9 in accordance with the schematic and the help of a photo of the completed amp circuitry. There is a very loud hum a few seconds after switch on. All the heaters light up. The amp produces output when the volume is turned up. When I switch it off the hum disappears immediately and the sound continues for a short while.
Someone on youtube describes an identical problem. He got 3 engineers to look at his amp. The third one found the schematic to be wrong and fixed it. Does anyone here know what this error in the schematic is?
YouTube
I finished my Boyuu A9 in accordance with the schematic and the help of a photo of the completed amp circuitry. There is a very loud hum a few seconds after switch on. All the heaters light up. The amp produces output when the volume is turned up. When I switch it off the hum disappears immediately and the sound continues for a short while.
Someone on youtube describes an identical problem. He got 3 engineers to look at his amp. The third one found the schematic to be wrong and fixed it. Does anyone here know what this error in the schematic is?
YouTube
Some recent changes on my Boyuu A9 amp
Here are some recent changes on my Boyuu A9 amp: removal of two changes that have proved irrelevant in terms of improving sound quality:
- suppression of pseudo-triode/pentode switching,
- suppression of the global feedback and its switching on/off.
I also changed some of the original resistors by Vishay resistors and simplified and made certain parts of the wiring, including the balancing resistors of the 6.3-volt heating tubes, photos below :
Here are some recent changes on my Boyuu A9 amp: removal of two changes that have proved irrelevant in terms of improving sound quality:
- suppression of pseudo-triode/pentode switching,
- suppression of the global feedback and its switching on/off.
I also changed some of the original resistors by Vishay resistors and simplified and made certain parts of the wiring, including the balancing resistors of the 6.3-volt heating tubes, photos below :
Hello everyone, I purchased an A10 upgrade. I'm going to change 5z4p to PSVANE 274B PSVANE HIFI Serie 274B Rectifier Vacuum Tube HIFI EXQUIS Electron Lamp Equivalant 5U4 5U4G 5Z3P 5U3C-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group and power transformer from amplifier boyuu MT-88 (500w). Does anyone have any ideas on this see A10 and A9 amplifier circuits..
merge-from-ofoct-1 — imgbb.com
An externally hosted image should be here but it was not working when we last tested it.
Today, as I have just received my last order of components, it's time to change the latest Chinese resistors with Vishay's top quality resistors !
Final wiring,
Resistance of the ultra-linear connection,
Resistance and decoupling capacitors of 6SL7 tube cathode
And my work table ...
Final wiring,
Resistance of the ultra-linear connection,
Resistance and decoupling capacitors of 6SL7 tube cathode
And my work table ...
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Well, i think that the PSVANE 274B is a good tube, but it's too expansive ! Take a look to theses tubes : 5U4GT Only $24.99 Shu Guang 5U4GT( 5U4G) Tube 8PINS Tube Ceramic Gold Foot 1Piece Free Shipping-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
or a NOS tube, like the JAN 5R4WGB NOS 5R4WGB Rectifier Tubes - www.thetubestore.com
But why do you want to change the power transformer is, on this amp, a model of correct quality, and there is no change to expect from this change, by the way, it's almost the only thing I did not change on my Boyuu A9 amplifier !
Thanks for the help,
Thanks for the help,
274B is a good tube, but it is not too expansive
it is avant-garde, With the transformer "Boyuu" was greedy, it is designed for short-term operation of the amplifier, after two hours of work, the hand does not transfer heat from the transformer, and the supply voltage sags.
In this mode, the transformer you will not get a good return from the amplifier. It is a good power transformer.
Shu Guang 5U4GT bad lamps are considered.
400W Raphaelite New Power Transformer 6550 KT88 EL34 EL156 Push-Pull PW400AB-230 | eBay or
GZbotolave Raphaelite 400W power transformer 6550, KT88, EL34, EL156 push pull Tube buffer-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
Transformer-A10-400w — imgbb.com
Transformer-A10-400wt — imgbb.com
Hello !
On my Boyuu A9 amp, I do not have this phenomenon of power transformer too hot and the B + does not collapse after 2 hours ! And yet, I often listen to music all day long !
Normally, a power supply transformer heats a lot, as long as you can put your hand on it and leave it, there is nothing wrong.
Gidu
On my Boyuu A9 amp, I do not have this phenomenon of power transformer too hot and the B + does not collapse after 2 hours ! And yet, I often listen to music all day long !
Normally, a power supply transformer heats a lot, as long as you can put your hand on it and leave it, there is nothing wrong.
Gidu
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In the Soviet Union, transformers were designed for high power.
For reliability and stable operation of the equipment. When heated, we lose efficiency and stress.
Now they do it on the verge of possibility, the slightest overload and the transformer will smoke, the end of the music.
It is necessary to restore justice and increase the power of the transformer
Ah OK ! The heating of the power transformer also often depends on the mains voltage : at home, it does not exceed 230 Volts. But, in Russia, with a 220 Volts sector, the transformer should not overheat normally, unless frequent surges !
Despite this, I noticed that at certain times of the day, the amplifier, as well as the other components of my system, were more or less hot: I think that it comes from the variations of the tensions of the sector and the temperature of the room !
You will see to control the mains voltage !
Despite this, I noticed that at certain times of the day, the amplifier, as well as the other components of my system, were more or less hot: I think that it comes from the variations of the tensions of the sector and the temperature of the room !
You will see to control the mains voltage !
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I welcome like-minded people!
What to expect from a power transformer in an amplifier with the power it can produce on a 200 mA power winding.
for normal operation of the amplifier, only two EL34s require 200 m + for 2x6n2p
At a minimum, for normal operation of the amplifier, the secondary winding of the transformer should provide 300 mA.
300W Power Transformer 6550,300B Stabilized filament 2A3,KT88 Tube Buffer | eBay
What to expect from a power transformer in an amplifier with the power it can produce on a 200 mA power winding.
for normal operation of the amplifier, only two EL34s require 200 m + for 2x6n2p
At a minimum, for normal operation of the amplifier, the secondary winding of the transformer should provide 300 mA.
300W Power Transformer 6550,300B Stabilized filament 2A3,KT88 Tube Buffer | eBay
Harsh sounding mids
Hey Guys
I'm new here, my first post.
I just built my a9. After some difficulty. I finally got it working. I've been playing it for a week now. It sounds good at low volumes, however when i turn up the volume, the mids start to sound harsh, and it is not pleasant to the ear. Does anyone have any advice? Is this normal?
Greg
Hey Guys
I'm new here, my first post.
I just built my a9. After some difficulty. I finally got it working. I've been playing it for a week now. It sounds good at low volumes, however when i turn up the volume, the mids start to sound harsh, and it is not pleasant to the ear. Does anyone have any advice? Is this normal?
Greg
Hello, to have a good sound the lamps need to work 100 hours.
I had what you described, now the music sounds great. I have a Boyuu A10 month.