Hello there,
I am currently working in China and I am thinking to visit the factory producing this amp US line 6P6P 10W + 10W super linear push pull tube amplifier, CLC filter, S / N up to 108db|Transformers| - AliExpress
It seems they are taking care of finding right components, but I am not an engineer so my knowledge is always limited, does people here have an opinion on this ?
They also have one similar with a closed box design.
I find it interesting these small chinese companies making vintage circuitry design come alive.
I am currently working in China and I am thinking to visit the factory producing this amp US line 6P6P 10W + 10W super linear push pull tube amplifier, CLC filter, S / N up to 108db|Transformers| - AliExpress
It seems they are taking care of finding right components, but I am not an engineer so my knowledge is always limited, does people here have an opinion on this ?
They also have one similar with a closed box design.
I find it interesting these small chinese companies making vintage circuitry design come alive.
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If you decide to purchase one of these, and take it home with you . . .
Be sure to get the amplifier's Power Transformer Primary Voltage rating the same as your
Home Power Mains Voltage rating.
110V does not work on 220V
220V does not work on 110V
Be sure to get the amplifier's Power Transformer Primary Voltage rating the same as your
Home Power Mains Voltage rating.
110V does not work on 220V
220V does not work on 110V
Yes I know this. I am from europe where we use usually 220V.
For this reason i avoid 110V, this makes a messy setup for me.
No opinion based on this amp ? I think i can even ask them to modify it if you see any dark points.
For this reason i avoid 110V, this makes a messy setup for me.
No opinion based on this amp ? I think i can even ask them to modify it if you see any dark points.
Hello from Greece! This amp has a design problem! I see in photo two big metal resistors very close to pcb! I think these resistors is cathode bias of final tubes! After a few hours gets very hot,and burn the pcb. It is dangerous to use this amp! Do not buy this crap !
Personally, not so much because of the placement of the metal resistors as pointed out by xenofonn, but I wouldn't because, well... that looks to my untrained eye to be a plastic chassis that all this is mounted on.
Look at the other shots on the aliexpress. I mean I could be wrong...
I like my Chinese amplifier chassis to be made of metal for that price.
Look at the other shots on the aliexpress. I mean I could be wrong...
I like my Chinese amplifier chassis to be made of metal for that price.
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the wiring too leaves a lot to be desired for. It does not take much to carry out neat wiring. In particular I see, what looks like tube filament wiring, which I assume is AC, being routed under and over what looks like power supply wiring as well as signal wiring, that is a BIG NO NO! And yes, plastic chassis, not at all good!
You'd be better off to safe your money and buy an amp made in Europe or the USA, you would definitely get your monies worth!
My advise, do not touch this with a ten foot pole!!
You'd be better off to safe your money and buy an amp made in Europe or the USA, you would definitely get your monies worth!
My advise, do not touch this with a ten foot pole!!
You can buy the PCB yourself and populate it, then get a suitable chassis and iron. There are many versions of this same PCB floating all over the eastern e-commerce sites from time to time. It's nothing special, and is based on this old schematic- it's a basic floating paraphase Dynaco A410.
I also posted my proposed changes to the circuit.
I also posted my proposed changes to the circuit.
Attachments
Very good advises here!
Only one point I can add, a simple but not unimportant one:
In Europe the voltage in now for many years on 230V.
Caisson,
Another option is this design, which I built last April... It has similar 12W per channel, but half the price. Good starting point for new interest, with room to improve.
I've changed this design 3 times, using same mounting chassis and transformers... it currently has the Dynaco ST35 design in it.
Jim
HiFi 6P1 Vacuum Tube Power Amplifier Class AB Push-pull Stereo Audio Amp 12W+12W | eBay
Attachments
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Lingwendil,
The Dyna circuit you posted is a good one.
EL84 Pentode tubes, or 6V6 Beam Power tubes.
Good idea . . .
You added a CCS (Constant Current Sink) for the input triodes.
That gets rid of the 2nd Harmonic that is not cancelled by an "LTP" resistor.
It makes the negative feedback's 'cleanup job' easier.
The Dyna EL84 and 6V6 use an Ultra Linear Output transformer. That makes both the linearity better, and the output impedance be lower, before negative feedback is even applied.
You chose to use Pentode mode for the EL84, Beam Power mode for the 6V6.
That means you do not have to have Ultra Linear taps on the output transformer. Gives more flexibility of output transformers to use
(Well, not all output transformers are stable with negative feedback, and perhaps more of a problem with pentode and beam power modes).
But both the gain of Pentode and Beam Power, and output impedance of Pentode and Beam Power are higher than UL mode.
And that makes it more difficult to properly adjust the negative feedback compensation.
It is simply a tradeoff . . . degree of difficulty.
Some output transformers are much harder to make the negative feedback stable, especially in the high gain Pentode and Beam Power modes.
Of course people do that all the time.
But sometimes there are threads on this forum asking for help to compensate negative feedback for pentode, beam power, and even UL modes.
The Dyna circuit you posted is a good one.
EL84 Pentode tubes, or 6V6 Beam Power tubes.
Good idea . . .
You added a CCS (Constant Current Sink) for the input triodes.
That gets rid of the 2nd Harmonic that is not cancelled by an "LTP" resistor.
It makes the negative feedback's 'cleanup job' easier.
The Dyna EL84 and 6V6 use an Ultra Linear Output transformer. That makes both the linearity better, and the output impedance be lower, before negative feedback is even applied.
You chose to use Pentode mode for the EL84, Beam Power mode for the 6V6.
That means you do not have to have Ultra Linear taps on the output transformer. Gives more flexibility of output transformers to use
(Well, not all output transformers are stable with negative feedback, and perhaps more of a problem with pentode and beam power modes).
But both the gain of Pentode and Beam Power, and output impedance of Pentode and Beam Power are higher than UL mode.
And that makes it more difficult to properly adjust the negative feedback compensation.
It is simply a tradeoff . . . degree of difficulty.
Some output transformers are much harder to make the negative feedback stable, especially in the high gain Pentode and Beam Power modes.
Of course people do that all the time.
But sometimes there are threads on this forum asking for help to compensate negative feedback for pentode, beam power, and even UL modes.
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oemcar,
For a low cost kit, the amp seems pretty good.
That amplifier appears to have output transformers with Ultra Linear taps.
But you mention doing 3 versions on that amplifier chassis, correct?
PCBs make it easier to wire a kit.
But PCBs make it harder to do modifications to the amp.
Was the chassis on that amplifier Aluminum, or Magnetic Steel?
For a low cost kit, the amp seems pretty good.
That amplifier appears to have output transformers with Ultra Linear taps.
But you mention doing 3 versions on that amplifier chassis, correct?
PCBs make it easier to wire a kit.
But PCBs make it harder to do modifications to the amp.
Was the chassis on that amplifier Aluminum, or Magnetic Steel?
wooo thanks for all these replies. I go on this forum before when i search some things but first time to post. It is filled with a lot of enthusiats : )
I checked on the chinese internet yes this amp from oemcar is cheap, 90 usd in china. they have a lot of variations with the same chassis, 6p6p6, hcel34, kt88, 6h9...
I was just asking, and seems i was right. Maybe not worth the airplane ticket to go to visit this factory. I well aware of companies like yaqin or line magnetic, but there is tons of smaller less knowns ones, and as product designer, it is not always clear what makes a good and expensive amplifier to me (cost of the labor i get it, but as i lake the electricity background i am missing out a big part). As far as i see, most of them are folded sheets of metal means the tooling is very cheap for them, means any small brands can make an amplifier.
this is their most expensive one following the same chassis
Nouveau garanti 100% 6N8P + KT88 tube a vide unique classe A pur tube audio amplificateur de puissance Kit de bricolage | AliExpress
But I am aware that a Jadis amplifier should be better than those cheap beasts but It's not always clear cut for me why the price can be more than x10 x20. (I said Jadis because i am french...)
I checked on the chinese internet yes this amp from oemcar is cheap, 90 usd in china. they have a lot of variations with the same chassis, 6p6p6, hcel34, kt88, 6h9...
I was just asking, and seems i was right. Maybe not worth the airplane ticket to go to visit this factory. I well aware of companies like yaqin or line magnetic, but there is tons of smaller less knowns ones, and as product designer, it is not always clear what makes a good and expensive amplifier to me (cost of the labor i get it, but as i lake the electricity background i am missing out a big part). As far as i see, most of them are folded sheets of metal means the tooling is very cheap for them, means any small brands can make an amplifier.
this is their most expensive one following the same chassis
Nouveau garanti 100% 6N8P + KT88 tube a vide unique classe A pur tube audio amplificateur de puissance Kit de bricolage | AliExpress
But I am aware that a Jadis amplifier should be better than those cheap beasts but It's not always clear cut for me why the price can be more than x10 x20. (I said Jadis because i am french...)
One thing to decide is whether you want a single ended amplifier, or a push pull amplifier.
The Noveau garanti 100% 6N8P + KT88 is single ended.
Most of the amplifiers on this thread are push pull.
The Noveau garanti 100% 6N8P + KT88 is single ended.
Most of the amplifiers on this thread are push pull.
To me this looks good engineering. The cathode resistor is large size 5 W wire wound 250 ohms resistor. It dissipates some 1.6 W only (20 V x 80 mA).
How would you do this ?
If people are having some debats here i try to reproduce the full description.
The shop is also selling some lundhal tranformers, so this is how i thought they are not a usual cheap/crap shop that can be found sometimes.
United States Dynaco line 6P6P 10W + 10W super linear push-pull tube amplifier
Dynaco 6V6 super linear circuit, 2 GE universal 6SL7 electron tubes of the United States amplify inverted push-pull output, and push 4 Shuguang 6P6P electron tubes.
Dynaco 6V6 circuit is classic and cleverly designed. The 6N9P tube has two functions, which is both voltage amplification and automatic balance inversion, and the 1K resistor is the finishing touch. This resistor is not only the 6N9P's cathode bias resistance, but also constitutes an inversion with the secondary of the output transformer The tail of the stage is also the negative feedback resistance of the loop! The combination of three functions saves parts and reduces additional noise and distortion.
The power stage uses a super linear (UL) structure, which takes into account the balance between efficiency and distortion. After a slight modification, the output power can reach 10W, THD = 0.4%, and the damping is greater than 4.0. With such simple indicators, it is truly outstanding!
The power supply is also unambiguous. With the use of CLC filtering, the overall S / N can be as high as -108db A weighted (absolute residual noise voltage 170uV). The low noise floor is basically that the ears are close to the horn and it is difficult to hear a little noise. Moreover, the 6 tube filaments are all AC-powered, full of warm bile.
Exquisite FR4 double-sided glass fiber plate gold-plated plate, thickness 2mm. Excellent circuit performance, equipped with gold-plated socket, 25W aluminum shell cathode resistance, Japanese ruby electrolytic, Dutch electrolytic, German Weimar capacitor cross-connect, precision five-ring resistance, Japanese chemical or ELNA supplement electrolytic. The wiring is reasonable and the line is quiet.
Germany 270μ450V electrolytic first-stage filtering. 2.8H 300MA choke. Wide frequency response ultra-linear push-pull 8K / 4 Euro 8 Euro output transformer, refer to the production of Shanghai Mido tube R10-2 amplifier output transformer.
Mido R10-2 high-fidelity amplifier, a domestically produced classic HIFI amplifier, was launched by Shanghai Radio No. 3 Factory in 1971. It was also the most representative high-fidelity tube amplifier at the time. The characteristics of the Mido R10-2 high-fidelity amplifier is that it does not hesitate to build Hi-Fi on the output transformer. The size of the output transformer and power transformer is generally the same, which is rare in the past tube audio. Not only is the material heavy, but the workmanship is very good and the sound is extraordinary. Mido R10-2 high-fidelity output transformer adopts the four-clamp three-winding method, uses a large cross-section iron core, increases the number of primary coil turns, and has a unique winding structure. Imported transformers of the same specifications.
Z11 iron core winding measurement system, 76 pieces stacked 30mm thick, iron cores inserted, nylon wire frame, high-quality oxygen-free copper enameled wire winding, 4 clamps 3, forward and reverse winding, layered and segmented winding, will leak leakage And distributed capacitance is reduced. 15W power, wide frequency response, great dynamics, and delicate sound! The effect is immediately visible!
When the parameters are measured at 1KHZ, the inductance of P1 and P2 is about 66H, the leakage inductance is about 74mH, and the distributed capacitance is 2300PF. The copper resistance of the primary P1 and P2 is about 429 ohms, the copper resistance of the secondary 4 ohms is about 0.5 ohms, and the copper resistance of 8 ohms is about 0.6 ohms.
The power transformer EI86 is 45mm thick, weighs 2.24Kg, and has ample power headroom. Imported aluminum alloy knobs, solid aluminum machine feet, 23-step 100K stepping potentiometer, American CMC gold-plated RCA socket, Japan Furukawa gold-plated power socket, large electric crystal speaker terminals, fever.
German Weidmichn plastic engineering case length 400 width 250 height 120mm (excluding machine feet). It consists of an upper cover and a bottom cover, and is made of cold-rolled iron plates.
The machine weighs about 9.9kg.
Dynaco Dynaco is an old-fashioned audio manufacturer born in the United States in the late 1950s. During the heyday of the vacuum tube, Dynaco once introduced the SCA35 pre-stage, Stereo30 and Stereo70 post-stage, which became the design basis for a series of Dynaco's future products. After 1966, the transistor became a trendy gadget, and Dynaco also had to launch the SCA80 and Stereo120 rear stages to cater to the market. Unexpectedly, it became the main cause of the company's airless injuries in the future. Dynaco has changed hands several times since then, but the traditional "bold" sound style has not changed. Today's Dynaco products, despite using modern production technology, still adhere to their traditional circuit design. In addition, they also insist on the civilian route that is not expensive, and use the internal design as much as possible, and do not waste more on the appearance. Although the black case is inconspicuous, it is a simple and nice product in the eyes of the wise people.
The shop is also selling some lundhal tranformers, so this is how i thought they are not a usual cheap/crap shop that can be found sometimes.
United States Dynaco line 6P6P 10W + 10W super linear push-pull tube amplifier
Dynaco 6V6 super linear circuit, 2 GE universal 6SL7 electron tubes of the United States amplify inverted push-pull output, and push 4 Shuguang 6P6P electron tubes.
Dynaco 6V6 circuit is classic and cleverly designed. The 6N9P tube has two functions, which is both voltage amplification and automatic balance inversion, and the 1K resistor is the finishing touch. This resistor is not only the 6N9P's cathode bias resistance, but also constitutes an inversion with the secondary of the output transformer The tail of the stage is also the negative feedback resistance of the loop! The combination of three functions saves parts and reduces additional noise and distortion.
The power stage uses a super linear (UL) structure, which takes into account the balance between efficiency and distortion. After a slight modification, the output power can reach 10W, THD = 0.4%, and the damping is greater than 4.0. With such simple indicators, it is truly outstanding!
The power supply is also unambiguous. With the use of CLC filtering, the overall S / N can be as high as -108db A weighted (absolute residual noise voltage 170uV). The low noise floor is basically that the ears are close to the horn and it is difficult to hear a little noise. Moreover, the 6 tube filaments are all AC-powered, full of warm bile.
Exquisite FR4 double-sided glass fiber plate gold-plated plate, thickness 2mm. Excellent circuit performance, equipped with gold-plated socket, 25W aluminum shell cathode resistance, Japanese ruby electrolytic, Dutch electrolytic, German Weimar capacitor cross-connect, precision five-ring resistance, Japanese chemical or ELNA supplement electrolytic. The wiring is reasonable and the line is quiet.
Germany 270μ450V electrolytic first-stage filtering. 2.8H 300MA choke. Wide frequency response ultra-linear push-pull 8K / 4 Euro 8 Euro output transformer, refer to the production of Shanghai Mido tube R10-2 amplifier output transformer.
Mido R10-2 high-fidelity amplifier, a domestically produced classic HIFI amplifier, was launched by Shanghai Radio No. 3 Factory in 1971. It was also the most representative high-fidelity tube amplifier at the time. The characteristics of the Mido R10-2 high-fidelity amplifier is that it does not hesitate to build Hi-Fi on the output transformer. The size of the output transformer and power transformer is generally the same, which is rare in the past tube audio. Not only is the material heavy, but the workmanship is very good and the sound is extraordinary. Mido R10-2 high-fidelity output transformer adopts the four-clamp three-winding method, uses a large cross-section iron core, increases the number of primary coil turns, and has a unique winding structure. Imported transformers of the same specifications.
Z11 iron core winding measurement system, 76 pieces stacked 30mm thick, iron cores inserted, nylon wire frame, high-quality oxygen-free copper enameled wire winding, 4 clamps 3, forward and reverse winding, layered and segmented winding, will leak leakage And distributed capacitance is reduced. 15W power, wide frequency response, great dynamics, and delicate sound! The effect is immediately visible!
When the parameters are measured at 1KHZ, the inductance of P1 and P2 is about 66H, the leakage inductance is about 74mH, and the distributed capacitance is 2300PF. The copper resistance of the primary P1 and P2 is about 429 ohms, the copper resistance of the secondary 4 ohms is about 0.5 ohms, and the copper resistance of 8 ohms is about 0.6 ohms.
The power transformer EI86 is 45mm thick, weighs 2.24Kg, and has ample power headroom. Imported aluminum alloy knobs, solid aluminum machine feet, 23-step 100K stepping potentiometer, American CMC gold-plated RCA socket, Japan Furukawa gold-plated power socket, large electric crystal speaker terminals, fever.
German Weidmichn plastic engineering case length 400 width 250 height 120mm (excluding machine feet). It consists of an upper cover and a bottom cover, and is made of cold-rolled iron plates.
The machine weighs about 9.9kg.
Dynaco Dynaco is an old-fashioned audio manufacturer born in the United States in the late 1950s. During the heyday of the vacuum tube, Dynaco once introduced the SCA35 pre-stage, Stereo30 and Stereo70 post-stage, which became the design basis for a series of Dynaco's future products. After 1966, the transistor became a trendy gadget, and Dynaco also had to launch the SCA80 and Stereo120 rear stages to cater to the market. Unexpectedly, it became the main cause of the company's airless injuries in the future. Dynaco has changed hands several times since then, but the traditional "bold" sound style has not changed. Today's Dynaco products, despite using modern production technology, still adhere to their traditional circuit design. In addition, they also insist on the civilian route that is not expensive, and use the internal design as much as possible, and do not waste more on the appearance. Although the black case is inconspicuous, it is a simple and nice product in the eyes of the wise people.
Caisson,
Was Post #16 a cut and paste from Chinese advertisement for this amplifier? Some hints are the description full of references to products from other countries- this is common to Chinese tube amps marketed in US...maybe elsewhere...I have to ask- Why is this? A topic for another thread perhaps.
The below cutout is comical (at least to me it was)-
Bile is a digestive enzyme produced in the liver.. not sure what that has to do w/ amp description unless online translator times spell check equals indigestion...IDK.
Another thing I don't get is:
'German Weidmichn plastic engineering case length 400 width 250 height 120mm (excluding machine feet). It consists of an upper cover and a bottom cover, and is made of cold-rolled iron plates.'
So is the enclosure plastic or 'cold rolled iron plates'?...Putting a tube amp in a plastic enclosure gives ME indigestion...LMAO
Jim
Was Post #16 a cut and paste from Chinese advertisement for this amplifier? Some hints are the description full of references to products from other countries- this is common to Chinese tube amps marketed in US...maybe elsewhere...I have to ask- Why is this? A topic for another thread perhaps.
The below cutout is comical (at least to me it was)-
Bile is a digestive enzyme produced in the liver.. not sure what that has to do w/ amp description unless online translator times spell check equals indigestion...IDK.
Another thing I don't get is:
'German Weidmichn plastic engineering case length 400 width 250 height 120mm (excluding machine feet). It consists of an upper cover and a bottom cover, and is made of cold-rolled iron plates.'
So is the enclosure plastic or 'cold rolled iron plates'?...Putting a tube amp in a plastic enclosure gives ME indigestion...LMAO
Jim
Six A three-
No sir- Original OT iron are 5k pri's w/ no UL taps.
On 3 versions, correct-
1. Original 6P1 / 6F2 Chifi,, complete w/ 'indigestion' talking points.
2. Audio Note ANK EL84 (rev E)
3. Dynaco ST-35 (First incursion into Triode preamp)
To implement-
Mapped tube socket locations onto PCB's... then added new schematic layout.
Changed, removed, added components... Modd'ed PC lines to generate Revised final boards, so that when final design PCB is populated... and I post pics here, hopefully you wont laugh...
as much
Chassis is 1mm non ferrous Stainless Steel.
Jim