Hi all
Just found this site after deciding I want to build a valve amp. I have chosen the following ebay offering: EL34 Single-ended Class A tube amplifier KIT for power stereo audio HIFI DIY | eBay
Am old enough to remember a battery portable valve radio in the house and also remember the transistor version that replaced it. Have had my fingers into everything electrical since the age of around 7. I don't have the patience to learn enough theory to design an amp, but understand the basic principles of operation of all the components. have a fluke DMM, hand held Velleman scope, bench supply etc and just added a variac for the first power up test. I know....another enthusiastic amateur....lol
Based on the component costs this seems like a bargain at under £200 posted from Germany. I'm soooooooooo tempted to press the button and buy it.....just wondered what your thoughts are, and if I were to post my step by step findings, would anyone be interested? (I get the cost and you get the laughs)
It would be for use in my workshop. Source would be a Fubar 4plus DAC/Headphone amp and currently JBL studio 1 speakers, although I would probably upgrade those if it sounded ok.
Cheers Mike
Just found this site after deciding I want to build a valve amp. I have chosen the following ebay offering: EL34 Single-ended Class A tube amplifier KIT for power stereo audio HIFI DIY | eBay
Am old enough to remember a battery portable valve radio in the house and also remember the transistor version that replaced it. Have had my fingers into everything electrical since the age of around 7. I don't have the patience to learn enough theory to design an amp, but understand the basic principles of operation of all the components. have a fluke DMM, hand held Velleman scope, bench supply etc and just added a variac for the first power up test. I know....another enthusiastic amateur....lol
Based on the component costs this seems like a bargain at under £200 posted from Germany. I'm soooooooooo tempted to press the button and buy it.....just wondered what your thoughts are, and if I were to post my step by step findings, would anyone be interested? (I get the cost and you get the laughs)
It would be for use in my workshop. Source would be a Fubar 4plus DAC/Headphone amp and currently JBL studio 1 speakers, although I would probably upgrade those if it sounded ok.
Cheers Mike
You can't really lose too much, so why not? The power output rating is realistic enough. The transformers seem pretty small.
Don't believe the power rating. A while back I got an assembled Chinese amp
AIQIN hifi exquis EL34 tube amps Single ended Class A handmade Scaffolding amplifier finished product Standard Black Edition-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
which circuit is much like the kit you are considering is described. It claims 10W in Triode connection mode, but actual measured is about 2.5W (at 5% distortion, mostly 2nd harmonic). I modeled its circuit in SPICE, and that is about all you can really expect given the transformer (not a huge lot more with ideal transformer, either).
That said, it sounds pretty nice with all the SET sound. I've been modding it, pushing it into A2 mode, but still expect only around 8W or so at best.
AIQIN hifi exquis EL34 tube amps Single ended Class A handmade Scaffolding amplifier finished product Standard Black Edition-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
which circuit is much like the kit you are considering is described. It claims 10W in Triode connection mode, but actual measured is about 2.5W (at 5% distortion, mostly 2nd harmonic). I modeled its circuit in SPICE, and that is about all you can really expect given the transformer (not a huge lot more with ideal transformer, either).
That said, it sounds pretty nice with all the SET sound. I've been modding it, pushing it into A2 mode, but still expect only around 8W or so at best.
I would like to see a schematic to make a fair assessment, for one the power output seems likely to be wrong so I don't know about the other specs, but for $200 the chassis tubes and iron make it worth it. Once you get the schematic you can hand draw it and post for the good people here to take a look before building. Sometimes the component values on these Chinese kits don't make any sense, you would think that the designers were competent but it's not the case a lot of the times.
I think this could be a fun project for you.......thumbs up from me
I think this could be a fun project for you.......thumbs up from me
Ok, the chassis and knobs are not as terrible as some of the older chinese amps I have seen. Hopefully the mains transformer is relatively quiet. I don't see any choke listed in the parts...
I doubt the output transformers will have any decent low frequency response. They are tiny, and any reasonably good single ended amplifier needs serious iron. I wouldn't use serious iron with EL34 though.
A global feedback loop will help low frequency response at the expense of transients and detail. I expect that is what is in the schematic.
6SL7 can drive EL34 single ended no problem. The problem is that it will sound like a HOT ROD, quickly go into clipping and not very musical..
Just being honest. I don't see much I would use in this kit.
I doubt the output transformers will have any decent low frequency response. They are tiny, and any reasonably good single ended amplifier needs serious iron. I wouldn't use serious iron with EL34 though.
A global feedback loop will help low frequency response at the expense of transients and detail. I expect that is what is in the schematic.
6SL7 can drive EL34 single ended no problem. The problem is that it will sound like a HOT ROD, quickly go into clipping and not very musical..
Just being honest. I don't see much I would use in this kit.
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The power out specs is fully unrealistic and those tiny OPT's just emhasize that fact. Assume some 5 W.
Thanks for all the responses which to be honest have been very constructive and largely supportive. I think I will have a go, as my main driver for buying it is because I love electronic construction projects and this one might even produce something I can use. It's only for my small workshop and the speakers are around 3 feet from me so I won't need a lot of power. The other bonus is that I think I will learn a lot in the process. I have bought 2 books to back up the project, both by Morgan Jones and I'm going to get a simple function generator (used from ebay) so that I can learn more about fault finding and measuring amp performance, both of which interest me loads.
I will order the kit today and when/if it arrives will post some pics of the contents as well as a copy of the schematic for you guys to have a look at. I'll also try to describe the quality of components for anyone else who might be thinking of a similar venture.
On a final note, my huge thanks for making me feel immediately welcome and please bear with me as my electronics knowledge is fairly basic
I will order the kit today and when/if it arrives will post some pics of the contents as well as a copy of the schematic for you guys to have a look at. I'll also try to describe the quality of components for anyone else who might be thinking of a similar venture.
On a final note, my huge thanks for making me feel immediately welcome and please bear with me as my electronics knowledge is fairly basic
Now look what you have all made me do !...Still it got rid of that annoying Paypal balance.
Since I can no longer be saved I guess you all know what is coming........ Anyway delivery from Germany is estimated to be between 21st - 27th Jan, but it does not say which year! I'll post some details as and when it arrives.
Glad my post is bringing some merriment to the proceedings. As for the scope it's just a basic 2Mhz hand held unit. I paid around £20 for it to enable me to trace audio signals. I'm hoping my basic tools will allow me to build this kit and then as my knowledge builds I will hopefully know what to chose in the way of more advanced test gear. Well, that's the plan anyway.
Since I can no longer be saved I guess you all know what is coming........ Anyway delivery from Germany is estimated to be between 21st - 27th Jan, but it does not say which year! I'll post some details as and when it arrives.
Glad my post is bringing some merriment to the proceedings. As for the scope it's just a basic 2Mhz hand held unit. I paid around £20 for it to enable me to trace audio signals. I'm hoping my basic tools will allow me to build this kit and then as my knowledge builds I will hopefully know what to chose in the way of more advanced test gear. Well, that's the plan anyway.
I'm surprised nobody mentioned it but does this "kit suitable for love" 
comes with schematics and/or instructions? I may have missed it but it's not mentioned in the listing. The advanced builders here can probably figure it out without them but since your title said "noob" if you don't have instructions nor schematics that will be a disappointing experience. And I believe that happens more often than you think with those Chinese kits...
comes with schematics and/or instructions? I may have missed it but it's not mentioned in the listing. The advanced builders here can probably figure it out without them but since your title said "noob" if you don't have instructions nor schematics that will be a disappointing experience. And I believe that happens more often than you think with those Chinese kits...
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