I use an old desktop computer with an external soundcard and a free program to do some tube work, it's limited but works.
Hi everyone
Glad to see my post getting used whilst I have been away....lol
Well.........estimated delivery was 21st - 27th Jan and it turned up on 21st, which is just 3 days from Germany via DPD. So, a 10/10 for picking a decent courier. Only defect to the box was a small piece of tape hanging off. Double boxed, each box from triple walled cardboard and covered 100% in film and tape. Inside the box the chassis with all iron mounted was firmly held by high density foam, valves boxed and wrapped separately and all other components secured inside chassis. No movement inside box, everything packed tightly....another 10/10 for preparation.
Close inspection shows exactly what I expected and absolutely as it left the factory....no dinks, dents etc. 10/10 for item as described. Schematic included as promised and it does not seem too complex at first glance....no doubt I will have some questions.
So, at this point in time I am very happy with the £159 I have spent and feel that the trader has done everything to ensure I get what he advertised on time and in great shape. Time will tell as to sound quality, but I have a couple of things on the go right now so will not be starting it straight away.
Anyway, here's a few pics for you to see. Someone suggested that I hand draw the schematic for you guys to have a look at....I'm assuming this is to avoid infringing copyright? The seller is someone called DoukStore and he also seems to trade as DoukMall probably for the US market. He operates from China but also has a Euro warehouse in Germany which enabled me to order without any customs charges. I have no connection with him other than as a new customer.
Glad to see my post getting used whilst I have been away....lol
Well.........estimated delivery was 21st - 27th Jan and it turned up on 21st, which is just 3 days from Germany via DPD. So, a 10/10 for picking a decent courier. Only defect to the box was a small piece of tape hanging off. Double boxed, each box from triple walled cardboard and covered 100% in film and tape. Inside the box the chassis with all iron mounted was firmly held by high density foam, valves boxed and wrapped separately and all other components secured inside chassis. No movement inside box, everything packed tightly....another 10/10 for preparation.
Close inspection shows exactly what I expected and absolutely as it left the factory....no dinks, dents etc. 10/10 for item as described. Schematic included as promised and it does not seem too complex at first glance....no doubt I will have some questions.
So, at this point in time I am very happy with the £159 I have spent and feel that the trader has done everything to ensure I get what he advertised on time and in great shape. Time will tell as to sound quality, but I have a couple of things on the go right now so will not be starting it straight away.
Anyway, here's a few pics for you to see. Someone suggested that I hand draw the schematic for you guys to have a look at....I'm assuming this is to avoid infringing copyright? The seller is someone called DoukStore and he also seems to trade as DoukMall probably for the US market. He operates from China but also has a Euro warehouse in Germany which enabled me to order without any customs charges. I have no connection with him other than as a new customer.
Attachments
Be sure to use 63/37 (eutectic) solder, preferably the "no clean" type, and a decent temperature controlled soldering iron.
If you haven't soldered much, practice first on some old parts or pcbs before tackling the kit.
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Hi all
I expected the design to get torn to shreds, so I'll chalk up another 10/10 to the supplier. I was missing the transformer connection details and emailed them last night before going to bed. Lo and behold I have an email this morning with the drawings........well considering it's a weekend I reckon that's pretty marvellous customer service too....10/10. So far I'm mighty pleased with my dealings with this company.
As to the design I am a bit baffled as to why there are a pair of twin triodes as first stage. What is the benefit of wiring them in parallel as wont each half produce exactly the same output voltage? I'm assuming you mean that I could use one half of each and use the second half as another stage of voltage gain? If I did that would I not run the risk of driving the EL34's with too high a signal? I would clearly want to wire it as per design at first, but it's useful for my learning to understand other options.
If I have posed this question correctly then I have learnt something since placing the order....lol I'm ok with soldering....it's eyesight and shaky hands that are now the enemy!
I expected the design to get torn to shreds, so I'll chalk up another 10/10 to the supplier. I was missing the transformer connection details and emailed them last night before going to bed. Lo and behold I have an email this morning with the drawings........well considering it's a weekend I reckon that's pretty marvellous customer service too....10/10. So far I'm mighty pleased with my dealings with this company.
As to the design I am a bit baffled as to why there are a pair of twin triodes as first stage. What is the benefit of wiring them in parallel as wont each half produce exactly the same output voltage? I'm assuming you mean that I could use one half of each and use the second half as another stage of voltage gain? If I did that would I not run the risk of driving the EL34's with too high a signal? I would clearly want to wire it as per design at first, but it's useful for my learning to understand other options.
If I have posed this question correctly then I have learnt something since placing the order....lol I'm ok with soldering....it's eyesight and shaky hands that are now the enemy!
The benefit is twice the transconductance, half the noise, and half the source impedance..
Remember when soldering to heat the work, and flow the solder into the joint. Wetting the tip with a wee bit of solder first improves hear transfer to the joint. Obviously don't over do it either, a few seconds of heating should be sufficient unless it is a big joint. Get a good iron, 40 - 60W is generally good, even better if you can spring for a temperature controlled unit. I am not sure whether you are forced to use lead free solder (RoHS) or not for diy projects in the UK, but if you are get a little bit of flux to use along with it. Lead free tin alloy solders don't give you the same shiny look of SnPb solders. Alcohol and a small stiff (acid brush in the U.S) brush is ideal for cleaning residue off of pcb assemblies after soldering and is environmentally about as benign as you can get.
Remember when soldering to heat the work, and flow the solder into the joint. Wetting the tip with a wee bit of solder first improves hear transfer to the joint. Obviously don't over do it either, a few seconds of heating should be sufficient unless it is a big joint. Get a good iron, 40 - 60W is generally good, even better if you can spring for a temperature controlled unit. I am not sure whether you are forced to use lead free solder (RoHS) or not for diy projects in the UK, but if you are get a little bit of flux to use along with it. Lead free tin alloy solders don't give you the same shiny look of SnPb solders. Alcohol and a small stiff (acid brush in the U.S) brush is ideal for cleaning residue off of pcb assemblies after soldering and is environmentally about as benign as you can get.
This circuit isn't that unusual, for example Conrad Johnson has often done this in their equipment.
Paralleling tubes doubles the output current and halves the output impedance of the stage, while keeping the voltage gain the same.
You don't need that much gain if there is no feedback, but improved drive of the next tube is good.
Looks like you did good
As mentioned before, you could use one of the paralleled triode to make up for gain loss if you decide to modify the circuit with some global feedback. Feedback could help improve the performance of this amplifier.
Other than that maybe outfit the sockets with some grid stop resistors for peace of mind. The circuit is pretty straight forward and should be great for a beginner project. I hope you get many hours of enjoyment from building the amplifier.
Get building and start listening
As mentioned before, you could use one of the paralleled triode to make up for gain loss if you decide to modify the circuit with some global feedback. Feedback could help improve the performance of this amplifier.
Other than that maybe outfit the sockets with some grid stop resistors for peace of mind. The circuit is pretty straight forward and should be great for a beginner project. I hope you get many hours of enjoyment from building the amplifier.
Get building and start listening
Hey Mike,
The grid stop resistor forms a low pass filter with the input capacitance of the valve, look into "Miller Effect" for a better understanding.
Check out the stickies at the top page of "Tube and Valves", there is lots of good info including heater wiring basics: http://www.diyaudio.com/forums/tubes-valves/211731-heater-wiring-good-bad-ugly.html
The grid stop resistor forms a low pass filter with the input capacitance of the valve, look into "Miller Effect" for a better understanding.
Check out the stickies at the top page of "Tube and Valves", there is lots of good info including heater wiring basics: http://www.diyaudio.com/forums/tubes-valves/211731-heater-wiring-good-bad-ugly.html
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