I am thinking of building this amp but using the EL34.
http://diyaudioprojects.com/Schematics/Mikael-Abdellah-SE-KT88-Amplifier.htm
I am attracted to the simple topology yet being a bit green I still have a few questions:
1. Is there a way to optimize this circuit for the EL34? Would it need a change in the cathode resistor?
2. Could I use the lower cost Hammond OPT's (125 SE I beleive) and how would I connect them to an EL34 for triode operation?
3. Which Hammond 200 series Power Trans would be the best for this circuit using the power supply circuit shown in Alex's build:
http://diyaudioprojects.com/Tubes/KT88/
http://diyaudioprojects.com/Schematics/Mikael-Abdellah-SE-KT88-Amplifier.htm
I am attracted to the simple topology yet being a bit green I still have a few questions:
1. Is there a way to optimize this circuit for the EL34? Would it need a change in the cathode resistor?
2. Could I use the lower cost Hammond OPT's (125 SE I beleive) and how would I connect them to an EL34 for triode operation?
3. Which Hammond 200 series Power Trans would be the best for this circuit using the power supply circuit shown in Alex's build:
http://diyaudioprojects.com/Tubes/KT88/
....help me decipher this?
Looks like a well designed circuit- has pretty much a detailed explanation of all the parts I would need. However, the schematic is a bit fuzzy so some of the values and more importantly- the way the output tube is wired- is hard to understand. Could someone help me decipher this?
http://angela.com/stereosingle-endedel34hi-fiamplifier.aspx
-Also, what the hell is up with the lug numbers on the driver tube? It looks like it uses two 6SL7's? Can someone better explain this circuit?
-This next question may seem really newbie but if a circuit calls for 100uf 25v but you can only find 100uf 50v, will that still be OK?
Looks like a well designed circuit- has pretty much a detailed explanation of all the parts I would need. However, the schematic is a bit fuzzy so some of the values and more importantly- the way the output tube is wired- is hard to understand. Could someone help me decipher this?
http://angela.com/stereosingle-endedel34hi-fiamplifier.aspx
-Also, what the hell is up with the lug numbers on the driver tube? It looks like it uses two 6SL7's? Can someone better explain this circuit?
-This next question may seem really newbie but if a circuit calls for 100uf 25v but you can only find 100uf 50v, will that still be OK?
While the schematic is not the clearest I can read it fine. Try zooming in using your browser.
For Triode operation you simply wire a 100 ohm 1/2Watt Carbon Composition resistor between pins 3 and 4 as per the schematic.
Driver tube numbers have one by itself and another in brackets E.g. 1 (1).
The reason is because the driver tube which is a 6SL7 is a dual triode, IOW two triode tubes in the same bottle so pin 3 would denote the cathode of lets say triode number one and (3) is the cathode of triode number 2. The Anode and Grid both have the same pin system and the filaments are shared by both triodes.
A 100uF@50V will always be safe to substitute for a 100uF@25V. IOW a higher voltage capacitor is safe but going the other way is trouble.
Before you go any further with any build I suggest you read up some more on Vacuum tube circuits or get someone who is familiar with them to help you.
Morgan Jones has a good book on the subject.
For Triode operation you simply wire a 100 ohm 1/2Watt Carbon Composition resistor between pins 3 and 4 as per the schematic.
Driver tube numbers have one by itself and another in brackets E.g. 1 (1).
The reason is because the driver tube which is a 6SL7 is a dual triode, IOW two triode tubes in the same bottle so pin 3 would denote the cathode of lets say triode number one and (3) is the cathode of triode number 2. The Anode and Grid both have the same pin system and the filaments are shared by both triodes.
A 100uF@50V will always be safe to substitute for a 100uF@25V. IOW a higher voltage capacitor is safe but going the other way is trouble.
Before you go any further with any build I suggest you read up some more on Vacuum tube circuits or get someone who is familiar with them to help you.
Morgan Jones has a good book on the subject.
I understand that the 6SL7 is a dual triode, I just don't get how it is wired in this circuit... is the second triode in the tube wired at all? For example, are both pins 3 AND 6 connected to one cathode resistor? If I knew this I could build this circuit...
Also... Does anyone see a problem with running some old Tung-Sol 5881's in this circuit? Or 6l6's?
Also... Does anyone see a problem with running some old Tung-Sol 5881's in this circuit? Or 6l6's?
You know, if you're willing to build a little negative supply, either of these designs (they're very similar) will sound and perform much better with negative supply ('fixed') bias. Post me privately if you want a picture of how to do this. If everybody in the thread asks, I'll put it up here. I am a very big exponent of fixed bias.
Aloha,
Poinz
AudioTropic
Aloha,
Poinz
AudioTropic
ambience exists said:
Andrewbee said:
RTFQ
If you read the schematic, there is an asterisk next to the 6SL7. In the notes it says that the triodes on the 6SL7 are connected in parallel. So, you will have two driver tubes, one per channel. You connect both the plates, both the grids and both the cathodes together.Cheers,
Chris
----> Its all good man, thanks for the replies. Just for clarifications sake, that means that on the cathode for example, the resistor is soldered to lug 3 and then lug three is wired to lug 6? Why is there different lug numbers for the above tube then? If you zoom in on the schematic the numbers for the cathode lugs seem to be different then the bottom tube. Is this just a schematic mistake? It is handwritten so that makes it a bit unclear.
Any word on whether those 5881's would work?
I think that the Angela JE Labs circuit is going to be my build with Edcor GSXE's. The circuit says to use 2.5k primary. Should I buy the 8 Ohm output to fit most speakers?
Any word on whether those 5881's would work?
I think that the Angela JE Labs circuit is going to be my build with Edcor GSXE's. The circuit says to use 2.5k primary. Should I buy the 8 Ohm output to fit most speakers?
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