it depends how much dynamics your loudspeakers need.
The el34 is the smoothest tube in PP, I love it, the eico is a fine design, however you would have the rebuild the interior if you buy a used one.
The el34 is the smoothest tube in PP, I love it, the eico is a fine design, however you would have the rebuild the interior if you buy a used one.
Well, i got a pair of Acro TO 350 , which is almost the same as the to 330, that i should pass it on to someone who would put it to use. If you live in the states shipping would be relatively inexpensive and they would allow you to use the original circuit, mostly.
You know..Slovakia is literaly the middle of europe. So I guess not xD And I dont have the finances at all to get myself other output transformers. I will use the original schematic anyways, because I think it will work good with the toroidal transformer. I think the toroidal transformer has better coupling so it should be even better. Everything else can be set with a EQ at the input so im not too worried about it not really sounding right.
The original EL34s were rated 800V on the plates.
There are enough ~~500V guitar amps that any new-made EL34 should stand 500V easily.
According to datasheet it should work. I currently own EL34s that are made at Shuguang factory. I dont know how much are these tube good in terms of quality. Optinally I live where JJ tubes are manufactured so getting those tubes wont be a big deal. The reason why I got the shuguang made ones because they are still cheaper shipped from china than the local production. If I would have the finances I would absolutely get the local tubes but you know how it goes.
What kind of realistic amounth of power could I get by powering the tubes at 500V anode voltage and with a 6k6 transformer?
If I would have bought the amplifier, it would be understandable that after all those years the entire interrior has to get gut out, or at least the capacitors.
However im not buying the amplifier, Im building it from the ground up. Dont have the original amplifier , but im going to build one. Granted its not going to sound like the real HF50 or HF60 because im going to use a absolutely different transformer (toroidal), hopefully even better more balanced than the opriginal. Im going to practically copy the schematic of the amplifier and put a different transformer in that is meant for EL34PP amplifier circuits. I excpet that I will have to modify the circuit to get it 100% working.
What kind of realistic amounth of power could I get by powering the tubes at 500V anode voltage and with a 6k6 transformer?
If I would have bought the amplifier, it would be understandable that after all those years the entire interrior has to get gut out, or at least the capacitors.
However im not buying the amplifier, Im building it from the ground up. Dont have the original amplifier , but im going to build one. Granted its not going to sound like the real HF50 or HF60 because im going to use a absolutely different transformer (toroidal), hopefully even better more balanced than the opriginal. Im going to practically copy the schematic of the amplifier and put a different transformer in that is meant for EL34PP amplifier circuits. I excpet that I will have to modify the circuit to get it 100% working.
toroidals cannot take much dc imbalance...
40 watts is realistic, build it in one case, take the original schematic and double the main caps, that should do it!
40 watts is realistic, build it in one case, take the original schematic and double the main caps, that should do it!
I will be using my powersupply. That I dont need much capactiance for because it stabilises itself. (I have made a SMPS specifically for vacuum tube power amplifiers). But I will most like get one of those 560V capacitors at 470uF anyways.
Here is another a question. In the schematic of the HF50/60 the phase inverter tube is a 6SN7. In the schematic of the HF52 they used the 6CG7. They seem to be practically the same tube but ina different glass and less power dissapation.
I was wondering if I coul modify the schematic so that it accepts a 12AX7 as a phase inverter. Or any noval current production tubes. (looking at the datasheet something like the 12BH7 should be a closer replacement for the 6CG7)
Would someone be kind enought to tell me how to modify the circuit so that it can accept the 12AX7 as the inverter?
Here is another a question. In the schematic of the HF50/60 the phase inverter tube is a 6SN7. In the schematic of the HF52 they used the 6CG7. They seem to be practically the same tube but ina different glass and less power dissapation.
I was wondering if I coul modify the schematic so that it accepts a 12AX7 as a phase inverter. Or any noval current production tubes. (looking at the datasheet something like the 12BH7 should be a closer replacement for the 6CG7)
Would someone be kind enought to tell me how to modify the circuit so that it can accept the 12AX7 as the inverter?
The original Mullard 5-20 circuit used a 12ax7 in the long tail pair inverter. Just do a search for it. However the Eico design is an improvement over the original design. The 6sn7 is a great tube for the inverter/driver and there are lots of NOS 6sn7 tubes to choose from. Why change a proven combination?
The 6SN7 sure is a great tube, but esthetically having one noval tube and three octal tubes does not go together well 😀 . Well and the price. Yeah the price also. I know shuguang offers 6SN7 tubes which cost 13 dollars. But visually they dont look the best. JJ 6SN7 are sure much better in every aspect. But theyre not cheap. I can still get to 12AX BH AU AT tubes cheaper than the decent 6SN7.
It is my only problem so yeah. My OCD just simply cannot take the look of a amplifier that has one small tube and three big tubes. (yeah that just sounded really dumb).
So I would like to change that tube to a different one. I am expecting something like a 12BH7 to be the closest to the 6SN7 (i dont really know).
It is my only problem so yeah. My OCD just simply cannot take the look of a amplifier that has one small tube and three big tubes. (yeah that just sounded really dumb).
So I would like to change that tube to a different one. I am expecting something like a 12BH7 to be the closest to the 6SN7 (i dont really know).
Yes youre right with that. BUT 6CG7 or 6FQ7 isnt produced in current factories anymore. That is why I want that change, to use current production tubes.
The ECC803s look good, but that will surely require modifications within the circuit?. Also, would it be really possible to use a 12AX7 or something along the lines? (12AX7, 12AU7 12BH7 12AT7, you get the point).
All of the vacuum tubes will be run with a separate stabilised DC powersupply exactly at 6,3V, no more, no less.
All of the vacuum tubes will be run with a separate stabilised DC powersupply exactly at 6,3V, no more, no less.
Well. It seems the thread is dieing. Im sorry for my stupidy of wanting to replace the 6SN7 with a noval tube that is still in production. Preferably any popular 12something7 tube. I am aware the amplifier wont sound as intended, maybe even underperform a slight bit. But I dont know how to modify the circuit to be able to even remotely put in such a vacuum tube.
Thank you for anyone who comes by and especially who can help and lets me know.
Thank you for anyone who comes by and especially who can help and lets me know.
CaterpilarSK,
Hope may not be lost.
If you look at the 6SN7 and the 12AU7, they have nearly identical specs at standard operating conditions of 90V plate, and of 250V plate. The 12AU7 filament can be wired for 6.3V, join pins 4 and 5 and connect to the 6.3V winding; and pin 9 to the other end of the 6.3V winding.
Some differences are:
12AU7 filament 6.3V @ 300 mA
6SN7 filament 6.3V at 600mA
12AU7 plate dissipation is 2.75 Watts
6SN7 plate dissipation is 5 Watts
Many amps that use a 6SN7 will not exceed the 12AU7 ratings. Generally, you will not have to change things like resistors, etc. Some say the 12AU7 is not very linear. Global Negative Feedback 'hides' distortion.I use 12AU7 without negative feedback. I must have bad ears, I enjoy amps that use them. I use ECC82 in those circuits. I purchase new production JJ ECC82.
Have fun.
Hope may not be lost.
If you look at the 6SN7 and the 12AU7, they have nearly identical specs at standard operating conditions of 90V plate, and of 250V plate. The 12AU7 filament can be wired for 6.3V, join pins 4 and 5 and connect to the 6.3V winding; and pin 9 to the other end of the 6.3V winding.
Some differences are:
12AU7 filament 6.3V @ 300 mA
6SN7 filament 6.3V at 600mA
12AU7 plate dissipation is 2.75 Watts
6SN7 plate dissipation is 5 Watts
Many amps that use a 6SN7 will not exceed the 12AU7 ratings. Generally, you will not have to change things like resistors, etc. Some say the 12AU7 is not very linear. Global Negative Feedback 'hides' distortion.I use 12AU7 without negative feedback. I must have bad ears, I enjoy amps that use them. I use ECC82 in those circuits. I purchase new production JJ ECC82.
Have fun.
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To say something sounds good is a purely subjective opinion. We cannot consider it as a form of judgement, measurement.
I did research the datasheets first and they look very similar. Not the same but similar. I have also gone trough multiple phase inverter circuits to see what are the differences and its really similar. The only thing to note the difference is the tube total dissapation. Im not worried about that because the phase inverter circuit shouldnt be really all that hard on the tube.
I would still prefer a 12AX7 over the 12AU7. The 12AX7 will most certainly need modifications done to the circuit (resistor values etc..). If someone could tell me how to modify the circuit so it can use a 12AX7 I would still prefer that over the 12AU7
I did research the datasheets first and they look very similar. Not the same but similar. I have also gone trough multiple phase inverter circuits to see what are the differences and its really similar. The only thing to note the difference is the tube total dissapation. Im not worried about that because the phase inverter circuit shouldnt be really all that hard on the tube.
I would still prefer a 12AX7 over the 12AU7. The 12AX7 will most certainly need modifications done to the circuit (resistor values etc..). If someone could tell me how to modify the circuit so it can use a 12AX7 I would still prefer that over the 12AU7
Is this not current production?
Welcome to TubeDepot.com!
I don't see why the 12BH7 could not me made to work though. Maybe someone smarter than I (not hard to find) can tell us why not.
Welcome to TubeDepot.com!
I don't see why the 12BH7 could not me made to work though. Maybe someone smarter than I (not hard to find) can tell us why not.
I did not see that. But knowing im from Slovakia the shipping will be a horrible money to pay.
The 12BH7 is a low gain tube. Much lower than the 6CG7/6SN7/12AU7.
It would probably require bith higher drive signal at the input of the amplifier to ge the desired output. To keep the same specification of the input level I would need to modify the voltage amplifier section which I really want to avoid.
I would only like to modify the inverter so I can use a 12AX7 preferably
The 12BH7 is a low gain tube. Much lower than the 6CG7/6SN7/12AU7.
It would probably require bith higher drive signal at the input of the amplifier to ge the desired output. To keep the same specification of the input level I would need to modify the voltage amplifier section which I really want to avoid.
I would only like to modify the inverter so I can use a 12AX7 preferably
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