Hi everyone!
I am building a 01A preamp using Ale Moglias circuit and gyrator boards 01a Preamp (Gen2) – Bartola(R) Valves
I am having problems with my gyrator boards. I already have four (4) boards and it seems only one is working (working board not pictured)
I had read and followed Ale's excellent build guide but I think the problem is me. I cannot figure out why using J310 the board does not work. The one that is working has a zener across the J310 position
When it is working, without an anode load, I can change the voltage across R6 by turning P1. With an anode load, 22k Ohms and B+ about 120 Vdc, I can change the voltage across the load through P1.
I have replaced the semiconductors on the non-working boards at least twice already. With the zener across J310, and voltage can be adjusted, I incorporate the board in the circuit (left channel) and then it does not work even if I increased the filament voltage. I then interchange the R channel working board to the L channel non-working board, and confirmed that it is not the channel circuits.
Is there something that I am forgetting not to do? Why is it that using J310 in the J310 slot does not work?
Here's a shot of the board installed in the preamp circuit
if you look at the top left inscription, I have started building this since 2017 but got sidetracked for a while 🙂
Abe
I am building a 01A preamp using Ale Moglias circuit and gyrator boards 01a Preamp (Gen2) – Bartola(R) Valves
I am having problems with my gyrator boards. I already have four (4) boards and it seems only one is working (working board not pictured)
I had read and followed Ale's excellent build guide but I think the problem is me. I cannot figure out why using J310 the board does not work. The one that is working has a zener across the J310 position
When it is working, without an anode load, I can change the voltage across R6 by turning P1. With an anode load, 22k Ohms and B+ about 120 Vdc, I can change the voltage across the load through P1.
I have replaced the semiconductors on the non-working boards at least twice already. With the zener across J310, and voltage can be adjusted, I incorporate the board in the circuit (left channel) and then it does not work even if I increased the filament voltage. I then interchange the R channel working board to the L channel non-working board, and confirmed that it is not the channel circuits.
Is there something that I am forgetting not to do? Why is it that using J310 in the J310 slot does not work?
Here's a shot of the board installed in the preamp circuit
if you look at the top left inscription, I have started building this since 2017 but got sidetracked for a while 🙂
Abe
There is nothing about J310 (J3) in the schematic you have posted. What do the instructions say about J310 (J3)?
On the third photo you soldered in a 1M resistor as R6 instead of a 4.7M resistor.
On the third photo you soldered in a 1M resistor as R6 instead of a 4.7M resistor.
Hello EL504!
The build guide says:
If you are using an LSK170 or 2SK170 device for J1, then you need to place on the pads labeled “2SK170”. The flat side will face to the gate stopper resistor R3.
If you are using the 2N7000 in TO-92 case, you will need to mount it in place of the 2SK170 (J1) but you need to invert the orientation. This means, flat side opposite to the 2SK170 mask drawing. If you’re using instead a J310, then you simply solder it in J3 position marked as “J310”. The flat part needs to face to the Rmu resistor.
Does this means with the 2SK170 in place, then J3 is not needed?
Build guide, depending on C1 use, says:
The low frequency response is primarily driven by the RC pair R6 and C1. Typically, I’d use the following combinations: 4.7MΩ and 220nF or 10M and 100nF.
My C1 is 0.22 uF.
Abe
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A quick search learns me that a J310 is a transistor. Than why you soldered in a (zener) diode at J3?
The part of the instructions you posted tell me that if you use the 2SK170, you should not solder in anything at J3. But i do not know the rest of the instructions so i can not be sure.
The part of the instructions you posted tell me that if you use the 2SK170, you should not solder in anything at J3. But i do not know the rest of the instructions so i can not be sure.
Hello El504,
Thanks for the reply!
I am trying to look for the post that Ale Moglia made on why install a diode in that location, but still searching.
Abe
I will take the diode out and try it again tomorrow as I cannot find the post. I believe that I read the instructions wrong.
Thanks again for your help!
Abe
Thanks again for your help!
Abe
I finally solved the problem on my preamp. I replaced the LND150 and it seems to work now. Some of the problems, L channel, seems to be tube related as well, replaced, and the circuit starts to behave well.
I now have about 116.0 V at the anode, about 3 mA current, and about 3.5 volts across filaments for the 301A's.
Preamp sounds great but too early to make a comparison with my Type 26. I find the type 26 an excellent preamp so I'll see how my 01A's compares to it.
Abe
I now have about 116.0 V at the anode, about 3 mA current, and about 3.5 volts across filaments for the 301A's.
Preamp sounds great but too early to make a comparison with my Type 26. I find the type 26 an excellent preamp so I'll see how my 01A's compares to it.
Abe