At the output, I’m now seeing
Left Channel
1.3mvAC/.5mvDC
Right Channel
1.3mvAC/.5mvDC
I did some wire cleaning.
Let’s see how it sounds…
Left Channel
1.3mvAC/.5mvDC
Right Channel
1.3mvAC/.5mvDC
I did some wire cleaning.
Let’s see how it sounds…
This is similar to your numbers you posted on post #98. Mostly the same.
Another tip which you have probably already checked: Make sure all your voltages on the actual Aikido circuit from a DC standpoint are also appropriate. Just to make sure there are no cold solder joints anywhere. The kit should have a guide for you or online from Broski's website info on Aikido Octal designs.
Best,
Anand.
Thanks. I have some “proper” air core inductors here that I use for crossovers.
Should hold up I suspect.
Should hold up I suspect.
Yeah, its just for safety if someone or something short the ground to blow the fuse or divert the current to the main 15 amps breaker and protect from fire, you don't want the tiny wire to fry and burn in case of some short , especially in tube amps
Hey.
I’m looking for the Akido schematic with the voltages, but am having no luck.
Does anyone have a link to this?
Thanks!
I’m looking for the Akido schematic with the voltages, but am having no luck.
Does anyone have a link to this?
Thanks!
You can use the chart in this manual:
https://www.audiofaidate.org/uploaded/lord_orione/Octal_Aikido_PCB.pdf
The upper and lower tubes always split whatever the B+ is. You can figure the cathode voltages by multiplying the cathode resistor times the current for that particular setting.
https://www.audiofaidate.org/uploaded/lord_orione/Octal_Aikido_PCB.pdf
The upper and lower tubes always split whatever the B+ is. You can figure the cathode voltages by multiplying the cathode resistor times the current for that particular setting.
Thanks!
I just went around every tube and measured DC at each pin relative to ground.
Left and right numbers are very close to each other. Just have to figure out how to organise the info for ease of presentation.
I just went around every tube and measured DC at each pin relative to ground.
Left and right numbers are very close to each other. Just have to figure out how to organise the info for ease of presentation.
Here are the voltages on the tubes
V1 and V3 are left
V2 and V4 are right
V1
G1 129.8
P1 264.6
C1 133.5
G2 0
P2 129.9
C2 3.61
V1
G1 130.3
P1 262.4
C1 130.3
G2 0
P2 129.9
C2 3.37
V3
G1 129.8
P1 264.5
C1 132.7
G2 .039
P2 130.1
C2 2.59
V4
G1 129.8
P1 264.3
C1 132.9
G2 .054
P2 130.3
C2 2.63
V1 and V3 are left
V2 and V4 are right
V1
G1 129.8
P1 264.6
C1 133.5
G2 0
P2 129.9
C2 3.61
V1
G1 130.3
P1 262.4
C1 130.3
G2 0
P2 129.9
C2 3.37
V3
G1 129.8
P1 264.5
C1 132.7
G2 .039
P2 130.1
C2 2.59
V4
G1 129.8
P1 264.3
C1 132.9
G2 .054
P2 130.3
C2 2.63
Good morning!
Look at your schematic on post #4. It would be MUCH easier if you can annotate that schematic with your DC voltages. And please be accurate about which tubes (i.e. in the above table, you’ve listed V1 twice).
Thanks,
Anand.
Look at your schematic on post #4. It would be MUCH easier if you can annotate that schematic with your DC voltages. And please be accurate about which tubes (i.e. in the above table, you’ve listed V1 twice).
Thanks,
Anand.
Very nice!
If you know the values of R3 and R7 you can essentially calculate how many mA of current is going through each stage. V1 and V2 are basically the input stage and V3, V4 is the output stage.
But in summary, it appears your DC voltage settings are fine.
Your hum, if you still have it, is arising from somewhere else and it's challenging to debug remotely!
Best,
Anand.
If you know the values of R3 and R7 you can essentially calculate how many mA of current is going through each stage. V1 and V2 are basically the input stage and V3, V4 is the output stage.
But in summary, it appears your DC voltage settings are fine.
Your hum, if you still have it, is arising from somewhere else and it's challenging to debug remotely!
Best,
Anand.
Thanks!
Yeah, they seemed to be ok.
The thing that caught my eye, was the DC on G2 on the output tubes (V3 and V4)
39mV and 54mV
Not sure if that is relevant?
Yeah, they seemed to be ok.
The thing that caught my eye, was the DC on G2 on the output tubes (V3 and V4)
39mV and 54mV
Not sure if that is relevant?
The hum can come from the supply through C6, and those DC mV on the grids should not be there, as if C6 is leaking. 🤔
I would disconnect the C6 (or R10) on one channel for a test and check if there is a difference.
R10 and R9 should be calculated according to the specific tube, there is a calculation at Broskie's website for checking.
I would disconnect the C6 (or R10) on one channel for a test and check if there is a difference.
R10 and R9 should be calculated according to the specific tube, there is a calculation at Broskie's website for checking.
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Thanks.
I’m with the kids for a couple of days, so will need to revisit when when they return to their mother.
I’m with the kids for a couple of days, so will need to revisit when when they return to their mother.
Thanks for pointing that out. I see C6 being there for filtering. I think double checking as you have suggested is a good idea. What is the value of C6? And is there only one C6 capacitor or are there 2, one for each channel?
Best,
Anand.
C6 is to block DC and pass AC rippled to G2 as part of the hum cancellation idea of the circuit. R9 is always 100K. R10 varies according to the B+ value. Some people use a pot there to dial in the precise cancellation. For the SP14 board it is 80.6K.
Per, if you haven't, measure R9 and make sure it is not off from 100K by any significant amount. Even 98K can unbalance the cancellation.
Per, if you haven't, measure R9 and make sure it is not off from 100K by any significant amount. Even 98K can unbalance the cancellation.