#002 Steel String Singer - almost there
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- martin manning
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Re: #002 Steel String Singer - almost there
Spanky! Are your step filters original or the updated version?
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Re: #002 Steel String Singer - almost there
I think it is best to wire the connector grounds together. I didn't see this in the video. The amp sounds nice!
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Re: #002 Steel String Singer - almost there
Your step filters. But they are not very effective, more subtle. I don't know if this is right, or if I have done something wrong. I'll check it one more time.martin manning wrote: ↑Sun Mar 10, 2024 3:53 pm Spanky! Are your step filters original or the updated version?
Cheers
- martin manning
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Re: #002 Steel String Singer - almost there
Hmm. That doesn’t sound right. You should be getting something very noticeable,12 dB difference top to bottom.
Re: #002 Steel String Singer - almost there
I have them in my other builds. But more like this:Raja_Kentut wrote: ↑Sun Mar 10, 2024 2:44 pm a cheap way to protect the OT against secondary open condition is a MOV (metal oxyd varistor) just solder it directly over one of the output windings. The rated voltage approx. 2x the highest expected output voltage. They look like a disk with about 15…20mm diameter.
The good thing with this MOVs:
when they fail because of overload, they fail almost always to short. (0 Ohm -> safe for OT)
and they give you two ways of alarm:
They release a fog with a stink of old fish and glow orange
https://www.premierguitar.com/the-immor ... -mods-pt-3
Cheers
Gerhard
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Re: #002 Steel String Singer - almost there
I just checked it. I've done it like this, except R29 100k, R32 1M:martin manning wrote: ↑Sun Mar 10, 2024 8:23 pm Hmm. That doesn’t sound right. You should be getting something very noticeable,12 dB difference top to bottom.
It's very subtle...
I think, I missed something here.
Cheers
Gerhard
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Re: #002 Steel String Singer - almost there
the speaker jacks should be grounded together with the phase inverter if you use negative feedback.Lothy wrote: ↑Sun Mar 10, 2024 1:48 pmThats it... those damn speaker jacks got no connection to the chassis, even with lock washers.
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- martin manning
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Re: #002 Steel String Singer - almost there
That schematic seems to be correct. R29 and R32 values were tweaked from the earlier version, but that isn't going to make the difference you describe. There must be some wiring error.Lothy wrote: ↑Mon Mar 11, 2024 6:56 amI just checked it. I've done it like this, except R29 100k, R32 1M:martin manning wrote: ↑Sun Mar 10, 2024 8:23 pm Hmm. That doesn’t sound right. You should be getting something very noticeable,12 dB difference top to bottom.
It's very subtle...
Re: #002 Steel String Singer - almost there
I think, I've done it right.martin manning wrote: ↑Mon Mar 11, 2024 10:23 am That schematic seems to be correct. R29 and R32 values were tweaked from the earlier version, but that isn't going to make the difference you describe. There must be some wiring error.
Here you see the 3 wires.
- white goes to the cap-bundle
- green to commons at filter-high
- red comes from pin 7 at filter low.
Here are the connectins on the board:
Maybe I'm expecting too much. I can measure different values, but I can barely hear any difference, when I switch the positions.
Cheers.
Gerhard
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Re: #002 Steel String Singer - almost there
correct, and it is the only truth.. people here using just random grounding for almost everything, or what they see from other people (the worst way), multiplying noise collected from the chassis directly via nfb loop
Re: #002 Steel String Singer - almost there
and what about this simplicity, R=47R 5W permanently soldered to the output jack?Raja_Kentut wrote: ↑Sun Mar 10, 2024 2:44 pm a cheap way to protect the OT against secondary open condition is a MOV (metal oxyd varistor) just solder it directly over one of the output windings.
Re: #002 Steel String Singer - almost there
yes, see here https://www.valvewizard.co.uk/Grounding.pdf
EDIT: "A separate wire
... should then run from the negative connection of the speaker jack back to an
appropriate star. ...If global feedback is used then the speaker ground
should be returned to the local star of whichever stage the feedback happens to be
applied to, which is usually the phase inverter (e.g., fig. 15.14)."
Last edited by Roe on Mon Mar 11, 2024 12:06 pm, edited 1 time in total.
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Re: #002 Steel String Singer - almost there
yes, but also no need, if you think that voltage feedback used in guitar amps has + and - terminal, and it is FEED BACK to the preamp stage,
both terminals need to be FEED BACK, + and -,
so plus or speaker live terminal returns over the NFB resistor, and MINUS terminal to the - of the preamp stage, and in our case gnd leg of tail resistor (PI), wires must travel together .
Spk jack must be not "grounded" of course, it will be grounded in PI gnd capacitor node.
And you are hearing in 90% of the cases speaker terminal is GROUNDED to the chassis..