Kingsley - Minstrel  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Frabbio
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Post by Frabbio »

Will something like this resolve issues? I've modified the routing of the heater supplies and added a fuse holder on board.

Image

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mmolteratx
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Post by mmolteratx »

That looks better. Basically you just need them to be parallel for the majority of the run to cancel as much of the radiating magnetic field as possible. Really you could ignore the 8.1 resistor and halve the current and decrease the field strength as a result.

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Post by jwpartain1 »

What kind of supply is this little guy running off of?

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mmolteratx
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Post by mmolteratx »

12VAC. Then the transformer steps it up to around 240V.

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Frabbio
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Post by Frabbio »

Perfect. Can you confirm the transformer is
Primary:
2x115 volt wired in series
Secondary
2x7volt wired in parallel?

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Post by mmolteratx »

This is the transformer used.

http://part.aboutsemi.com/amveco/62010.html

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Post by Frabbio »

Yeah, i see that on the schematic, i'd like to know how it is wired, especially the secondary (it's in parallel (7volt) or in series (14v)?)

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Frabbio
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Post by Frabbio »

Ok, i had confirm of what i said before by looking at the gutshot, the primaries are wired in series, the secondaries are wired in parallel, applying 12 volt on a 7 volt transformer gives higher anodic tension.

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Post by Liquids »

I've been using a chassis not a stomp box tube pedal I'm working on from the ground up (and will be able to switch it remotely via a small box on my pedal board from wherever).

I don't like that the Kingsley products use a passive & primal 3-band EQ, which is invariably mid-scooped and then will go into a typically mid-scooped amp = harsh sound, from my experiences.

A baxandall can at least be set flat and has much better control over restoring bass lost in the gain stages trying to keep things from being mushy.

Those in the US - Allied has multiple very cheap chassis-mount transformers that would be perfect for tube preamps if you arent' trying to squeeze everything into a stompbox. If you are there are still choices albeit restricted in voltage etc...the classis fender standalone reverb unit and champ power transformers should be more than adequate as well if they meet your voltage requirements...tubesandmore.com and allen amplification also sell tube preamp power transformers.

I'm liking mine alot, and avoiding the lame step-down wallwart for 12v heaters---> step up transformer for plates by simply wiring a power cord to a regular transformer is nice.

Heck, EHX used mains power and a internal transformer for quite a few of their classic pedals. And I suspect that if one could get a hold of one of their classic over-sized flimsy enclosures it would be plenty of room for a transformer, 2 preamp tubes, turretboard and stompswitch if you MUST have your preamp on the pedalboard.

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Post by jwpartain1 »

Frabbio could you post a file with just the traces? I'm interested in etching this one :D

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Frabbio
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Post by Frabbio »

Here it is :)
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Kingsley minstrel final board v5.jpg.zip
(290.11 KiB) Downloaded 445 times

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Intripped
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Post by Intripped »

hey Frabbio, any news?
did you build it?

i'm considering building this preamp as well, i'd like to have a confirm: does it work\sound good?

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Post by mmolteratx »

Liquids wrote:I've been using a chassis not a stomp box tube pedal I'm working on from the ground up (and will be able to switch it remotely via a small box on my pedal board from wherever).

I don't like that the Kingsley products use a passive & primal 3-band EQ, which is invariably mid-scooped and then will go into a typically mid-scooped amp = harsh sound, from my experiences.

A baxandall can at least be set flat and has much better control over restoring bass lost in the gain stages trying to keep things from being mushy.

Those in the US - Allied has multiple very cheap chassis-mount transformers that would be perfect for tube preamps if you arent' trying to squeeze everything into a stompbox. If you are there are still choices albeit restricted in voltage etc...the classis fender standalone reverb unit and champ power transformers should be more than adequate as well if they meet your voltage requirements...tubesandmore.com and allen amplification also sell tube preamp power transformers.

I'm liking mine alot, and avoiding the lame step-down wallwart for 12v heaters---> step up transformer for plates by simply wiring a power cord to a regular transformer is nice.

Heck, EHX used mains power and a internal transformer for quite a few of their classic pedals. And I suspect that if one could get a hold of one of their classic over-sized flimsy enclosures it would be plenty of room for a transformer, 2 preamp tubes, turretboard and stompswitch if you MUST have your preamp on the pedalboard.
Mine sounded great but I ran it into a THD with a James tone stack.

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Post by Intripped »

a couple of questions :hmmm:

is C13 correctly oriented in the schematic? and why C13 and C14 have different values?

has anybody measured the actual voltage on C15 and\or C16 in the original pedal?

thanks
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Kingsley Minstrel schem2.PNG

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Post by johngovan1234 »

Can someone reuploaded the schem and board layout. Thank you.

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rantony
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Post by rantony »

Hello everybody,

Could someone propose a suitable bridge rectifier (component part number) for this project? (According to the schematic, there are two.) Also, some examples of this pedal version were made with a "sizzle knob" at the rear. (See picture)

Image

According to a website, "turning the knob all the way down takes it out of the circuit giving you a stock Minstrel V1. Turning it up adds extra top end sizzle."

Does anybody know exactly how to wire this knob and what value and type it should be?

Thank you all and happy new year 2023!

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Post by ppluis0 »

rantony wrote: 02 Jan 2023, 20:42 Could someone propose a suitable bridge rectifier (component part number) for this project?
Hi rantony,

Found in the web a gutshot of a Kingsley Jester that looks to be same power supply topology depicted in the previous schematic:
Image

The board that includes the fuse holder have a 1 Amp diode bridge for the high voltage. The commercial denomination of that bridge is "W10"

Also four discrete 1N4001 diodes to feed the heaters of the tubes can be seen at the right of the fuse.

Happy new year !!!
Jose

EDIT:
There is a picture at the very beginning of this thread that shows the internals of a Kingsley Minstrel where a couple of diode bridges are installed at each side of fuse holder:
Image

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rantony
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Post by rantony »

Hi Jose,

Hi ppluis0 !

Thank you for your answers! I knew those bridge rectifiers were a standard thing but wasn't sure about the specs needed. I'll look for some W10 for a clean work.

Now, another question I forgot to ask in order to have all the correct information prior to start building the project:

On the schematic, we can see two voltages from the power supply: V1 and V2. Are these voltages identical??? Also, where exactly do we connect these voltages? My assumption is that R4 must be connected to R7 and that R11 must be connected to R15. I suppose that one voltage goes to R4-R7 and the other one goes to R11-R15. In other words: one voltage for each valve. If so, how am I supposed to know which voltage (V1 or V2) must be connected to which valve?

PS: Regarding the sizzle knob mentioned in my previous post, I'm very curious to see if someone will be able to provide some "secret" information...

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Post by ppluis0 »

Hi Tony,

The tradition in tube power supply is that the most sensitive stages need Vcc more filtering.
So, the point taken from C6 is to feed the first tube (the two triodes at left of the diagram) and the node comprising C15 is connected to the second tube that has the tonestack and drive the output jack.

I'm also intrigued about the sizzle potentiometer...

Cheers,
Jose

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