You might want to check here: Mod Garage: Inside Yamaha’s Dry Switch

 

You might want to check here: Mod Garage: Inside Yamaha’s Dry Switch

Thanks, I read with interest, and the linked article about the focus knob.

Maybe I am just blind to it, but neither of them mention the transformer...

"Located on the DPDT switch of a push-pull tone pot, Yamaha's Dry Switch consists of a 330k resistor and a 3300 pF capacitor connected in parallel."

 

Revstar always seemed like a good guitar to me.

 

Well, the article is from 2019. Possible that the aforementioned transformer was added to select models since then. I will note that a transformer can be used as an inductor, and placed in series with the signal to cut bass.

 

see over on the right side of this picture. I see a capacitor, a couple of resistors, a volume pot and a 5-way switch and the pull/push tone control. And lurking in the corner is a f*$&ing great transformer. I'm very curious how this is all wired up. If I could get the range of noises out of my build that you could get out of a revstar I would be very happy.

 

see over on the right side of this picture. I see a capacitor, a couple of resistors, a volume pot and a 5-way switch and the pull/push tone control. And lurking in the corner is a f*$&ing great transformer. I'm very curious how this is all wired up. If I could get the range of noises out of my build that you could get out of a revstar I would be very happy.

View attachment 431126

Just a note about the new revstars - the first gen revstar's have the dry switch (which is very similar to the bass contour rolloff on the Reverend guitars except without the ability to control how much you can rolloff). With the new Revstar's, only the entry level Element line has the dry switch. The new Standard and Japanese models have the "Focus Switch" which smooths out the treble frequencies and boosts the mids and lows. The pic from the video with the transformer is from one of the guitars with the "Focus switch".

I like the new models but I prefer the dry switch and the neck profile on the gen 1 Revstar's (the newer models have a slightly wider neck that I didn't like as much). I originally was thinking about trading in for one of the newer ones but instead I will be hanging onto my RS502:

 

@mhammer you make a very good point. Maybe it's not a transformer at all, maybe it is an inductor...

 

@greco yes, I think that's it.

5 Key Differences between Transformers and Inductors | Custom Coils Blog

The transformers and inductors are two important devices used in the electronics. There exists a misconception that these are the same because they look similar in construction and appearance.

www.customcoils.com

For an inductor... "When there is a change in the current that passes through the coil, then a voltage is created, according to Faraday’s Law."

Out on a limb (and borrowing heavily from my undergrad Physics) I am guessing that when in the circuit this inductor will elevate the output voltage. In conjunction with a resistor/capacitor it could really shift the signal.

 

Transformers DO more than mere inductors do, yes. But ultimately, they are coils. Small transformers are often used AS inductors, simply because their primary or secondary coil has the "right" inductance for some purpose.

 

thats actually a super switch and it has a few caps on it as well.

 

@knight_yyz that's the one that was under my first post. There's no inductor in that circuit. I suspect it's an older version.

 

i watched the video and it almost triples the voltage output of the stock pickup. .213 VAC to .585VAC

 

.213 VAC to .585VAC will increase the output impedance by a factor of 7.54 in a passive device...it will load-down much easier for the same input device. Is that what you are looking for?

 

oooh! look! the rabbit hole...

Inductance

Knowing something about it can keep you from doing dumb things.

blackstoneappliances.com

 

here's a better picture from this German site

Test: Yamaha Revstar RSE20, RSS20 & RSP02T

Der japanische Hersteller bewies schon immer ein Händchen für ansprechende eigenständige Designs. Etliche seiner Gitarren sind zu echten Klassikern geworden, allen voran die SG2000, die seit 1976 bis heute zum Yamaha Line-up zählt. 2015 erschien die Revstar-Serie, die vom Design britischer...

www.gitarrebass.de

 

You could try contacting Yamaha support for the parts manual or if you want to order the exact parts. They gave me their parts manual a couple years back when I was thinking about buying locking tuners for my RS502. Here's the manual they sent me

 

None of those schematics include a transformer and none of the images provide sufficient detail to produce an accurate schematic, without the schematic it's speculation. I don't believe that they are using the transformer as an inductor...how else are they tripling the signal out as noted in post#12.

 

and another... just so they are all in the same place

NGD, REVSTAR Std 2.0

Visited my nearest guitar store a couple of months ago to get a replacement chorus pedal. They had a some demonstrator Revstars in there... had to try the Std 02t and 20, couldn't help myself. Haven't had a 24.75 scale mahogany maple cap guitar with that type of bridge before. Les Pauls have...

www.strat-talk.com

 

angellahash has a go at a wiring diagram in that same forum, but @Paul Running you're right, it's speculative

https://guitarnuts2.proboards.com/thread/9930/revstar-new-tone-control?page=1

 

Okay, by their schematic, the transformer is wired as a paralleled inductor.

 

 

Question is: how is the output almost tripled?

 

Isn't that exactly what inductors do?

Generating High Voltage with an Inductor

A review of inductor basics as related to switching power supplies in generating voltages.

www.bristolwatch.com

.

 

I believe that an inductor can generate a momentary spike in voltage at the resonant frequency but not continuously through the entire bandwidth.

 

learning more about what inductors do in AC circuits, their generated signal will lag the input signal by 90 degrees, or a quarter phase. A signal boost plus a phase shift.

AC Inductive Circuits

An Inductor is usually a coil of wire that sets up an alternating magnetic field around it when an alternating current flows through it .Inductance is the property of an inductor that opposes the change in current. It is measured in Henry. Due to this inductance , a back emf is induced in the...

www.electronicshub.org

.

 

Here is the full video

 

I'm not so sure the schematic Paul shows is accurate. I can't see where the role of transformer in that drawing would increase the amplitude of the output signal. It would certainly alter the tone, but as drawn does not seem to impose any noteworthy level shift in the level.

The Les Paul Recording guitar also includes a transformer. However, its role is to turn the low-impedance pickups into a higher-impedance output, such that it can either be used direct into the board (where the normal low impedance is similar to what a voice mic would be), OR it can feed a regular old guitar amp.

To be honest, I'm kinda stumped here.

 

it's meant to be a low to mid boost of 6db. You can really hear it when he turns on the boost with the bridge pickup.

 

Okay, now the circuit looks familiar (please excuse the rusty brain). A similar circuit is used in my V2 for midrange boost.