[QUESTION] ROCK/PAB/JAZZ 3-way toggle

[Bombacaototal]

I am struggling to get a single 3-way toggle switch to be Rock (TOP) / PAB (MID) / Jazz (BOTTOM) without using an additional relay board.

Has anyone done it? This is what I got so far but obviously with mistakes.

EDIT: Schematic corrected on page 2

[Reeltarded]

I haven't had coffee, but isn't PAB simply break the TS ground at the mid pot? I just had a fight with logic on a DPDT bypass so I am not the guy to talk to right now but since I haven't had any coffee I don't have sense enough not to talk.

[Charlie Wilson]

Use on-off-on.
CW

[Bombacaototal]

Use on-off-on.
CW

Thanks CW. Do you have any wiring diagram references?

[Charlie Wilson]

I think the story is that someone(Andy Brauer?) found that if you balanced the jazz/rock two way toggle in between positions you got the PAB boost. In some of Dumbles amps including #124, he used a toggle with a middle off position. As far as wiring, just wire it like a regular two way and the middle off will give you the PAB boost.
CW

[Bombacaototal]

I think the story is that someone(Andy Brauer?) found that if you balanced the jazz/rock two way toggle in between positions you got the PAB boost. In some of Dumbles amps including #124, he used a toggle with a middle off position. As far as wiring, just wire it like a regular two way and the middle off will give you the PAB boost.
CW

Thank you very much for the reply Charlie

That is a great tip. I will follow your advice

My schematic above is actually the #124 wiring without the relay so I think it is somehow on the right track

[FUCHSAUDIO]

And note; it’s gain boost (stack bypass), NOT mid boost.
Yes, Brauer claimed he discovered it. Don’t know of HAD doing it, however.

[martin manning]

Yes, Brauer claimed he discovered it. Don’t know of HAD doing it, however.

#124’s rear panel PAB switch was not wired to activate PAB, it only transfers control to the foot switch. ;^)

[pompeiisneaks]

Yes, Brauer claimed he discovered it. Don’t know of HAD doing it, however.

#124’s rear panel PAB switch was not wired to activate PAB, it only transfers control to the foot switch. ;^)

Yeah I had to have Charlie Wilson explain to me how to wire it to get it working

~Phil

[Max]

I think the story is that someone(Andy Brauer?) found that if you balanced the jazz/rock two way toggle in between positions you got the PAB boost.

AFAIR nearly all users of an original 1st and/or 2nd generation ODS noticed, that when sliding the jazz/rock (guitar/mic) sliding switch, there's a 'PAB' tone in the middle position of this sliding switch (IMO it's rather obvious when sliding slowly from rock to jazz). When introducing the 3rd generation ODS chassis this sliding switch was replaced by a toggle switch with (most often) only 2 positions. But with some fumbling and patience you can also find this 'PAB middle position when using a 3rd generation ODS amp'.

In some of Dumbles amps including #124, he used a toggle with a middle off position.

AFAIR a 3 position jazz/rock switch with a PAB middle position is a rather usual feature of all the transition generation and 4th generation ODS amps. And the middle position of the rock/jazz toggle switch of ODS 150W #0121 is even labelled "PB".

Cheers,

Max

[FUCHSAUDIO]

Yes. I saw this by accident with certain switch suppliers. When switching rock/jazz you got a level jump. I later realized that jump was the same as opening up the gain boost circuit, which is basically opening the middle switch terminal(s) which kills the stack. I later (in the newer series of amps) moved to a three position switch, plus adding a secondary boost elsewhere in the circuit, separate from the PAB.

Andy said "I told Dumble to make the switch a three way" but I guess he (apparently) wasn't a fan of change, or felt it was redundant to the PAB switch.

[martin manning]

Andy my point above is that #124 was built that way, or at least it was part of the Skyliner update. A close look at the rear panel PAB slide switch lugs confirms that.

[talbany]

It just happens that in the center position (between 2 way or center off 3 way)both floats the wiper of the bass pot to the bottom of the treble which lifts the bass pot out of circuit. The only difference then being the lack of 22 or 10M resistors on the relay board in the center off reduces the loading vs the PAB switch on the back which keeps them in circuit. Some people hear the difference others cannot tell. It would make some sense though if HAD did a Skyline update to add a 3 way center off to the rock/jazz on the front and then convert the rear switch to control footswitch. AFIK 124 did not have a 3 way switch on the front and is unknown why Dumble wired the rear switch the way he did?.Given the amp was updated to Skyline specs at some point could be a request from the customer we can only assume?

As far as the layouts go!.If the layout specifies a particular amp (124/183/102) what you get is how that amp is wired (quirks and all) given the limited info we had at the time.The earlier Layouts labelled low plate Skyliner or 2nd or 3rd generation was not directed at any 1 amp but an overall collection from different sources of info obtained through pics and reliable schematics and from those who have been inside many different amps of the same generation.
We should remember Dumble customized many of his ODS amps across many different generations so it's not as easy as here is a schematic or a layout that is just like say Rick Vitos or Steve Ferris or Larry Carlton's amplifiers at the time. This is why IMO it's pretty important to try to read up on each amp before you build it chances are many of these little design mods have been discussed here at some point!


Tony

[Charlie Wilson]

Tony, the layout for #124(classic) does show a DPDT jazz/rock switch with a center off.
CW

[talbany]

Tony, the layout for #124(classic) does show a DPDT jazz/rock switch with a center off.
CW

Charlie
If memory serves the 3 way switch was later added to the classic layout because I/we discovered that switch later on the Gregor Hilden amp #094 (I believe) as well as the Blue Keiser amp (Doppler on the Dumble) both were classics. At the time I did the layouts I did not have or see a Skyliner with the 3 way. Perhaps Max can jump in here and verify if one exists.
BTW. I added a paragraph on my last post (just before you posted) clarifying a few things about how some layouts were amp specific and others were not.
I hope this helps!
Tony