4th Generation 100 watt

[67plexi]

It passed the flame test, all voltages spot on. And it sounds great. And the deep switch is good.
well balanced amp from clean to overdrive and fet. Bias -32.5 6L6GC quad made in USA.

Thanks to all, Steve.

[LeftyStrat]

Awesome! We need clips. I'd love to hear the classic preamp with 100 watt power amp. What kind of filtering in the power supply?

[sonicmojo]

Nice, my favorite amp circuit! Did you add a boost? I notice a second relay on there.

[67plexi]

Thanks' the first filter stage is 300uf @ 500v x2 = 150uf @ 1000v.
Yes it has a PAB, and 100k overdrive ratio pot. The deep switch shines using the fet with a acoustic guitar. As far as clips go it will take time. I need to build a combo or a head box next.

Steve.

[67plexi]

One more photo.

[dreric]

Nice to see you building again! Looks like a cool amp. Is the overdrive ratio the same as the #60 ODSR?

Eric

[67plexi]

Eric, On ODSR I used 250k OD ratio and 2MEG2 for the clean ratio

#60 is a killer slide guitar amp it cuts through the mix like no other ODS amp.

Steve.

[Structo]

Looks nice Steve.

Can you tell us about the OD trim pot on the back

[67plexi]

Tom, Thank you, It's just a 100k CTS pot to fine tune the overdrive.

[Max]

I'd love to hear the classic preamp with 100 watt power amp.

Just to avoid misunderstandings:

Most of the original 3rd generation ODS amps don't have a "classic" tone stack but the "pre-classic" tone stack documented in this layout: https://tubeamparchive.com/download/file.php?id=14344

The "classic" tone stack - documented in this layout: https://tubeamparchive.com/download/file.php?id=14346 - you'll find in most of the transition generation and 4th generation ODS amps.

AFAIK the transition generation ODSR #0060 (originally in a head cabinet and not yet in Bonnie Raitt's combo cabinet) hasn't originally been built with a 3rd generation "pre-classic" tone stack and a 3rd generation "pre-standard" OD circuit, but has originally been built with a "classic" tone stack and a "standard" OD circuit. Later AFAIK it has been updated to "skyline" specs with some special tweaks. As beeing owned by Jackson Browne and used in his studio AFAIK #0060 is the result of a constantly ongoing updating process anyway.

Cheers,

Max

[67plexi]

Max I'm no Dumble expert this new build is a pre skyline eq.
To clear up the confusion #060 ODSR is a older build not this one.
Thanks' for your input, Steve.

[odourboy]

You should have tinned your copper bus bar - looks way cooler!

[67plexi]

Good one thanks.

[LeftyStrat]

Just to avoid misunderstandings:

Most of the original 3rd generation ODS amps don't have a "classic" tone stack but the "pre-classic" tone stack documented in this layout: https://tubeamparchive.com/download/file.php?id=14344

The "classic" tone stack - documented in this layout: https://tubeamparchive.com/download/file.php?id=14346 - you'll find in most of the transition generation and 4th generation ODS amps.

AFAIK the transition generation ODSR #0060 (originally in a head cabinet and not yet in Bonnie Raitt's combo cabinet) hasn't originally been built with a 3rd generation "pre-classic" tone stack and a 3rd generation "pre-standard" OD circuit, but has originally been built with a "classic" tone stack and a "standard" OD circuit. Later AFAIK it has been updated to "skyline" specs with some special tweaks. As beeing owned by Jackson Browne and used in his studio AFAIK #0060 is the result of a constantly ongoing updating process anyway.

Cheers,

Max

Still trying to understand the terminology.

pre-classic tone stack: 50 watt amps
classic tone stack: 100 watt amps, low plate (some, like #124 were later modified to skinner).
skyliner: 100 watt amps, high plates

Is this correct?

[stevlech]

pre-classic tone stack: 50 watt amps
classic tone stack: 100 watt amps, low plate (some, like #124 were later modified to skinner).
skyliner: 100 watt amps, high plates

The tonestacks are the EQ circuits and have nothing to do with output power.

2nd generation has a 100k slope resistor, caps are 510pf/.01uf/.1uf
and 500k linear/250kAudio/1M audio pots

3rd generation is similar but with a 250k Audio treble pot

Classic tonestack has 100k slope, 330pf/.047/.1 uf caps
250k Audio/100k Linear/250k Audio pots

Skyliner has 150k slope, 2200-500pf/.01/.1 uf caps
250k Linear/250k Audio/500k Audio pots

There is more to it and there are variations, but these values are common amongst several known amps.


I hope this helps.