Phase Inverter Education...

[GTRJohnny]

I am looking at an amp that was listed as having a long tail phase inverter. What does this mean in regards to tone? I don't really need to know the technical part, as it will only confuse my tiny mind. But, how this changes the tone compared to other phase inverter options would be helpful...

Thanks!

 

[hasserl]

Later, smoother breakup; more crunch, less fizz.

 

[Blue Strat]

Also worth noting is that it's the most commonly used PI type in guitar amps. Most of the other PI types would be found in < 15 watt amps, and lower powered 1950's amps.

 

[GTRJohnny]

Cool. I've been looking at an Allen Brown Sugar and wasn't sure if this was just a Brown year Fender thing. So, from what you're saying it make sense that the smaller amps (ie: Princeton) uses a different PI. Thanks, guys!

 

[gtrnstuff]

My brief and incomplete rundown: You can check the schematics to be certain.
The long tailed PI was used in the most popular, later version tweed Bassman 4-10, and the Marshalls that are based on that, most Brown and all Black and Silver face Fenders except the Princeton, Princeton reverb, Champ.
Older cathodyne PI in tweed Deluxe, Super, Bandmaster. And Dr.Z Galaxie, based on the Super. And the BF SF Princetons, PR's.
There were other types in older circuits, that don't seem to be as popular.

 

[Timbre Wolf]

There were other types in older circuits, that don't seem to be as popular.

Paraphase and cathodyne (or split-load) phase-inverters, found in the earliest Fender amps (for example) do not allow the amp to produce as much power as later long-tail pair (LTP) style. These lower-output designs have their own character, however, which some players prefer. But the amplifier evolution favored the louder is better paradigm, so the more efficient LTP style has predominated ever since the late-'50s.

Check out those early-'50s tweeds, though. They're not completely useless.

- Thom

 

[Blue Strat]

Check out those early-'50s tweeds, though. They're not completely useless.

- Thom

Shhhhh! This is where you're supposed to instruct people on where to send those "useless" amps for proper disposal.

 

[Timbre Wolf]

Shhhhh! This is where you're supposed to instruct people on where to send those "useless" amps for proper disposal.

Well... they're usually pretty beat up and ugly, and most of 'em have their own characteristic odor (to put it nicely). Definitely not as appealing to the masses as a shiny NEW "reissue." Not to mention old tweeds have got genuinely neurotoxic lead-based solder. Best to leave these amps in the care of professionals.

- T

 

[Blue Strat]

Well... they're usually pretty beat up and ugly, and most of 'em have their own characteristic odor (to put it nicely). Definitely not as appealing to the masses as a shiny NEW "reissue." Not to mention old tweeds have got genuinely neurotoxic lead-based solder. Best to leave these amps in the care of professionals.

- T

For proper disposal send to:

Timbre Wolf Crappy/Toxic Amp Disposal Service
123 Main Street
Anytown, CA 91234

 

[Timbre Wolf]

For proper disposal send to:

Timbre Wolf Crappy/Toxic Amp Disposal Service
123 Main Street
Anytown, CA 91234

Thanks for the plug, Mike. And remember, folks, it is best to leave the old tubes in place - you never know what might fall out while you're trying to remove them.

 

[GTRJohnny]

So, would this "split-load" version be what I would find in my Clark Beaufort or my old wide-panel Tweed Super?

Paraphase and cathodyne (or split-load) phase-inverters, found in the earliest Fender amps (for example) do not allow the amp to produce as much power as later long-tail pair (LTP) style. These lower-output designs have their own character, however, which some players prefer. But the amplifier evolution favored the louder is better paradigm, so the more efficient LTP style has predominated ever since the late-'50s.

Check out those early-'50s tweeds, though. They're not completely useless.

- Thom

 

[Blue Strat]

So, would this "split-load" version be what I would find in my Clark Beaufort or my old wide-panel Tweed Super?

5E3's use the split load PI. What circuit number is the Super?

 

[tjs]

While we're on the subject of PIs, how big a difference does Tweed vs. Blackface PIs make in a circuit? Obviously there's a world of difference between the two amps as a whole, but suppose you installed a 5f6A PI into an otherwise stock blackface amp. Would the amp still sound pretty much like a blackface with earlier breakup or would it sound significantly more tweedy?

 

[Blue Strat]

While we're on the subject of PIs, how big a difference does Tweed vs. Blackface PIs make in a circuit? Obviously there's a world of difference between the two amps as a whole, but suppose you installed a 5f6A PI into an otherwise stock blackface amp. Would the amp still sound pretty much like a blackface with earlier breakup or would it sound significantly more tweedy?

Bad example because the 5F6A uses a long tailed pair. Tweed amps run the PI gamut.

It's not really possible to describe tone in words...but using a split load PI from a 5E3 in a blackface Deluxe WOULD make it sound more like a tweed...partially because of earlier breakup but also the character of the breakup.

 

[Timbre Wolf]

So, would this "split-load" version be what I would find in my Clark Beaufort or my old wide-panel Tweed Super?

The 5D4 tweed Super ("wide-panel") uses a paraphase phase inverter. Not sure about the Beaufort.

- T

 

[GTRJohnny]

It's a 1955 5D4.

5E3's use the split load PI. What circuit number is the Super?

 

[tjs]

Bad example because the 5F6A uses a long tailed pair. Tweed amps run the PI gamut.

I know. My question is about the differences in component values within the long tailed pair architecture - all else being equal, how big of a difference is there between the 10k/470 in the 5F6A vs the 6.8k/820 in the 6G6B vs. the 22k/470 in the AA864? If you put tweed bassman PI values in a blonde or blackface bassman, would the amp still sound pretty much the same aside from being warmer and breaking up earlier, or would it sound radically different?

 

[Blue Strat]

I know. My question is about the differences in component values within the long tailed pair architecture - all else being equal, how big of a difference is there between the 10k/470 in the 5F6A vs the 6.8k/820 in the 6G6B vs. the 22k/470 in the AA864? If you put tweed bassman PI values in a blonde or blackface bassman, would the amp still sound pretty much the same aside from being warmer and breaking up earlier, or would it sound radically different?

It wouldn't take long to find out...and you'd have a REAL answer instead of a list of undefined tonal adjectives which might not match YOUR undefined list of tonal adjectives.

It's true.