Sovtek Long Plate PI

Orange Amps Technical Q&A's

Moderator: bclaire

Post Reply
robbvant
New Member
Posts: 27
Joined: Thu Jan 11, 2018 10:01 pm

Sovtek Long Plate PI

Post by robbvant » Fri Feb 01, 2019 6:06 am

has anyone had any issues putting a sovtek long plate in their PI
i read somewhere its not recommended in a cathode biased amp.
i am using one in my TH30, and i really like the improved tone.
I got JJs in the rest of my preamp section. It sounds great as long as it doesnt decrease the tube life of the long plate and run it too hard.
anyone know anything at all about this?

Les Paul Lover
Duke of Orange
Posts: 6648
Joined: Tue Aug 18, 2009 9:08 am
Location: Derby, England

Re: Sovtek Long Plate PI

Post by Les Paul Lover » Fri Feb 01, 2019 7:07 am

Like yourself, I've read about it online.

Never experienced it myself. It might be true, it might simply be hearsay.
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute

Rlw59
Rocker
Posts: 240
Joined: Sun Oct 15, 2017 3:31 pm
Location: DFW, Texas, USA

Re: Sovtek Long Plate PI

Post by Rlw59 » Fri Feb 01, 2019 5:47 pm

First I've heard about it. I'm curious -- any links? Or a rough description of the potential issues?

Long plates are fine for pi in fixed-bias amps. Why not for cathode bias?
----------------
The only issue I've heard about long plates is that they're more prone to becoming microphonic in high power combo amps.

robbvant
New Member
Posts: 27
Joined: Thu Jan 11, 2018 10:01 pm

Re: Sovtek Long Plate PI

Post by robbvant » Mon Feb 04, 2019 6:20 am

here is what i read...

Cathode followers are used primarily as tone stack drivers and depending on how they are set up, also contribute to the tone. They also can be used as a type of cathodyne Phase inverter, typical on Orange amps and some of the Peavey Classic 50 designs.

Basically Cathodes on preamp tubes see very low voltages, usually around 1.5volts or less. When they are set up as cathode followers, the cathodes can see 150 to 200 volts depending on the design.

Usually 12AX7's have a limitation on the heater voltage (heaters are inside the cathodes) and the voltage on the cathode. Typically 12AX7's have a heater to cathode limit of 150 to 180 volts. Most of the New Sensor Tubes can only handle 100volts. That includes EH12AX7's, 12AX7LP, LPS, and the newer Tung Sol tubes.


Just keep the New Sensor Sovtek stuff out of cathode follower designs and you should be fine.

robbvant
New Member
Posts: 27
Joined: Thu Jan 11, 2018 10:01 pm

Re: Sovtek Long Plate PI

Post by robbvant » Mon Feb 04, 2019 3:54 pm

But if you look up the spec sheets, tung -sols are rated for 180 v and the sovtek lps says 200v
So...

Les Paul Lover
Duke of Orange
Posts: 6648
Joined: Tue Aug 18, 2009 9:08 am
Location: Derby, England

Re: Sovtek Long Plate PI

Post by Les Paul Lover » Mon Feb 04, 2019 11:09 pm

Dunno....

I can tell you one of my amps has a sovtek in the PI slot and has had it from factory 10 years ago. In that time, the amp has burnt a set of EL84 to a nice toasty crisp, but that PI is still going strong.
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute

Rlw59
Rocker
Posts: 240
Joined: Sun Oct 15, 2017 3:31 pm
Location: DFW, Texas, USA

Re: Sovtek Long Plate PI

Post by Rlw59 » Tue Feb 05, 2019 7:53 pm

robbvant wrote:
Mon Feb 04, 2019 6:20 am
here is what i read...

Cathode followers are used primarily as tone stack drivers and depending on how they are set up, also contribute to the tone. They also can be used as a type of cathodyne Phase inverter, typical on Orange amps and some of the Peavey Classic 50 designs.

Basically Cathodes on preamp tubes see very low voltages, usually around 1.5volts or less. When they are set up as cathode followers, the cathodes can see 150 to 200 volts depending on the design.

Usually 12AX7's have a limitation on the heater voltage (heaters are inside the cathodes) and the voltage on the cathode. Typically 12AX7's have a heater to cathode limit of 150 to 180 volts. Most of the New Sensor Tubes can only handle 100volts. That includes EH12AX7's, 12AX7LP, LPS, and the newer Tung Sol tubes.


Just keep the New Sensor Sovtek stuff out of cathode follower designs and you should be fine.
Ahhhh. Cathode bias, cathodyne PI, and cathode follower are different things.

There are some fixed bias amps that have cathodyne PI's. And some cathode biased amps have long tail pair (LTP) PI's.

And it's not the long plate design that's an issue, but an issue with some current production long plates.

And there's a false generality about Oranges having cathodyne PI's. The original OR80/120's had cathodyne PI's, but almost all modern Oranges have LTP PI circuits.

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests