Balanced phase inverter tube?

[AniML]

Re: Balanced phase inverter tube?

Get yourself a bic pen like this one, pull out the ink barrel, and use the opening to carefully straighten the tube's pin. It works...

Then a couple months later you decide to pull the $15 tube out of your $500 amp and the softened/weakened pin breaks off in the socket, but you don't realize it until you cram it further into the socket with another tube's pin

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

Then a couple months later you decide to pull the $15 tube out of your $500 amp and the softened/weakened pin breaks off in the socket, but you don't realize it until you cram it further into the socket with another tube's pin

That's exactly what's probably going to happen with those Shuguangs.

 

[GilmourD]

Re: Balanced phase inverter tube?

Then a couple months later you decide to pull the $15 tube out of your $500 amp and the softened/weakened pin breaks off in the socket, but you don't realize it until you cram it further into the socket with another tube's pin

You haven't lived dangerously until you tried to put an Intel Celeron with a bent pin that you straightened out with tweezers into its socket and then overclocked the snot out of it.

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

And just think all this started with a discussion of phase inverters. I have a balanced 12AX7EH in there now, with more "unbalanced" tubes in reserve in case there are issues.

 

[AniML]

Re: Balanced phase inverter tube?

And just think all this started with a discussion of phase inverters. I have a 12AX7EH in there now, with more "unbalanced" tubes in reserve in case there are issues.

Ok, I'll bite.

I just got a Peavey C20MH that came stock with 2x JJ EL84s and 3x Ruby HG+ preamp tubes. Just put a Tung Sol RI in V1 a NOS Raytheon 7025 short gray in V2 and a ANOS RCA Command 5751 in V3.

I am considering getting a Mullard RI and JJ ECC803S to try in V2 and to the point of this thread a Sovtek LPS for V3 PI. Nothing wrong with the amp now but just the usual tone chasing. Supposedly, per the Peavey forums, the Tung Sol / JJ / LPS combo is the secret sauce for a Peavey Classic, with the LPS being the staple of that tube set.

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

Buying tubes is kind of addictive. The more you get, the more you want.

 

[GilmourD]

Re: Balanced phase inverter tube?

Buying tubes is kind of addictive. The more you get, the more you want.

Right? I get e-mails from The Tube Store and AmplifiedParts.com with stuff on sale and I usually complain that I'm broke. LOL

 

[Hank-]

Re: Balanced phase inverter tube?

You haven't lived dangerously until you tried to put an Intel Celeron with a bent pin that you straightened out with tweezers into its socket and then overclocked the snot out of it.

Dude.. had multiple bent gold contacts in the socket with a duo core processor. Figured it needed thermal paste, when it didn't help, left the cpu as deemed broken until after 5yrswhen trying to salvage stuff noticed the issue & its all in working order.

 

[GoldenVulture]

Re: Balanced phase inverter tube?

Dude.. had multiple bent gold contacts in the socket with a duo core processor. Figured it needed thermal paste, when it didn't help, left the cpu as deemed broken until after 5yrswhen trying to salvage stuff noticed the issue & its all in working order.

Ha, chips are funny like that, bios chips do it too. They build up some weird charge inside and won't work. Leave it lying around for months, some times years and slowly they settle back to what they should be, and work.

Difficulty level boast : Soldering back on a broken CPU pin, a row or two in [ around a 500 pin CPU ]

 

[GoldenVulture]

Re: Balanced phase inverter tube?

Then a couple months later you decide to pull the $15 tube out of your $500 amp and the softened/weakened pin breaks off in the socket, but you don't realize it until you cram it further into the socket with another tube's pin

Did you ?

 

[AniML]

Re: Balanced phase inverter tube?

Not with tubes. But back in the late 80s, populating RAM boards with chips you had to be careful

 

[moshpit817]

Re: Balanced phase inverter tube?

Here's what Tube Depot's website says about it:

"The 12AX7EH provides high gain with ultra low noise and a detailed - musical tone that rivals the most desirable NOS types. Unique spiral filament eliminates that filament-to-cathode induced hum common on AC-powered amps. This tube can be used in phase inverters / preamp sections / driver sections - It really does well in all applications."

With a description like that I would try one of these as well,can't hurt to try it.. Also as said above I have tried and used one of the JJ ECC803 balanced tube in a PI slot before,and in my situation I didn't notice much difference in a high gain 100 watt head than the Groove Tube that came in it when I bought the amp.

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

These aren't super easy to find, but eBay Canada came through with a nice tube pin straightener.

View attachment 77983

 

[Powerstrokedr]

Re: Balanced phase inverter tube?

My personal opinion, the Mullard 12AT7 lasts dang near forever and sounds great. Theye aren't that expensive either. Yes, I know all the nos blah blah...but this is one nos tube that is available and not stupid priced that does a great job!

 

[Demanic]

Re: Balanced phase inverter tube?

(redacted)

I don't know about sound better, but certainly smell better.

Sent from my MotoE2(4G-LTE) using Tapatalk

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

As an audiophile I tend to be pretty selective about what I'll buy into. Still, I'm trying not to bring that baggage into this. Everything I've heard about phase inverters, matching, and biasing has come (to me) from the guitar community.

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

Is this a modern day amp.?
Without measuring plate voltage, the mili "Volt" number is meaningless.
To make things "easier" for consumers.....modern day amps suggest a certain mV because they know (within reason) what plate voltage their amps run at.
That said. you have no idea what percentage of bias any given manufacture is recommending when they tell you to turn the knob until it reads XYZ.
There is biasing, and then there is biasing.
Sticking a meter in the ports on the back of an amp is designed to let you safely install new power tubes and keep on playing. It is a calculated convenience but is not exactly "setting the bias" of an amp.
good luck

This post was the catalyst that started it all for me, made me decide to learn what biasing an amp really means.

 

[LLL]

Re: Balanced phase inverter tube?

I see the Einsteins deleted relevant, valuable information again. Good job, guys. :thanks:

 

[Mincer]

Re: Balanced phase inverter tube?

Let's be kind to each other, and the mods, please. Keep this discussion on topic.

 

[MrTondo]

Re: Balanced phase inverter tube?

Back to the phase-inverters: I always like to refer to the valve wizard in relation to these questions .

His explanation can be found here. In short there are a couple of common options for the phase inverter commonly seen in push-pull amps:
-You can have a very balanced design in the phase inverter (which is the traditional way to design it for a push-pull amp). In this case a balanced phase-inverter will give a very linear response with less harmonic content. When using a non-balanced phase-inverter there is more chance of introducing more 2nd order harmonics in the circuit, which is generally what we like as guitar players.
- You can already have a slightly unbalanced phase-inverter (which is what the valve wizard here advocates for guitar amps to introduce more 2nd order harmonics), in that case a balanced phase-inverter will give the 'designed' amount of 2nd order harmonics, while an unbalanced inverter tube may either increase or decrease that effect.