It is currently Tue Mar 17, 2020 5:12 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 16 posts ]  Go to page 1, 2  Next
Go to page 1, 2  Next
Author Message
Post subject: V3 tube in Blues Jr
Posted: Wed Jan 05, 2011 8:35 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Aug 04, 2010 10:28 am
Posts: 69
Location: Vancouver Is, B.C. Canada
In my quest to improve the tone in my Blues Jr, i have been swapping various tubes in the amp's V1 and V2 positions: ie., Jan Phillips 5751, EH12AX7, and Tungstol 12AX7s.

However, what about V3, the PI? Since it has little influence on tone, am i better off leaving the stock GT12AX7R/12AX7WC or an inexpensive 12AX7 in V3? I don't see the purpose of using a more expensive 12AX7 tube in V3, or am i wrong?

Thanx for your help,
cheers.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: V3 tube in Blues Jr
Posted: Wed Jan 05, 2011 9:30 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Sounds like you have it right to me canucklehead. V3 has little effect on tone, but some. Your best tube should go in V1. I have all three spots with 12AX7WC in my BJr. I could hear a small difference in sound with a lower gain tube in V3, so I kept the 12AX7WC there also, as I wanted the most preamp gain that I could get. :)

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Thu Jan 06, 2011 4:02 am
Online
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14050
Location: Province de Québec, Canada
A good tube it help in PI. PI work hard, like you power tube, itis very important.


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Sun Jan 09, 2011 4:09 pm
Offline
Aspiring Musician
Aspiring Musician

Joined: Wed Aug 15, 2007 6:46 pm
Posts: 575
Location: Indy
stratele52 wrote:
A good tube it help in PI. PI work hard, like you power tube, itis very important.


+1. You should change the p/i when you change power tubes.

_________________
The design of each element should be thought out in order to be easy to make and easy to repair.
Leo Fender


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Sun Jan 09, 2011 4:53 pm
Offline
Professional Musician
Professional Musician

Joined: Sun Dec 19, 2010 12:00 pm
Posts: 1389
Mached triode is also a good principle for V3. 8)

_________________
Tissan

*'52 Telecaster RI, '57 Stratocaster RI, Gibson ES175 RI, Washburn Hawk 1980, Epiphone Casino MIK 2000, 57' Deluxe Knotty Alder, BDRI ...*
https://soundcloud.com/pierrou
http://www.youtube.com/user/Jazzenfamille


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Sun Jan 09, 2011 5:06 pm
Offline
Aspiring Musician
Aspiring Musician

Joined: Wed Aug 15, 2007 6:46 pm
Posts: 575
Location: Indy
Tis-san wrote:
Mached triode is also a good principle for V3. 8)


Agreed. Unless you are running a split load p/i, like my 5E5-A project.

_________________
The design of each element should be thought out in order to be easy to make and easy to repair.
Leo Fender


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 1:35 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
rjake wrote:
You should change the p/i when you change power tubes.


Totally unnecessary.

Exerpted from http://www.aikenamps.com/TI_Aiken_Q&A.html

"Q: Do I need to replace my driver tube every time I replace my power tubes?
A: No. This is an "old wive's tale" propagated by the tube vendors who want to sell you more tubes. The "driver" tube, or phase inverter as it is more appropriately known, is under no more stress than any of the other preamp tubes. The output stage of a normal guitar amplifier is AC-coupled, class AB1 or class A1. The "1" suffix indicates that the tubes do not draw grid current during any portion of the input cycle. A "2" suffix indicates grid current during some portion of the cycle, as in class AB2. Since almost all guitar amps are class AB1 or A1 (it takes a DC-coupled cathode-follower or interstage transformer to be able to drive the power tubes into the positive grid region), the phase inverter does not have to supply any current to the grids (it can't really source current anyway - it only sinks current through the plate load resistor, which is quite large, and inherently limits the plate current to a few mA). The AC coupling (capacitor coupling) between the phase inverter and the output tubes precludes any flow of grid current anyway. The output tube grids will merely act as a grid clamp, shifting the bias downward as the output is driven harder. This in no way stresses the phase inverter tube. In addition, the plate load resistors and the bias current in a typical phase inverter are identical to the preamp stage values, indicating that they are operating in the same area, dissipation-wise, so they cannot be "wearing out" any faster. In fact, the reverb driver tube on a typical amplifier is dissipating more power than the phase inverter, and should be replaced more often, if anything. Don't be misled by the higher plate voltage on the phase inverter either, because the cathode is usually sitting somewhere around 30V - 100V above ground, which lowers the plate-to-cathode voltage by that amount. The plate-to-cathode voltage is what determines the power dissipation of the tube, not the absolute plate voltage."

_________________
Bill

Image


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 1:50 pm
Offline
Aspiring Musician
Aspiring Musician

Joined: Wed Aug 15, 2007 6:46 pm
Posts: 575
Location: Indy
bluesky636 wrote:
rjake wrote:
You should change the p/i when you change power tubes.


Totally unnecessary.

Exerpted from http://www.aikenamps.com/TI_Aiken_Q&A.html

"Q: Do I need to replace my driver tube every time I replace my power tubes?
A: No. This is an "old wive's tale" propagated by the tube vendors who want to sell you more tubes. The "driver" tube, or phase inverter as it is more appropriately known, is under no more stress than any of the other preamp tubes. The output stage of a normal guitar amplifier is AC-coupled, class AB1 or class A1. The "1" suffix indicates that the tubes do not draw grid current during any portion of the input cycle. A "2" suffix indicates grid current during some portion of the cycle, as in class AB2. Since almost all guitar amps are class AB1 or A1 (it takes a DC-coupled cathode-follower or interstage transformer to be able to drive the power tubes into the positive grid region), the phase inverter does not have to supply any current to the grids (it can't really source current anyway - it only sinks current through the plate load resistor, which is quite large, and inherently limits the plate current to a few mA). The AC coupling (capacitor coupling) between the phase inverter and the output tubes precludes any flow of grid current anyway. The output tube grids will merely act as a grid clamp, shifting the bias downward as the output is driven harder. This in no way stresses the phase inverter tube. In addition, the plate load resistors and the bias current in a typical phase inverter are identical to the preamp stage values, indicating that they are operating in the same area, dissipation-wise, so they cannot be "wearing out" any faster. In fact, the reverb driver tube on a typical amplifier is dissipating more power than the phase inverter, and should be replaced more often, if anything. Don't be misled by the higher plate voltage on the phase inverter either, because the cathode is usually sitting somewhere around 30V - 100V above ground, which lowers the plate-to-cathode voltage by that amount. The plate-to-cathode voltage is what determines the power dissipation of the tube, not the absolute plate voltage."


I stand corrected. I'll have a talk with my wife. :shock: I do respect Aiken, and he explained it well.

_________________
The design of each element should be thought out in order to be easy to make and easy to repair.
Leo Fender


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 2:22 pm
Offline
Professional Musician
Professional Musician

Joined: Sun Dec 19, 2010 12:00 pm
Posts: 1389
+ 1 for Bluesky and ++ for AB 1&2 accurate explaination 8) 8) 8) 8)

_________________
Tissan

*'52 Telecaster RI, '57 Stratocaster RI, Gibson ES175 RI, Washburn Hawk 1980, Epiphone Casino MIK 2000, 57' Deluxe Knotty Alder, BDRI ...*
https://soundcloud.com/pierrou
http://www.youtube.com/user/Jazzenfamille


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 2:30 pm
Online
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14050
Location: Province de Québec, Canada
rjake,

I disagree of what you said. "........ is an "old wive's tale" propagated by the tube vendors who want to sell you more tubes. "


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 2:47 pm
Offline
Aspiring Musician
Aspiring Musician

Joined: Wed Aug 15, 2007 6:46 pm
Posts: 575
Location: Indy
stratele52 wrote:
rjake,

I disagree of what you said. "........ is an "old wive's tale" propagated by the tube vendors who want to sell you more tubes. "


I didn't say it. Randall Aiken of Aiken Amps said it. Bluesky636 quoted him. Aiken's explanation looks convincing. I thought the "old wive's tale" was true based on the higher voltages going to the p/i tube.

_________________
The design of each element should be thought out in order to be easy to make and easy to repair.
Leo Fender


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 8:06 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
stratele52 wrote:
rjake,

I disagree of what you said. "........ is an "old wive's tale" propagated by the tube vendors who want to sell you more tubes. "


Argue with Randall Aiken.

_________________
Bill

Image


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 8:33 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Fri Nov 09, 2007 7:46 am
Posts: 1019
Location: State of Confusion
rjake wrote:
stratele52 wrote:
A good tube it help in PI. PI work hard, like you power tube, itis very important.


+1. You should change the p/i when you change power tubes.

If you google this topic, you'll find quite a few arguments on both sides of the issue on various forums; also on whether the PI tube should be balanced or if that's a waste of $.

Sometimes it's hard to find the truth. :?

_________________
The quintessential sound of 60/70's R&R:
Fender Tube Amps
Gibson Guitars


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 9:59 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
RVM lead wrote:
rjake wrote:
stratele52 wrote:
A good tube it help in PI. PI work hard, like you power tube, itis very important.


+1. You should change the p/i when you change power tubes.

If you google this topic, you'll find quite a few arguments on both sides of the issue on various forums; also on whether the PI tube should be balanced or if that's a waste of $.

Sometimes it's hard to find the truth. :?


I'll take Randall Aiken's "truth" over your average forum poster's any day. :wink:

_________________
Bill

Image


Top
Profile
Post subject: Re: V3 tube in Blues Jr
Posted: Mon Jan 10, 2011 11:29 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Fri Nov 09, 2007 7:46 am
Posts: 1019
Location: State of Confusion
This too is a forum and like the others, has it's referenced experts as do they.
Leaves one confused :?

_________________
The quintessential sound of 60/70's R&R:
Fender Tube Amps
Gibson Guitars


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 16 posts ]  Go to page 1, 2  Next
Go to page 1, 2  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: Google [Bot], stratele52 and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: