Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
- Thread starter Kommerzbassist
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Kommerzbassist
Thunderbirdologist
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
hmmm interesting... but what is QA?
hmmm interesting... but what is QA?
Marcel
New member
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
The Tolerance... but here is the paper:
http://www.guitaramplifierblueprinting.com/Tubeprimerandselection330.pdf
The Tolerance... but here is the paper:
http://www.guitaramplifierblueprinting.com/Tubeprimerandselection330.pdf
Kommerzbassist
Thunderbirdologist
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
Thanks man... I think I need to take a look into those Chinese tubes...
Marcel said:
Thanks man... I think I need to take a look into those Chinese tubes...
Kommerzbassist
Thunderbirdologist
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
Well... if I buy them, I'd go for the GTs anyway...
Marcel said:
Well... if I buy them, I'd go for the GTs anyway...
Lake Placid Blues
New member
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
Tweed Fenders and most pre SLX Marshalls use two preamp tubes and one PI. The treble Ch and the bass ch use each 1/2 of V1. The signal is then mixxed before going to V2, and then on to the tone stack. Some amps don't even use both triodes in V2.
A Master Volume Marshall (JCM800 2204/2203) uses only one channel, so V1A feeds into V1B, before going on to V2.
The Jubilee placed an additional LED diode gain boost network in between V1B and V2. The "clipper diodes" not only clipp the signal some what after V1B, but drive the signal through V2 harder, essentially making V2 share in producing the total amount of overdrive gain.
Later amps like the SLX, JTM/JCM600 series, and the JCM2000's use an additional preamp tube inserted inbetween what was previously considered V1 and V2, instead of diodes. This adds two additional all tube gain stages. No clipper diodes are needed here. After the first stage (v1A) it goes through the preamp gain control, and in ultra gain mode, then on through no less than five potential all tube gain stages, before reaching the tone stack. Reverb send and return is handled by op-amps.
BF Fenders are a different design. Each Ch has it's own "V1", with the tone stack for each ch in between V1A and V1B. The signals are then mixxed and sent to V3, before then going on to the PI.
Mesa Boogie and other early high gain designs essentially take the BF design and run the two Channels through each other in series, creating 4 high gain stages before the master volume. Recto's place the tone stacks farther down the line.
Except for the PI in the BF's, they all run mainly 12AX7's, so only using higher gain 12AX7's than already in use, will increase gain much.
As was also pointed out, each 9-pin minature is actually two tubes in one bottle.Kommerzbassist said:
Tweed Fenders and most pre SLX Marshalls use two preamp tubes and one PI. The treble Ch and the bass ch use each 1/2 of V1. The signal is then mixxed before going to V2, and then on to the tone stack. Some amps don't even use both triodes in V2.
A Master Volume Marshall (JCM800 2204/2203) uses only one channel, so V1A feeds into V1B, before going on to V2.
The Jubilee placed an additional LED diode gain boost network in between V1B and V2. The "clipper diodes" not only clipp the signal some what after V1B, but drive the signal through V2 harder, essentially making V2 share in producing the total amount of overdrive gain.
Later amps like the SLX, JTM/JCM600 series, and the JCM2000's use an additional preamp tube inserted inbetween what was previously considered V1 and V2, instead of diodes. This adds two additional all tube gain stages. No clipper diodes are needed here. After the first stage (v1A) it goes through the preamp gain control, and in ultra gain mode, then on through no less than five potential all tube gain stages, before reaching the tone stack. Reverb send and return is handled by op-amps.
BF Fenders are a different design. Each Ch has it's own "V1", with the tone stack for each ch in between V1A and V1B. The signals are then mixxed and sent to V3, before then going on to the PI.
Mesa Boogie and other early high gain designs essentially take the BF design and run the two Channels through each other in series, creating 4 high gain stages before the master volume. Recto's place the tone stacks farther down the line.
Except for the PI in the BF's, they all run mainly 12AX7's, so only using higher gain 12AX7's than already in use, will increase gain much.
Kommerzbassist
Thunderbirdologist
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
Just tell me which of the slots in my TSL will affect gain most and I'll be fine when I read it tomorrow...
thanks and good night
Uhm... ok... I'm too tired to be able to understand what you just wroteLake Placid Blues said:
Just tell me which of the slots in my TSL will affect gain most and I'll be fine when I read it tomorrow...
thanks and good night
Lake Placid Blues
New member
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
V1 and V2.
Kommerzbassist said:Uhm... ok... I'm too tired to be able to understand what you just wrote
Just tell me which of the slots in my TSL will affect gain most and I'll be fine when I read it tomorrow...
thanks and good night
V1 and V2.
Lake Placid Blues
New member
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
...as long as it's preamp "gain" your primarily concerned with.
If it's head room in the poweramp you want to mess with, then it's the PI.
Sorry for being too complicated:smack:
...as long as it's preamp "gain" your primarily concerned with.
If it's head room in the poweramp you want to mess with, then it's the PI.
Sorry for being too complicated:smack:
Gearjoneser
Gear Ho
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
I think of the 1st position as the main provider of initial tone and gain level. Then, the 2nd as the determining factor of 'size of the EQ,' which means you can tell a little difference in a bright/thin sounding tube and a dark one. The 3rd position (phase inverter) on most amps, is more of an electrical function, rather than a creator of tone, so I just tend to want a nice quality/dependable tube like a JJ. My preference is for a hot Chinese 1, warm Russian 2, and reliable tube like a JJ ECC83 for the phase inverter.
For other positions, like reverb driver or FX driver, I just use good tubes that I didn't use for 1 & 2.
I think of the 1st position as the main provider of initial tone and gain level. Then, the 2nd as the determining factor of 'size of the EQ,' which means you can tell a little difference in a bright/thin sounding tube and a dark one. The 3rd position (phase inverter) on most amps, is more of an electrical function, rather than a creator of tone, so I just tend to want a nice quality/dependable tube like a JJ. My preference is for a hot Chinese 1, warm Russian 2, and reliable tube like a JJ ECC83 for the phase inverter.
For other positions, like reverb driver or FX driver, I just use good tubes that I didn't use for 1 & 2.
Lake Placid Blues
New member
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
The JCM2000 series have an extra tube compared to the traditional setup. This extra tube is installed right after V1. This is the main distortion producing tube in the JCM2000 preamp.
Installing a lower gain PI, such as the 12AT7, does indeed cause the power tubes to stay clean longer. Conversely, installing a 12AX7 in a amp that normally uses a 12AT7, will cause earlier power tube breakup. If it already uses a 12AX7 for the PI, then finding one with a bit more gain, MIGHT give even earlier, power tube distortion. A 12AX7 already in use for the PI, means that your essentially already maxxed out there, so any increase may not be noticable.
The JCM2000 series have an extra tube compared to the traditional setup. This extra tube is installed right after V1. This is the main distortion producing tube in the JCM2000 preamp.
Installing a lower gain PI, such as the 12AT7, does indeed cause the power tubes to stay clean longer. Conversely, installing a 12AX7 in a amp that normally uses a 12AT7, will cause earlier power tube breakup. If it already uses a 12AX7 for the PI, then finding one with a bit more gain, MIGHT give even earlier, power tube distortion. A 12AX7 already in use for the PI, means that your essentially already maxxed out there, so any increase may not be noticable.
Kommerzbassist
Thunderbirdologist
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
(Or, could you just tell me what tube does what there, cause I'm a bit confused by the layout... and is the "effects" tube responsible for drive AND reverb?)
Which one is it when looking at the amp, the one next to V1 in line or the one that is out of the line?Lake Placid Blues said:
(Or, could you just tell me what tube does what there, cause I'm a bit confused by the layout... and is the "effects" tube responsible for drive AND reverb?)
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L
Lewguitar
Guest
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
I use mostly NOS RCA 12ax7 and 12at7 tubes in my amps. But if you're looking for a great 12at7 the new EI Gold 12at7 is supposed to be excellant. I am now a SOVTEK dealer and do stock the EI Gold tubes. Thanks! Lew
Quencho092 said:
I use mostly NOS RCA 12ax7 and 12at7 tubes in my amps. But if you're looking for a great 12at7 the new EI Gold 12at7 is supposed to be excellant. I am now a SOVTEK dealer and do stock the EI Gold tubes. Thanks! Lew
Lake Placid Blues
New member
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
AFAIK, the JCM2000's don't have a dedicated reverb only tube. At least I can't find this indicated on the schematics.
Marshalls are usually layed out in numerical sequance. V1 farthest away, then V2, V3,.... and so forth. The PI, whatever it's number, is the one closest to the output tubes.Kommerzbassist said:
AFAIK, the JCM2000's don't have a dedicated reverb only tube. At least I can't find this indicated on the schematics.
Lake Placid Blues
New member
Re: Tube question: Importance of 2nd gain stage & phase inverter gain-wise.
Going to too low gain of a PI tube will also make the amp less loud overall as well. Basically, the 12AX7, the 12AT7, and the 12AY7, can be used in place of each other without altering the loudness too much.
If you use an AX then you can go to a AT and this would be the result. More clean headroom. I know of people that would do this to Marshalls and Hiwatts when they needed to use it for a bass amp.Marcel said:
Going to too low gain of a PI tube will also make the amp less loud overall as well. Basically, the 12AX7, the 12AT7, and the 12AY7, can be used in place of each other without altering the loudness too much.
