Phase Inverter question
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Sure, but none of that will push anything harder, quite the opposite.
Producing lower gain in the pre-amp will not enable higher gain later on, it just means the knobs get turned up more to achieve the same loudness as before.
What pushes the power section is turning up the master volume.
Period.
Use an attenuator to reduce loudness, if that is your wont.
Producing lower gain in the pre-amp will not enable higher gain later on, it just means the knobs get turned up more to achieve the same loudness as before.
What pushes the power section is turning up the master volume.
Period.
Use an attenuator to reduce loudness, if that is your wont.
^^ exactly. That's why I state on the particular attenuators I sell, that they can be used to push you preamp harder, but not your power amp. some advertise that they act like a power soak, but they're not... those are a different type of attenuator
Those ain't attenuators, they're passive volume pots inserted into an effects-loop.
They, also, do not "push" anything. They allow you to turn up the pre-amp, then reduce loudness with the gizmo in the loop. If you have a master-volume amp, these devices are superfluous. :roll:
They, also, do not "push" anything. They allow you to turn up the pre-amp, then reduce loudness with the gizmo in the loop. If you have a master-volume amp, these devices are superfluous. :roll:
It's a matter of semantics I suppose:
http://en.wikipedia.org/wiki/Attenuator_%28electronics%29
And yea, you're right, they don't "push" anything by itself
That's why I try to make it clear in my description... I don't want to mislead anyone. They have their uses (I use one in my rig in a looper to lower my emg's level for clean presets), but not as some advertise
http://en.wikipedia.org/wiki/Attenuator_%28electronics%29
And yea, you're right, they don't "push" anything by itself
yup, it can be used to crank up the preamp and then reduce it's volume before the poweramp. And , again yea, it's definitely not the same type as a power soak.MrMarkIII said:
That's why I try to make it clear in my description... I don't want to mislead anyone. They have their uses (I use one in my rig in a looper to lower my emg's level for clean presets), but not as some advertise
94Tremoverb
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A 12AT7 works very well as a phase inverter in Mesa amps, but does the opposite of what you want if you want a more pushed sound. It opens up the tone and reduces the power amp gain, kind of a more 'vintage' sound. It does mean you have to turn the master volume up further for the same amount of power stage overdrive, but it doesn't push anything harder. I've preferred a 12AT7 PI in all the Mesa amps I've tried it in.
kiff, thanks for your honest description. There are too many sellers of these devices (which are very useful, for some amps) with very misleading claims for them.
kiff, thanks for your honest description. There are too many sellers of these devices (which are very useful, for some amps) with very misleading claims for them.
soundchaser59
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My PI tube is a 12AU7 (ECC82). With that in there it seems I can turn the master up a lot more without ear bleed....
94Tremoverb
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Yes, you will be able to - the 12AU7 has substantially less gain than either the 12AX7 or the 12AT7, roughly a fifth of the X and a third of the T. The tube gain isn't the only factor, but it does make a noticeable difference - it will expand the useful range of the MV for those people who only use it in the lower half. Most amps have more than enough gain built in to still reach full power if it's needed, you just need to turn the master up further. You should also find that the amp sounds more open and clear because the bandwidth of the 12AU7 is greater, although it doesn't make as much difference in a guitar amp as the specs look like it should because it's still limited by the speaker response.
Hmmm, I might give that a try with my markIV. Will that help with having the MV on 1-1/2 being a good rehearsal volume, and 1-3/4 drowning out the drummer? Also I'm wondering what effect it has on the GEQ. Boogiebabies has talked of how the GEQ uses the PI tube to do it's thing. Would this reduce the db gain/cut?94Tremoverb said:
94Tremoverb
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The graphic EQ definitely does not use the PI tube - it's a completely separate solid-state circuit. It *is* the last function stage before the phase inverter, but that's all.
(Apologies if you did not know that the Mesa graphic is solid-state - but it is. This is nothing to get bothered about, it uses discrete transistors operated purely clean, so it doesn't affect the tone, just the EQ. It's also always in the circuit even when the EQ is bypassed, so you don't gain any 'purity' by turning it off. Believe it or not they even used this turned-off GEQ circuit - called the 'Mojo Module', of course with no mention of EQ or transistors - in the Blue Angel and Maverick, because it *improved* the tone!)
A 12AU7 in the PI should open up the MV range a bit, but I don't know how much. It's worth trying though, even good NOS 12AU7s are not expensive.
(Apologies if you did not know that the Mesa graphic is solid-state - but it is. This is nothing to get bothered about, it uses discrete transistors operated purely clean, so it doesn't affect the tone, just the EQ. It's also always in the circuit even when the EQ is bypassed, so you don't gain any 'purity' by turning it off. Believe it or not they even used this turned-off GEQ circuit - called the 'Mojo Module', of course with no mention of EQ or transistors - in the Blue Angel and Maverick, because it *improved* the tone!)
A 12AU7 in the PI should open up the MV range a bit, but I don't know how much. It's worth trying though, even good NOS 12AU7s are not expensive.
I know this is an old topic but....I posted a similar one in another forum and was wondering how a 12AU7 would affect a Mark IVA in the PI postion. One poster said that it ruined the sound and lost all gain, can't remember which Mesa they tried it in. Just curious trying to get a feel. I play mostly classic hard rock. Also how would this tube work in the reverb V4 slot? Thanks
Think of the tube as a water hose. Using a lower-gain tube is like pinching the hose - less water. In the case of the tube, less output.
To get the SAME water output with a pinched hose, you need to turn up the faucet. For the reverb, turn up the knob. You will get the SAME amount of reverb at 10 that you used to get at 5.
To get the SAME water output with a pinched hose, you need to turn up the faucet. For the reverb, turn up the knob. You will get the SAME amount of reverb at 10 that you used to get at 5.
swbo101 said:
Is there not enyone else that have actually tryed putting a ecc82 in the pase inverter slot other then me, a mesa boogie mark amp is not build on thory and scematics , but on sound and guitar respons , a guitar amp is in effect a direct extension of the guitar sound, so basicly its also a instrument, so in "theory", that is why designing a guitar amp with a 3 gain stage preamp design is all about the sound and respons.
A martin wetern guitar a violin or eny other string intrument are tuned and designed by ear, because the matmatics and sience of today is still lightyears behind the capebility of the human ear wich is a direct extenion of the human brain and its respons to what it hears.
If we are talking a hifi amp it a different story and here sience have more to say.
Its not like a HIfi replay system where you want it to embark as littel sound carateristics as possible so you can get the most fatefull replay of the guitar sound recorded.
The two amp designs filosofies are utterly different
I dont know the sience behind the phase inverter but putting the ecc82 in there did not effect the vol of the power section, but greatly effected the gain carateristics of the preamp, and those carateristics are why i bourgt the amp.
And yes putting a complty wrong spec tube in a amplifire that relay so heavyly on the preamp tubes is like putting complty wrong strings on a stradivarious violin to make it sound less loud .
Again thise is only related to my IIc+ it might work out differently in a mark 4 or 3.
It dos not work in the v5 in my amp like i hoped it would( yes i also read on the net that i could turn the amp up louder and getting the same sound in theory) meaning i could turn the amp up louder, it just made the sound crappy , at least that was my findings.
I think its because a mesa mark amp is preamp orrinted design compared to marshall epicialy the older ones
The only way to know exactly what happens and not just in thory is to try it out, or call mesa boogie up and have them explain why the put a 12ax7 in there .
You'd do better to get a couple of good NOS 5751's and putting them in V1 and V3 positions.In my experience,a 12AU7 is too low to put in the PI on any amp,except some Hi-Fi amps that were designed for it in that position.I think it would kill your reverb,too low a gain to drive the pan,then the weak signal from the pan is made weaker by the lower recovery gain of the AU7.swbo101 said:
Thanks for everyone's input....I got this tube by mistake. Bought a bunch of AX7's,but one was a AU7. Just wanted to see if I could have used it anywhere before I went to return it. At this point it appears to be pretty useless for me. Just going to bring back to the store. Much appreciated!!!
94Tremoverb
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If putting a 12AU7 in the PI killed the preamp gain and tone but didn't affect the master volume setting, are you *sure* you put it in the PI slot? Just asking, because what you found is the exact opposite of what should happen - which is that the preamp gain (which is entirely before the PI and not affected by it) won't change, but the drive to the power tubes will - and exactly what *would* happen if you put the 12AU7 in V1. (Or another of the preamp gain positions.)
I'm not saying the 12AU7 is necessarily a great choice for the PI - although I've tried them there in several amps and found them to be quite useful, while very different from the 12AX7 - just that it should definitely affect the power stage and not the preamp gain. There will be a *slight* gain change in that the PI is part of the negative feedback (presence) circuit, but it still won't affect the main preamp distortion.
Why not try it before you return it? It won't do any harm, and you may find something interesting...
I'm not saying the 12AU7 is necessarily a great choice for the PI - although I've tried them there in several amps and found them to be quite useful, while very different from the 12AX7 - just that it should definitely affect the power stage and not the preamp gain. There will be a *slight* gain change in that the PI is part of the negative feedback (presence) circuit, but it still won't affect the main preamp distortion.
Why not try it before you return it? It won't do any harm, and you may find something interesting...
The 12AU7 in the PI could give the impression that the pre gain was lowered since it lowers the drive to the power tubes,and the power tubes are what you actually hear at the speaker,one might interpret it as lower gain in the pre.94Tremoverb said:
