The Watering Hole

I'm listening to music through my Cowon X7 MP3 player through my Yamaha HS5's using the NANO PATCH volume control you suggested. I have to give you a thumbs up, again, on this thing. I think it's a damn good product. Really clean, no noise, simple product. It's kinda amazingly simple and absolutely clean sounding. Doesn"t add any shit to what you hear. Really impressed with this. It actually does exactly what it's meant to do. thanks again. :)

It's passive???    :P

Yep, I'm pretty sure it's passive.  It wasn't all that expensive IIRC either.  

No, not bad.  It is passive though.  Basically a pot in a box with jacks.  Works for what he wants, so it's ok, just had to give him some crap.  

I love these pot in a box things people are selling for you to put in the loop of your tube guitar amp, and advertising how it allows you to "get cranked power tube tone at love volumes!"   LMAO  Don't these clowns even know what they are selling?  Almost as funny as the people claiming that putting a 12au7 or whatever lower gain tube in the preamp gives your amp more clean headroom.  NO SPARKY, all it does is allow you (force you) to turn your volume up higher with less distortion BECAUSE THERE IS LESS VOLUME MORON!  

Rant over.  MP3's forever!  

DreamTheaterRules — Jan 23, 2014Almost as funny as the people claiming that putting a 12au7 or whatever lower gain tube in the preamp gives your amp more clean headroom.  NO SPARKY, all it does is allow you (force you) to turn your volume up higher with less distortion BECAUSE THERE IS LESS VOLUME MORON!

hmm... I dunno about that. maybe you don't run into output tube headroom issues too often?

No I don't, but that's not the issue.  Dar and I had this conversation a long time ago.  It's kind of long to get into it.  Simple answer:  Using a lower output pre-amp tube does not give you any more clean headroom.  It lowers the gain at (in theory, depending on circuit,etc.) any gain stage that follows it.  This means that you never push the power amp section as hard.  This does not mean you have more cleans or "more clean headroom."  It means you have less gain.  Oversimplifying, but, yes, it might go to 7 or even 10 without distorting with a low gain pre tube, where it used to distort at 3.  But that's ONLY because the 3 was pushing your amp harder, meaning that 3 or wherever it started distorting, is as loud as the 7 or 10 now with the lower gain tube.  

Another way:  Whatever your output stages limit is for clean output before it starts to clip, that limit is the same regardless of whether it's getting hit with 1,2 or 5 stages of preamp gain.  Some amps, like some of the classic fenders, are designed to be clean all the way up.  That means the pre stages never push themselves into clipping, and they don't push the power stage into clipping.  Whenever the signal that hits that power amp section is sufficient to push it past the clipping stage, it hits that wether it's one preamp tube and the volume is on 10, or it's 5 tubes and it's on 2.  Whenever the preamp gain level is enough to push it to that limit, no matter how many stages or how wide open they are or aren't, it hits that limit.  But, that limit DOES NOT change depending on the preamp gain.  

You could put 2 12 ay7's in instead of one and maybe crank everything and never get clipping.  But that is not more clean headroom, it is a lower gain level that can't push the power section enough to clip.  

This is a VERY common misconception. I read it all the time at TGP and about once a week I see someone post something like I just did, saying that it is not correct.   Over the years since Dar and I discussed this, I've seen some big name amp guys pop in and say this as well.  There is a bit more too it, this is generalizing, but correct.  

So, going from a 50 watt amp to 100 watt amp, adds clean headroom.  Adding bigger OT's or power supply caps, can add clean headroom.  Lowering gain in the pre stages can not add clean headroom, it only changes the position of volume or gain knobs relative to achieving clipping.  

If I get time, I'll do a little better, more detailed explanation tonight.  For now, think about this.  Let's say it takes 50 dB of gain to push any power amp stage it's limit so anything more than 50 dB starts to clip.  Lets say one 12ax7 can put out 50db gain per gain stage.  (I'm making up numbers for example, but this is how it works.  

You can have an amp that has 1 12ax7 and that gain stage is pretty wide open.  You'd have to turn the amp up all the way to 10 to get full volume and it wouldn't clip the POWER section.  

Now you have an amp with 2 12ax7s.  Typically in multiple gain stage amps, each stage due to shelving, EQing etc, usually passes on around 20 db of gain to the next stage.  Lets say we use 3 of the four gain stages available (2 per tube) for gain and the other for the tone stack.  We now have approximately 60 dB of gain available.  Now, the pre-amp will push the power section to clipping if we turn it up past 7.  

Or, same second example but we let 25dB gain through at each stage, now the power section clips when up past 5.  

Now we go 4 12 ax7 high gain amp.  That clean limit is still hit when we reach that 50dB input limit.  But we have TONS of gain now.  We dial most of pre-amp gain and pull each stage down to 20 db to control the beast.   This one can have pre-amp clipping even at low volume.  So how do we judge clean headroom?  That can confuse people, but our theory still holds.  If we dial the pre-amp clean or use the clean channel, doesn't matter... as long as it's clean and we don't exceed 50dB gain, clean power stage!  But even if we use multple gain stages and the preamp stays fairly clean, when we hit the power stage with 60 dB it's overdriven.  

There's way more too this, but, lower gain tubes are really like just turning the gain down.  When you do, you lose volume.  To get that volume back you have to turn it back up.  The clean headroom limit does not change though.  

ok, this seems to be a jargon thing hanging up on "clean"... so, honest question:

if I am sending a signal to a limiter, and it's clipping 12dB... then I modify the signal so that it's clipping 6dB, what is that new state called, in terms of headroom, relative to the prior state?

I understand your point that there is no clean headroom at all in this example - I need the correct term for what I've experienced with my amps, I guess.

officially, you just lowered the "clipping threshold."  If that were a POWER amps clipping threshold you were talking about, you would have lowered the clean "headroom" when you lowered it's clipping threshold.  

What I think may confuse people is the gain staging.  Your example uses one stage.  Thus, not applicable to a power amp stage where preliminary signal boost (aka the pre-amp stages) are required to get the signal up to a level that can make that power amp stage work.  

Or, if your example were applied TO the pre-amp stage, it would make it clip earlier, and due to lower level, not push the power stage as hard... again meaning it (power stage) isn't clipping.  

Give me more detail on what you mean about what you're experiencing with your amps, and I'll try to elaborate to the best of my ability.  

DTR, that's not entirely accurate. For example, you completely leave out the transconductance range of the tubes, at which point, there is no more available gain.  Gain does no just increase linearly, it's a parabolat.  And you don't distort the input stage of your power tubes... no matter what you are hitting them with... that would just sound awful.  The phase inverter transconducts... a 5751 more than any other tube... so it has more available output at the same input level... or put another way, reaches maximum loud with a quieter input signal.

So does the volume pot work in the fx loop?  Well, it makes the amp quieter.  It's pre-phase inverter, so you might decrease the effect of any PI distortion.  But not likely to make the sound much different.

Yeah, it's essentially a pot with jacks.  Of course there is some switching logic in there, to switch multiple outputs to multiple inputs. Also a headphone amp, I believe. If I were to make it I'd use a stepped switch with precision resistors, and it would cost a lot more. It's very hard to get pots that are accurate enough to function as this sort of passive volume system, however many reviews on this box are good so it seems to be reasonably well specced.  


For your example, ironsheep, I wouldn't call it headroom but dynamics.  Once you hit 0 and start pushing down with a limiter headroom is gone.  At that point changing the level you are compressing is affecting the overall dynamic range, but not affecting the headroom, which is gone.

DreamTheaterRules — Jan 23, 2014You'd have to turn the amp up all the way to 10 to get full volume and it wouldn't clip the POWER section.  

 

You don't clip the power tubes with an input. Unless the amp is broken maybe...

ah, ok. "I run an AU to get more dynamic range out of my power section"... that sounds right.

"I have some headroom on my mic preamps, they run about 6 dBs short of clipping"

Charger, I didn't completely forget anything, I said I would keep it simple so I spoke in generic terms.  

I never said a power stage clipping was the same thing as a preamp stage clipping, but.... a power stage can't clip????    Have to say, never heard that one before....   This isn't symantics either.  Clipping means anything other than the ability to cleanly reproduce all transients.  Whether that clipping is a a nasty noise (like digital) a "distortion" or simply  running out of power=compression, it's still clipping.  It IS when the power stage runs out of ENOUGH power to cleanly reproduce the input wave form.  Power amp can't clip????  Please explain that statement.  

Yeah, only at the ole Hole can a argument be engaged in over a Thank You.  ;D

I just like the damn thing.  ;D

Hookbender — Jan 24, 2014Yeah, only at the ole Hole can a argument be engaged in over a Thank You.  ;D

I just like the damn thing.  ;D

NO YOU DON'T!!!!

(J/K!)  :D

I'm impressed Hookbender, Even with a funny haircut, you can get people stirred up just by saying thank you.  ;D ;D

Now I'm confused. (I know, again)  Is a Clown a Moron because a 12AU7 sounds cleaner to him, or because he doesn't have his audiophile terminology correct???  Did you call these people morons on the site they posted the erroneous information?

Now I'm scared to talk about my driver tubes, I might get called names.

i don't know what the fuck your talking about. I quit reading when I realized it was a argument about something I couldn't give a damn about. ;D ;D ;D

Oh my.  I should have known better.   :-[

First of all, the "moron" thing was very tongue in cheek.  I wasn't saying anyone who believes that is a moron.  This misconception is mentioned about 10 times a day at The Gear Page, and about once a week I read someone post how it is not correct, and give a detailed explanation of why.  They later someone else will say it and people start linking to that post.... anyway....  Then it will be mentioned 20 more times in the next week that someone says they do it, then the whole thing repeats.   Not calling anyone a moron!!!!! JOKING about the way it keeps happening there!  

I am completely certain that this is the only site at which I've ever called anyone a moron.   8-)  

Now, IF your question was supposed to be serious I'll answer it.  Let's use two examples because I want to keep it general but don't want someone coming in and saying "that doesn't apply to this example.  There are numerous amp designs and there are MANY differences in them.  My statement that lower gain preamp tubes do not equal more clean headroom apply in principle to all so lets use two extremes.

1- we'll call this a Fender because it's clean to the bone.  With everything on the amp turned up to 10, the power amp doesn't clip NOR does the preamp.  This is the simplest example and the "purest" example if you will.  Dropping a 12ay 7 in this amp will in simple terms, do nothing but lower the volume!  If turning it all the way up won't overdrive pre or power stage with a 12ax7, all you do is lower the gain levels throughout the whole amp, when you drop an ay7 in there.  This amp will now simply not get as loud as it did before.  Thats the only difference.  

1A- would be a fender amp that if you crank it up to 7, the preamp is still clean but at this point it now overdrives the power section.  Dropping a lower gain pre tube in this amp, will maybe allow you to turn it up to 10 with no power amp OD.  But this is NOT clean headroom being extended, it again, is lower gain through all preamp stages equaling a lower level of power being put out by the power section, hence it does not overdrive/compress etc.  At 10 the ay7 amp in this example is still not as loud as the ax7 amp was on 7.  

2- we'll call this a mesa amp.  It has multiple gain stages and there is a ton of preamp OD available.  This changes things somewhat.  Let's use the "modern" channel on my Mini Rectifier for example, and lets say that even at 10:00 on the gain knob, it's already grinding.  If we drop an ay7 in V1, we lower he gain on stage one and two.  All this does, is perhaps allow us to turn the amp up to noon or a little above before we hit that grind we had at 10:00 before with the ax7.  With both amps at 10:00 it IS cleaner, but it's also quieter.  So, YES if you leave the settings the same and replace the ax7 with an ay7, it WILL be cleaner but it will also be quieter, because all you did in essence, was turn the gain down in that stage, buy using a lower gain tube rather than by turning the knob down.  

Just remember, that's preamp gain and IS NOT RELATED to "clean headroom"  as used when discussing guitar amps power sections.  

And lastly, "headroom" is not some audiophile BS term.  Headroom is the same in a high end stereo power amp, as it is in a guitar amp. It is reserve power that an amp has to meet transient peaks.  More watts = more headroom.  Bigger OT's = more headroom and bigger power supply caps = more headroom.  More headroom can equate to more punch when you pick hard, to deeper, tighter bass and more total output with you hit notes hard.  

the thing is, I've had these THD amps for years. they're made for tube swapping - I have checked out all sorts of things as far as gain staging, driver values, input... blah blah -- but, because I've done all of this on my own, I don't use the proper language -- it's all "this one gets raspy, that one is microphonic... the green one isn't very musical but combined with the mullard is awesome... that 6L6 breaks up a bit early, might want that AT in the driver... that KT66 sounds good but never really breaks up, even with an AX" etc. it's not that I don't know what these things sound like (believe me, I do), it's that I don't write or talk about them often (or, at all) -- verbal description is not a big part of my day.

when I saw "clean headroom", I didn't think of the thing you intended - I was thinking, as we've cleared up, "dynamic range". I'm not sure, now, if I ever have any clean headroom at all... probably not! why use tubes if you want clean headroom??? but that would probably lead to another argument... heh.

Bingo.  Now here is my understanding of Headroom.  It is wiggle room before the amp distorts.  As described here.

http://www.fender.com/news/headroom-what-is-it/

I have had a Univalve, Bi Valve, and a PicoValve.  Let's take the PicoValve for example.  Andy Marshall designed that amp with zero wiggle room, with 2 - 12AX7 and you pick the Powertube.  Very tough to get a clean sound out of it.

Put a 12 AU7 in it, and now you can get a clean sound out of it.  Now I guess I'm a moron, but there is a little room before the amp distorts.  By Fenders Definition, That is Clean Headroom.  It runs better with a 12AT7, less wiggle, but very usable.

So by adding a 12AU7, it got headroom.  I know, I'm a moron.

Ok, one more attempt at getting myself out of trouble for the joke, and then I will just shut the hell up.  

The "moron" comment was a JOKE made regarding the CONSTANT AND ONGOING discussions about this at The Gear Page.  The "moron" was in reference to people who have had Randall Smith (owner of Mesa Boogie) or Jeff Bober (Budda) or one of the other top amp guys in the country, come in and explain gain staging vs. clean headroom, and then the same guy says a couple weeks later that he got more clean headroom when all he did was change the gain staging.  So, I don't know why I offended anyone when I said that above but at this point apparently my best bet is to either not discuss anything here or strictly state facts, never opinions, never try to have fun, never crack a joke, or just shut up and not comment.  

Dean, here's the thing.  I read the Fender link and it explains exactly what "clean headroom is" and it is not what you are describing.  What you are describing is preamp gain staging.  Use their car example:  If your car goes a max of 65 and some MORON is in front of you on the interstate going 64, you only have 1 MPH of "headroom" to pass him.  You pull into the fast lane and it takes you a mile to get past him.  But if your car goes 100 MPH, you have way more headroom.  You pull out in the fast lane and punch it, zip up to 75 or so, fly past him, then pull back into the slow lane and set your cruise on 65 MPH and the whole time your left turn signal has been on.  Which car had more headroom?  Headroom is just what fender said, reserve power.  

The confusion with gain staging as I tried to explain, is this.  Use my Mini Rec example.  I can get crazy gain, at levels where my power tubes aren't putting out one watt.  That IS NOT because I ran out of clean headroom (power stage!) it's because I have multiple gain stages in the preamp stage overdriving each other creating the OD, which is the same thing you are describing with your amp.  

Conversely, you are gigging every week and you have found that your 25 watt amp is PERFECT for your band, because when you crank it up it is just loud enough for rhythm, and when you hit it with your tube screamer for solos, it get's just enough louder to stand out.  Then, your drummer goes to rehab and you get a new drummer.  This guy is way louder than the last guy and suddenly you aren't loud enough.  You turn your amp form your former sweet spot of 7 up to 10.  The problem is, the amp doesn't get ANY louder, it just compresses more because you had already reached it's peak output.  Now, turning it up further only added overdrive, not VOLUME.  Now, your rhythm isn't loud enough.  Your first solo comes and you hit your tube screamer... What the????  It didn't get any louder at all, it just added more gain/compression, sustain, but NO volume.  Why?  You had no headroom left.  

The thing that is so confusing about this, is that all amps work differently.  Many times the preamp distorts before you run out of clean headroom/ power amp capacity/volume.  Some preamps stay clean but offer enough drive to put the amp to it's max at 4-5 and then  the power amp starts to compress/OD even though there is no preamp distortion.  Then some can go crazy gain levels even before the power amp is ever pushed at all.  

It's terminology.  Your amp can be distorted and still be WAY into the "clean headroom" area of it's operation if, the distortion is coming from the preamp and the power amp is nowhere near it's limit.  Pre-amp distortion has NOTHING to do with "clean headroom" which is only related to the power amp stage.  Clean Headroom = max volume capacity, power reserves, etc...  Another example:  Turning on a distortion pedal when the amp is at low volume, is similar to preamp stages overdriving each other.  The OD is just coming before the preamp.  But, has nothing to do with power stage clean headroom.  

Please let me know if I am helping clarify this at all, or if you still disagree or are offended and would rather me just shut up and go back to work.   :-X

Sorry, but examples just keep coming.  Here's another one.

Headroom is the same thing in an amp as it is in recording!  If you are keeping your mix levesl at -12dB, you have 12dB headroom (and I know if it's digital you probably really have less because you don't ever want it to hit 0, while if it's analog it can probably go plus 3 without problems, but that is not the focus of this discussion!)   If you are running that same mix at -6dB peak, you only have 6 dB of headroom.  You have 6dB of room left before you hit the max.  Just like the amp, it doesn't matter if you are using preamp distortion on your amp, clean headroom is how much room you have left before it maxes out volume wise, without compression/clipping/OD or whatever is applicable to that device.  Now look at some of the modern slammed mixes that sit 1-2 dB below clipping.  There is NO headroom left on these at all.  They can't get any louder.  That's why Charger and I complain at times about the lack of dynamics in these recordings.  They compress them so the quietest stuff is near max level, and turn the level up to where it's almost at max.  NO headroom.  

I remember having this discussion one time YEARS ago with Jamie.  He wasn't buying some of this either because he was using a 5751 in his C30 and saying "more clean headroom."   Dar and I talked to him and Dar told him that to prove what we were saying, I could bring a dB meter to WHStock and show him that while yes, the amp was clean on 10 instead of compressing by the time it hit 7, it was also not as loud on 10 as it was on 7 with the ax7.  Then Dar got real detailed about each gain stage of the C30 and "here is how many dB of gain this stage is passing with this tube vs that tube.  He scientifically showed us how many dB of gain had to hit the power stage of the C30 in order for it to run out of headroom and that with 12ax7s it was possible.  Then he took that chart we all had showing the comparative gain of the varios 12a.... tubes and showed us how much lower gain would pass through each stage if we swapped this tube vs. that one.  My knowledge is not at the Dar level!  I have to use the RC calcs, and gain stage calcs to figure all of these things.  He was doing them in his head (so yes, it was hard to keep up).  

But again I say, the terminology is the confusion.  And again I offer to bow out if I have been offensive.  (To anyone except the MORON who was going 64MPH in front of Dean.)  

two things DTR:

1) I didn't think you were calling me (or anyone here) a moron. I wanted to understand why the way you used "clean headroom" didn't match my experience... the further explanations sorted that out.

2) while I thank you guys for the info, I'll still think about headroom the way I used to even with this correction... because it's not important to me to be correct, it's my desire to be understood. if I say "I'm running an AU in the driver for more headroom" you may cringe but, and this is the important part: you, along with everyone else, will know exactly what I'm talking about and what I mean.

if I said "I'm running an AY to get more carrot"... well, that would be another story.

First off, I'm just busting your balls, Howie.  I never thought you were were calling me a moron.  I just thought that my "practical" use of a 12AU7 warranted waving a flag.  The tone is clean.  Not a lower volume distorted tone.  I did read your earlier post and I will read your above posts.  I don't think you're wrong, though, in this case, I don't think I am either.

I usually let you rant and don't mind much.  I thought this a little closer to home.  Plus the loose use of moron, is similar to Madonna's use of the N-Word.  It could be offensive.

I'll read your above post and get back to you.  Maybe start a thread in the proper section about these low watt amps.

"before the sound starts to break up and distort."  That is a partial quote from the Fender link, but the key word is SOUND.

Anything before is headroom, from their definition.  I get your schoolin'  ;D But I still get a clean tone by adding a 12AU7, with a little headroom. :D

Sheep, I get it.  I was only trying to explain how it works, and clarify terminology.  I never said you were wrong in what you heard, or your experience.  I just stated that the terminology that was used on a regular basis at TGP, was not correct.  I'm thinking by personal pics and signatures, it may be someone else who was more offended.   :-[  Dang it, now he changed them back!   ;D

I am the one who brought this up.  LOL  I didn't "correct" someone else who said something I didn't agree with.  I noted the guys at TGP who keep talking about it even though it has been explained there 100 times. Here, it hasn't been discussed in years.  I have always been one who wanted some level of understanding of how or why things worked, so that I could make educated choices AND use those things to my advantage or objectives.  I was not trying to say "you guys are wrong."  I was trying to explain how things worked and what these changes really did to your amp.  Understanding it is part of the journey for me.  If a guy comes to me and says he wants a great clean tone from his amp and will use pedals for gain, but wants the amp to be great clean tone all the way up, I am not going to suggest he buy a high gain or mid gain amp, and then drop in low gain tubes.  I'm going to suggest he buy a great clean amp.  If a guy says he already has an amp and can't buy another one and how does he make it cleaner, I'd suggest the opposite.  If he says he loves his amp but the new band he's in is too loud and it's just not loud enough for the new band, I tell him he needs to get a bigger more powerful amp to keep up.  (More headroom, had to sneak that in there).  

Lastly, understanding can lead to better use of the things we have.  Example, what Charger was saying earlier about PI distorting, etc... I didn't want to get that technical, but, changing V1 to a lower gain tube lowers the gain at every other level in the amp.  (this is true unless the amp has enough gain stages to eventually add back the gain you gave up in stage one because they can make it up in stages 2,3 and 4 or whatever).  So when doing this, you may not hear that PI overdriving the same as you did with the ax7 and that may be a good thing or bad thing.  You might be better off with the ax7 and just turning the master up more and gain down some, because it affects the whole chain.    just saying.  But if you crank the master all the way, and then need it be cleaner, you can drop a lower gain preamp tube in and it will clean up the tone if either pre or power stage was overdriving, because it lowered gain through the whole chain.  

Is anyone here getting the opinion that it must be my slow season at work?  Not many people buying houses when it's freaking 1 degree outside at NOON!  

DreamTheaterRules — Jan 23, 2014Charger, I didn't completely forget anything, I said I would keep it simple so I spoke in generic terms.  

I never said a power stage clipping was the same thing as a preamp stage clipping, but.... a power stage can't clip????    Have to say, never heard that one before....   This isn't symantics either.  Clipping means anything other than the ability to cleanly reproduce all transients.  Whether that clipping is a a nasty noise (like digital) a "distortion" or simply  running out of power=compression, it's still clipping.  It IS when the power stage runs out of ENOUGH power to cleanly reproduce the input wave form.  Power amp can't clip????  Please explain that statement.  

Did you read what I wrote? I said "you don't clip the power tubes with an input".  You posted a lot about the gain of the input tubes... i was merely noting that input gain from the preamp sections does not clip the power tubes.  The power tubes distort... when you turn them up... but aren't clipped inherently by the input coming off the phase inverter... you can have a massively distorted wall-of-gain input coming into the PI, and the power tubes, at low volume, are going to reproduce that cleanly... People make audiophile tube-powered stereo amplifiers, that are incredibly accurate and do not clip... as you know.

You turn your amp form your former sweet spot of 7 up to 10.  The problem is, the amp doesn't get ANY louder, it just compresses more because you had already reached it's peak output.  Now, turning it up further only added overdrive, not VOLUME.  Now, your rhythm isn't loud enough.  

Also remember that volume is logarithmic--if you're running your amp at 7 and you turn it to 10--say the control is linear, and you go from 7 watts to 10 watts... That's barely a volume difference.  Say it's a logarithmic pot, and 7-10 actually adds 5 watts... that's 3dB difference.  You always have to double power to increase volume by 3dB. But essentially this is true--there's a point at which your power transformer cannot give any more wattage to your power tubes and you just won't get any louder, e.g. you can stick a bigger power tube into an el84 amp and it's not going to get louder unless the transformer is oversized.  With the smaller tubes they're going to reach their limit and simply not have any more electrons to give if the transformer is oversized, thus limiting volume.

Just as a side note, we use amps in the 5-15 watt range in our jams, if I ever turned an amp up to 7 it would kill people.  In fact, we run the amps around 9 o'clock, and use attenuators on all but the 5w amp. Sometimes the 5w amp gets turned up to 10 o'clock, like last night, which was a fucking loud jam.

Did you read what I wrote? I said "you don't clip the power tubes with an input".  You posted a lot about the gain of the input tubes... i was merely noting that input gain from the preamp sections does not clip the power tubes.  The power tubes distort... when you turn them up... but aren't clipped inherently by the input coming off the phase inverter... you can have a massively distorted wall-of-gain input coming into the PI, and the power tubes, at low volume, are going to reproduce that cleanly...

Exactly!  Explained that above in my Mesa example.  Again, I was simplifying and referring to gain stages and the preamp ones developing the gain that eventually hits the power stage.  I know exactly what you are saying and agree of course.  

Here's a bit of irony for you guys.  In a power stage, or in a simple tube amp with few gain stages, if you want to increase headroom, do you want higher, or lower gain (rated) power tubes and preamp tubes?    Ok, the "irony" gave it away...  you want higher, because the gain of a tube when tubes are rated, does not refer to "gain" as we often refer to it, meaning more grit, grind, OD or whatever.  Higher rated tubes both pre and power, have more OUTPUT.  They don't distort more.  They do have the ability to perhaps distort the next gain stage more, but only because they have more output.  Which means, yes folks, higher gain rated tubes have more clean headroom.  

Now, if you don't believe that because you dropped a high rated 12ax7 in your Marshall or Boogie and it had more "gain" or overdrive, that is because of what I described.  These amps have multiple gain stages.  Dropping a high gain tube in V1 pushes every stage after that harder.  It will overdrive the next stage harder.  But, in terms of headroom, which is the top end limit before we run out of gas, the higher gain tube raises that.  It adds more headroom.   If you want the highest headroom you get get from your existing amp, buy the highest rated output tubes you can get.  What they rate as "gain" is output level capability and = headroom (again, assuming the power supply and caps are up to the task).  

Another example for those who haven't puked yet:  I dropped a bigger Hammond OT in one of the Valve Jr's I had.  Due to the biasing, that OT itself didn't give any more "watts" to the amp.  But it definitely gave it more headroom.  That amp mushed out when cranked all the way.  Back it down to 3/4 and it was fine.   At full volume hitting a chord hard sounded like you had a compressor on.  It ran out of gas.  With the bigger OT, you could turn it up all the way and it wasn't mushed out.  AND even up all the way when you whacked a chord hard, it was louder.  The bigger OT added headroom.

And Charger, I have another brand new Hammond OT for a Valve Jr that I'd sell you cheap if you want it.  I bought two and sold the Jr.s before I ever got the second one installed.  

the thing that's making me laugh about all this is that, as it turns out, I despise clean headroom and do everything I can to set my amp up to kill it off. heh.

That's what I've been trying to tell you!   LOL   (J/K!)

Seriously, think about this... people talk about wanting that power tube distortion all the time.  Power tubes don't really produce distortion (like solid state or especially digital devices do when they go past their limit.   What they do is compress.  I have been known to be a bit of a smart ass at TGP and when people say something about wishing they could push their power tubes to distortion at home but it's just too loud, I'll post a picture of a compressor pedal and not even say anything and then just see where the conversation goes.  LMAO  Some guys always get it and when others start posting "what does that mean?" they'll explain it.  Of course, I always post smiley faces when I do it.   ;D ;D

Another thing I almost always do is have a boost on.  While I know it is not exactly the same, a boost does to V1, what a lot of level coming in does to the power stage.  But, without having to turn the volume up til the power stage runs out of gas.  That's why I always say you can make your amp sound more cranked by slamming V1 with a boost.  

I guess the thing that confuses me, and maybe many others is the words "clean" and "headroom" together.  I get that the pre-amp is unrelated to the Power stage, as far as headroom goes.  I'll yield there.  I'm a wrong moron. ;)  

The thing that I like to do is get a clean tone, and then push it with a pedal.  The little 5 watt amp is great for that, only it is hard to get a clean tone out of the box.  Hence my confusion, because you can clean it up by lowering the pre-amp gain.  Most of the jargon is over my head.  What I can do is swap tubes and improve the tone.

Howie, I was just alarmed at the way you screamed MORON about a situation that I fell in to.  I thought you were calling me. LOL!

My Bad.  I'll leave you alone to rant.

yes! blackfinger in the loop is very close... but output tubes sound distinct - they're just awesome sounding compressors for guitar. my mic pre's are shitty compressors for guitar... heh.

I now think the phrase "clean headroom" should be replaced by "peak headroom".

I'm interested in rms headroom, or lack there of... ;)

(lol, I can't imagine clipping rms... good lord)

((on second thought... is that even possible?))

Dean, In my defense, I said the word "moron" when describing people at TGP who discuss this all the time, and have had heavy hitters come in and explain it over and over, then they say it again two weeks later.  I also said it before you ever posted in this thread, and I said it jokingly.  And then, I've ranted for two days just trying to make sure you knew I was not saying that about you.  You are one of the last people I'd call a moron.  Unless of course, you are in front of me in the fast lane going 64!    ;D ;D

Yes, you are right in that the "clean" can confuse people.  People think "clean tone" = "clean headroom."  Saying "I put a 12at7 in V1 to get a cleaner tone" would make sense, where saying "I put a 12at7 in V1 to get more clean headroom" would be an incorrect usage of terms.  

So Dean, for the record, people who misuse terms aren't morons.  Morons are people who drive too slow in front of me.  Please try to get this straight.  

Edit:  Sheep, right.  Comps and slamming V1 are not identical.  In the same vein... maybe real close at times, but not the exact same.  But MUCH easier on the ears.  Also, I don't recall you ever saying before that you were trying a comp in the loop.  That's interesting... I've done that a bunch of times over the years.  

I've tried it but don't use it - output section compression sounds better. but yeah, it does sound good in the loop, just not as great.

a Barber Tone Press might work better there, with the Blend function.... I'm only speculating. I don't know what I'm talking about.   :)  

The product in question has loads of clean headroom. ;)