What is overhead room/clean room

Placidcasual79

I am I saying that right? What actually is it? At a gig tonight we had a very last minute change of PA - the resultant lack of channels meant I couldn't mic my amp and had to have it cranked. I found it difficult to keep my tone clean and my EP booster and Tube screamer created a lot more distortion/break up than I'd like......

mgaw

clean headroom...the amount of volume available before break up

Placidcasual79

Thanks - I think I ran out of it tonight....... I play a Fender blues deluxe

Placidcasual79

Is it even possible to run out of it?

jellybelly

Very much so - fewer watts means less available power. Once you get to a certain point with a valve amp it just gets grittier rather than louder. It can be mitigated a little by using a more efficient speaker, and I tend to find I get more out of combos if they're off the ground on a beer crate or table or something, but every amp has a limit. 

That said, if it's a blues deluxe (40w - one of the tweed covered fender amps right?) you must have been VERY loud!! A blues JUNIOR (15w) on the other had might struggle at some gigs. 

stratman3142

jellybelly said:

Very much so - fewer watts means less available power. Once you get to a certain point with a valve amp it just gets grittier rather than louder. It can be mitigated a little by using a more efficient speaker, and I tend to find I get more out of combos if they're off the ground on a beer crate or table or something, but every amp has a limit. 

That said, if it's a blues deluxe (40w - one of the tweed covered fender amps right?) you must have been VERY loud!! A blues JUNIOR (15w) on the other had might struggle at some gigs. 

That's what I was thinking. I've used a 40W Hotrod Deluxe III, which I assume is from the same family as a Blues Deluxe, at numerous gigs and I've not had a problem with clean headroom. Although it was mic'd at really big venues.

Was the amp very loud, which would be well past 3 on the volume control on my Hotrod?

MattFGBI

The blues deluxe breaks up earlier than the hot rod. 

stratman3142

MattFGBI said:

The blues deluxe breaks up earlier than the hot rod. 

Ah. Thanks, I stand corrected.

ICBM

Clean headroom is not always the same as maximum output power - depending on the circuit, the amp can start to distort in the preamp before it reaches full power in the power amp.

As Matt says the Blues and Hotrod Deluxes illustrate this very well - they are the same output power, but the Blues starts to distort earlier - in circuit terms its clean channel is actually more like a lower-gain version of the drive channel.

The clean channel on the Hotrod is designed differently and will go louder clean - I'm not 100% sure if it remains clean all the way to the point the power stage overdrives (you would need to check with a scope), but it's certainly much closer.

For real maximum clean headroom at around 40W you want something like a BF/SF Pro or Super Reverb - they don't overdrive before full power output at all, clean volume was the goal for amp designers then.

EricTheWeary

The other thing that comes up occasionally is the ' why doesn't my overdrive pedal make my amp any louder on gigs, it worked okay at home' question, which is the amp running out of headroom and anything more going into the front end just getting squished. 

ICBM

To put it non-technically , for me where it matters is the ability to hit a really loud clean chord and not have the amp distort at all, not even on the initial attack. That needs a substantial amount of power and an amp with a properly clean channel to achieve.

Interestingly it's less affected by the perceived volume difference between valve and solid-state amps too, in fact a powerful solid-state one will often do it slightly better.

Placidcasual79

Thanks guys - very helpful. It is a 40w Blues Deluxe (tweed covered one). The gig last night was louder than usual (Las minute change of PA).  It was a struggle to keep it clean last night - I wasn't happy with my tone all through, especially my pedals.

What I usually do is have the amp up very high (8 maybe) and the volume down on the guitar - is that likely to be a factor?

ICBM

Not really, it probably won't make any difference. The overdrive in the amp will be occurring after the volume control so it's really just the combined level that matters.

The only way I can think of that might give you a bit more headroom is to put a clean boost in the FX loop and back the amp's volume off a bit.

Placidcasual79

ICBM said:

Not really, it probably won't make any difference. The overdrive in the amp will be occurring after the volume control so it's really just the combined level that matters.

The only way I can think of that might give you a bit more headroom is to put a clean boost in the FX loop and back the amp's volume off a bit.

Thank you.  I don't mind that warm break up sound the amp gives me sometimes - but last night it seemed harsh. I am sure I could smell burning or that 'hot' smell coming from the amp. I've had a look this morning and all looks well.

I am becoming disillusioned with this, my first value amp, after initially falling in love with it.

ICBM

That 'hot' smell is usually the lacquer on the speaker voice coil winding. It's fairly normal if the speaker hasn't been pushed that hard before and isn't likely to be a problem.

Placidcasual79

ICBM said:

That 'hot' smell is usually the lacquer on the speaker voice coil winding. It's fairly normal if the speaker hasn't been pushed that hard before and isn't likely to be a problem.

Thank you ICM. I appreciate you sharing your knowledge.

DrJazzTap

That must have been loud! I have the same amp and I only struggled with clean headroom once.
That was with a full brass band and playing against a 1500w PA 
Did you try the other input jack? Iirc one is for high output guitars I think.

Placidcasual79

DrJazzTap said:

That must have been loud! I have the same amp and I only struggled with clean headroom once.
That was with a full brass band and playing against a 1500w PA 
Did you try the other input jack? Iirc one is for high output guitars I think.

It seemed vey loud. Its a nine piece band with horns etc. Usually we do out own PA, unfortunately on the night our PA couldn't be used. The venue gave us a 4 channel mixing desk which we used and then had to put the vocal and horn mics though the DJ's PA - which was ridiculously loud. Of course it was impossible to get a good mix and the amp was the only thing un-mic'd.

The band are having a meeting tonight to sort our PA situation out once and for all. We've been borrowing for 6 months. Hopefully we'll agreed to make a kitty and get our home. I am going to ask the good people of this forum for advice.

DrJazzTap

Yeah it might be the fact that like matt at fender said it's designed to break up earlier than the hot rod. I know the only time mine started to break up, it was bastard loud. 
You may need something else moving forward.

Voxman

ICBM said:

To put it non-technically , for me where it matters is the ability to hit a really loud clean chord and not have the amp distort at all, not even on the initial attack. That needs a substantial amount of power and an amp with a properly clean channel to achieve.

Interestingly it's less affected by the perceived volume difference between valve and solid-state amps too, in fact a powerful solid-state one will often do it slightly better.

+1 - Probably two of the cleanest and loudest solid-states when I was younger were the Roland JC120 and the HH IC100. The latter not only had incredible headroom and volume, but it's silver fascia with green illumination looked very cool in its day - but it's 'sustain' switch was just horrible!  

Placidcasual79

I am considering a change.... I have some money coming so a new guitar and amp is a distinct possibility.......  something that sounds like this would be good -