More Headroom For A Blues Deluxe Reissue

[Chuck H]

I looked into it a little more, and...

The schematic shows the clean channel volume pot is a 250k 15% taper wired as a damn variable resistor. Not much to be done there Changing to a 10% would make a small difference, but the real issue is that the volume control isn't wired as a voltage divider. Attempting to change that would interfere with the other channel topologies.

Mesa offers a 250k 5% taper with solder lugs. A 5% taper should make a notable difference.

https://store.mesaboogie.com/product...dio-taper.html

You'd need to panel mount it and solder it to leads from the board where the original pot was. I've done this before with no trouble.

[Leo_Gnardo]

The schematic shows the clean channel volume pot is a 250k 15% taper wired as a damn variable resistor. Not much to be done there

Though the volume pot itself isn't a voltage divider in this circuit, the pot - wired as a rheostat (variable resistor) - in series with the fixed resistor "above" it does make a voltage divider. A couple more field solutions: you could solder a resistor across the pot which limits the maximum volume available with the control at 10, and decreases the volume proportionately so the user can dial up the control further eliminating the complaint "it's already too loud by the time I have it dialed up to one & a half." Downside, tone won't be quite as bright. Which would be perceived as a good thing to most users of these amps.

Another, the series resistor "above" the pot can be increased, same results, perhaps the tone will be a little brighter.

The no fuss no muss solution of using lower gain V1 tube should not be ignored. Recently a customer responded to subbing in a 12AY7 here joyously "this is just what I've been looking for! Why don't they do this at the Fender factory?" Well, they did, 1959 on back. I'd recommend trying that first, before swapping pots & resistors, what a tedious job that is.

[rich64]

JMF, Rather than flog my client over his choice of amp/rig as a service man I'm going to do my best to give him what he wants. My headroom/output statement refers to the fact that regardless of bias setting the thing will get plenty loud (a technical term for customer pleasing) and clean-ish. There still is a little "fizziness" in there. Take me to task if you must for my lack of specificity regarding "numbers" but for 35 years I've pleased my clients and been able to communicate clearly with fellow techs. That said I DO appreciate you taking a few minutes to address my post. A Blues Deluxe is not my choice of amp either. However I could use it at one of my gigs along with my pedalboard and do just fine. Have a blessed day, 64

[rich64]

Hello Chuck H, Your statement "If the amp is performing, and I'll bet it is if it's adjusted correctly and not broken, then YOU DO NOT HAVE A HEADROOM PROBLEM!!!!!!!!!!!!" is rather astute if not self evident. Like most folks that participate in these forums I'm well versed in gain structure within an amp and the signal chain external to it. I guess that I am making this reply to thank you for your one sentence suggestion at the end of three paragraphs of scolding. Funny how much consternation the word "headroom" and the assumption that I am "THAT guy" that doesn't understand its meaning caused. 64

[glebert]

Rich64, wanted to go back to the original post and get a clarification. You say it lacks headroom but has ample output power. As others have said, headroom means different things to different people. Juan's definition works for him but is not how I use the term. When you say "ample power" does that mean measured with a scope or meter, or actual loudness? As I said earlier, I found my HR Deluxe to break up to easily based on dynamics, if you would hit a note with increasing intensity it would be clean, clean, clean, clean, totally distorted, but just momentarily before it cleaned up as it decayed. A chord seemed like the first note would be distorted and clean up halfway through, or vice versa. I found tube rolling to help with the gain/slope sort of problem that I was getting dynanically, but it did not make the amp any louder.

If louder is what is needed no one has mentioned a speaker swap, I don't know how efficient the BD stock speaker is vs. something aftemarket.

[Chuck H]

None of it was directly related to you as a tech. It's just become such frustrating internet jargon that the number on the volume knob = loudness. So when an amp breaks up at three or four some players think the amp would be louder if it didn't break up until eight.?.

It's also become a common fix for these issues to use a lower gain tube. That would change the gain structure of all the channels (for better or worse). If that's the goal, fine, otherwise the issue needs to be handled at the circuit.

So none of of my previous posts should have been viewed as judgement toward you personally. Just me trying to fight the hoards of misinformation that you were bound to intercept. Remember, we do not know what you do or don't know and there are plenty of techs out there that don't know much. You might have been one for all the information we have.

But taking it personally is cool too. Maybe swap that second cup in the morning for decaf.?.

[Jazz P Bass]

"There still is a little "fizziness" in there."

???????

At what output wattage?

From glebert's post:
" if you would hit a note with increasing intensity it would be clean, clean, clean, clean, totally distorted, but just momentarily before it cleaned up as it decayed. A chord seemed like the first note would be distorted and clean up halfway through, or vice versa."

That is to be expected at or near the maximum clean output of the amp.
Over the edge is over the edge.

On most newer Fender amps, that is '4' on the volume knob. (depending on guitar input amplitude)

[Chuck H]

On most newer Fender amps, that is '4' on the volume knob. (depending on guitar input amplitude)

Right! With any humbucker hotter than a PAF you get down to a setting of 2.5 to 3.

And yes, there are little warbles and voltage spikes in the signal of a vibrating string through a pickup. Especially with humbuckers. These can make an amp seem to crackle annoyingly right at the line between true clean and clipping because these spikes can be generously over what's necessary to clip the amp where the rest of the signal stays below the threshold. The phenomenon is most common when higher bass levels are dialed in.

[J M Fahey]

JMF, Rather than flog my client over his choice of amp/rig

"flog"??????
In a Musician/Tech relationship he is asking you about a technical problem,you provide the correct answer , which in this case is : "that amp does not provide much headroom to begin with"

as a service man I'm going to do my best to give him what he wants.

which is? .......

My headroom/output statement refers to the fact that regardless of bias setting the thing will get plenty loud (a technical term for customer pleasing) and clean-ish. There still is a little "fizziness" in there.

Ok.
It is caused either by crossover distortion, which can be solved by proper biasing, or lack of clean power, which can not. (since biasing won´t add a single watt to current power out)

Take me to task if you must for my lack of specificity regarding "numbers" but for 35 years I've pleased my clients and been able to communicate clearly with fellow techs.

That presumed clear communication starts with a conflicting statement in the very first question.
I suggest "troubleshooting" which includes a couple tests and measuring, without that it´s not much of tech talk.

That said I DO appreciate you taking a few minutes to address my post.

You´re welcome.

A Blues Deluxe is not my choice of amp either. However I could use it at one of my gigs along with my pedalboard and do just fine.

Cool.
Can your customer do the same, with his pedalboard and at his gigs?

As a side note:

There still is a little "fizziness" in there.

may also mean there is some oscillation or instability present .... but I don´t dare tell you to scope it.

[Enzo]

Hi rich, welcome to the forum.

Just an observation: when you have only three posts on the forum, we cannot assume very much about your experience, skill level, troubleshooting ability, or much else. So it is not obvious to us that you would have considered or tried anything in particular.

[rich64]

Hey there Enzo, Thanks for the kind greeting. As well as your observation. In no situation that I am new to do I expect automatic credibility. I need to remind myself of this here. I find the notion of being able to speak with a large community of fellow techs valuable and fun. While I know that any group will contain some with strong opinions I suppose I wasn't prepared to be scolded or shouted down. I am of the mind that even if I were a newbie encouragement would be preferred to all caps yelling. All of that said I value the experience and yes, the opinions of the forum members. I hope that I can be of value in this forum as well.64

[J M Fahey]

I wasn't prepared to be scolded or shouted down.

No need to, because you weren´t ... ever.
Not in this thread at least.

I am of the mind that even if I were a newbie encouragement would be preferred to all caps yelling.

Where?

All of that said I value the experience and yes, the opinions of the forum members.

Thanks.

In my particular case please reread post#5:

a) I treated you as a full equal *Tech* .... and to be able to offer solid suggestions, instead of ... um ... "opinion" which is what you find by the truckload in all other Forums (My Les Paul, Harmony Central, The Marshall Forum, etc.) I suggested instead you grab your multimeter, inject some signal, >>measure<< and if possible >scope< the amp.
"What Techs do".

Do you think I would have suggested doing so to a regular Musician? Or a noob?
I treated you as a full equal *Tech* , asked you to do exactly what I would have done if I had that amp on my bench. What else?

b) Meters show numbers on their screens, I asked you to post them here.
Depending on results might suggest other tests, what to adjust or replace, etc.

c) shouldn´t need to remind it, but please notice my suggestions on post #5 start with the word: >>please<<

I hope that I can be of value in this forum as well. 64

Oh, no doubt about that

PS: one last suggestion: please sign full "rich64" .... we have another "64" member who is very active and helpful and it might be confusing: PDF64
Thanks.

[glebert]

I thought this thread turned toward condescension pretty quickly. But hey, when people ask for free advice (myself included) sometimes you get some attitude include at no charge.

[Chuck H]

I thought this thread turned toward condescension pretty quickly. But hey, when people ask for free advice (myself included) sometimes you get some attitude include at no charge.

And just what does that mean coming from you?

[Enzo]

Ohhh, how about we just go back to amplifiers?