Attenuator for 50w Single Rec + 2x12 Rec Cab

[sourcandyrizz]

Good day everyone,

I recently had to move to a condo and need to find a solution to have more granular control over the volume of my setup.

At this time, I have to creep the output knob up extremely carefully. There's unfortunately a jump in volume there that makes it either slightly too quiet or slightly too loud.

I would appreciate if we could avoid the discussions about tone of the amp for now and just find a solution so I can practice in my condo even though the tone might be affected by the low output. I don't want to buy a separate cab for 'bedroom' level practice.

My understanding is that an attenuator between the amp and the cab is what I'm after.

1. Any suggestions on which one to get?
2. Is there any drawbacks to the attenuator other than the tone? From what I read somewhere it might make tubes burn out faster. If so how much faster are we talking?
3. Is there any other solutions you can think of?

4. I don't know if this is relevant but I currently have the cabinet wired from the 8ohm output on the amp (the cab is 8ohm as well). Would there be any electrical dangers to going from one of the 4ohm output on the amp to the 8ohm cab? Any wear and tear related issues? Would it mean that the volume is cut in half? I understand that ohm means resistance and it's sort of how hard the amp has to push again the speakers in the cabinet.

Thanks for taking the time to read this and look forward to everyone's input.

Signed – a newbie when it comes to gear.

 

[JustPassingThrough]

Easiest thing would be to change the pot for one with a smoother taper. $5 and 20 minutes and job done.

I personally don't like attenuators with rectifiers where all the good stuff comes from the preamp and whenever the power tube distortion comes in, they sound like total butts. I'm not sure that's worth the expense just for a smoother taper on the volume control.

Or, even a passive volume in the fx loop could work. This is what JHS stole from Beavis Audio and markets as the little black box, but you can make one easily for about $10, it's just a pot.

But it's your money and your amp.

 

[sourcandyrizz]

Easiest thing would be to change the pot for one with a smoother taper. $5 and 20 minutes and job done.

I personally don't like attenuators with rectifiers where all the good stuff comes from the preamp and whenever the power tube distortion comes in, they sound like total butts. I'm not sure that's worth the expense just for a smoother taper on the volume control.

Or, even a passive volume in the fx loop could work. This is what JHS stole from Beavis Audio and markets as the little black box, but you can make one easily for about $10, it's just a pot.

But it's your money and your amp.

Thanks for your reply.

Regarding the JHS Little Black Amp Box, I just looked into it and the website states not to use it in a parallel FX loop which is how the 50W Single Rectifier is setup from my understanding. So unless I'm missing something, I assume this isn't a viable solution unfortunately. That's a shame because that sounded like the best solution.

Regarding changing the output knob, that sounds like an interesting idea. A few questions:

1. Is it just a matter of how much current the knob lets through at the various levels?
2. Without getting you to do the legwork for me, what "spec" would I need to be look for? Is there some kind of name for the "volume curve" of a knob so I know what to look for to compare my options?
3. And would the information about the factory installed one be available anywhere?

 

[JustPassingThrough]

Ah yes, I forgot they had parallel loops back then. Luckily to change it to a series loop it's 5 minutes work and moving a single wire and then the loop works a whole lot better as well- I don't think Mesa use parallel loops these days, they've learned that nobody likes them.

1- sorta, a volume control is a voltage divider. It's the exact same mechanism as a gain control, it just sends some signal one way, and the other just bleeds to ground. It's a short question with a long boring and technical answer, but that's the jist.

2- For volume controls, the single rec uses a B250k pot on rhythm channel, and a A1m pot on the lead. You didn't mention which channel was suffering the most but I always use A taper pots.

And that's the crux of your question: the taper of the pot. B taper pots bunch a lot in the ends of the taper (so 0-1 and 8-10 get all the action), A is more gradual to our ears. There's essays and theses on the topic, and pedants will be along shortly, but I use A pots for volume in amps and pedals.

3- Yes, it's on the schematic.

Don't give JHS your money. This is the 'little black box'. You can make them in 10 minutes.