[bangraman]

I'm building my 'Max Wart' amp based on the META42, which is already looking pretty spectacularly warty. There are already 8 switches for a start. This one will definitely need a "For Authorized Personnel Only" placard on it

I'm thinking about incorporating a series/parallel switch for the two 9V cells to deal with the demands of different phones. It's not a problem to implement but my friend was not forthcoming on whether there are other issues to be concerned with. Can anyone point out any flaws with this plan?

 

[Chipko]

Parallelling the batteries will only give longer batterylife. The amp is powered by the electrolytic capacitators so it won't help driving hard to drive phones.

Only do it if you might need to forsake soundquality to gain running time between charges.

 

[bangraman]

Yes, that is the reason for wanting to switch. Some phones don't need more than 9V operation in my opinion. Some do. I figured since I was going for max warts and I have plenty of room on the front panel I might as well populate it with switches. Have 8 so far

 

[myself, aka me]

If you don't mind me asking... what are all these switches for?

 

[bangraman]

Each headphone output (there are two) has selectable output impedance as well as independent crossfeed and bass boost (pause as 90% of the amp builders recoil in disgust). So that's 6 already.
Then there's the input select and the power switch. I am thinking about a manual switch for power source selection instead of relying on the break of the power socket, and I might even include a gratuitous LED on/off switch... perhaps with a little LED on the switch to let you know when the LED is off

Anyway, any other opinions... thanks

 

[Ambush]

Did you consider using multiple rotary switches instead? I'm just curious as to your planning and rationale.

 

[myself, aka me]

If you unwittingly paralleled too many 9V batteries.. you might blow a diode? Hehe.

I don't think a rotary would work..
Although, if there were three or crossfeed positions then maybe a rotary switch would be useful.

I see..
Headphone One impedance 120/0 [as a largely uninformed guess

]
Headphone Two impedance 120/0
Bass on/bypass
Crossfeed on/bypass
Input select 1/2
Power on/off

Personanlly.. If you're going to do LED on/off, why not an illuminated power switch?

You could roughly integrate on and off with the volume - a bumpy volume knob and a toggle switch?

All the others are independent.. gotta have crossfeed, bass, and high impedance output all in one, for bassless mono recordings with.. *example of headphone that likes high impedance output*. So a rotary wouldn't work. Unless I don't understand rotary switches. It's 1 am. I'm feeling stupid.

I only had one beer..

 

[JMT]

As Chipko mentioned, wiring the batteries in parallel will only allow for extended cell life. But, you said:
Quote:

Some phones don't need more than 9V operation in my opinion. Some do.

What would indicate the need to wire the batteries in series, which essentially gives you 18v (+/- 9v).

 

[bangraman]

The amp will be knobtastic. It'll probably end up looking like an DIY aircraft panel. I might even put one of those old-style VU dials on... Oh I like that idea. It's just another silly little amp which will take my 'warted out' concept to it's logical conclusion.


Me... What I meant is not an LED light for the power (which it obviously will have), but a totally gratuitous switch to turn the power LED on and off

Then that switch could have a smaller LED on top of it to show you when the power LED is off

I like this idea so much I might actually do it

Anyway, back to the power. I haven't been able to explain myself... I wanted the option of having long-life 9V or 18V as I believe some phones don't hugely benefit from 18V. So the question would be are there problems with regularly switching the batteries from serial to parallel? I doubt I will switch often but I just wondered if anyone had any comments to throw in, either as far as the batteries are concerned or as the basic META design goes. Really it is another gratuitous switch but I like this idea.

 

[bralack42]

Yeah! I've always wanted to get some of those aircraft switches that have the red plastic shield safety over them and you haveta flip the red thing up to get to the toggle, which is a big huge beastly toggle that says "flip me and something cool will happen!" Also, some other big switches, levers, and meters would rock too! Also be sure to add LEDs to indicate whether crossfeed is activated and which input/output jack is currently set.

 

[PeterR]

Quote:

Originally posted by bralack42 Also be sure to add LEDs to indicate whether crossfeed is activated and which input/output jack is currently set.

...and a "test lights" switch to light up all LEDs at once...

 

[bangraman]

That is a SPLENDID idea bralack42. I think I will have to try and hunt down some of those switches.

"Crossfeed on my mark... 3...2...1... Mark!"

Wahahhahaha!

 

[Chipko]

I'm doing it the other way around, by the cunning use of flip-flops and relays I get source, xfeed on/off, xfeed wide/narrow and impedance switch on a single joystick I found at RS-components #249-3381. It will be wallpowered so power goes on the back of the amp.

Since the relay can be put where the signal is it shortens the signalpath as well, Not very costly either.

I can post the schematics once finished if anyone is interested.

 

[bangraman]

That's FAR too elegant for what I have in mind

Post the schematics by all means, I'm sure we'll be interested.

 

[myself, aka me]

My recently finished CMoy is the complete opposite of your WART42. It has one switch, the power. I only used one 'cause it was a hole there. RCA in, and a headphone out.

It does resemble a [previous?] incarnation of a bangraman META42 - the 9V battery clip is mounted on the outside *rolleyes*.

Oh, it looks cool. I haven't stuck purikura on it either.

I see my 1AM typing isn't very descriptive.. I meant, use an illuminated power switch as an LED on off switch. Use a seperate one for power. Should be ugly enough for your amp.

Your amp is going to look like our rocket club's launch control box. To complete the look [why not? it has about 8 switches, LED for each, an ARMED and LAUNCH button, key for starting it up, multiple channels..] you need an orange pelicon box. Yellow and black diagonal stripes. Oh, and you can run it off your car battery...

.