[zkool448]

Thanks flecom.

I'm fortunate enough to meet a fellow head-fi'er today who lives in the same city as I do. He's got more electronics skills and enough knowledge than I could ever possibly learn in my lifetime

Anyway he's actually working on a balanced version of the Bijou, ironically the same amp I'm about to build (but not balanced) once my parts arrive from GlassJar. We discussed the topic of VU meters and coincidentally he had managed to source several VU meter units from overseas that he plans on putting on his his amp projectss, including ones that almost look like the McIntosh's. Long story short, he's going to start working on the design and get some working vu meter installed on our builds.

Here's a draft of the Bijou case I'm currently designing, and I also included below a photo of the actual dual VU meter that he graciously loaned me today to get its exact dimensions from.

LED VU meter:

Analog VU Meter:

The VU meter:

We didn't really get into the nitty-gritty deatails too much but it sounds very promising with a very high probability that we can get this thing going (finger crossed)!

 

[nullstring]

I feel that an LED meter for a tube amp is a bit of a mismatch

I'd go for the analog meter.

I plan on putting two in my bijou when I make it

 

[zkool448]

I agree. LEDs were the original plan, but by the looks of it I belive I'll end up with analog instead.

 

[zare]

Not exactly like McIntosh..

BTW, it's little bit bigger the one above ..

 

[zkool448]

I think those look even better. I can just picture all five tubes uplit with matching blue LEDs, and a blue ring Bulgins

 

[mattcalf]

New thread with similar stuff here.

This is a good link, not sure if it's been mentioned here yet.

Just for general info, don't want to make you have to choose between more cool Vu meters zk.

 

[kuroguy]

ZK,
If what you want is an amusingly bouncing needle then just install a 100K pot across the output and tie the meter to the wiper through a series resistor and to ground. Adjust the pot for a sufficiently amusing needle bounce and be done with it. Requires 2 trim pots, 2 resistors, and 2 meters. Couldn't be easier.

 

[zare]

Quote:

Originally Posted by kuroguy /img/forum/go_quote.gif ZK, If what you want is an amusingly bouncing needle then just install a 100K pot across the output and tie the meter to the wiper through a series resistor and to ground. Adjust the pot for a sufficiently amusing needle bounce and be done with it. Requires 2 trim pots, 2 resistors, and 2 meters. Couldn't be easier.

That depends what kind of meter it is(DC/AC). All this cheap meters are DC so you'll need rectification. This pdf is nice read(original link).

 

[zare]

Quote:

Originally Posted by mattcalf /img/forum/go_quote.gif New thread with similar stuff here. This is a good link, not sure if it's been mentioned here yet. Just for general info, don't want to make you have to choose between more cool Vu meters zk.

Nice feed. I was looking into making something on those lines with atmel, but more in the line for controlling the pre-amp(plus LED(OLED) VU), but still prefer the look of the classic VU.

 

[zkool448]

Quote:

Originally Posted by zare /img/forum/go_quote.gif That depends what kind of meter it is(DC/AC). All this cheap meters are DC so you'll need rectification. This pdf is nice read(original link).

Nice article indeed

JLM Audio looks to be based in Australia (mattcalf, you should check the neigborhood

). The nice article was featured on Audio Tech magazine -- a nice read indeed.

 

[mattcalf]

JLM is smack bang in Brisbane, in the same state as me but still 1,685 km away.

Good to see another Aussie audio store though.

 

[CptanPanic]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif dude, here's how simple it is: Schematics Depot (tm) - LM3914 based battery monitor and LM3915/LM3916 VU Meter I'm telling you, you can air-wire it. this is the display chip I was talking about: Digi-Key - 160-1066-ND (Lite-On Inc - LTA-1000HR) they used to sell them at radio shack, years and years ago. so now, its just 2 things to connect together. no biggie.

For that bargraph display, do they make one that is panel mount? How would you mount that to a case?

 

[linuxworks]

here's a shot of that bargraph chip being used on a board for debugging:

I'm displaying 7 bits out of the 10 possible on that display. so I cover up 3 with tape (lol).

it fits into an IC socket (careful with its pins, though). that socket could be soldered to a board and that board be parallel mounted to the front panel. a rectangle hole could be cut.

 

[Alpha 1 Omega]

Quote:

Originally Posted by amb /img/forum/go_quote.gif McIntosh's analog power meters are indeed nice. They have an extraordinary dynamic range, much more so than the typical "VU" meters that could typically manage only about -20dB to +3dB. For a meter to be of practical use (rather than just as visual amusement), 0dB would need to be calibrated to the maximum rated output power of the amp. Let's take the β24 as an example, 0dB would be around 180W into 8 ohms. On a conventional analog "VU" meter, the meter needle would hardly move when the amp is putting out 1.8W, and that's usually already a fair amount of sound pressure level on most speakers. If you crank up the sensitivity of the meters to show movement at low/mid volumes, then the meter would simply peg on the right hand stop when the amp is called upon to deliver more of its power (not to mention that the meter then ceases to "measure" anything meaningful). Notice that the meter on the 1200W monoblock McIntosh MC1.2KW amp, the meter has almost 60dB of range: McIntosh | Power Amplifiers/Integrated Amplifiers Now, THAT meter will show something from pianissimo to fortissimo! An analog meter like that could only be achieved with a special meter drive circuit that has compressive gain. Not only that, if you have actually seen these meters in action you'll notice that they have a very fast attack time but slow decay. So they are peak-reading meters that could actually register music transients, rather than the ballistics of ordinary VU meters that could only show average levels. I've yet to see any DIY amp with an analog meter that sophisticated (I'd like to be proven wrong, though -- and am especially interested in knowing what meter mechanism is used and what circuit is used to drive it). Btw, McIntosh is just one example. Back in the late '70s and early '80s there were a number of commercial amps with comparable analog meters (until LED or fluorescent bar graph meters became popular). LED/fluorescent bar graph meters don't have to deal with a mechanical moving mass, so the attack/decay times can be controlled easily with electronics, and the dynamic range issue is also easy if you use the right chip/circuit to drive it (and have enough segments to give adequate resolution). I've built a few power amps with LED meters way back when, but these days I just find that flashing lights distracting.

i would bet it is a new stepping motor like they use in a lot of new car gauges .

 

[linuxworks]

too easy to front-end a mech meter with a processor and change its curve.

steppers are more expensive so I doubt they'd waste such mechanics when only sending 'smoothed dc' to a meter is all you'd need.