VU Meters: Let's See 'Em!!

[MakeMineVinyl]

Supposedly the McIntosh meters accurately measure power. I am sure some Mac fanatic can explain how -- that lets me out, though!

PS I am not too crazy about the Fluoroscan meter displays (either), FWIW.

Unless they're doing something beyond what I've experienced, they are strictly voltmeters. Since they use that autotransformer gizmo on the output of their amps, the voltage and power should be the same regardless of speaker impedance.

 

[Feanor]

So I might as well throw my Phase Linear 400 in here. Unfortunately the meters aren't illuminated in the pic ...
.

 

[Sal1950]

So I might as well throw my Phase Linear 400 in here.

She's a grand ole girl!

 

[Feanor]

So I might as well throw my Phase Linear 400 in here. ...

She's a grand ole girl!

Yeah, but the Phase 400 was a really terrible sounding amp, (apart from the fact that "all amps sound the same") -- harsh, glassy highs and opaque.

 

[MakeMineVinyl]

SAE 1500 watt 2-HP

 

[Cbdb2]

Unless they're doing something beyond what I've experienced, they are strictly voltmeters. Since they use that autotransformer gizmo on the output of their amps, the voltage and power should be the same regardless of speaker impedance.

I believe the autoformer is to even out the power delivered to different impedance speakers, not to even out the power over the bandwidth of the speaker. So the power meter will be more acurate speaker to speaker (4ohm to 8ohm) but we still have variations in idividual speakers at different freqs. Say your voltage meter reads 1v. At resonance the speaker impedance is 34 ohms, this is 1/34 watts, and when the impedance drops to 4 ohms at 400hz the power increases to 1/4 watt, the meter hasnt moved even though the amp is putting out 8 times as much power. The only acurate way is to measure both voltage and current and the phase between them. Which brings me to my question. If a theoretical amp drives a purely capacitive load, how much power does it use to put none out?

 

[mhardy6647]

Yeah, but the Phase 400 was a really terrible sounding amp, (apart from the fact that "all amps sound the same") -- harsh, glassy highs and opaque.

They had a tendency (or, at least, a reputation) to fail rather spectacularly, too.
There's a PL 200B upstairs. I'm still not really sure why.

Of course, there's a Crown D-150 and IC-150 up there too -- those, though, I know were dump finds.

 

[mhardy6647]

back on topic

TC1000 by Mark Hardy, on Flickr

Actually, only peripherally on topic These meters claim to be peak-reading, rather than calibrated to VU levels and ballistics.

 

[mhardy6647]

ahh, here you go.
They even say "VU" (Volume Units) on them in large, friendly letters

TC-777 2 by Mark Hardy, on Flickr

 

[anmpr1]

A) Supposedly the McIntosh meters accurately measure power. I am sure some Mac fanatic can explain how -- that lets me out, though!

B) I am not too crazy about the Fluoroscan meter displays...

A) From the MC500 Audio Critic review, #23, 1995:

...these are geniuine wattmeters, not just voltmeters calibrated for watts into 8 or 4 ohms. They actually measure the voltage and the current, multiply the two measurements, rectify and average the product, and display true watts with peak hold.

...true wattmeters are nice to watch, but a pair of Bryston 7B monoblocks (500 w/ch) will cost you $2605 less and give you comparable performance, and then some.

IMO, at this level of price, cosmetics plus whatever useful information you get from the Macmeters is not something anyone can dismiss simply by comparison with another, less expensive but comparable amplifier, sans meters. At the Mac price point one is also dealing with emotional stuff, and the fact that for most of their customers it really wouldn't be a full blown McIntosh without the blue.

B) I have heard (no first hand experience) that Pioneer fluoro-meters tend to lose illumination over the years, and there is no fix for that.

 

[mhardy6647]

A) From the MC500 Audio Critic review, #23, 1995:

...these are geniuine wattmeters, not just voltmeters calibrated for watts into 8 or 4 ohms. They actually measure the voltage and the current, multiply the two measurements, rectify and average the product, and display true watts with peak hold.

...true wattmeters are nice to watch, but a pair of Bryston 7B monoblocks (500 w/ch) will cost you $2605 less and give you comparable performance, and then some.

IMO, at this level of price, cosmetics plus whatever useful information you get from the Macmeters is not something anyone can dismiss simply by comparison with another, less expensive but comparable amplifier, sans meters. At the Mac price point one is also dealing with emotional stuff, and the fact that for most of their customers it really wouldn't be a full blown McIntosh without the blue.

B) I have heard (no first hand experience) that Pioneer fluoro-meters tend to lose illumination over the years, and there is no fix for that.

The Fluoroscan meters (VFDs) do indeed wear out, just like a CRT or a fluorescent tube, over time (more to the point, over time when "on"). The two CT-F900s here are still reasonalbly bright & clear.

No comment from your point A -- other than to say "thanks" for providing some substance to my vague recollection that the Mac meters really were/are power meters of some sort. The cult of McIntosh doesn't seem much different to me than the cult of Harley-Davidson (e.g.).

 

[MakeMineVinyl]

The Fluoroscan meters (VFDs) do indeed wear out, just like a CRT or a fluorescent tube, over time (more to the point, over time when "on"). The two CT-F900s here are still reasonalbly bright & clear.

No comment from your point A -- other than to say "thanks" for providing some substance to my vague recollection that the Mac meters really were/are power meters of some sort. The cult of McIntosh doesn't seem much different to me than the cult of Harley-Davidson (e.g.).

I've found that these displays can go somewhat back to normal if left on continuously for a day or so, but when turned off for any period of time, they go back to their original state. YMMV

 

[mhardy6647]

I've found that these displays can go somewhat back to normal if left on continuously for a day or so, but when turned off for any period of time, they go back to their original state. YMMV

This is making me think of the old CRT "picture tube brighteners"
That sounds plausible, and I think I've even noticed it myself on tired old VFDs.

As an aside -- the electronic configuration of a VFD can be exploited to turn one into a relatively crude but functional triode.
https://hackaday.com/2013/11/09/vfd-display-becomes-an-amplifier/
https://www.eham.net/article/20809

As a further aside -- there's actually a modern, purpose built triode based on ahem "VFD technology": the Korg NuTube.
https://korgnutube.com/en/

And, to take this to its illogical extreme -- Pete Millett's designed a hybrid headphone amp around the NuTube
http://www.pmillett.com/nuhybrid.html

Maybe @amirm would like to test one of these to compare it to the Bottlehead Crack?

 

[MakeMineVinyl]

This is making me think of the old CRT "picture tube brighteners"
That sounds plausible, and I think I've even noticed it myself on tired old VFDs.

As an aside -- the electronic configuration of a VFD can be exploited to turn one into a relatively crude but functional triode.
https://hackaday.com/2013/11/09/vfd-display-becomes-an-amplifier/
https://www.eham.net/article/20809

As a further aside -- there's actually a modern, purpose built triode based on ahem "VFD technology": the Korg NuTube.
https://korgnutube.com/en/

And, to take this to its illogical extreme -- Pete Millett's designed a hybrid headphone amp around the NuTube
http://www.pmillett.com/nuhybrid.html

View attachment 81272

Maybe @amirm would like to test one of these to compare it to the Bottlehead Crack?

I've seen data sheets on the NuTube, but I didn't realize that it glowed like that.

 

[Sal1950]

It might be fun to get or build one of these.
They'd look pretty kool dancing in the dark.
https://nixiekits.eu/product.php?key=magic_eye_vum

 

[mhardy6647]

magic eye tubes -- little special purpose CRTs.
http://www.magiceyetubes.com/

The 6U5 was a fairly common albeit earlier example -- this description is from RCA Receiving Tube manual RC-17, available from Pete Millett's wonderful site: www.tubebooks.org


Some of us -- ahem -- still use devices that 'measure' signal strength (typically) with magic eye tubes.

Not an optimum exposure, but - maybe - you get the idea.
Here's another: the DM80 "exclamation point" used, e.g., in several EICO tuners, such as this HFT-90

Besides radio signal strength, they were also fairly common (at one time) as record level indicators on tape recorders (particularly smaller/less expensive consumer hifi tape recorders).

(not lit in this case, sorry)

(and this V-M illuminates the magic eye only when recording, not in playback, sorry)

 

[Doodski]

magic eye tubes -- little special purpose CRTs.
http://www.magiceyetubes.com/



Some of us -- ahem -- still use devices that 'measure' signal strength (typically) with magic eye tubes.

View attachment 81454
Not an optimum exposure, but - maybe - you get the idea.
Here's another: the DM80 "exclamation point" used, e.g., in several EICO tuners, such as this HFT-90
View attachment 81455

Besides radio signal strength, they were also fairly common (at one time) as record level indicators on tape recorders (particularly smaller/less expensive consumer hifi tape recorders).


View attachment 81458
(not lit in this case, sorry)
View attachment 81459
(and this V-M illuminates the magic eye only when recording, not in playback, sorry)

I really like your Sherwood tuner and integrated amp.

 

[mhardy6647]

I really like your Sherwood tuner and integrated amp.

Me, too

The Sherwoods were - and are - really dandy tuners. Excellent sound and not expensive (compared to, say, McIntosh tuners... which sound a little better but cost a lot more).
The Sherwood amps weren't bad, either.

 

[Doodski]

Me, too

The Sherwoods were - and are - really dandy tuners. Excellent sound and not expensive (compared to, say, McIntosh tuners... which sound a little better but cost a lot more).
The Sherwood amps weren't bad, either.

I had the tuner and amp before. I traded them for a pair of Altec compression drivers and matching horns.

 

[mhardy6647]

I had the tuner and amp before. I traded them for a pair of Altec compression drivers and matching horns.

I like those, too (well, particularly many of the classic Altec drivers) -- the Altec horns I really like, by and large, I cannot afford.