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Post by kilroyrock on Aug 12, 2016 13:17:20 GMT -6
i'll get some resistors after work today for what they're "supposed" to be and see if it makes a difference. I gotta get another monitor mount anyway
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Post by EmRR on Aug 12, 2016 13:34:52 GMT -6
I'd agree with svart. But $6! But there is a schematic somewhere, it ain't like it's 'added value' that should be withheld! It's like buying a banana peel for half the price of the whole banana.
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Post by Deleted on Aug 12, 2016 17:46:36 GMT -6
Yes, without a schematic, you are working blindly.
Trace the circuit on the PCB, if they sold without schem.
For six dollar it may be more like a breadboard that is not very flexible.....
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Post by Bob Olhsson on Aug 13, 2016 11:50:52 GMT -6
The only real VU meters ever made were Westons. They were very expensive and pretty much only found in broadcast consoles. They were meant to be used with peak indicator lights.
Ampex offered them as an extra-cost option. The regular cheap ones were intended for line-up tones. As always cheap won out over quality in the audio marketplace.
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Post by keymod on Aug 14, 2016 6:19:11 GMT -6
Could your level difference have anything to do with the fact that that driver board is un-balanced line while the Big Knob output is balanced???
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Post by rocinante on Aug 15, 2016 9:03:01 GMT -6
I bought a $6 one too but it worked as advertised and it went with the piece of gear it was in when I sold it. We have options though. I've been researching the micro-controller route lately and im 99% sure thats where im going with my meter bridge. But let's return to this: I just found the other older cheap Chinese vu driver so we'll do it together. This is an easy circuit to trace and I'd bet my left hand its a rip off from something else that has a schematic. Putting the two together is our difficulty, albeit not a terribly hard one. First one to find it on the internet gets to have a bumper sticker that says "I heart cheap chinese shit"  |
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Post by kilroyrock on Aug 15, 2016 11:09:39 GMT -6
I bought a $6 one too but it worked as advertised and it went with the piece of gear it was in when I sold it. We have options though. I've been researching the micro-controller route lately and im 99% sure thats where im going with my meter bridge. But let's return to this: I just found the other older cheap Chinese vu driver so we'll do it together. This is an easy circuit to trace and I'd bet my left hand its a rip off from something else that has a schematic. Putting the two together is our difficulty, albeit not a terribly hard one. First one to find it on the internet gets to have a bumper sticker that says "I heart cheap chinese shit" So I got it (sheepish grin).
keymod - Big knob handles balanced/unbalanced just fine, and has +4/-10 switches everywhere - it wasn't so much the level as the chip. This is what I did wrong:
I went to baynesville here in Baltimore, picked up the resistors and replaced them. Then I plugged everything back in, and the needles were pinning hard +3+. I thought "damn, so much line noise with these higher values! now I have to switch them back!"
So I switched it back, so I could get back to my baseline. and the needles were now pinning with the original parts! Talk about confusing.
One thing I did was installed a socket for the op amp, because I got 50 for 5 bucks from amazon. So I moved it and the needles acted different. I pushed in the chip a little more, and it started pumping a little, but then I pushed a little more (I swear this sounds dumb, I feel dumb) and it started to work right, but a bit too hard.
After appropriate gain staging, I was able to get them to bump as expected. In the end, if I had just soldered the chip to the board, I would have been fine, but because I'd rather not solder chips to boards on things I build, I guess I didn't push hard enough to get the chip to socket correctly.
I feel down right dumb.
2 things to take away:
1. Always recheck your sockets, who knows what wonky shit is gonna happen when dealing with Chinese parts 2. These $6 boards work!
I'm not sure how great my meters are, but they seem to be pretty responsive. Hopefully this is enough to level match a kick drum and bass guitar, which is the whole purpose of this nonsense!
Now I want bigger meters since proof of concept is there. I also need to build some sort of box to house this thing. But I'm about 15 bucks in the hole with the 3 meters I've bought (2 for stereo, 1 for a different style to compare) and the vu meter board.
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Post by rocinante on Aug 15, 2016 14:35:11 GMT -6
Ahh that's not dumb. Not even close.
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Post by Deleted on Aug 16, 2016 18:09:44 GMT -6
Opamp sockets are source of MANY problems.
When i buy used "broken"/ "for spare parts" units on ebay, my first thing is to upen up and push all chips into the socket, quite rabiate. You wouldn't believe, how many problems disappeared. Sometimes I see how techs tried to fix the problem with resoldering large parts of the board around where the problem could be identified, sometimes whole channels in stereo units, and they obviously did not even check the mechanical contact of the sockets - which can go bad with e.g. corrosive stuff after long time. It's like seemingly "dead channels" of old consoles, where the only problem is lightly corroded insert jacks that can be made working with pushing and pulling a plug in and out. Often enough no one checked this out.
Always check mechanical contacts intensively first. It pays off. IME source of much more problems than cold solder joints or parts out of specs. And often enough very easy to fix...
So yes, stuff like exactly this is pretty often overlooked, sometimes even by experienced techs. No reason to feel dumb at all.
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Post by kilroyrock on Nov 19, 2016 14:12:12 GMT -6
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Post by stormymondays on Sept 18, 2017 10:32:05 GMT -6
I'm also longing for a nice set of VU Meters. Any more ideas?
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Post by EmRR on Sept 18, 2017 11:58:13 GMT -6
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Post by stormymondays on Sept 18, 2017 12:06:38 GMT -6
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Post by EmRR on Sept 18, 2017 12:32:52 GMT -6
The Crookwood isn't bad on cost. If you price real VU's of that size with real specs, and an attenuator or buffer amp that gives calibrated steps that load correctly, it's never inexpensive.
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Post by Deleted on Sept 18, 2017 13:39:18 GMT -6
I've had the Crookwood 2u stereo ones as part of my mastering cosole for six years now, love them!
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Post by EmRR on Sept 18, 2017 13:45:56 GMT -6
You gotta remember real meters were the single most expensive part on any amplifier. People might have trashed entire old systems, and robbed only the meters off the chassis for later use. Not even the audio transformers, just the meters. There's a lot of meters floating around from specific 1930's Western Electric amps that are now $10K-$40K apiece if fully intact. You can get an idea of how many of those amps must have existed at one time just from the current number of their meters surfacing on ebay.
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Post by kilroyrock on Oct 14, 2017 21:53:45 GMT -6
I'm confused by that question
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Post by rocinante on Oct 15, 2017 10:40:28 GMT -6
I built a digital vu meter using and arduino and oled's, and it was actually damn accurate.
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Since I'm in Europe, I will probably go for these: