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Post by gouge on Jul 21, 2015 17:29:09 GMT -6
I'm looking at buying an orban 418a and hoping someone might have some advice.
when I went to pick it up I plugged it in and the on light was dead. so I decided not to take the risk in case it was stuffed. anyways, the seller offered for me to take it to the studio and try out prior to committing.
I'm in the studio in a few days so have opened it up on my dining table and tested a few things. some of the opamp IC's I've checked and they are all seeing 15v at their pins which is correct.
here is the odd thing.
when I apply a signal test tone to the input and measure the output I am getting what I think are some weird readings. as I turn the attenuator knobs clockwise the ac voltage on the output goes up even though the meter is metering an increase in compression.
I have the multi meter red on the pin 2 (hi) output of the channel measuring AC. both channels measure the same voltages.
according to the manual as the input attenuator knob is turned clockwise the compression will increase and the meters are showing this to be the case.
please help a newbie tech head. |
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Post by jeromemason on Jul 21, 2015 18:25:04 GMT -6
It's a FET compressor isn't it? I believe it's like an 1176, where if you increase the input the volume will rise along with compression, then you adjust the output to compensate.
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Post by gouge on Jul 21, 2015 18:58:58 GMT -6
yeah it is like an 1176.
something doesn't seem right to me though because the output voltage is higher than the input voltage.
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Post by jeromemason on Jul 21, 2015 23:25:59 GMT -6
Doesn't sound like anything is wrong to me, sounds like a typical 1176 style compressor. If you increase the input gain, its going to add to the output gain if the output gain knob is not attenuated.
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Post by gouge on Jul 21, 2015 23:41:36 GMT -6
ok, must have a bunch of gain built in like the 1176 does. I'm only feeding it +4db and I'm measuring 6-7v on the output with no attenuation.
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Post by jeromemason on Jul 21, 2015 23:48:26 GMT -6
Did you check for DC on the outputs?
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Post by gouge on Jul 21, 2015 23:58:36 GMT -6
i'll give that a go tonight. I did check the tl072 opamps and they measured in the decimal places but I hadnt't tried the output.
cheers.
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Post by gouge on Jul 22, 2015 6:34:49 GMT -6
Dc offset on the output was down around 1mV.
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Post by gouge on Jul 22, 2015 22:32:52 GMT -6
decide to pony up the cash...... on light is not working but welcome to daddy new comp thingy.
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Post by jeromemason on Jul 23, 2015 0:17:16 GMT -6
You can swap those 72's for some much lower noise opamps too. Sounds like they are driving them pretty hard too, those opamps are not the ideal choice IMO to be driven.... you could even get some DOA adapters and go 2520 through that baby. Is the output/input transformer coupled?? What kind if so??
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Post by gouge on Jul 23, 2015 1:28:33 GMT -6
it's a transformerless design. has a an electronic balanced input and unbalanced output. opamps are socketed. mix of can and dip8
I've got some tl2072 oamps here i'll try out.
I'm not sure I can replace the 072 with 2520 types. 072 are dual. I do remember seeing other option online though. miniature discrete opamps that were dual. when I get some time I'll go through the circuit board and report back. early inspection and no components are referenced and some opamps have been marked to conceal their type.
like all of my gear i'm keen to attack it. :-)
what pushed me over the edge with this was i sang through it today and when being slammed and clipping the distortion it put on my vocal was a sound I'd like to experiment with.
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Post by jeromemason on Jul 23, 2015 2:24:08 GMT -6
They make a DIP DOA's, I've never used them, but they stand up straight instead of the normal orientation. I bet it would be pretty badass with some of those, being as high gain as it is, sounds like it would make some iron on the outputs sound purdy too. That's the fun of those old Orban processors, you can mod the hell out of them and turn them into some kickass pieces of gear. The EQ's you can make into some really nice boxes. Good design, just not so good components.
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Post by gouge on Jul 23, 2015 5:10:32 GMT -6
App studio has a dip8.
I've got a pair of lundahl 5402 transformers.
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Post by gouge on Jul 27, 2015 18:40:31 GMT -6
photo of inside.
Attachments:
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Post by gouge on Aug 1, 2015 18:40:19 GMT -6
Anyone got a 418a they want to sell?
After using this one a bit I'm pretty keen to leave it stock. :-)
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Post by jeromemason on Aug 1, 2015 19:39:33 GMT -6
There's a lot of improvement in there in cap swaps if you wanted to smooth it out though. I'm sure it's gritty right now, and sometimes that's just what you need. Are those the stock opamps? Kinda throws me off to see dip footprints with cans in.
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Post by gouge on Aug 1, 2015 20:55:32 GMT -6
There's a lot of improvement in there in cap swaps if you wanted to smooth it out though. I'm sure it's gritty right now, and sometimes that's just what you need. Are those the stock opamps? Kinda throws me off to see dip footprints with cans in. yeah it can be gritty when pushed but I was very surprised out how nice it sounded and really surprised at how flexible it was. I was really up for doing a component upgrade but I enjoyed what it did so much I just can't bring myself to do it.
if I can find another i'll definitely mod that one. I'd guess modded it would be a much more transparent unit.
it has a really nice action on most stuff. I liked that it isn't as punchy as the dbx comps I have. still brings the room into the equation but doesn't push the staging forward like the dbx.
I wouldn't mind a 500 series mono channel clone or 2.
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Post by jeromemason on Aug 1, 2015 21:19:26 GMT -6
Cloning an Orban! Blasphemy!  Do you have a schematic of this? You might be able to change some values to get some more bottom and girth out of it and keep the character. Actually IME doing cap swaps doesn't mess around with the character all that much, just the detail and feel. It's a FET compressor so I don't think you're going to change how it compresses by doing some cap swapping. |
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Post by gouge on Aug 1, 2015 21:41:03 GMT -6
I'll upload the schematic bit latter. Would enjoy talking through options.
The signal is bandpassed which would be an obvious place to improve the frequency response.
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Post by gouge on Aug 2, 2015 15:37:55 GMT -6
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dgbt
New Member
Posts: 3 
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Post by dgbt on Aug 3, 2016 18:59:32 GMT -6
I have two 418s. one is currently not working on the right side.. bought it drunk... long story. hah. I'd like to swap out all the opamps in mine with faster cleaner ones...I like the idea of having a modded one and a grittier one.
How do you go about adding input and output transformers? that would be pretty cool to put some nice transformers in there.
Also, i'm curious about pulling out the resistor for the attack time circuit, which is fixed around 2ms, and putting a pot in there to see how much variance I'd get.
Not too many people talking about these things anymore. I think they are totally cool.
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