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Author Topic: New amp - New to the forum (Randall RG80 Classic content)  (Read 2655 times)

Big McLargehuge

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New amp - New to the forum (Randall RG80 Classic content)
« on: March 03, 2016, 10:48:50 AM »
Howdy, all

I just picked up a used Randall RG80 'Classic' off of Craigslist and I have a few questions.

First of all: What the heck is this thing?! I mean, I know what it is, but the internet is nearly devoid of info regarding this particular model. I've emailed Randall asking for a manual or schematics or any info at all, but no reply. There's a "Speaker Load" button on the back, and I'd really like to know what I should be setting it to.

Secondly, it's got a few issues that maybe you can advise me on:
The clean channel (which is very pretty, btw) gets a *tiiiiiny* bit of bleed from the gain channel. Most of the pots are dirty and crackly (an easy enough fix to be sure) and I wondered if this could have anything to do with it. Say for instance that you are on the clean channel; turning the volume pot for the drive channel causes audible pops and crackles on the clean channel. that shouldn't happen right?

The drive channel for its part doesn't seem like it's up to snuff in and of itself. I thought Randalls were known for their high-gain chugga chugga distortion. This thing barely breaks up with the gain knob dimed. Seems weird.

Also, both channels sound "fizzy" when you put a dirt pedal in front of them.

In any case, I only paid $80 for it, so I don't mind throwing a little more cash at it to get it in ship-shape. Oh, and are there any mods that can be done to an amp like this (for more gain, for instance)

Thanks!




« Last Edit: March 03, 2016, 10:53:33 AM by Big McLargehuge »

J M Fahey

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Re: New amp - New to the forum (Randall RG80 Classic content)
« Reply #1 on: March 03, 2016, 11:01:31 PM »
Howdy, all

I just picked up a used Randall RG80 'Classic' off of Craigslist and I have a few questions.

First of all: What the heck is this thing?! I mean, I know what it is, but the internet is nearly devoid of info regarding this particular model. I've emailed Randall asking for a manual or schematics or any info at all, but no reply. There's a "Speaker Load" button on the back, and I'd really like to know what I should be setting it to.
It is or claims to be the same as the old RG80, in itself the exact same guts of famous RG100 but packaged inside a combo and driving a heavy 12"

Now you know the old saying: if it says "Vintage" or "Classic", or "Reedition" anywhere on the front panel ... then it is not  ???

So what I say applies to the original one, "reissues" have a trend of "improving" things ...  :loco

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Secondly, it's got a few issues that maybe you can advise me on:
The clean channel (which is very pretty, btw) gets a *tiiiiiny* bit of bleed from the gain channel. Most of the pots are dirty and crackly (an easy enough fix to be sure) and I wondered if this could have anything to do with it. Say for instance that you are on the clean channel; turning the volume pot for the drive channel causes audible pops and crackles on the clean channel. that shouldn't happen right?
Original channel switching was crude: they'd actually ground the volume pot of the unneeded channel, but they'd still run full on all the time, so a little "bleed" is almost inevitable.
No big deal when used live.
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The drive channel for its part doesn't seem like it's up to snuff in and of itself. I thought Randalls were known for their high-gain chugga chugga distortion. This thing barely breaks up with the gain knob dimed. Seems weird.
Originals didn't actually distort much when used "normal", even on the Red channel.  :o
One knob could be pulled to add a couple diodes which clipped a lot, gave you chugga chugga ,whatever, but killed a lot of volume.
It was meant to distort in a studio at lower volume.
Maybe that boost jack in the back panel does that, try it.

I bet Dimebag drove them hard, I don't believe Guitar players claiming: "oh, it's just me guitar, me amp and a cable ... plus my absolute awesomeness of course :lmao: "

Even the simplest sound in the World, Keith Richards, uses a (hidden)  rack full of stuff ... his vintage style Tweed high power Twins use Celestions instead of official Jensens, etc.

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Also, both channels sound "fizzy" when you put a dirt pedal in front of them.
In my book, all fizzyness complaints translate into a single root cause: you are not playing loud enough.

Even a firebreathing Marshall MkII sounds weak and thin if attenuated down to home levels.

Dimebag said: "at low power these amps are buzzy as Hell; at full power they turn into mud, there is a magic point around 6 or 7 where fizz turns into mud, just in the middle is where it's killer"
Try it, it's easy to find by ear.  It's also LOUD.

So much so that he did not use the Master volume as a volume control but as a tone control; once set he left it there.

Then he'd use more or less amps depending on where he played, from one to 6 or 7 amps.
Quote
In any case, I only paid $80 for it, so I don't mind throwing a little more cash at it to get it in ship-shape. Oh, and are there any mods that can be done to an amp like this (for more gain, for instance)
On the original, gain was fully milked to the last drop.
On the improved reissue, who knows?
No one ever saw its schematic.

They claim to have also solved the "volume drop with distortion boost" ... who knows?

Almost forgot: Randalls are pure current output amps, instead of voltage output as most others.
That means that amp will have way more or less gain depending on what speaker load you are using, I suspect that button changes gain configuration, probably acouple power resistors, to compensate for that.

Another possibility is that they offer a crude way of impedance matching:
the switch connects output jacks in series (2/4 ohms) or parallel (8/16 ohms)

But never saw the schematic, so it's just a guess, yet you can confirm that switching it increases/decreases gain when used with the same speaker, please test that and post results, also what does the boost jack do.

Big McLargehuge

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Re: New amp - New to the forum (Randall RG80 Classic content)
« Reply #2 on: March 04, 2016, 10:22:03 AM »
Wow, thanks for the great response!

I'll get my hands on a footswitch and try out that boost feature. Still no word from Randall though.

EDIT: Randall just wrote back to inform me that my amp was made in 1998. They also attached a "manual". It was not helpful.
« Last Edit: March 04, 2016, 11:43:36 AM by Big McLargehuge »

DrGonz78

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Re: New amp - New to the forum (Randall RG80 Classic content)
« Reply #3 on: March 04, 2016, 03:34:37 PM »
Just to note: The original RG80 amp had bleed between both channel A and B. However without the foot switch connected it would actually enable both channels stuck on continuously. It looks like this new "Classic" version has a channel switch on the face plate according to your picture. Also, the old RG80 used an old style Cinch Jones connector plug and this new amp has the regular 1/4 inch adapters.
“A person who never made a mistake never tried anything new.” -Albert Einstein