Another great craigslist find, this vintage all tube amp hails from the early 70s (01/05/1972 to be exact, as penciled in under the chassis itself).
As a background, Plush amplifiers were made from 1969 thru 1973, apparently direct copies of either a fender showman or a twin reverb. Its main striking feature is the now identifiable “tuck and roll” covering not unlike that of Kustom amps, instead of the regular tolex coverings. Not surprisingly they were sued, either by Kustom or Fender (not sure), and its been said they went out of business due to bankruptcy from these litigations (but the story goes that they went on to become Earth Sound Amplifiers, who in their early life also had tuck and roll covering on their early amps, though nothing real conclusive to support this Plush-Earth Sound connection other than whats been generated thru forums and posts). Earth Sound also went the way of the dinosaurs eventually.
Trolling craigslist one night, the ad “PA tube head – $100” immediately caught my eye. “Tube” and “$100” together are usually a good indicator of a possible good deal, so i checked it out. Two things stood out – the tuck and roll covering, and a bunch of knobs to match several inputs. Whoa! Mixer? it said PA, so i googled the name, and sure enough most results were about asking the same question i have: what is a Plush Amplifier?
A website about plush amps did answer most of that question, so i called the number on the ad right away, and left a message. As a follow up i also emailed. I got a response the next morning, and proceeded to arrange for pickup. A little drive out to the country on a sunny early sunday afternoon is a nice change – one of the cool things i enjoy about out-of-the-way weekend drives.
The guy was nice, and spoke about how being a drummer, he had not much use for the amp anymore. It did power on, but didnt hook it up to a cab or even try it out – we spoke at length about the virtues of vintage and analog instruments. In the end i almost got an unloaded 2×18 ampeg cab, but having a small car, it wasnt going to be an easy transport (and i have no more space in my house!). i DID get a project solidbody guitar also for cheap – a double cutaway setneck Aspen brand, no pickups and with a bad paintjob, all other hardware included. for $5 with a harshell case also included, i couldnt turn it down. But that’s another story….
INITIAL START-UP AND RESTORATION:
As soon as i got home, i plugged the head into a 2×12 cab loaded with Carvin British Series US-made speakers. The tubes glowed and warmed up, and sound came thru once i plugged a guitar in.
It sounded clean, though several knobs wont turn, and some are stiff. The reverb didnt work, and channel 4 sounded weaker than the other 3. No big hum or extraneous noise were heard (other than what i was making thru the guitar), so the guitar is functional as is, just needs work.
A couple of contact cleaner sprays allowed the stiff pots to twist easier, but there were 6 that were completely stuck and frozen – no amount of clamping and pliers twisting freed it loose. I ended up replacing them temporarily with my own stock of Alpha pots, eventually ordering the correct size (i had the correct values, but they were mini pots – it works great, but it just looked odd to keep it that way). Reading the stamped code on the back showed they were Centralab pots, and man – NOS are expensive! So i got the next best thing – CTS pots. as soon as they arrive, ill be opening up the amp again.
I ended up changing two pots, and moving the current pots around to get all of the untwistable ones on one channel – at least i can have 3 usable channels til i get the orders in.
Workng without schematics (there were NONE found anywhere online), i made sure the values are correct for the gain and master volume pots (1 Meg), but i didnt inspect the tone pots – i thought they were all 250k. I realized it later when i saw the midrange control pots were 100k. oops! oh well, thats a lesson for me, plus its not that big of a deal – it will be corrected when i get the order in.
but for now, the goal is to get it to full working condition. After the pots were properly cleaned with contact cleaner, i proceeded to check the preamp tubes by removing one at a time and playing each channel- with a pencil, i marked each preamp tube that corresponded to what channel, and to what sockets they were in. Doing this i found out each channel had its own preamp tube. More on that later…
It had a reverb in and out RCA connectors in the back, and seeng no reverb tank inside the cab, i hooked up a working spare reverb tank i had lying around, and didnt have any reverb response either. Bummer.
So on to the next step – I removed the preamp tubes (6 12AX7’s, one 12AT7, and one 12AU7), and replaced them for now with new production EH 12AX7’s, 1 NOS RCA 12AT7 and 1 RCA 12AU7.
THE SPRING REVERB CAME TO LIFE!!! I dont know where its coming from, but its there alright. The old preamp tubes must be in their last legs. The dry sound is now much stronger, and the reverb sounds quite lush.
The 4 power tubes were Japan 6L6GC’s, and were all branded the same (Realistic), looking like they were all from the same batch, a good chance they are matched. Ive seen several plush amps online pictured with non-matching pairs. I havent tested these yet, but they sounded strong. I may tube-roll with my own old stock 6L6’s, but i I see no need to replace them at this time.
After a few more sound checks, i decided to replace the bigger electrolytic caps. After almost 40 years, even though it sounds strong and there were no tell-tale signs of impending burnup or blowout or simple failure, its best to be on the safe side.
Unscrewing what looked to be non-original non-matching screws, the bottom easily fell off, and revealed not just point to point wiring with most of the smaller components on a slim turret board, but the reverb tank as well – THERE IT IS! It looked exactly like my other non-working accutronics tank, only the Plush’s tank had pitting and some rust on it.
There were 3 big caps in the under side, and one cap can on top of the chassis. I had to snap a picture of the cap can’s side where the cap values are stamped on since it was in an awkward unreadable spot. 3 20uF/500V were needed for this cap can, and 2 80uF/350V and 1 40uF/450V (in series with one of the 20uF caps) under the chassis.
I kept close to the same values, only substituting a 100uF cap on the 80uF ones, and a 47uF for the 40uF. I figured i can replace with a bigger value, but i wanted to hear as close as possible to how the original amp sounded. I can always up the values later on if i see fit (this can also raise the headroom, which for a PA system is paramount, then again im mostly going to plug in a guitar here anyway).
THE JAM TEST
So now that most of the amp is in working, its time to put it thru the Jam Test. 😉 I must say – this is one LOUD MONSTER! Cleans are excellent, and not ice-picky at all. It barely overdrives! To most modern-day guitarist looking for “breakup” or high gain sound, this is a drawback, and not for them at all. This is after all a P.A. amplifier, so its setup NOT to distort. I guess thats one reason the Plush engineers thought best to copy a dual showman or a twin reverb, all for their clean headroom. This one has it! and i thought thats all it had.
My buddy came over for our regular jam, and we put it thru the paces, and lo and behold, he dialed it enough to get real overdrive. WHERE THE HELL IS THAT COMING FROM?!? we took a look at the settings. He was plugged in to Channel 1, gain at 8, bass at 2, mids at 9, and treble at 3. Main volume is at 8. DAMN! turning up the mids and lowering the bass and highs, made this a promising dirty rockin machine!
Further tests revealed the amp is picky about what to get it to overdrive – it wanted bright pickups. The guitar he played was a Luna brand, while i tested a dean Evo (both humbucker equipped). The Evo sounded dark on the Plush (detuned to D). I plugged in a Squier ’51 that had a GFS Dream 180 bridge Humbucker (described on their site as having “…the sparkle and chime of our Retrotron Nashville, along with the fat warm bottom of our Alnico PAF pickups”, “…made to combine the chime and jangle of vintage Filtertrons with the warmth and body of a great pair of vintage PAF’s). It worked well – the biting overdrive pushed the amp to sound grittier at higher volumes.
For about 3 hours of jamming we used it, plugging different guitars and in different settings. Everything worked, even the 4 frequency cut/bost switches. All 3 hours were earcandy!
On a separate note: You can tell we used “cheap” guitars. It only goes to show that even low-end guitars can sound amazing if you use a great-sounding tube amp. You can have a super high end guitar that costs a couple thousand dollars, but it will still sound like crap if you pair it with a bad-sounding amp. This is one reason why i shifted to tube amps from being a simple guitar-tech. Knowing tube amps completes the circle of a great electric guitar sound.
And it DOES helps to play decent too. 😉
ONE BIG SAFETY ISSUE
I’m putting a 3-prong cord in.
The amp came with the original power cord, but with a replacement 2 prong plug (must have worn off, as ive seen pictures with the original plug wearing out right at the plug base). This is then hooked up inside the chassis to a standby switch and a separate 3-WAY toggle switch that has the ON setting up, the OFF setting in the middle, and a Reverse Polarity in the down position.
Back in the day, there used to be NO standard for grounding electrical appliances and equipment. When you have several amps plugged in to the same mains, hum can occur, which can be mitigated by turning the plug around. In this case, you just flip the switch down to set it to the correct polarity.
The problem here is that one you flip down the switch, the chassis or any metal part of it becomes HOT instead of the Ground, and electricity will pass through it. and once you plug your guitar in, it will pass through YOU as well. touch a metal part of another amp that isnt in the same polarity, and you complete a circuit – YOU GET ELECTROCUTED! happened to me. On THIS amp. I flipped the switch down too hard, and kept it ON (reversed polarity), and touched a different properly grounded amp. YIKES!
Im tempted to make the all-in-one bypass/off/on mod with the 3way toggle switch, but i much prefer a separate bypass switch. Seems more traditional, plus might as well use whats on it.
During the jam test, after we figured out how to coax a crunchy tone out of the 1st channel, we copied the same settings over to channel 2, but it didnt sound as good, and didnt crunch as hard. At first i thought it was the overstated midrange value (250K instead fo 100K), but later on i figured it out with an experiment.
A clue was in one of the post of another Plush owner about modding it, who mentioned that “…each of those channels have a separate section”. Preamp? Hmmm…. so i went to town and one by one took out a preamp tube and turned the amp on. Lo and behold, it revealed the tubes that were responsible for getting the sound thru each channel (duh), and even for the reverb! Looking at what i thought was the correct layout, the tubes did NOT line up. I had a high-gain 12AX7 tube in the reverb section, and a 12AU7 in for channel 2. No wonder it sounded weak! a quick change of tubes effectively brought up the volume AND gain, now at level with the rest of the other channels. This also made for a much tamer reverb with a 12AU7 in it.
Now that i know which tube sockets control which channel correctly, there will be preamp tube rolling! I do have a stash of used old stock Mullards, RCAs, Sylvanias, and GEs i can try – heck, i may just simply put a different preamp tube for each channels, and then do an ABCD test.
Pots will be set back to stock values as soon as the order comes in. Later on one channel will possibly be converted to a twin reverb tone stack. Im thinking another can be set to blackface bassman tone values. along with mods as well (maybe). Im keeping at least ONE channel stock.
A review of the schematics for a dual showman and twin reverb shows that there IS a difference with the pot values, at least the mids. Dual Showman and Twin reverb mid pots show a value of 10K, while the mids on the Plush are set to 100K. The Bass and Treble are all the same at 250K. Bassmans have theirs at 25K.
This was one of my oversights – i assumed the gain and master volume were all 1Meg, and all the tone controls were all 250K, so for the tone, i just simply transposed some over to the other channels without checking. So for channel 2, the mids are set at a higher range (250K), though the difference is noticeable only at much higher gain – the overdriven sound has that thick discernible midrange tone. at lower gain settings the clean tone sounds the same as the other channels, though this is only a preliminary test. Most of the Jam Test were in full overdrive on channel 1, and clean tones across the other channels.
SOME FINAL THOUGHTS (FOR NOW)
This is THE most interesting amp ive acquired, hands down. 100W via 6L6GCs, FOUR DEDICATED CHANNELS (!!!), and an excellent-sounding reverb. ON ALL 4 CHANNELS, SWITCHABLE! It even has 4 frequency boosts/cuts (though i leave them all ON, and just futz with the tone controls). Its simple when you boil it down to what it does, but it does it 4 times! This has the potential to be a versatile guitar amp. And who can deny its quaint soft tuck and roll cover? Its almost perfect – there arent any noticeable tears, just a little nick here and there – pretty clean for something thats been around over the 38 years.
Almost looks like a foot stool. i beter make sure this is NEVER put on the floor – people may think its furniture to sit on!
Great amp, even better price! 😉
Some more pics: