Jarvini 6/18/2017 11:56 AM
Wilsic sound 50 watt valve amp
Hi all anyone out there know anything about the wilsic sound 50watt valve amps I've just inherited one along with 2 celestion g12m 25watt 16ohm greenbacks 1 celestion g12h 30watt 8ohm blackback and 1 100 watt 16 ohm eminence big cat!!! the amp is in pretty good nick with all the valves still in it the ecc83valves are all mullard and one of the el34 valves is mullard too the other el34 and the gz34 don't have any names on though my main question is does anyone have any stock photos of the guts of one of these amps as every photo I've found online look completely different from each other and mine is no exception are there any schematics out there for these amps I know they made a miles platting version which also looked slightly different but mine appears to be a mix of the two I don't want to fire it up until I've made sure that it's safe to do so but it's quite hard with nothing to check it against first I would welcome any info on the amp I've got a few pictures of the amp but they exceed the forums limit I can however email them to anyone who is willing to help Me ??
Enzo 6/18/2017 12:30 PM
I can't help your request, but firing it up ought not be a problem. If you are timid, treat it like an amp you just built. Fire it up with no tubes in it first. ANy fuses blow? Or better yet, use a bulb limiter. If it passes the fuse test, then check to see that heater supply reaches the sockets. Now install only the rectifier tube. Does it fire up OK? And can you turn on the standby switch (assuming it has one) without losing a fuse? And now does B+ hit the appropriate pins on the sockets? Be aware, with no tubes, the B+ voltage will stay at maximum voltage throughout the string. And finally, install the power tubes. Do them one at a time if you like. DO they power up OK? Generally the small tubes, with their high resistance plate loads are not in positions to blow fuses or burn things out, so I'd install the lot of them, and sort out any problems that arise. I generally power such a unit through my metered outlet - a current meter inline with the mains - so I can see if the unit draws excess current, even if working seemingly well. As to them all looking different, I know nothing of this amp maker, but the pictures I came up with all look like home built circuits, and I mean like one at a time rather than production line (I could be wrong). That alone will make amps look different. It appears to be a simple amp, a 12AX7 per each similar channel, plus a phase inverter. SO you should be able to trace out a schematic from the circuit in short order.
DrGonz78 6/18/2017 12:47 PM
I am posting this link below just to show another version of the amp. I am guessing you already came across this page, but either way it is interesting to look at still. [url=http://www.chambonino.com/work/miscguitar/misc4.html]Repair of a Wilsic 50 Watt Guitar Amp[/url] Like Enzo mentioned the amp does not look too complex to draw up a schematic of preamp and power amp sections either. As far as posting pictures on the site here you need something like Gimp or Photoshop to be able to resize the images to reduce them to about 1200x900. That always made them smaller sized but big enough to see great detail on the post. Gimp is free open source software and easy to use. [url]https://www.gimp.org/downloads/[/url]
Enzo 6/18/2017 12:57 PM
Actually, that chassis picture is good enough we could draw a schematic from it if we could enlarge it some.
DrGonz78 6/18/2017 1:17 PM
Here is a larger pic of it...
Jarvini 6/18/2017 2:25 PM
Thanks for the reply Enzo i sort of followed your instructions and fired it up in stages and all is good all the valves glow nicely!! in 8 ohm mode it sounds fantastic no hisses pops crackles just a great tone all the pots work, all four inputs work and both outputs work too i couldnt crank it too loud as a 2x12 cab in a shed with a strat at this time of night usually involves the police being called but it sounded great one problem though when i switched to my 1x12 16 ohm cab and changed the amp to 16 ohm output it sounded awful muffled crackly and just awful so im not sure if its been modded in some way its had a pretty awful mains lead change to add an earth so who knows im not quite at the stage of drawing schematics yet or sticking test probes into things i dont understand yet as this can be deadly ive ordered some books on tube amp design and construction and i am currently teaching myself electronics (you got to start somewhere) im a guitar player at heart but once i took this amp out of the crude box it was stuffed into i was hooked and determined to make it sing again so even though it works in 8 ohm mode im still not sure if its safe to use ?
Jarvini 6/18/2017 2:30 PM
Thanks for the reply DrGonz78 yeah i have come across those photos in my searches and i have taken your advise and installed gimp on my pc (luckily my girlfriend uses gimp for her illustrations so she gave me a quick crash course how to use it) and i have reduced my pictures which i will add in the thread below
Jarvini 6/18/2017 2:49 PM
the pictures now reducedin size
g1 6/18/2017 3:15 PM
Does it use a jumper plug to change impedance? (picture of rear panel if you can) If so, was it set on 8 all the time it was sitting? Chances are the 16 ohm socket for the jumper is oxidized and needs cleaning.
Jarvini 6/18/2017 4:04 PM
rear panel pic
yes the amp has a jumper plug that you change to alter the output from 4 to 8 to 16 ohm and it has sat in my mother in laws spare bedroom for 20 plus years (i never knew it was in there !!!!)and the plug has been set to 8 ohm for god knows how many years ive attached a pic of the rear panel it also has a jumper plug to change input voltage but this has been bypassed internally so its permanently on 240v input i plan to change this back when i address the awful mains lead modification considering its sat doing nothing for all that time it sounds pretty good [ATTACH=CONFIG]43816[/ATTACH]
Enzo 6/18/2017 4:16 PM
A 16 ohm speaker on the 8 ohm tap should work just fine, any degradation of hte sound would be subtle, not gross. I'd agree your plug is probably grubby.
teemuk 6/25/2017 12:34 AM
Miles Platting schematics can be found here: [url=http://edgaraudio.se/tubes/MilesPlatting/Schematics/]Index of /tubes/MilesPlatting/Schematics[/url]