WEM Control ER-15 (my project amp)

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modman
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Post by modman »

I was so lucky to be able to pick up a small 15W WEM head. It sounded already good before, but changing most of the old caps for new high-end caps did away with some high end sizzle and gave me much mo' bass.

I found the schematic, will make notes about the actual values found in the amp when I can find back my notes.

Did pay much, came with a speakerless pick a bass cab, but I'm testing it now on two 80s stock Fender speakers in series (needs 16 ohm)

Here's the WEM history by the man himself:
http://www.wemwatkins.co.uk/history.htm
Dedicated WEM site with pics and schematics
http://www.vintagehofner.co.uk/britamps/watkins.html

Some pictures of my unit

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edit: added some missing pics
Last edited by modman on 13 Oct 2007, 13:47, edited 1 time in total.
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AL
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Post by AL »

Well that's an odd looking little guy. Point to point and half of the circuit is on one side of the chassis and the rest on the other side. Bet is sounds great.

8)

AL

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modman
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Post by modman »

Saw some people on ebay claiming to have paid 80 EUR for this head, if you believe them. At the other end of the scale I found this one at $1700 AUS

http://www.grouseguitars.com.au/wemdualten.htm

I forgot an action pic - samples after the weekend probably.
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Post by Goop_buster »

Thats one cool amp you have there modman. Congrats :D

80 EUR sound almost ridiculously low. It must be worth a lot more.

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Post by bajaman »

Yum Yum - Mullard EL84 tubes too :wink: :lol:
bajaman

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Post by holgar »

Hello modman,
I got exacly the same amp! It is humming a little, but does a nice sound. Too sad it just works with 15 Ohm, because I would like to use it with my small 1x12 8 Ohm box. What I love most is its weight and size; just like a handbag :-)

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Post by modman »

Hi Holgar,

I still profoundly crazy about it myself. Mine had some hum and very subtle crackling in the top registers. After I recapped channel 1, sound improved noticeably. It also was considerably louder than before so hum decreased by nature.

I rewired the 12" speakers of my old Fender solidstate in series to make it see 16 ohms. The amp really like that, but not evident, want to go for a 1 x 12" eventually, but haven't looked around for a replacement speaker.

Do you have the head or also a pick a bass cab?


thanks for chiming in!
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Post by holgar »

Hi modman,
it is too sad, I do not have the original cab. When I bought this amp, I wanted to mod it to a 18w Marshall. When I am informed correctly, Jim Marshall copied this little amp to make his own produkt, like he did it with the Bassman design too ...
But I am too busy with tweaking my Metro 50w and the stompboxes :-) beside my real work.
Regards Holgar

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Post by flood »

hey modman, i had one of these. bought for about €175, sold it for €225, and immediately regretted it. i loved the tone of that little bugger. not too many features... but that was something i liked about it. oh, it absolutely sang when overdriven. i doubt i'lll find it that cheap too soon...

i now play another oditty, a 4XEL84 italian steelphon guitar/bass amp. this one set me back about €90, and sounds pretty decent. it has an oversized OT, and i can't turn it up much like i could do on the control 15.

i would suggest that you hang on to that for a while. it's a keeper. i don't know about collectors value, but WEM watkins do not go cheaply on ebay germany.

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Post by bajaman »

slightly off topic but relevant to this thread. :wink:
I was given a TRIX of London - possibly late 50s valve amplifier.
it was obviously designed for hifi - a three position rotary switch selects mag PU, ceramic PU, and radio. it has a volume control and a treble and bass control also.
Someone had rescued it from going to the dump - landfill etc., and sold it in a recycling centre for $5!!!!!
I removed the metal cover and there was 2 x EL84 output tubes, 2 x ECC83 preamp tubes and an EZ81 rectifier tube. I removed the bottom panel and observed a very neatly laid out wiring scheme - all wires bent at right angles and carefully laid out. :D
After first testing the tubes, I powered the amplifier up and observed a rather sad oscilloscope picture of the output waveform into my 8 ohm dummy load.
SO ( and here is the point of this ramble) , I measured the voltages on the 5 x TCC .05uf 350v waxed covered coupling capacitors - every one of them showed leakage - ( a capacitor is supposed to block DC voltage - 250v DC one side and 0 volts on the other side), some showed as high as 20v DC on the input grids of the output tubes, wher i was expecting to fin 0 volts (cathode biased) - no wonder the amp looked and sounded sick. :wink:
I replaced them with suitable .047uf 630v dc film types and it made a huge difference, but still there was something wrong, so i replaced the cathode bypass capacitor ( 130 ohm cathode resistor), which was a 22uf 25vdc Dubilier type, with a 220uf 63vdc electrolytic and the scope picture showed another marked improvement. I plugged my guitar in to it, and although the radio input was a little quiet, (needs another gain stage) i was blown away by the AC15 style tone I was getting from it.

MORAL of this story - if it is over 30 years old, replace ALL the coupling capacitors and electrolytics, before you shell out money on tubes - your ears will thank you for this :wink: :lol: :lol: :lol:
bajaman

ps: if anyone is interested I can post some gut shots

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Post by modman »

Oh, Baja, don't make me hungry for more, because a friend send me this link

http://www.kapaza.be/Muziek_en_instrume ... erker.html

he wanted 250 EUR, I have a gut pic, but too late to upload now.
It's an Italian guitar brand that used to build for Vox too, but I find no info on this one at all.
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Post by bajaman »

I will take some photos and post after the wekend then :wink:
bajaman

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