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12th February 2011, 12:04 AM
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#1 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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Building something better with a Chinese SE EL34B Amp DIY Kit
There have been a couple of threads that have some discussion about this kit, but I thought I'd pull a few thoughts together here. It may be simpler for future readers to have the links and a few pictures in one thread.
To start: The 'kit' is sold via eBay and is titled 'SE EL34B Amp DIY Kit' - a search will turn it up It's been discussed here and also over there The 'kit' comes with a schematic and non-matching layout diagrams. In this thread there was a strong recommendation (from Eli Duttman and Ezequiel) for a different SRPP circuit, using 6SN7 tubes (the kit has octal sockets/cutouts). Link to the recommended circuit: 1.000.000 de Circuitos Eletrônicos Audio: SRPP 12AU7 / EL34 SE That's what I built. |
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12th February 2011, 12:07 AM
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#2 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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It all worked out fine in the end, but I wouldn't recommend this kit, at all.
Shipping was expensive but fast, and the packing was fairly good (the usual Chinese crumbling styrofoam beadboard...). |
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12th February 2011, 12:09 AM
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#3 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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A few problems were obvious right away.....
No hole for the PT, and holes for the OT leads were too small to fit grommets (no grommets in kit...) Stainless chassis - I hate working with stainless....but it is nice and shiny.. |
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12th February 2011, 12:11 AM
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#4 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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Output transformers didn't fit inside the OT covers.....so I had to do a workaround with tab bending and lockwashers under the machine screw heads...
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12th February 2011, 12:19 AM
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#5 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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The kit recommendation was for a buss-style build.
These can be very nice-looking (and sounding, if you do them properly) but I haven't had much luck on the couple of occasions I've done a build with a buss. I just slapped in some lug strips and got to work. Some of the extra lugs came in handy later, when I was 'adjusting' the PS to give the correct (lower) B+. (added another RC section). I added switches for the NFB and also a 'Pentode/Triode' switch. BTW- I didn't use any of the caps or resistors that came with the kit. The quality looked a bit suspect and the electrolytics were all radial-style, which I don't use with point-to-point wiring. Not a very neat wiring job, but it works. Fortunately, it doesn't have to look pretty to sound pretty! |
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12th February 2011, 12:23 AM
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#6 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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Switches and chassis top....
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12th February 2011, 12:24 AM
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#7 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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For testing, it's quite useful to take a few minutes building a 'frame' to support the chassis when it's inverted...
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12th February 2011, 12:27 AM
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#8 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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Something else which wasn't included in the 'kit' was a bottom cover. I really think all projects should have these, for safety's sake.
A piece of aluminum plate from the local recycling yard and some cutting and drilling later.... BTW, save those perforated steel bottom covers from old gear - they make good drilling templates. Just clamp to your new work and head for the drill press..... |
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12th February 2011, 12:32 AM
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#9 |
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diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
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I also cut a couple of hardwood end plates to use instead of the supplied particleboard items, and made a matching knob.
I'm happy with the results- it sounds very good, and is dead-quiet when the music stops. I ended up using EL34s (Russian equivalents), some NOS 6SN7s I had on hand, and a 5R4GYB rectifier. The power transformer is right at its limit - hot enough that I don't want to keep my hand on it for more than a few seconds - so I put the supplied PT cover on the shelf for another project. |
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12th February 2011, 01:15 AM
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#10 |
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diyAudio Member
Join Date: May 2005
Location: Victoria, B.C.
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Nice work. I'm sure your efforts will help those unfortunate souls who bought one of these and don't know what to do with their unfinished amp.
jeff |
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