Suppo Audio -- New Chinese EL84 PP amp for CHEAP.

[bigjppop]

Alright, so I think I've decided I'm going to tear down my Suppo and rebuild it into a new chassis. I've got some super nice, highly figured Bubinga that I think will make a really nice chassis.

So, while I've got it all pulled apart I figure I might as well do a little modding. I'd appreciate everyone's thoughts on my plan.

Mod:

Fuse/power switch
Switch to Triode mode (based on the thoughts here Review of Suppo Audio's first offering - EL84 Push Pull)
Replace C2, C3, C14, and C15 (.1uF 400V) with some Sonic Craft .22uF 600V caps that I've got sitting around
Replace volume pot

That's what I'm sure of. I read somewhere that someone recommended replacing C4 (and I assume C16) as well but I'm not sure on that one. I don't want to replace caps just to replace them. Thoughts? I've also thought about upgrading the OPT's to the little Edcors but I'm not sure on that either. It will run me about $40-$50 for the pair but I don't know how much better they will be. I've read suggestions to replace the bridge rectifier with better diodes but I don't really know what that means. Also, I've read that a regulated power supply of some sort would be great in here as well but again, don't really know what that means. Regulated PS for dummies anyone?

One thing that really drives me crazy about this amp is that some of the tube sockets are a little crooked so I'm hoping to try and fix that while I'm at it. I've heard its a bear to remove tube sockets from a PCB but I've never tried it. Any suggestions here?

Anyway, hopefully all that makes sense. My overall goal is to do this as cheaply as possible. If I'm going to be dumping a lot of money into this I'd rather just save the cash and build the upcoming Tubelab Simple P-P. In case anyone needs it, the schematic is on the first page of this thread.

[spaudio]

Hi everyone,

Sorry I am late for this disscution. Looks many people enjoy this little amp.
We are busy improving the EL34 and redesign the cases for the EL84.
some improvmen is easy to say and hard to accomplish. for example: dual voltage input and dual safe power switch. we tried to use dual voltage input switch (115/230) but found that it effects the sound a lot. may be just because a little bit longer wires inside. It take us a lont time to fix the problem.
I will look careful all the threads and reply all questions. but please allow me some time to do it.
Thanks you for concerning this amp.

Joe suppoaudio

[bigjppop]

Originally Posted by spaudio

Hi everyone,

Sorry I am late for this disscution. Looks many people enjoy this little amp.
We are busy improving the EL34 and redesign the cases for the EL84.
some improvmen is easy to say and hard to accomplish. for example: dual voltage input and dual safe power switch. we tried to use dual voltage input switch (115/230) but found that it effects the sound a lot. may be just because a little bit longer wires inside. It take us a lont time to fix the problem.
I will look careful all the threads and reply all questions. but please allow me some time to do it.
Thanks you for concerning this amp.

Joe suppoaudio

Good to see you back on here Joe. I think we're all very curious on your EL34 amp and would really appreciate a estimated timeline and price.

[dmkbox]

Yeah Joe, thanks!
We wait :-) !

[spaudio]

and thanks this guy
Br, br0082012@gmail.com

I don't know who is him yet. but he sent me two email reminding me that I should reply to this post.

thanks

[Bosk]

G'day bigjppop,

I've already performed the following mods on my Suppo EL84:
Added a mains fuse & DPST power switch
Replaced all wire in the signal path with silver/teflon
Bypassed half the electrolytic caps
Replaced bridge rectifier with 4x discrete diodes
Replaced binding posts & RCAs
Result: noticable improvement already!

When the rest of my parts arrive I plan to upgrade the volume pot & Chinese tubes, bypass the rest of the electrolytics and change the coupling caps. I may do the triode mod too, though I may need some more detailed instructions as I'm not sure precisely what values of resistors go where.

I've thought of re-casing mine too bigjppop, the main reason being it would facilitate the upgrading of the output transformers. Most likely I'll upgrade the rest of the amp and then see where it's at.. already I like what I'm hearing!
If you do go ahead an upgrade your OPTs though, bear in mind most people say that these are the things which have the largest bearing on the sound of a tube amp, so you might want to invest the bulk of your money here.

Regarding upgrading your bridge rectifier with diodes, this page shows how it's done:
http://www.hificollective.co.uk/pdf/diode.pdf

You can also buy all the diodes mentioned here:
diodes listing page

I've never had to remove a tube socket from a PCB before (this is my first non-headphone tube amp) but I can easily imagine it being not a nice job. I personally wouldn't bother unless one of the sockets is really crooked.
That said if you're committed, you could always buy some nice teflon tube sockets and swap them in there.

Anyway, best of luck with all your mods and please keep us informed of your progress!



Oh- and just in case you might be interested you can checkout my humble review of the Suppo amp here:
Review: Suppo GV-3 EL84 ($220 delivered)

[bigjppop]

Bosk:

I read your review a few days ago and it's actually what pushed me over the edge with redoing mine. I've enjoyed it in stock form so if I can get it stepped up a little for not much money... why not?

Thanks for the links on the diodes; it doesn't appear to be that much of a challenge, what did you think?

Once I get going I'll definitely put some pictures up. My new chassis should for sure have room for bigger OPT's, I just have to decide if I want to justify forking out the dough.

[tubesteve]

I will test this amp according to EN60065 safety standard, and i will not be surprised...

[spaudio]

Just a short message first,
We are upgrating the EL84 now they will have new case in 4days. this AMP will have fuse installed. But in our test, no fuse better than fused. that fuse will effect the sound. We don't use fuse in our own listening AMP. some one wil say dangerous. Oh yes, just depend on how you evaluate and control the risk.

Earth grounding issue: we connect the earth via the PCB to chasis and to the power socket. isn't that enough? or we should do more?

we will change the Vol pot and the power switch. should not let the machines fail just because of this two small parts.

the V2 case of EL84 would look like the EL34 shown on our website. but smaller size.
The EL34 price: we will set a good price for our DIYaudio members. special price for DIYaudio member around $360-$400. this AMP weight around 17-20KG with packge, maybe more. So the shipping cost is expensive too (around $180). If people can group-buy 3AMP, then we ship 3 together, then will be $450($150 each).

[tubesteve]

sorry, forgotten: not only the volume pot are fakes, capacitors in china, Rubycon , Wima, etc etc. brands are fakes as well. there is a long, long list which i have to deal every day. here in shenzhen huaqiang bei road, futian district. a lot of this stuff is sold. worse than that: the sell also used components after cleaning them up. ICs, capacitors, or, selling components, which fail customers request for performance and being rejected. manufacturers purchase departments will buy them and built into devices...so it comes to a cheap product. next worst: manufacturers ("engineers") even dont have suitable equipment or the knowledge to test their products. data publishing is therefore rare.....chinese companies come and go as the weather does. as a tester here in this blessed countriy, i could tell you nice stories. and tube amps are a big topic.