I know that VT4C.com sell rather cheap output transformers here:
Audio Catalog
I can't vouch for the quality of their transformers however, having not tried them myself.
so far, i have used different suppliers here. the results average to bad, for PP and SE.
most tube amp manufacturers do the transformers by thenselves in order to save costs.
Most transformers are done on an Ei core with Z11 material, claiming, imported from japan. many of the transformers failed a HV safety-test in our lab or other things maybe wrong such as winding directions, windings cancelling each other. for SE, the airgap ist just not existing , metals are screwed together without insulation of the screws.or they have a bad frequency response, which is the corrected by stron NFB. or, you order today in a company, if you want repeat order, the company does not exist anymore...
most tube amp manufacturers do the transformers by thenselves in order to save costs.
Most transformers are done on an Ei core with Z11 material, claiming, imported from japan. many of the transformers failed a HV safety-test in our lab or other things maybe wrong such as winding directions, windings cancelling each other. for SE, the airgap ist just not existing , metals are screwed together without insulation of the screws.or they have a bad frequency response, which is the corrected by stron NFB. or, you order today in a company, if you want repeat order, the company does not exist anymore...
First remove as much solder as possible.
Then cut the pins.
Remove the socket.
Solder the pins out, one by one.
Any other method will take too much heat and time.
Suppo uses 3 identical cathode resistors parallel in each channel, easy to recognise.
Remove them and replace them with 2 resistors of 390 Ohm (2 or 3 Watts) in each channel.
I placed them on the underside of the pcb to be able to change them if necessary.
I stayed on the safe side there, some tubes certainly can be biased hotter.
360//360 as cathode resistor will be better for some tubes, but then again,
if you want to do some "tube rolling", you better stay on the safe side.
Rest of the instructions:
Small error, I marked the cathode resistor as 185, that should be 195 ohm (390//390).
Somebody mentioned that connecting grid and anode the way I do, might cause oscillation,
but when I asked for a technical explanation, silence was the answer.
From my knowledge of 6P15 and EL84, when correctly biased, this is not possible.
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Hello,
it was me who mentioned the fact that a direct connection might cause parasitic oscillation if the connection is too long. Well, I have tested (and measured ) both connection types with and without the 100 Ohm resistors. Using a 100Ohm resistor is the safe way to go.
Best regards,
George
it was me who mentioned the fact that a direct connection might cause parasitic oscillation if the connection is too long. Well, I have tested (and measured ) both connection types with and without the 100 Ohm resistors. Using a 100Ohm resistor is the safe way to go.
Best regards,
George
Hi Guys
I am new to the forum (first post) so please forgive me if this is in any way incorrect.
I like the look of the Suppo GV-1 which has generated much comment here, indeed I have sent a few e-mails to them but a lack of any response makes me nervous of dealing with them. Are they still in business?
I wish to build my own Amp and I have read the threads on the Chinese Amps with great interest. Indeed I am of the opinion I may be better off buying one of these Amps and moving the components into a chassis more of my liking.
Is this a good way to start?
Opinion seems divided as to their quality of components and design, so would I be better off trying to find good circuit diagrams for me to attempt to build as my experience increases?
Thanks in advance
Peter
I am new to the forum (first post) so please forgive me if this is in any way incorrect.
I like the look of the Suppo GV-1 which has generated much comment here, indeed I have sent a few e-mails to them but a lack of any response makes me nervous of dealing with them. Are they still in business?
I wish to build my own Amp and I have read the threads on the Chinese Amps with great interest. Indeed I am of the opinion I may be better off buying one of these Amps and moving the components into a chassis more of my liking.
Is this a good way to start?
Opinion seems divided as to their quality of components and design, so would I be better off trying to find good circuit diagrams for me to attempt to build as my experience increases?
Thanks in advance
Peter
OneyedK, thankyou very much for your help!
I'd like to go ahead and perform the Triode mod but being a newbie to tubes would like to be absolutely sure I know what I'm doing!
Could you please be so kind as to confirm that the following procedure is correct?
Suppo EL84 Triode Mod:
- Solder pins 7 & 9 of all four EL84 sockets together.
- Cut PCB traces from pin 9 on each EL84 socket.
- Replace resistors in the following manner:
I'd like to go ahead and perform the Triode mod but being a newbie to tubes would like to be absolutely sure I know what I'm doing!
Could you please be so kind as to confirm that the following procedure is correct?
Suppo EL84 Triode Mod:
- Solder pins 7 & 9 of all four EL84 sockets together.
- Cut PCB traces from pin 9 on each EL84 socket.
- Replace resistors in the following manner:
An externally hosted image should be here but it was not working when we last tested it.
amp building
for those who wish to make their own amp: start from the scratch is my best advise. doing so, there is something to learn and understand. some circuits on the internet have also some flaws and often the mains transformer delivers a different voltage under load, so that a claimed DC operation point of the valves in nearly not guaranteed. making its own design includes more fun, as well. let the chinese do the copy jobs.
for those who wish to make their own amp: start from the scratch is my best advise. doing so, there is something to learn and understand. some circuits on the internet have also some flaws and often the mains transformer delivers a different voltage under load, so that a claimed DC operation point of the valves in nearly not guaranteed. making its own design includes more fun, as well. let the chinese do the copy jobs.
i found some pictures from inside suppo. the pictures maybspeak for themselves, here the link:
Google-Ergebnis für http://tyhong.com/audio/pic/workshop_s.jpg
Google-Ergebnis für http://tyhong.com/audio/pic/workshop_s.jpg
tubesteve, thanks for your interesting perspective as an engineer in China, especially the bit on transformers and companies coming and going. The reason I bought a cheap amp two years ago was that building an amp from scratch was an overwhelming thought, but buying something for a couple of hundred dollars that I could tweak and learn from sounded like a good direction, and I'm glad I went that way. That is what I see as the biggest benefits of an amp like this, it's a foot in the door and a great learning tool. There is no way back then that I could have made a sensible decision on PP or SE, what power output required, which kit or commercial amp, which speakers to use with it etc. I didn't even know what the "valve sound" was all about.
Have you ever considered sourcing power and OPT's in China, testing them for quality and selling them on ebay or through an established local vendor? For those outside USA, like me, I am looking at around $200 for iron alone for an EL84 amp, and it would be easy to spend a lot more than that. This makes an amp like the Suppo appear to be good value, and I think its the pick of the bunch right now for several reasons. I think it will make many owners happy, and maybe just a few unhappy, depending on their reasons for buying it in the first place.
Have you ever considered sourcing power and OPT's in China, testing them for quality and selling them on ebay or through an established local vendor? For those outside USA, like me, I am looking at around $200 for iron alone for an EL84 amp, and it would be easy to spend a lot more than that. This makes an amp like the Suppo appear to be good value, and I think its the pick of the bunch right now for several reasons. I think it will make many owners happy, and maybe just a few unhappy, depending on their reasons for buying it in the first place.
Great post Ian44.
Like yourself, one of the main reasons I chose to buy this particular Chinese amp was because building a tube amp from scratch was/is a daunting project when you've never tried it before, especially if you've never worked on high voltage audio gear before.
The Suppo has given me the chance to live with the the tube sound without breaking the bank. I'm now in a better position to contemplate my next amplifier upgrade.
You're welcome, if you're Joed, and if you can continue to stay out of the snake oil business, keep improving your GV1 and 2, and try and go mainstream with this great starter amp, your sales are going to go through the roof. I have recommended your GV series several times in the last month alone. But the major concerns here in the U.S. have already been mentioned in the last several posts (re-used unreliable parts, etc).
It's going to be interesting to see how your GV amps evolve in the next year or so -and- are then tested by enthusiasts in the western markets- that will be your acid test!
I for one, so far, would like to see better transformers, a full factory triode mode, better internal components, wood cases, and better top grade NOS tubes.
If we can get you to post a simple step-by-step procedure that even a 15 year old could do, as well as a parts list, from your efforts there down under here, I'm sure everyone would love it! Maybe making it sticky status for the Suppo GV series amps. Thanks Bosk
ok, i understand, if you like the suppo as a kind of base for your experiments. for the transformer: i let quite some manufacture after my specs. i bought quit an amount of pre manufactured, too. i never considered to sell transformers, first of all, i am in a full time job as engineer here in china, second, each design needs (slightly) different transformers, even for triode mode of pentodes, where the normal transformer either in PP or SE does not work properly, etc. for the manufacturers, we often had to tell them, how to make it correct, or better.
Yes, that's exactly the way I did it. Used a short wire to connect 7 and 9.
Also, before you remove te resistors, cut them away first, they're as hard to remove as the tube sockets.
I for one, so far, would like to see better transformers, a full factory triode mode, better internal components, wood cases, and better top grade NOS tubes.
With all of that this little amp would no longer be a bargain; just the "top grade NOS tubes" could VERY easily cost more than Joe is charging for the entire amp.
To try and make this Suppo amp more or less than what it really is seems to be missing the mark. To get a tube amp with this kind of sound quality at $130 USD is quite impressive. It may or may not have used parts and the build quality is not world class, but it's only $130 folks and it's enjoyable to listen to, especially with a few upgrades. I've had mine now for over two months and I haven't had any safety issues. Several friends and relatives have listened to my system with the Suppo amp and they are impressed with the sound quality of this amp. It's not the last statement in tube amps, but I can assure you that it sounds better than other amps costing much more.
Bosk,
Any idea on the diode ratings to use for upgrading the bridge rectifier?
Bosk,
Any idea on the diode ratings to use for upgrading the bridge rectifier?
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On the subject of bridge > discrete diode "upgrade",
I think there is much more to win in upgrading the coupling, decoupling and psu capacitors.
Next step would be balancing the phase splitter, maybe by installing an adjustable ccs in the anode of the first gain stage.
If all is done, check the feedback loop, I still have to do some measurements, but I think it's a bit off the way it is now.
But before you start, make the cheapest mod --> triode
I think there is much more to win in upgrading the coupling, decoupling and psu capacitors.
Next step would be balancing the phase splitter, maybe by installing an adjustable ccs in the anode of the first gain stage.
If all is done, check the feedback loop, I still have to do some measurements, but I think it's a bit off the way it is now.
But before you start, make the cheapest mod --> triode
Many thanks OneyedK. I hope to perform this mod on my amp next week and will be sure to post my impressions here in this thread.
I hope you don't mind but I have two more minor questions for you regarding the mod:
- Does it matter how close to the socket I cut the traces from pin 9?
- Will I lose any power switching the amp to Triode mode? Stock form is 8 watts but I do most of my listening @ 9 o'clock on the dial so it's not a big factor for me, I'm just curious.
- Why is it that in the schematic each replacement resistor is 195, when in reality I'm using 2x390 per side, for a total of 4x390? (apologies if the answer is an obvious one but I'm a newbie to the world of tubes as I mentioned)
As for you yourself, having performed this mod and rolled the tubes on your own amp are you satisfied with what you're hearing or do you have any further mods in mind?
How do you feel the modded Suppo stacks up against other tube amps you've heard or owned?
Once again, thanks for your help.
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