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

[hecthern]

I received my amplifier very well packed. Connect speakers and let it burned for 48 hours. I connect a CD player and what a surprise. I never expected such a realistic sound. All the instruments sound natural. I can hear things I never hear before.Something like musicians breathing and fingers touching the instruments.

[Ian444]

I might be able to add something useful here, having bought a few cheap Chinese amps over the last 2 years or so. (When I say "cheap" I mean sub-$400 amps.)

It won't be too hard to tweak this amp if one felt the urge, some other amps from China have much more difficult access to the PCB, so this is a plus IMO.

Nice to see it has 4 and 8 ohm speaker outputs on it. Also the company appears to have a tube tester to match the output tubes, good to see. It does appear that Suppo are selling a value for money product rather than "just another valve amp."

This Suppo amp appears to have a relatively decent schematic so no problem there. The power supply looks a bit unusual with 6 x 220uF caps on it, and no C-R-C network, can someone confirm that? If the power transformer is undersized it will get hot, the 80W spec on the webpage, I wonder if that's the transformer rating or the max power the amp will draw from the mains?

On a new amp its a good idea for peace of mind if you can measure (or get someone to measure) the B+ and heater voltages to make sure the power supply cap voltage ratings are OK and the heater voltages are within spec. Then measure the voltages across the R11 and R20 cathode resistors on the output tube pairs and calculate the approx power dissipation for the output valves. If all is within limits then good.

If I was still in the market, I would get one for sure. This one appears to be better value than anything else I have seen so far, and I would hope for nice sound. An excellent introduction to valve amps, or a base for an EL84 that you want to build. I cannot buy the parts alone to build this type of amp in my country for this sort of money. It would be interesting to know what B+ this amp is running. But buyer beware, as we have already seen, minor mistakes like the power switch not working, or maybe the amp has no earth connection, these are things to be expected from my experience. I regard the sub-$400 Chinese amps as a prebuilt kit that need to be checked over carefully. Be careful. I hope they sound really good.

[rhing]

On the other Suppo thread in this forum, Review of Suppo Audio's first offering - EL84 Push Pull, jims measured the B+ on the power tubes and drivers. I can check the heater voltages later this week. I am enjoying listening to music with this amp too much to open it up again.

Taking advice from Joe, I just installed a pair of OS RCA 6FQ7 clear tops in place of a pair of Russian 6N1P-EVs, and there's just no comparison, even with the stock 6P15 power tubes still in place. Later this week, I am expecting a matched quad of new production Genalex Gold Lion EL84s. To date, I've replaced the input wiring with Teflon-insulated Silver wire, replaced the stock RCA connectors with Teflon-insulated RCA connectors, and I put in a 50k SMD resistor stepped attenuator.

Suppo EL84 Internal 8.JPG

This really opened up the sound and with the RCA 6FQ7 drivers in there, it is really rich sounding. I hear greater bass extension and definition, a focused image with spacing between instruments and vocals and a larger soundstage. I also bought a pair of OS Sylvania 6CG7 tubes to try out as well. These tubes are almost as tall as the EL84s.

6CG7 Sylvania 6FQ7 RCA cleartop.JPG

I plan to install the Ampohm PIO/Tin foil coupling caps over the holiday break along with a better IEC inlet, fuseholder and DPDT switch.

bigjppop, you'll hear a bit more bass extension with more driver break-in on your Omegas and stand mounting. This amp sounds really good with my Fostex FX-120 monitors, but with full range speakers like the Klipsch Forte IIs, it really sings with bass down to the 30's.

[bigjppop]

[QUOTE=

I plan to install the Ampohm PIO/Tin foil coupling caps over the holiday break along with a better IEC inlet, fuseholder and DPDT switch.

bigjppop, you'll hear a bit more bass extension with more driver break-in on your Omegas and stand mounting. This amp sounds really good with my Fostex FX-120 monitors, but with full range speakers like the Klipsch Forte IIs, it really sings with bass down to the 30's.[/QUOTE]

I think the IEC/fuse/switch setup will probably be my first mod (just to keep things safe). Caps will probably be next but I think I'll hold out for a bit until I get a better feel for the stock sound.

Also glad to hear that things will get better in the base department with a little time. I know its pretty much impossible to get low base out of my little monitors so I'm also looking at finding a decent sub. Anybody think I'd have a problem running a sub in parallel with my Omegas? i.e. running the sub speaker level and simply having two sets of speaker cable coming off the same binding posts on the Suppo?

[Ian444]

Thanks for the link rhing, I did not see that thread, kind of made my earlier post redundant. Glad you guys are enjoying it. What a cool unit.

The power transformer is a bit of a worry if it's getting hot. Is it an issue or non-issue or being fixed by Joe with a bigger tranny? In my country, if I had to buy a bigger transformer that would easily be another $100 due to 50 or 60 for the tranny and the rest in shipping, taking the edge off the economical original cost of the amp.

bigjppop, I haven't used subs, can't answer your question. You can run 2 x 8 ohm speakers in parallel from the the 4 ohm speaker outputs on the amp (per channel) if that helps.

[Franz Gysi]

I dont know about the heat of the little Suppo Amp.

But dont worry about a little bit heat!

I can show you this two little Telewatt EL84 PP amps, more than 50 years old and no problem with the heat:



I could toast a piece of bread to golden colour on it, no joke!

And I remember a old story within Studer / Revox R&D: the boss, walking through the laboratory, touched transformers. When he did not burn the fingers (below 50 degrees celsius) the trannie was oversized.

Also not a joke!

Franz

[rhing]

Ian444, everything gets hot, because the tubes get hot. I only notice the round power transformer cover getting hot, because the power tubes in front of it are emitting enough heat to warm it up. I've had other tube amps that heated up more, and had no problems with them.

The bigger issues are that bigjppop has had a problem with his power switch operating properly, the lack of a fuse and power connection to a DPDT power switch, and some of the quality problems with construction like loose screws inside a chassis. I had a faulty volume pot and had to repair it myself. I was going to post a review of this amp on another forum for people who aren't necessarily DIYers, but I wouldn't recommend this amp for people who cannot safely work on a tube amp themselves. 250 to 300 volts is nothing to play with. If Suppo addresses these quality problems, they'll have a fine amp to sell.

[bigjppop]

Originally Posted by rhing

The bigger issues are that bigjppop has had a problem with his power switch operating properly, the lack of a fuse and power connection to a DPDT power switch, and some of the quality problems with construction like loose screws inside a chassis. I had a faulty volume pot and had to repair it myself. I was going to post a review of this amp on another forum for people who aren't necessarily DIYers, but I wouldn't recommend this amp for people who cannot safely work on a tube amp themselves. 250 to 300 volts is nothing to play with. If Suppo addresses these quality problems, they'll have a fine amp to sell.

I have to agree here. I've had a little extra time on my hands after the holiday madness (been putting together toy strollers and kitchen sets instead of amps) and have spent a little time with my Suppo. I still think it sounds great, but the quality control issues are starting to bug me a little more. I was finishing up my Tubelab Simple SE today (of course I am missing one more piece and have to go back to the store again!) and decided to dig around in the Suppo to see about fixing my power switch, adding a fuse, etc. It turns out that fixing that issue is going to be a little bigger chore than I thought. The switch itself is bent/twisted into place in order to "make it fit". As I took apart the chassis to get to the switch (and add in a couple of the screws that were missing when I received the amp) I noticed that pretty much every piece of the chassis is bent/twisted again, I assume, to "make it fit." Even many of the screw holes have been drilled out so that things that didn't line up, do now. All in all, even though the amp sounds great, unless you're a committed DIYer (why else would you be reading this) in its current form, the Suppo might not be the best choice for Grandma.

I recognize that I got one of the first amps off the line and I know that one of the reasons Joe offered this community such a great intro price was to help iron out some of the kinks so I'm hoping future amps are going to be better. If the price is right on Joe's next EL34 offering I'm still probably going to buy one of those.

Hopefully Joe is still reading this forum and can help tweak some of these issues. I'm sure the cost would be tiny to fix most of these problems and even if it added a few bucks to the final cost I'm sure you'd still have a very competitive amp. So, better fitting and thicker chassis plates, power switch moved slightly so that it doesn't need to be bent/twisted into place to fit behind the IEC socket, properly wired power switch, a fuse, and a couple of screws in the holes that were missing them. Any other suggestions from the community? Like I said above, still a great sounding amp; just needs a little TLC and it would be awesome!

[jean-paul]

Hi, I got the old version and it was unfortunately damaged from transport. The toroid was loose in its case because the package apparently had been transported upside down. The weight from the toroid had drawn its bolt through the 2 mm thick chassis. The hole for the bolt was already drilled a bit too big which did not help. The toroid had to be taken out of its case but this could only be done in a destructive way. I also needed to remove the output transformers but their screws were covered by the case with the toroid. So it was not very service friendly.

Joe was very helpful and offered to send me a new revision of the amp. Of course I accepted his offer and waited patiently. Two weeks ago the amp arrived. I was away last week and haven't listened yet. I did power it on with resistors at the outputs and it becomes hot indeed. Not too hot but class T amps made me forget that amps can get hot !

It has 3 mm thick panels so no sagging of the upper panel and the build quality is better than the old version. The bottom panel is also 3 mm thick. It is also better layed out internally. The side panels are black now instead of the orange of the first model. The output transformers are better placed and the power transformer is a classic power transformer bolted down with 4 bolts.

So better build quality and a better chassis. I probably will drill several 4 mm ventilation holes in the chassis just after the valves/tubes and in the bottom panel as it is completely closed now causing heat buildup that can be avoided. Better convection for better longevity of the amp. It also lacks a power fuse which should be there IMO. No loose screws etc. like with the old model. If you have any questions about the differences please let me know as I still have the old one for comparison.

Bigjppop, I suppose the bent chassis your amp has is from transport as the older orange one I have has nice fitting panels despite the damaged toroid/case. It is quite a heavy amp and getting it to Europe without damage is hard to do. The first orange version was well-packed but damaged and the black one was even better packed but it also has some scratches from rough handling by the postal services. Although packed in very thick styrofoam the postal service managed to treat the amp so rough that the amp had gone through the styrofoam.

[bigjppop]

Originally Posted by jean-paul

Bigjppop, I suppose the bent chassis your amp has is from transport as the older orange one I have has nice fitting panels despite the damaged toroid/case. It is quite a heavy amp and getting it to Europe without damage is hard to do. The first orange version was well-packed but damaged and the black one was even better packed but it also has some scratches from rough handling by the postal services. Although packed in very thick styrofoam the postal service managed to treat the amp so rough that the amp had gone through the styrofoam.

Actually the packaging was some of the best I've ever seen in any product I've purchased; VERY WELL packed. So, no shipping damage. On my amp the top plate has sagged from the weight of the PT and the bottom plate is bent in the other direction because the OPTs don't quite fit. Anyway... Overall, packaging was awesome and at least for me, definitely not an area Joe needs to improve on. No worries there.