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Old 18th November 2009, 04:12 AM   #1
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Default Review of Suppo Audio's first offering - EL84 Push Pull

Aesthetics and Build Quality

The Suppo Audio 6P15 Amplifier is quite a small amp, measuring 185mm wide by 245mm deep by 135 high (including rear terminals and tubes installed). Made from machined aluminium screwed at the corners into small blocks of aluminium, it feels quite sturdy, although some more screws along the length of it would make it a little more solid. The output transformers (of decent size) are located below deck, so the top panel is populated by only the six tubes, a cylindrical transformer housing (a toroidal power transformer is used) and a small power switch toward the rear. The top, front, bottom and rear are all brushed aluminium, the sides of the amp and top of the transformer housing are a deep orange anodised aluminium. Upon first look, I wasn’t a huge fan of the color scheme (my girlfriend’s first word upon seeing it was “cute”, so it seems to be okay with her) but it has grown on me. I might prefer a different color for the sides might be preferable, but it is by no means ugly. A small, recessed brass-colored volume knob is the only protusion from the front panel.

Heat and Internal Constuction

I have found that this amplifier tends to overheat somewhat. It is quite warm in Australia at the moment and the ambient temperature in the room the amp is in is around 25 degrees centigrade. Without the extra help of a fan (80mm computer variety) it gets quite hot, with both the top plate and power transformer housing becoming too hot to touch. A small fan directed at the top plate brings this down to a much more reasonable temperature, only warm. The internals seemed to be of a good quality, with a thick double sided PCB in use, as well as Nichicon caps and decent sized output transformers. There were a few issues on the inside: the screws holding the transformers down had come loose (simple fix) and there was a complete omission of a power fuse. I wired an inline fuse on the hot side (note: only the hot side of the power was switched, the neutral was always closed; I prefer both hot and neutral to be switched) to be safe.

Sound

The first thing I checked when I plugged the amp and turned on the amp was the noise floor, which was fantastic, when I put my ear right to the speaker, there was no hum, hiss or buzz. Good so far. The amp came with Chinese (Shuguang I believe) tubes - four 6P15/EL84 power tubes and two 6N1 preamp tubes. Initial impressions (first five hours) have been good. It has good tight bass, defined mids and the highs aren’t overly harsh. The whole frequency range is well covered, but there is something about the sound that doesn’t sit right with me. I still prefer my Simple SE, but definitely a good start. I have some Russian equivalent tubes on the way which I will test it with, I have a feeling they will improve the sound a lot. I should note that I have tried Shuguang tubes in my Simple SE and didn’t like the sound, finding it to be to harsh; when I installed the Russian 6P3S-E tubes (still my favourite tubes) it took on a much nicer sound, more neutral and had a certain warmth to it. For these reasons, I don’t plan to make any concrete comments on sound until I receive the new tubes. For the price of the amp (I believe it is priced around US$150) it is a lot better than I was expecting. The sound is only a stone’s throw from the quality of my Simple SE, I have been quite impressed. I will do secondary and tertiary reviews once the tubes have burned in and once the Russian tubes arrive (I am really looking forward to what they do with the amp)

A Note to be Made on Shipping

This is the second amp I have received from Suppo Audio, the first was all but completely wrecked in transit. An electrolytic had come right off the board and the transformer was shot, I wasn’t even able to get it back to a testable state. Joe from Suppo was fantastic to deal with and (after I sent through pictures and whatnot) he delivered a brand new amp for my testing. This one has worked from the get go. Joe has improved the packing of the Suppo amps, now using a box inside a box and packing much more tightly (movement is the killer during transit) resulting in the second amp arriving in perfect nick.

Final Thoughts

I have been rather impressed with Suppo Audio’s first offering. With a few tweaks (namely sturdier construction, addition of a fuse and a preferable change of color scheme) I think they have the ability to create some very fine, yet cheap, tube amplifiers. I very much look forward to their next offering (I’m thinking a 6L6 push-pull perhaps) Well done.

Feel free to ask any questions that you may have. Nic.
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Old 18th November 2009, 05:08 AM   #2
rhing is offline rhing  United States
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Default Initial Impressions of the Suppo Golden Voice

I received my Suppo Golden Voice amp today and played it for about five hours. The amp arrived in great condition. When I hooked up my system, I guessed that the outermost binding posts corresponded to the 8 ohm OPT taps. No loose parts as far as I could tell. The construction is nothing like a McIntosh amp, but my wife thought it was "cute." When I turned the unit on, there was an initial pulsing sound coming from the right channel speaker. This caused my Fostex driver to move in and out quite noticeably. I turned the volume pot up a bit, and the pulsing sound disappeared. After the unit warmed up a little more, I returned the volume pot back to its starting position and there was no more noise. After that, as MellowTone said, this amp was very quiet. I didn't hear any buzzing, hum or hiss from my speakers. I also have a friend's Anthem Integrated One amp on loan. This has an octet of EL84 power tubes, and this thing is a noise monster. The humble Suppo showed up the giant on noise control.

I listened to the following CDs tonight:
  1. Bill Evans Trio - Waltz for Debbie
  2. Miles Davis - Kind of Blue
  3. Diana Krall - Love Scenes
  4. Laurie Anderson - Mister Heartbreak
  5. Paul Paray & the DSO - Ibert, Suppe, Ravel
I have to say that this little cheapie is very impressive. I'm not making any final judgments yet, but this little box has some potential. As far as I can tell, this amp sounds better than a stock Trends TA-10.1 Class D amp, which I happen to like. It has detail, great tone and some muscle to reproduce a fair amount of bass out of my Fostex FX120 monitors. The soundstage is very nice, deep and big like a good EL84 amp is able to reproduce.

On the downside, the balance seemed like it leaned toward the right at times. I'm not sure what that was about. As the amp played longer, the image stabilized and remained centered. I would hear some crackling noises on occasion. I think my amp had a minimal amount of burn in and what I heard was burn-in artifacts. I think the pot needs to be replaced with a better unit.

One thing is for sure, I found myself enjoying the music with this amp rather than studying its sound. It has good PRaT as I'm sure the generous amount of negative feedback in the circuit gives the amp very good control. Still, I really liked the warmth of tone that these tubes gave. I think I might like this amp more than my Onix SP3 (a.k.a. Melody Valve SP3). I'll reserve judgment until I give this amp more playing time and a wider range of material.

It's 8 watt per channel power rating is deceptive. This amp has plenty of juice to drive my Fostex speakers to very loud levels in my small listening room (11 ft. w x 12 ft. l x 9 ft. h). I haven't pushed it yet, but I do know that I still have room to work with. The pot starts at 7 o'clock and the loudest I pushed it was around 11 o'clock. At this level, the soundstage spanned across the room without any audible strain. It clearly has more muscle than the Glow Audio Amp One single ended pentode EL84 amp I tried in my system.

The amp does get hot, but it's Fall here in the San Francisco Bay Area, so it also doubled as a space heater tonight. It's still a lot cooler than the Anthem Integrated One with 13 tubes and my Onix SP3 with 10 tubes. I like this little box. I think it was money well spent, especially with Joe's special offer to us. I will post more listening impressions later on and some comparisons to other amps I have on hand.

Suppo Golden Voice EL84 Amp.JPG Suppo Golden Voice Front.JPG
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Old 18th November 2009, 11:59 AM   #3
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Well you guys are both getting me excited. I'm still waiting for the mailman to bring me my cables and until he arrives my amp is just sitting there staring at me. It's like when Santa forgets to bring you batteries for your new toy on Christmas morning!
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Old 18th November 2009, 12:09 PM   #4
rhing is offline rhing  United States
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I'm using the Woods Yard Master Patio Cord from Walmart as described in this article:

6moons audio reviews: DIY*Cables - The White Lightning Moonshine

These have worked well for me.
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Old 18th November 2009, 01:36 PM   #5
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Default schematic

Just post a schematic for MOD

Enjoy it and Modify as you like

thanks MellowTone and Rhing
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File Type: jpg 6P15.jpg (372.3 KB, 1996 views)
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Old 18th November 2009, 10:48 PM   #6
lowpoke is offline lowpoke  Australia
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What are you guys on? I think that gold anodised finish looks SWEET! It's about time we saw some variation on ... well, black.
(However, gold volume knob isn't rocking my world )
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Old 19th November 2009, 03:44 AM   #7
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Hmm, I don't like the orange! I'm thinking of a couple birch trim board from the Depot, stained cherry, and slapped on the side.

btw

I've been looking @ Class D mini amps on Ebay for a Small, cheap, but nice sounding sytem to go on the night stand for bedtime music. Could this amp be the answer? I'm worried about the heat just inches from my face here in sunny Florida. Why would this have a heat problem? Too many tube too close together? I just don't know how I feel about something like this firing off all night while I sleep next to it. Whatya Thinks?
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Old 19th November 2009, 04:52 AM   #8
rhing is offline rhing  United States
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I don't think this amp is any hotter than any other comparable EL84 amp. It's the nature of the beast. Living in Florida where it can remain hot at night, I would recommend a cool-running Class D amp like one of the Tripath-powered amps. I think this amp sounds better than many of the lower-powered Tripath amps like the Trends TA-10.1--it has that holographic soundstage and warm tone that only tubes can produce.
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Old 22nd November 2009, 04:37 AM   #9
rhing is offline rhing  United States
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After listening to this amp a few days, I have to say that the most disappointing result is the lack of balance between the channels. Proper balance would come and go. It finally seems to have settled with the sound coming stronger from the right channel, so it's really difficult to get a solid image. I've tried switching the driver tubes and then the power tubes between channels. I even tried the 4 ohm taps versus 8 ohm taps hoping there might be some odd anomaly with the output transformers. Still nothing. I opened the amp and checked the wiring, and it doesn't seem like anything was out of place.

Suppo Golden Ear Inside 1.JPG

I hope that Joe at Suppo can work something out here. I hope it isn't a case of poorly matched output transformers or the left output transformer going bad. Even at the special offer price, balanced channels should be a given in a stereo amp.

I also noticed that the top plate is starting to sag a bit in the middle.
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Last edited by rhing; 22nd November 2009 at 04:43 AM. Reason: Added photo
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Old 22nd November 2009, 08:14 AM   #10
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Might it be a problem with the volume control? I'd think a better pot/attenuator would be good upgrade.
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