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

[bigjppop]

Originally Posted by OneyedK

Better safe than sorry, best read Georges excellent guide before entering the high voltage zone that every tube amp is.
Electrical Safety

Everything unplugged...
I put the amp upside down on the edge of my desk.
Resting on it's transformer. Tubes "hang" over the edge...
(the transformers are heavy enough to keep the amp in safe balance)
Remove the bottom cover.

First connect the speakers again.
Then connect the negative connector of your voltmeter (black probe) to the amp's ground, I clipped it to one of the black speaker posts.
Make sure you meter in on and switched to Volts DC.

Plugin the amp and switch it on.
Wait 2 minutes before you start measuring, let tube temperature and voltages become stable for a while.

Put one hand on your back.
Now you can take the red probe of your multimeter and start poking around (with the free hand), make sure you touch only one pin at a time (we don't want to scare ourselves or destroy the amp).
Prepare for a slight "hum" or "buzz" in the speakers when you touch a tube pin with the red probe. This is perfectly normal, but you better know this in advance.

Thanks for the excellent walk through. I have read George's guide and am familiar with the "one hand behind the back" principle. Actually, the Tubelab Simple SE was my first project.

Once my shipment arrives I'll test this out.

Thanks!

[OneyedK]

Ah, great!

In that case, after measurement, you could change R7 and R16 to the optimum value for the 6CG7.
(3k9 instead of 2k, if I'm correct)
Or you could go in dirty and replace one resistor (R7 or R16) with a 5k trimmer and adjust for 1/3 of the available B+ (you can measure that on the large capacitor close to the volume pot) on pin 3 of the 6CG7.

[OneyedK]

Not finished soldering, but here's the schematic...

6P15P's biassed a bit hotter, Rk should be around 180 Ohm, in my case, I'll have to do with 330 and 390 parallel.

Already added the 100 Ohm resistor between anode and g2 of the power tubes, g2 ran over spec without it. I used 100 Ohm now, will try lower later...

Lowered Zout of the concertina PI, tubes I intend to use (6N1P, E88CC and even ECC85) can take the current. (might even be happier with more current)
Chose 100k for the anode load of the driver stage, R7 and R16 will be temprorary trimmers, just to be able to try every tube with the right bias.
--> did not change te feedback loop yet, will have to do that later.

On the schematic, black values were from the original schematic, blue values are the actual values from my stock GV1, red values will be mounted asap...
Unless someone sees a stupid mistake or a grave misjudgement in component choice/calculation.
Thanks for your feedback!

[bigjppop]

Looking forward to reading about your findings.

[creekkumar]

Hi there,
I wanted to try a tube amp. Compared and read few posts. After reading all these posts, I decided to order the Suppo EL84 amp. Within couple of weeks, I received the amp. When I first opened the box, I realized two things, one the amp had rattling sound inside it and the other one was, preamp tubes were 12AT7 instead of 6N1P. When I opened up the amp, I realized that the one of the power supply caps was detached and the other one was loose. I solder them back, installed the supplied tubes and fired the amp. I have very good quality SS amp, diy Nelson F5 amp and good quality cd player. Compared to two amps this sounded more detailed and better. It was a good surprise especially compared to other one being 10 times more expensive. Only one thing I did not like about this was it was not as clean sounding as what I am used to listening to. I decided to modify this amp. First I converted it back to 6N1P driver tube. Replaced driver and power tubes with Russian EV tubes. Now it sounded cleaner and musical, the way I like it. (Between 12AT7 vs 6N1P, it’s your choice. I preferred 6N1P). In next mode, I removed stock RCA connection, volume pot and connected DIY RCA silver cable directly to the circuit without volume pot. I like to use remote control for volume and changing sources. So currently I am using SS amp as preamp. This mod brought major change in sound quality. The transparency went way beyond my expectation. My next mode was to replace all caps and rectifier with schottky diodes. I used ASC, MTube for power supply and Teflon cap for decoupling, silver mica and film for pF values and Elna caps. I even changed the IEC socket, fuse & speaker terminals. All these changes were implemented together so can not distinguish effect of each change but it brought the amp to close to the sound I was looking for, very clean from top to bottom, detailed, airy, very firm sound stage & transparent. All these mods cost me more than this amp itself. Is it worth? I would say is debatable. The minimum few mods I recommend for this amp is volume pot, RCA cable with better shielding, two film caps in power supply - one next to electrolytic (20 -50 uF bypass with 0.1 uF) and one replacing 22uF for driver tubes. All other modes are at your discretions. You may not get enough return on your investment. This amp is well though off and it is a good value.
Have fun doing what you do…..

Creek

[rhing]

Any photos of your mods/upgrades?

[Rockmore]

It's a real shame.. the Golden Voice GV-1 is already phased out in all it's glory and is no longer sold or available. It had to be the best bang for your buck out there.

[rhing]

I saw that too. I still have my modded unit and use it every now and then. It's a good amp as long as you know DIY tube audio. Otherwise, it's one step away from a junk heap with its reliability issues and lack of support from Suppo.

My primary amp is a modified Magnavox EL84 console amp I bought off eBay for $100. It came with the original Magnavox labeled Mullard 6EU7 driver tubes and Magnavox labeled Mullard 6BQ5 tubes. They all test very well. That alone was a bargain. I keep the Mullards around for special occasions. but I use my reissued Genelex Gold Lion EL84s for everyday listening. This amp hasn't fried the Gold Lions like the Suppo did (this was before Suppo changed their tune about using EL84s in this amp). So it actually cost me less to upgrade the Magnavox amp, plus it's all point-to-point wiring. This made it much easier to upgrade all the resistors and caps. The results are astounding, and I have a matched quad of Mullard 6BQ5 tubes on top of all that.

That said, I think it's worth getting hold of a Magnavox 6BQ5 console amp, either the single ended or push-pull amps, and modifying one of those before buying a Suppo amp. They cost less, they are better built, and they sound much better.

[TerribleT]

Hello Suppos owners,
I've been using my GV-1 amp just about everyday since I got it 9 months ago. After some minor modifications, this amp has been great. I've recently got my Thorens 124/SME 3009 combo running and I am amazed at what my my modest system can do. I think maybe this is a good time to do the triode mod to get the most out of my new front end.
Then suddenly a a few days ago a cackling/spitting noise started in one channel and then a low level hum. I swapped tubes around and determined the 6P15 output tubes were at fault. So I need your advice on what brand I should buy and from which vendor. Do I need to buy matched pairs/quads? Please any advice would be appreciated.
Regards,
David

[Kristian]

You can't go wrong with these:

6P15P-EV / EL83 / SV83 tube - Hi Fi audio tubes - Tubes-Store.com

Originally Posted by TerribleT

Hello Suppos owners,
I've been using my GV-1 amp just about everyday since I got it 9 months ago. After some minor modifications, this amp has been great. I've recently got my Thorens 124/SME 3009 combo running and I am amazed at what my my modest system can do. I think maybe this is a good time to do the triode mod to get the most out of my new front end.
Then suddenly a a few days ago a cackling/spitting noise started in one channel and then a low level hum. I swapped tubes around and determined the 6P15 output tubes were at fault. So I need your advice on what brand I should buy and from which vendor. Do I need to buy matched pairs/quads? Please any advice would be appreciated.
Regards,
David