Actualy "Sweet Peach + tube amp" will work, thats how I found this amp outside of ebay where it is sold as an HLLY tube amp. It is manufactured by Xiangsheng electronics co. out here in the real world. It makes 13 watts in SE triod mode, 89db signal to noise ratio and less than 1% THD. Though it's far from beautiful I will say it lacks some of the silly bits of rubbish found on many of the other lower end amps from China, no goofy handles, bits of wood or blue leds hiding under the tubes. I'll try to take some pics of the guts.
This is just weird...
Hefei XiangSheng Electronic Co.,Ltd - Products - Vacuum Tube Amplifier - Integrated Tube Amplifier
Its like a new section of the internet for me. All my searches end up with sites wanting me to buy in bulk and get quotes to sell them in my country. Still havent found anything close to $300 shipped. Most are $250-300 + $150 shipping. For that price its beyond tinkering and i could make my own with american iron. Still id love a SE with a 4ohm and 8 ohm tap.
Hefei XiangSheng Electronic Co.,Ltd - Products - Vacuum Tube Amplifier - Integrated Tube Amplifier
Its like a new section of the internet for me. All my searches end up with sites wanting me to buy in bulk and get quotes to sell them in my country. Still havent found anything close to $300 shipped. Most are $250-300 + $150 shipping. For that price its beyond tinkering and i could make my own with american iron. Still id love a SE with a 4ohm and 8 ohm tap.
Spielbergo, so which model you eventually got? They have more then one model which is "13 watts in SE triode mode"?I guess you mean GU-50 tubes by Soviet tubes? I made an enquiry about GU-50 tubes to HLLY a while back asking that are they a direct replacement for FU-50? The reply was, that they are not and they don't recommend any other tubes used in this amp. Very strange as the GU-50 should be a direct replacement...
Thats very strange about the FU50/GU50, all the research I have done suggests they are identical. All the tubes used are soviets, 1x 6n1, 2x 6n3, 2x FU50. I have been to Xiangsheng's site and there is only one FU50 SET amp, they also have a KT88 model. If in doubt it is the small one that has SWEET PEACH silk screened huge across the front panel. I will try to open it up tonight and see if there is a chassis ground or fuse.
I removed the bottom panel and was surprised to see that the chassis is in fact grounded to the plug earth. There is no fuse. The layout is fairly tidy and logical. Just for fun I tried the built in mm phono preamp, yikes!!The opamp used in the circuit doesn't even have any labeling of any kind. I see two trimmer pots with leads going out to the FU50 grids but there aren't any for the input tubes. Might the input tubes be self biasing? I took some pics of the innards.
Attachments
Are you sure there's no fuse? Sometimes they're built into the power entry connector. If not, you should really install one in that puppy! If something shorts out, (like a bad output tube), you can do some serious damage, like burned out transformers or even a fire. For a few bucks you can buy a inline fuse holder from Radio Shack, along with a 1 or 2 A Slo-Blo fuse. You don't need to drill any holes. Connect it between the hot (black) power cord wire, right after the switch and the primary of the P/T.
99% of all input (small signal) tubes are self (cathode) biased.
99% of all input (small signal) tubes are self (cathode) biased.
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The inside of that amp looks nice. The modular construction is a bonus to us DIY'ers who like to rip things apart.
The mains fuse is probably integrated in the mains IEC connector, accessible from the outside.
Power supply looks like it uses full-wave rectifier, not the voltage-doubler that we find in many cheap Chinese amps, and there is a proper filter choke.
The two input tubes are (probably) Chinese 6n3 which can be swapped for Russian 6n3, or US 5670 / 2C51. Only one half of each tube is used.
One driver tube 6n1, one half used for each channel.
The FU50 power tubes seem to be permanently connected in triode mode.
SveinB.
The mains fuse is probably integrated in the mains IEC connector, accessible from the outside.
Power supply looks like it uses full-wave rectifier, not the voltage-doubler that we find in many cheap Chinese amps, and there is a proper filter choke.
The two input tubes are (probably) Chinese 6n3 which can be swapped for Russian 6n3, or US 5670 / 2C51. Only one half of each tube is used.
One driver tube 6n1, one half used for each channel.
The FU50 power tubes seem to be permanently connected in triode mode.
SveinB.
My Sweat Peach amp came in too.
Here's the packaging it came in. No, it's not adequate. A binding post snapped off and there's a dent in the front panel.
HOWEVER, according to the EMS slip, the shipping cost was 1971 RMB. Converted to US dollars, that is more than I paid for the entire auction ($270). Someone is losing money here.
Here's another picture of innards
The power transformer appears to be wired for 220V operation. The manufacturer simply added a 110V to 220V transformer in front of the original power transformer. There's nothing wrong with this. It just makes the voltage switch on the IEC socket useless.
Here's another picture with the amp stacked on top of my Yarland 845 amp.
The volume control is actually a stepped attenuator. That's pretty cool.
Considering it has a phono preamp and USB DAC, this is one hell of a deal. The sound is good. It's got lots of power. The transients are decently fast and the bass is substantial.
I'm definitely happy with this buy.
Here's the packaging it came in. No, it's not adequate. A binding post snapped off and there's a dent in the front panel.
An externally hosted image should be here but it was not working when we last tested it.
HOWEVER, according to the EMS slip, the shipping cost was 1971 RMB. Converted to US dollars, that is more than I paid for the entire auction ($270). Someone is losing money here.
Here's another picture of innards
An externally hosted image should be here but it was not working when we last tested it.
The power transformer appears to be wired for 220V operation. The manufacturer simply added a 110V to 220V transformer in front of the original power transformer. There's nothing wrong with this. It just makes the voltage switch on the IEC socket useless.
Here's another picture with the amp stacked on top of my Yarland 845 amp.
An externally hosted image should be here but it was not working when we last tested it.
The volume control is actually a stepped attenuator. That's pretty cool.
Considering it has a phono preamp and USB DAC, this is one hell of a deal. The sound is good. It's got lots of power. The transients are decently fast and the bass is substantial.
I'm definitely happy with this buy.
Sorry to hear about your Peach being damaged Mazuki, mine had a couple of tiny scuffs which is amazing considering the condition of the packaging. I just noticed the fuse a few hours ago in the socket, I guess we need better lighting in our household. Have you checked your bias settings for the FU50's yet (at least for consistency between left to right channels)? I'm a little concerned about the lack of r2, r3 on the right side FU50 socket considering the heater supplies are in parallel. I have a russian 6n1p installed without any drama but thats terrible news about the GU50's not being compatible, if one was ambitious enough they could figure out the pin configuration for the FU50 to GU50 and just wire point to point underneath the tube socket instead of using the board.
Mazuki, strange that the GU50 did not work.
From the photos, the tube socket pin numbering appears to be correct for GU50. Since there is no guide pin I guess there could be a risk of wrong insertion, or the pins may not fit correctly in the socket?
We have no curves or other data for the FU50, so it is a possibility that the biasing could be wrong for GU50. If B+ is close to 400V the GU50 should probably have about -60V on the grid for 80mA.
Svein.
From the photos, the tube socket pin numbering appears to be correct for GU50. Since there is no guide pin I guess there could be a risk of wrong insertion, or the pins may not fit correctly in the socket?
We have no curves or other data for the FU50, so it is a possibility that the biasing could be wrong for GU50. If B+ is close to 400V the GU50 should probably have about -60V on the grid for 80mA.
Svein.
From what I can see the pins seem to jibe with my GU50 datasheet but I may have missed something as I'm playing with the amp and putting up sheetrock all at the same time. The pins on these tubes are not "keyed" so you can install them anyway you like, looks like both the FU50 and GU50 have a marker cast into the rear of the glass to prevent installation mistakes but the chinese marker may be 90, 180 degrees out of position, I don't have my GU50's yet to compare to. This really is a very pragmatic design, the modular approach allows the manufacturer to offer an array of different SE tube amps using the same chassis and I'm sure many of the same internal parts, like Mazuki said even the power transformer is the same from region to region we just have a step up transformer installed for our "110". I'm going to power the peach back up and take some voltage readings for the grids and B+.
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