New member saying hello

Hi All. David from West Yorkshire in England here. I've been a HiFi nut since I was 14 and now over 50 years later, I have a setup I can live with! I prefer tubes to trannies (electronic in each case) but use both in my system. This comprises a Linn LK1 preamp with Dirak power supply running a parallel SET amplifier with switchable feedback and a Chinese Naim Nat 250 clone (separate power supply and power amp). The power amps are switchable via a Dynaudio switch connected to a pair of Neat Motive SX2 speakers. I use the SET for serious listening and the clone for everything else although the clone can give the SET a run for the money al round! At the front is a heavily modified early Rega P3 (sits on an SRM/TECH silent base and an acrylic platter has replaced the glass original) with a new 330 tonearm and Ortofon Q blue cartridge. The MC feeds a Tisbury Audio Domino phono preamp going into one of the LK1's line inputs (the MC stage on the Linn gave out some time ago and I haven't fixed it yet). On digital, we have an Apple TV and a GoodmansIMG_2770.jpg Spotify Connect box feeding, respectively, Amazon HD at CD quality and Spotify high res at max res (16 bit / 44.1 / 320 kbps). These go into a TOSLink switch feeding a Cambridge DACMagic 100 which outputs to the LK1's other line input. I can switch between Apple TV, Goodmans and the TV as I please. I also use the LK1's tape output to feed the SET with any of the pre-amp's inputs should I choose to use the SET as an integrated amp. Altogether, it's a pretty powerful and musical system that is versatile enough to work for both serious and background listening. The picture above is the SET amp, which I ordered from an enthusiast in Poland (no way could I afford a branded model and this is as good as and even betters SETs costing several thousand dollars). It has adjustable feedback (including 0dB). The Chinese clone looks pretty non-descript in comparison, but you can see it on eBay. I have not had it long, but it's really rather good IMHO, with speaker protection circuitry built-in. I know it's a bit of a cheat, but I don't have the money for even used Naim gear and as it's not a faithful copy, I can live with the guilt! More info and pictures later.u
 
Last edited:

guiller

Active Member
Hi David, welcome to the HFH community! Would you please tell us a bit more about your SET amplifier?
 
Hi David, welcome to the HFH community! Would you please tell us a bit more about your SET amplifier?

Hi Guiller. The SET is fairly conventional but uses slightly unconventional power tubes. The audio circuit design is fully discreet throughout including standard input triodes (6H8C, two per channel) and the two unusual 6S33S power tubes you see in the picture. These are double triodes, with both filaments in each tube operational, providing parallel SET operation with or without feedback. It has a solid state power supply and regulator and massive, specially wound (for SET operation) output transformers. The amp develops a reasonable (for a SET)16W per channel into either an 8 or 4 ohm load, although the power valves and transformers are capable of handling a lot of current, so the amp is much more dynamic than these meagre specs might suggest. It does take a good hour to warm up properly and it runs very hot when it does! I ordered it from a guy in south east Poland who specialises in making affordable kit based on tried and tested circuit design for enthusiasts like me. Incidentally, the power tubes are of Russian origin and designed originally for use by the Soviet military as radar switches! They use fixed bias here (you can see the adjustment meter in the photo). There's space at the back for four inputs and the volume pot is a good motorised alps type. The heater and high tension supplies are switched separately; you can't switch on the HT without the switching on the heaters first! Hope the information is useful. Please let me know if you want more details. I have a hand-drawn circuit design from the builder that I just need to transcribe into a proper diagram, but haven't got round to it yet.
 

guiller

Active Member
Hi Guiller. The SET is fairly conventional but uses slightly unconventional power tubes. The audio circuit design is fully discreet throughout including standard input triodes (6H8C, two per channel) and the two unusual 6S33S power tubes you see in the picture. These are double triodes, with both filaments in each tube operational, providing parallel SET operation with or without feedback. It has a solid state power supply and regulator and massive, specially wound (for SET operation) output transformers. The amp develops a reasonable (for a SET)16W per channel into either an 8 or 4 ohm load, although the power valves and transformers are capable of handling a lot of current, so the amp is much more dynamic than these meagre specs might suggest. It does take a good hour to warm up properly and it runs very hot when it does! I ordered it from a guy in south east Poland who specialises in making affordable kit based on tried and tested circuit design for enthusiasts like me. Incidentally, the power tubes are of Russian origin and designed originally for use by the Soviet military as radar switches! They use fixed bias here (you can see the adjustment meter in the photo). There's space at the back for four inputs and the volume pot is a good motorised alps type. The heater and high tension supplies are switched separately; you can't switch on the HT without the switching on the heaters first! Hope the information is useful. Please let me know if you want more details. I have a hand-drawn circuit design from the builder that I just need to transcribe into a proper diagram, but haven't got round to it yet.

Hi David. Very interesting description! Those 6S33S tubes certainly look nice (and yield quite a bit of power!). Many thanks for taking the time to describe your SET amp.
 
Top