consistent Posted January 31, 2005 Share Posted January 31, 2005 Hi All, I am looking at adding a valve amp (SET)to my collection and would like to know what noise & hum levels are acceptable or should I say not very noticeable when driving Khorns. I understand the lower the mv rating the better but at what sacrifice, 300B'S, KT66'S, KT88'S and the list goes on. Thanks Guys. Quote Link to comment Share on other sites More sharing options...
consistent Posted February 2, 2005 Author Share Posted February 2, 2005 Hi Again, Any body help? Quote Link to comment Share on other sites More sharing options...
dodger Posted February 2, 2005 Share Posted February 2, 2005 ---------------- On 2/2/2005 3:07:18 AM consistent wrote: Hi Again, Any body help? ---------------- As with SS, Tube equipment noise and hum specs vary. What amp are you looking at. Unfortunately, it's not something a blanket answer can be given. Hum and Noise, unless problem high usually is not noticable when playing music. dodger Quote Link to comment Share on other sites More sharing options...
consistent Posted February 2, 2005 Author Share Posted February 2, 2005 Hi, The following are the specs, it's a home made, hope this helps: This auction is for the TWEAKER MK3, a Universal Single Ended amplifier using 6SL7 or 6SN7 driver valve and 6L6 or EL34 or KT66 or KT88 output valves and a GZ34 / 5AR4 rectifier valve. Hand crafted in Australia. Point-to-Point wired operating in class A with switch-able Triode / Ultra Linear pentode mode. It has 2 line level inputs giving up to 12 watts rms per channel output (KT88). The circuit is my own design, which I have been working towards the past 18 months. You can use a 6SL7 or 6SN7 (your choice) driver valve. Each channel uses one of the two triodes as a voltage amplifier. This is then capacitor coupled using audiophile grade paper in oil capacitors to the output tube configured in Single Ended ultra linear or Triode mode. The output tubes are easily biased by you the user, simply plug in the provided multimeter and adjust with the provided screwdriver. (See pictures, thats 600millivolt not 600 volts, quite harmless). No negative feedback is used. This should be testament to the circuit design, quality workmanship and parts used. Its made the way a tube amplifier should be, simple. Less components means less coloration of the sound. The power supply uses a GZ34 (5AR4) rectifier tube with capacitor and choke filtering. The advantages of a tube rectifier are less power supply noise and prolonged valve life as the HT voltage is gradually applied to the tubes as the heaters warm. The output transformers are the work of much research and testing by myself and friends, made right here in Australia. No mystery transformers hiding inside massive tin cans here. What you see is what you get! The frequency response in circuit is very good. These measurements are from THIS actual amplifier, with the KT66 and 6SL7 valves installed. Frequency response is very good from 22hz to 38khz. Hum is less than 1.5 millivolt on each channel. My speakers are 96db efficient and no noticeable hum can be heard from as little as 30cm from the speaker cones. Measured rms power output is: KT88. 12watts EL34. 8watts KT66. 9watts Hum 6L6gc 9watts KT88 = 2.5 millivolt. KT66 = 1.4 millivolt. 6L6gc = 1.0 millivolt. EL34 = 1.6 millivolt. All wiring is point-to-point using component leads where possible. Only good quality parts have been used. Micamold power supply cap, Elna cerafine bypass caps, paper in oil coupling caps. Ceramic valve sockets, gold plated rca sockets, 4mm speaker banana socket-binding posts. A volume pot is wired via a selector switch to the gold plated rca inputs so a pre-amp is not required (but can be used if desired). Around 0.7 volt is needed for full output. The amplifier uses one 6SN7 or 6SL7 driver valve (each channel using one of the two internal triodes), 2 KT88s, EL34s, KT66s or 6L6gcs output valves. The valves included with the amplifier are: a VERY rare old stock Sylvania 6SL7WGT military issue, a rare old stock Sylvania 6SN7 angle black plate, and a old stock Admiral USA made 6SN7. 2 Brand new Valve Art KT88s, 2 brand new Valve Art KT66s, 2 brand new Valve Art EL34's and 2 Very Rare USA JAN (joint army navy) Military brown base 6L6WGB's This valve line up alone is worth hundreds. All the old stock valves test very good on my AVO Mk1 valve tester. The chassis is French polished oak, with polished 2mm aluminium top plate and vented aluminium bottom plate. Included in this auction are: 1 New TWEAKER MK3 amplifier chassis. 2 New Valve Art EL34 valves. 2 USA JAN 6L6WGB valves 2 New Valve Art KT88 valves 2 New Valve Art KT66 valves 1 New Sovtek 5AR4 Rectifier valve 1 Sylvania angle black plate 6SN7 valve 1 Sylvania 6SL7WGT valve 1 Admiral (re-branded RCA) 6SN7 1 Valve display stand Comprehensive manual Circuit diagram. Multimeter for setting bias Screwdriver IEC mains lead. Thanks Quote Link to comment Share on other sites More sharing options...
3dzapper Posted February 2, 2005 Share Posted February 2, 2005 That sounds lika a fun little amp! The hum figures are in the good range. I find that in my room, YMMV based on background noise, etc) under 2mV is inaudible with my Khorns. I'd be most intrigued with the single ended sound of the 6L6s. They are a sweet sounding tube in PP. Of course the specs do not reflect what the amp will ultimately sound like. That is dependent on the circuits and components used. The add doesn't state if the 22Hz is the -X db point of the amp or the design low end of the trannies. If the price is right, try it and have some fun. Rick Quote Link to comment Share on other sites More sharing options...
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