cap has a reactance value of 155.35 ohms at 41 Hz., and would match an 1554 ohm cathode resistor to achieve his goal. At least Weber says that's the engineering goal. The bypass cap is to have one tenth the reactance value of the cathode resistor resistance at 41 Hz. Gerald Weber, who likes more bottom than me because he plays in a power trio, says that it is good to engineer the bypass cap for an octave below the anticipated lowest frequency.Ĭapacitive reactance formula: Xc = 2Pi F CĪn open “E†string on the guitar is 82 Hz. Best regards and thanks for the support and input ds, Phil I hope this helps and is what your were wondering about. They can still be picked up for about $300 on ebay. Wonderful distortion when over-driven yet low notes are distinct and seperate. The sound is very chimey and is capable of striking extreem artificial harmonics (gibbins/ZZTops). It came with an Oxford 12" low end speaker and sounds OK with the stock speaker but really shines with a vintage Jensen. Diamensions are about 19 wide x 22 high and lightweight. It is a 12 watt package and was manufactured from about 1974 to 1979, the silverface era. It is the only Fender design that used a interstage transformer and as far as I know the only manufacturer that ever tryed that design for Guitar amps.
It is gaining respect as a 6 string guitar amp and the values are leaping lately. If what you are asking is about the sound/size/specs on the Fender Musicmaster Bass amp here is my thoughts on the amp. I don't want to damage my circuit by doing something wrong.Īxlesup - what about that amp? How big? What speaker? How does it sound. Audiophiles seek the perfect sound with no distortion where as Guitar players seek a moderate amount of distortion and "sag".Ĭan you clarify your answer for me? I understand that the higher valued cap will prevent the voltage at the cathode from floating but how does the "floating/not floating" voltage effect the final sound? Or am I missing a totally different idea/reason? I have noticed here that the two different types of circuit are designed differently at times. I am wondering if the answer you gave is coming from an Audiophile's viewpoint or a guitar amp builders viewpoint. I understand what your are saying and it makes perfect sense however all the single ended guitar amps I have looked at have a small cap on the 6v6 cathode. The cathode cap should be bigger than 25 uF, though - it can be much smaller or even omitted in push-pull, since the cathode voltage is relatively constant (when current in one tube goes up, the other goes down). PSS: For a prior technical disscussion here at Ant Radio on this circuit there is a link here: and if not than what is the simplist way to convert the original circuit to a Single ended amp while retaining the interstage tranny with it's 15K resister. The interstage transformer with the 15K resister across the primary is an integral part of the sound and I want to keep it.Īt the moment I am just looking for a simple answer to wether it is safe to simply pull a tube on this circuit. I adore the sound of the original circuit but am looking to reduce the output to say. My question is this: Can I pull one of the 6v6 to lower the output? I have this amp and have tryed pulling 1 6v6 and it sounded fine, but I did not want to run it more than a minute for fear of a melt down. Look carefully at the circuit before answering please. Please note and remember that the phase inverter in this amp is an audio interstage transformer. I have a question about the following circuit.
Original 2 x 12 inch JBL grey alnico speaker cab with black tolex. Stamped with AE 1164 on amp = week 11 year 1964. All 6 filtercaps exchanged year 2019 with fresh 4 x 20/500volt Spraque and 2 x 100/ 450V Illinois (=stong sounds and low noise).
Newer bias cap = more stable bias (=good). Most capacitors original, only 4 newer 25/25volt for best performance. S-marked (= originally sold in Sweden) Nice strong tubes: 2 x 5881 matched, 4 x 12AX7. Original OT (Output-transformer) marked 6430 = week 30 year 1964. Original choketrafo marked 6341 = week 41 year 1963. Sounds great! Fully serviced and ready to be played for many years! This amp also features the desirable 6G6-B circuit, popularized by Brian Setzer.Īn extra knob was added in the 1970s on back for line out, now converted to a midrange+ knob on the normal channel (= original sound + more mid if wanted-sounds great!).ĦG6B model. White knobs on black panel.With the great regarded Presence knob.Both top and cab are recovered in black tolex and newer speaker cloth.This is one of the rare transitional models, which features largely brownface circuitry and cosmetics with a black faceplate.
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