#300B TUBE AMP FULL#

#300B TUBE AMP FULL#

Of special note is that 12AU7(ECC82) is used in parallel for the 2nd stage to drive the 300B tubes to full power- resulting in 200Vp-p without clipping. In addition, current detecting circuit is moved from the cathode side to the B-power side resulting in even better sound quality.Ī very orthodox design is used for the voltage amplifying stage to bring out the outstanding characteristics of the famed 300B tubes. Priviledges of both self-bias and fixed bias. ■ New active automatic bias adjustment systemįor the 300B tube bias, the power supply is equipped separately, and a ”New active automatic bias” is used where the amp detects plate current and automatically adjust the grid voltage. Consequently, the overall NFB is minimized as well as the chance for the transient response. The NFB is applied to the cathode of the 300B by the third winding of the OPT as well as to the voltage amplifying stage. To make the most of the 300B tubes, the characteristics of various parts and circuits, including OPT, have been improved. ■ Stable NFB circuit for great audio quality This results in the noise level as low as less than 1/10 of that of TU-8300R. In addition, all power is stabilized to reduce residual noise as much as possible. This results in a reduction in even negligible noise spikes.The windings of the power transformer include individual windings for the filament heater(A- Power), high voltage (B-power), and bias to stabilize the Negative Feedback (NFB) circuitry(C-Power). The rectifier consists of schottky barrier diodes that require shorter recovery time. Limited production, without tubes.Ī high efficiency, low magnetic flux leakage R-core is used. This September, with minimal modification from TU-8600. Upon such request, we reproduced TU-8600 as a revised version TU-8600R Ran out so quickly that we received many requests for reproduction from both domestic and Those tubes are expensive, too, so you'd better be very motivated to build such an amp.TU-8600, a 300B single-ended tube amp kit released as a limited production model for 2017, Since the biggest proponents of the 300B are audiophiles looking for clean hi-fi reproduction, I wonder whether the challenges & limitations of the 300B are worth working around to build a guitar amp. You could lessen drive requirements by accepting less output power and perhaps skewing the design towards more distortion in the 300B. Could be that you need a separate, higher-voltage power supply for the driver. The 12w example above will likely have an idle bias around -80v per tube, so the phase inverter will need to deliver 160 peak-to-peak which will complicate the design of that inverter/driver. There's a chance such an amp will be perceived as 'dark' due to the low odd harmonic distortion compared to push-pull (and maybe pentode/beam power) output stages.Ī single-ended 300B amp will need very good filtering in the power supply ahead of the output transformer, as the 300B's low internal resistance will leave the majority of power supply ripple across the OT primary, sending a lot of hum to the speaker.Ī push-pull 300B amp will not make as much demand on the power supply filtering, but trades that for very stout phase inverter/driver requirements. And that 12w will need more than triple (nearly 4x) the drive signal as a push-pull pair 6V6s making the same output power. And first-approximation of the (single-ended) output stage using 400v plate, 90mA idle current for the max 36w plate dissipation will yield only ~12w. As a triode, it's already going to have less color/distortion than a typical pentode or beam power tube. I suspect it would not be a terribly interesting sound, unless you work to lower output power and increase distortion in the 300B. I have not played a guitar amp using a 300B.

300b tube amp