Lloyd....I entirely appreciate that all three units were evaluated from factory spec. In my previous post I merely sought to comment upon the areas of performance where Roy felt the REF10 to be slightly constrained, in particular, separation, transparency and tonal delicacy, in that all those points can be ameliorated and said aspects notably transported to another level with the substitution of a pair of GE 6550A's
The same applies to any later production ARC pre amplifier utilizing Sovtek 6550 power regulators including the 5se and 40 Anniversary.
thanks Lloyd
as you and I know. cj GAT Rules OK.
are you going series 2 anytime soon?
Its not an inexpensive upgrade so while it is on the list, i suspect it is some time away. You?
Like you, this upgrade outside of the USA is about double what it costs inside. Not planned anytime soon, especially when the GAT sounds so great on top of Stillpoint 5's and with Telefunken 6922 tubes.
Unfortunately there is very little technical information available on this upgrade. Previous times I always knew pretty well what were the changes, but not this time.
Unfortunately there is very little technical information available on this upgrade. Previous times I always knew pretty well what were the changes, but not this time.
Unfortunately there is very little technical information available on this upgrade. Previous times I always knew pretty well what were the changes, but not this time.
This update includes the introduction of an improved circuit in the regulator for the main audio power supply. The new regulator also features increased filter capacitance. the new circuit resides on a new master pc board. A great many very costly parts get moved to the new board. The update also includes boosted output coupling capacitance, again using more of the CJD Teflon capacitors. The tubes have also changed to NOS Phillips PC88s.
Gents,
thanks for this...what is the function of the 'regulator' of the main power supply? What does increased filter capacitance do?...is this like capacitance like in an amp where this is effectively stored energy giving the preamp its own internal source of energy for transients, peaks, speed of delivery, etc?
What is the function of output coupling and again what does increased capacitance do? Thanks!!!
just trying to understand the main thrust of what appears to be 2 power-related changes, including increases in capacitance.
The regulator is responsible for supplying a constant DC to the gain and buffer stages - typically uses a non feedback series regulator controlled by a string of zeners. More capacitance will reduce noise and impedance in the low frequencies.
The increased capacitance in the output capacitor will extend low frequency. However the subjective effects of these changes are sometimes much greater and in expected areas.
The ACT2 series 2 was essentially a simplification of the circuit reducing the number of parts in the power supply, re-allocating the teflon capacitors used in the pre-regulator to the unique regulator. But I can not see what can be done now - there was only one regulator stage left!
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