AR SP8 mk2 high output volume
If anyone interested, this is the schematic of the
Puresound A30 http://lampizator.eu/AMPLIFIERS/CHINA/bewitch%206550/IMG_5576.jpg IMO, leave the Puresound A30 and AR SP8 stock, just simply set the Puresound A30 volume knob at 12 or 1 o'clock is the best solution. |
OP, If the Puresound A30 is to be used as an amplifier (i.e. driven by a separate preamp), its volume control should be fully turned up. You are definitely degrading the signal if it's at 1 o'clock. As mentioned, given the mismatch between the AR and the A30, it would be best for you to use the A30 as it is, an integrated amp. Tube rolling is one thing you may look into if you're looking for a particular sound. Start with the driver tubes if you wish. |
@georgehifi thank you very much for your advice. If you take it to a technician, you could also complete the operation by reducing the gain at any of the Puresound inputs.As I have already mentioned, I have followed the manufacturer’s instructions, which in the Puresound instruction book says not only that it can work as a power amp but that it can also do it in an excellent way, textual words. @audite84 with the volume of the Puresound at maximum it continues to work, so I do not understand why if we put it at 1 there is more degradation of the signal. It is true that if the manufacturer indicates this, this reason must exist, except that it is written thinking that most of the current preamplifiers need more volume. |
@georgehifi thank you very much for your advice. If you take it to a technician, you could also complete the operation by reducing the gain at any of the Puresound inputs.As I have already mentioned.Sorry but no, again introducing series impedance at the A30 inputs is not on, with no thought for impedance ratio matching (min 1:10) between stages. Best would be to completely take the Blue Alps out of the circuit (not just turn it up or bridge it out) introduce a metal film 100kohm input resistor to ground , and then reduce the gain by 1/2 of the total preamp tube stage with feedback resistance of R14 on imhififan circuit diagram. Cheers George |
@tenoris Having looked at the schematic supplied by @imhififan I agree that essentially this amplifier is actually a power amplifier supplied with three inputs and a passive volume control. Since the control is 100K and given the characteristics of the input tube, you can successfully operate the volume control to reduce the level of signal coming from the ARC without degradation. However if the sources are high level (in other words not phono), I am still having trouble seeing what good the ARC can do for you unless the sources are not physically fairly close to the amplifier. It seems that you are saying that it nevertheless sounds better this way- so I am curious, what improvements are you hearing? BTW I do not recommend tampering with the feedback resistor- such things can lead to oscillation, and if the schematic is correct there appears to be little or no compensation for a variety of frequency poles present in the amplifier design- by increasing feedback, any one of these poles could cause the amp to be unstable. |
