analogadikt
Well-Known Member
I had been using this Akai 1710 R2R as a standalone SE amp. After I sold it the new owner requested me to change the hardwired connections for the amp to switched ones, so here are a few pics of the modjob. It should be noted that these mods are fully reversible.
The original under chassis view.
4 pole two way switch
Switch installed and wired.
In the first position of the switch the input socket is connected to the preamp and the preout is connected to the poweramp through the tone control as per the original schematic. Throwing the switch to the other position connects the input directly to the volume control. The internal ss pre is completely isolated between the line in socket and the tone control. The volume control becomes a passive pre, feeding the all valve driver and output stage. The unit was tested at my place connected to the Jensen floorstanders. The owner was pleasantly surprised at the ease with which this 4wpc amp handled the big speakers. He has now paired them with Akai SW156.
NOTE OF CAUTION/DISCLAIMER
Valve gear has high voltages that can be lethal. Vintage equipment may suffer from corroded wiring that can short, leaky capacitors that can explode, and selenium rectifiers that can explode and stink. So if this post inspires you to get inside your vintage valve gear, please do that only if you have experience and note that you are solely and completely responsible for your actions and consequences.
Regards,
The original under chassis view.
4 pole two way switch
Switch installed and wired.
In the first position of the switch the input socket is connected to the preamp and the preout is connected to the poweramp through the tone control as per the original schematic. Throwing the switch to the other position connects the input directly to the volume control. The internal ss pre is completely isolated between the line in socket and the tone control. The volume control becomes a passive pre, feeding the all valve driver and output stage. The unit was tested at my place connected to the Jensen floorstanders. The owner was pleasantly surprised at the ease with which this 4wpc amp handled the big speakers. He has now paired them with Akai SW156.
NOTE OF CAUTION/DISCLAIMER
Valve gear has high voltages that can be lethal. Vintage equipment may suffer from corroded wiring that can short, leaky capacitors that can explode, and selenium rectifiers that can explode and stink. So if this post inspires you to get inside your vintage valve gear, please do that only if you have experience and note that you are solely and completely responsible for your actions and consequences.
Regards,
