Boulder 500ae amp
You may need to add a gain control to reduce the drive to the next stage if you end up with too much gain. Hopefully someone will check my numbers as I did this in my head. I'd bypass the cathode resistor to prevent it from providing negative feedback and reducing distortion. As a first gain stage you can swing +/- 10V and not clip but get close.Īfter looking close at the plot, I'd try to drop the anode resistor down to 1K although I don't know if this is really practical. To get there you need a 2600Ohm cathode resistor. This should put you with a plate current around 5mA. I'd start out with a supply of 300V, 200-250V at the plate, cathode bias of -12 to -14V and use a plate resistor around 15K ohms. This is where I'd look for 2nd harmonic distortion. If you drop the current down low and use a low value of plate load resistor your load line will be in a very non-linear portion of the curve. Take a look at this data sheet and look at the plate curves on sheet 3. Some are discussed on this forum, after the hapless new owner wonders why he has spent good money to degrade his sound. There are plenty of these around on the internet. Achieving loop stability might be interesting, though!Īlternatively, just buy a badly-designed preamplifier or buffer. Design a good linear amp, with negative feedback, but include in the negative feedback path a square-law stage. The net weight is 52 kilos (115 pounds), shipping weight is 65 kilos (144 pounds). Then don't have any overall feedback, as this will mix the even with the original signal to create more odds.Ģ. It has two of the special YBA 1000 powersupplies, totally 2000 VA powersupply, and they are not torodial type but C-core and according to YBA they are much better and also 3 times as expensive. Or use a variable-mu valve such as EF92 or 6BA6, as these will generate lots of evens. Include an amplifying stage which has a square-law response - ECC82/12AU7 can do this if biassed correctly (for this application). There are two ways to deliberately add evens without adding too much odds as well:ġ. It will faithfully pass on any even harmonics in the input signal. Note that a P-P output stage only cancels even harmonics generated within itself.