Hi chaps, I'm new here. Been dabling in electronics as a hobby on and off for years, and have now got one of these kits on order. I do however have a couple of questions!
Fistly, the resistive loads issue:
mwhouston wrote:
beaubbe wrote:
I was wondering if anyone knows what is the stage resistive load for this preamp. I'm somewhat of a newby when it comes to this, but from what a read and understood from the schematics of this amp, the resistive load is specified by the R1 (or R101) resistor. So that would make a 100k stage resitive load for this preamp. Is that right?
If you are talking about the load on the cartridge it is decided by R1 (R101). On the original schematic that is 100K which I would say is too high for most MM cartridges. My suggestion would be to make R1 (R101) 47K. Look to your cartridge specs. for the suggested loading. It can vary quite a bit.
If you have a MC cartridge I would leave R1 (R101) at 100K. The MC preamp will provide loading to the cartridge. If you don't have a MC preamp take a look on this forum for my Le Pacific MC preamps or Hiraga MC preamp.
I have a Dual 505-4 TT with a Ortofon ULM 68E cartridge, but cannot find any specs on the resistive load. It's an MM cartridge so I'm thinking 47k, but what if this is not correct? I'm therefore inclined to swap out the 100k resistor with a 100k Pot, or perhaps a 25k fixed and a 100k pot, to allow for a bit of flexibility - any thoughts or comments?
Second question: I'm looking to power the amp with a switchable mains/transformer, or on board battery power source. In order to limit the number of banks of AA (Ni-Mh) cells I'll need, any idea what the minimum operating voltage of this kit is? Would something like 24v be OK? Can I go lower?
Many thanks in advance for your help
Peter