Here's a simple little improvement that i've had wonderful results with. Splice in a simple diode (1N4007 or similar) in between the screen grid of the pentode and the Plate with the cathode of the diode pointing toward the screen grid.
Easy to remove if you don't like it. But every pentode amplifier stage i've tried it in shows a marked improvement (extended range, lower dynamic compression, etc.) Admittedly i haven't tried it in such a low level stage as 1st phono, but worth a try...
I've been looking for new mc phono circuit to try, and i think this may be it! Nice job =)
Easy to remove if you don't like it. But every pentode amplifier stage i've tried it in shows a marked improvement (extended range, lower dynamic compression, etc.) Admittedly i haven't tried it in such a low level stage as 1st phono, but worth a try...
I've been looking for new mc phono circuit to try, and i think this may be it! Nice job =)
Here's a comparison of the HMN to my Linn LK-1 which has a dedicated MC input:
An externally hosted image should be here but it was not working when we last tested it.
I will have some boards made as a Group Buy -- I'll absorb the cost of the first set of prototypes -- but I have to figure out all the mistakes I made on the first set. Price will be the manufacturing plus shipping to the US. I think it's going to work out to be something like $7.20 per board. The board will have provisioned the amplifier, hv supply, set of regulators (4x) and heater supplies.
Mistakes I made on my prototypes included spacing some of the mosfets a bit close, failing to include take off points for the heaters, building in only one set of HV regulators (SY recommends 2), using a 2A bridge rectifer for the heaters instead of 5A (seems to work fine, however). I'll provision it for various types of caps (Wima, Vishay, etc.) and make it a bit easier to tweak the R and C values for the RIAA equalization.
Mistakes I made on my prototypes included spacing some of the mosfets a bit close, failing to include take off points for the heaters, building in only one set of HV regulators (SY recommends 2), using a 2A bridge rectifer for the heaters instead of 5A (seems to work fine, however). I'll provision it for various types of caps (Wima, Vishay, etc.) and make it a bit easier to tweak the R and C values for the RIAA equalization.
Yes, I am going to have some boards made -- it requires a bit of tweaking the original since SY specified 2 regulators -- one per channel. I am not going assume that folks will use transformers with wires rather than PCB pins.
I would think we'll have the boards in about 2 weeks.
I think I will have plenty of power supply boards since folks ask for these all the time, regardless of what they happen to be building!
I would think we'll have the boards in about 2 weeks.
I think I will have plenty of power supply boards since folks ask for these all the time, regardless of what they happen to be building!
The boards are almost designed -- they differ from the one I used for my prototype in having 2 regulators -- looks like 10.000" by 8.400" -- I will have about 50 of them made available at cost for SY's "minion". The power supply boards can (and should) be separated from the RIAA board.
I also have a bunch of the WIMA caps that I'll package separately.
I also have a bunch of the WIMA caps that I'll package separately.
An externally hosted image should be here but it was not working when we last tested it.
This isn't in SY's article:
I did buy a bunch of the network caps and measured them on my RLC Bridge.
An externally hosted image should be here but it was not working when we last tested it.
I did buy a bunch of the network caps and measured them on my RLC Bridge.
