I think going to more current (wattage) PSU is what he meant. Most wall-warts are in the 1 to 2-amp range.
What's my boggle with phono preamps?
- Thread starter 63pontiacgp
- Start date
wyn palmer
Addicted Member
Why not? It's an AC transformer, not a DC source, so it keeps the transformer magnetic fields well away from the sensitive stuff.
The original DIY design used a SMPS with a custom supply filter to produce +/-15v and it was driven from mains using an IEC connector. Keeping the hum down was more challenging than with the wall wart which had AC voltages about 1/8 of the mains voltage in the US and 1/16 in Europe, and that was without an internal transformer.
wyn palmer
Addicted Member
Phono stages- at least the ones I design, only use 100-200mA secondary current. If you want a darn good headphone amp then it goes up to 1A.
So, I've looked at the Pyxi since this thread started. I have a HOMC cart and I just don't see, or read, how a moving coil is set up to be used? I assume the dip switches??
Also, I'm with Mr63Pontiacgp, a silver face would be nice!
Also, I'm with Mr63Pontiacgp, a silver face would be nice!
wyn palmer
Addicted Member
HOMC cartridges generally use a 47k load and the cap should be set at the minimum. That means that all switches are up. The gain will be 45dB- the front panel switch will be to the left. The settings are in the manual.
LOMC cartridges use lower load Rs.
The prototypes had a silver face. Sota decided to go all black in production. There really isn't anything that I can do about that, I'm not affiliated with them in any significant way so I can't exert any influence on their production/marketing/sales choices.
Yes, but unless I misread, you were not satisfied with any Phono preamp until the Pyxi?
wyn palmer
Addicted Member
It has half wave rectifiers, a snubber, large storage caps, a capacitance multiplier, and properly capacitive loaded semiconductor regulators plus local opamp decoupling and supply filtering for the dual supplies.
Sounds good.
I think a lot of phono pre-amps use AC/DC wall warts. They run off 20-24 VDC. Right?
wyn palmer
Addicted Member
Yes. Sometimes they use lower voltage and use dc-dc converters to produce the dual supplies.
Thanks Mike,
I am learning from this thread, so far, I am pretty happy with my new to me Marantz 2270 phono stage, but I do not have anything to compare it to.
For 300 dollars I think I can delve into a Pyxi and if it disappoints, I am not out of big dough.
I am learning from this thread, so far, I am pretty happy with my new to me Marantz 2270 phono stage, but I do not have anything to compare it to.
For 300 dollars I think I can delve into a Pyxi and if it disappoints, I am not out of big dough.
wyn palmer
Addicted Member
Edit: It also has ground planes carefully broken up to create effectively star connected grounds which come together at the output phono sockets. This avoids the possibility of circulating ground currents- either from the power supply or from the channel signals. The signal grounds are "serial", flowing from the input ports to the output ports and no current should be permitted to flow "back" into TT/cartridge port. This also means that "balanced" inputs are totally unnecessary.
The supplies also are star connected with small series Rs and adequate local decoupling caps and are referenced to the low impedance regulator outputs. This ensures minimal output to input feedback, even through the supplies.
The end result is a remarkably low interaction, low distortion environment, and extremely high clarity without false brightness or "smearing".
This serial grounding is accomplished in the PCB tracings. Right? No external wiring, outside the board.
Thanks!
Thanks!
wyn palmer
Addicted Member
It's internal. It uses the external preamp for the ground/signal path, thus ensuring proper signal current flow.
This is turning into something I "gotta" have vs. something I need.
BilboBaggins
Addicted Member
That happened to me. Wyn Palmer piqued my interests a few years ago I think with the DIY version. I can be slow to make a move, but once I'm ready, I'm in 100%. I like the mat black look. Fits well with my JVC and Kef units as well as the micromega stack. It is great as it gives me a baseline reference point with many other members.
I know that earlier I'd posted that I've had 50 preamps. That was wrong, it's actually 34 plus maybe a couple that I've forgotten about.
I should have investigated other things at the time, cable routing, etc. I also recently replaced both audio cables on my tables and the caps on my Pioneer's power supply board. Anyway, with the Sota on my Dual and the Darlington Labs on my Pioneer I am quite happy and I'm going to stay that way for quite a while.
These are just my opinions:
If you looking for truly low buck the Pyle PP999 at less than 20 bucks I feel is a decent performer.
The 100 dollar U-Turn Pluto out performs the Mani and Mani II.
At 300.00 the Sota Pyxi performs well above its price point.
Exposed tube phono preamps: Budgie, Bottlehead, Pro-ject, and the like were the most prone to noise.
My least favorite of all was the Puffin.
End of ramble.
Mike
I should have investigated other things at the time, cable routing, etc. I also recently replaced both audio cables on my tables and the caps on my Pioneer's power supply board. Anyway, with the Sota on my Dual and the Darlington Labs on my Pioneer I am quite happy and I'm going to stay that way for quite a while.
These are just my opinions:
If you looking for truly low buck the Pyle PP999 at less than 20 bucks I feel is a decent performer.
The 100 dollar U-Turn Pluto out performs the Mani and Mani II.
At 300.00 the Sota Pyxi performs well above its price point.
Exposed tube phono preamps: Budgie, Bottlehead, Pro-ject, and the like were the most prone to noise.
My least favorite of all was the Puffin.
End of ramble.
Mike
BilboBaggins
Addicted Member
Useful information! This is the kind of information that someone looking for information on separate phono preamps would find extremely useful. Thanks!