I'm looking to build a phono stage and headamp in the same case, and am looking for some advice for where to get a phono stage. I really just want a circuit board, as i will be adding my own power supply and case.
I need to keep the price as low as humanly possible, as I'm a poor student whose debts are currently squeezing the life out of him!
It turns out building a great phono stage is hard. There are two EQ curves, and keeping a high slew rate and low noise with those curves is a difficult design problem.
I have considered building a FLAT low noise amplifier, then doing the EQ in DSP in the computer. A flat amp can have very wide frequency response, high slew rate and low noise, which are impossible with the heavy EQ required in a phone amplifier.
There were two exceptional phono stages build when vinyl was in its heyday.
The best was a card which was balanced in and out, with a very low impedance output and variable loading on the input (to match the cartridge). It was made by Bill Sacks at Straight Wire Audio in Arlington, Virginia. Sadly, the company is out of business, but he made thousands, many of which went into quality conscience radio stations. With vinyl all but gone from radio, many have hit the market.
He chose slew rate and accuracy over signal to noise ratio. This is a fine decision except for those who expect to see 100 dB plus signal to noise ratios out of their electronics. It doesn't matter though, because most vinyl cannot beet 60 dB by much, and commercial pressings are worse, and polystyrene is MUCH WORSE.
The other manufacturer was db. They were db Systems, or db Labs, or db Products or something like that. I have one but all that is on the front is db in a box. Anyway, it is a very minimalist pre-amplifier, but very clean. It has lower noise than the Straight Wire phono stage, but a lower slew rate. Both have wide bandwidth.
One thing to keep in mind when encoding vinyl to a CD. When CDs were first produced, making the disks was difficult. They were pushing the envelope regarding the size of the pits on the disk. SO, it was decided to make the data rate the absolute minimum. That is why the sample is so course, and the sample rate so low, just above the Nyquist frequency. Data reduction was in it's infancy, so it wasn't used.
Thus, we are now saddled with an inferior standard, but it is the standard.
Analog is, and will always be the gold standard. One can only approach analog when the sample rate approaches infinity, and the size of the sample also approaches infinity. We chose poorly.
SO, when you encode vinyl you get the limited dynamic range of the vinyl, plus the sample artifacts of the CD.
phono stage advice wanted!
Linear Mode
