Reference RIAA pre-emphasis circuits for sale

[jesusfwrl]

Dear trolls,

I am in the process of developing an RIAA pre-emphasis preamplifier for disk cutting. We started by building the reference RIAA pre-emphasis networks described by Lipshitz in his AES paper and by Hagerman on his paper available on his website. The purpose of this exercise was to test the performance of some of the reference networks and compare it to our finished product.

However, as usual we have ended up buying far more components than we need and have decided to offer for sale some ready assembled passive RIAA pre-emphasis circuits to anyone interested. To those not on the technical side, these can be used before the power amplifier that drives the cutter head to create the necessary equalisation for disk recording. As they are passive circuits, there is a 40 db attenuation on the signal at 1K, which means that you might need a preamplifier before or after this circuit to bring the level back up to normal. As these are reference networks, their performance is exceptionally good. These would also be ideal for modifying old equipment that were built before the RIAA curve was invented.

Some pictures:

The modified Lipshitz version.


The original Hagerman version.

We have the following versions available:
1. Original Lipshitz - 3180uS/318uS/75uS/0.47uS - 50 ohm input
2. Modified Lipshitz - 3180uS/318uS/75uS/3.18uS - 600 ohm or 50 ohm input
3. Original Hagerman - 3180uS/318uS/75uS/3.18uS - 50 ohm input
4. Modified Hagerman - 3180uS/318uS/75uS/3.18uS - 600 ohm or 50 ohm input

The modified Lipshitz and Hagermann can also come in any input impedance you would prefer. Output impedance for all is 600 ohm.

All circuits are assembled on silver plated terminal strip, using silvered mica and polyester capacitors and metal film resistors with a 0.1% tolerance. Silver/lead solder used. They can either be shipped with flying leads as seen on the pictures or with XLR/RCA/Jack connectors as required. We can use high quality gold plated Neutrik XLR connectors and gold plated RCA connectors or silver plated jack connectors. We can even build the whole thing in a tidy box for you or we can supply it as it is for you to implement in your own project.



We can ship worldwide.
Our aim is to develop an active disk cutting preamplifier that can be used with a variety of different power amplifiers and cutter heads, that could even act as a benchmark. I have no idea when we will have any of the finished units available, but I know that they will not be cheap. For those of you on a budget, this is a good opportunity to get an RIAA pre-emphasis circuit with excellent performance and very low cost to experiment with.
As there are many variables to this, the price will depend on your requirements. Obviously, these are monophonic, so you need two for stereo.

[dimi751]

Hi Jesus

This is fantastic I love experimenting !

How much is the modified lipshitz in stereo female to female RCA ??

Dimi

[jesusfwrl]

Hi Jesus

This is fantastic I love experimenting !

How much is the modified lipshitz in stereo female to female RCA ??

Dimi

Thank you for your interest, Dimi. The connectors are secured on a panel from the outside, while the circuit sits on the inside, this means that the connectors have to be soldered to the circuit after they have been mounted on a panel.

Would you like the circuit built into a box or panel?

Or, would you prefer me sending you the circuit and the connectors separately and you can solder them in place in your own box? Or, would you like the connectors soldered into the circuit without a box and you can figure it out from there? I have some small stainless steel panels that I can use for this, if you'd just like a panel and not a complete box, or I can use a standard aluminum project box.

The price for a stereo unit with gold plated RCA connectors, built into an aluminum project box would be $150 plus shipping, which shouldn't be much as it's not very heavy or big. This would probably be the most expensive option. If you're not into super high quality, I can also use cheaper RCA connectors without gold plating and so on.

[jesusfwrl]

As an indication, one of these circuits with no connectors or box would cost $ 30.
So, two channels for stereo would cost $ 60 with no connectors or box.

The rest will depend on the cost of the materials and the amount of time it is going to take me to drill the holes and put everything together.

[dimi751]

I sent you a pm

[studiorp]

Why only 600 ohm on output ? Could be better use for example 60k...

[jesusfwrl]

60 k ohm output impedance??? What would you drive with it?
Ideally, for most audio applications you want a high input impedance and a low output impedance to prevent distortion and hf loss. Older studio equipment used the standard of 600 ohm both for output and input impedances, which also works. So, if you do not have identical matched output impedance and input impedance, then you want a low impedance output to drive a higher impedance input. As 600 ohms is the widely used audio standard, these circuits were designed to that. This could be made higher on these circuits if required for a particular purpose, or it could be made lower, but it would change the attenuation factor.

The 600 ohm input impedance also comes from the audio standard and the 50 ohm input impedance is only there because most test signal generators have a 50 ohm output. For these circuits it is important to have the input impedance matched exactly to the output impedance of whatever equipment you are using to drive it, for example a tape machine/CD player/mixing desk. If the impedance is not identical on the input side then you would be relocating the HF point, which means that it will no longer be an accurate reference circuit but it would still work as a RIAA pre-emphasis for most practical purposes. The 600 ohm output of the RIAA stage is meant to drive much higher input impedances.
This circuit is meant to drive an amplifier, so the 600 ohm output will work just great with a 60 k ohm input impedance on a power amplifier.

[jesusfwrl]

My surplus has now been sold. These are no longer available. I will keep you updated when I have the final product ready.