The Secret Society of Lathe Trolls

Hi Trolls it's been awhile since I visited here. I had a customer ask for a single frequency pair HP and LP filter to replace his aging HT75s. I designed a board with balanced or single-ended I/O and relay bypass and thought some of you might be interested. The filters are 18 dB/octave Sallen-Key a...

Forgot to ask. What has been your experience observing playback crosstalk polarity?

I agree with everything you said in your blog. This is priceless: Part of the problem is that mastering engineers and cartridge manufacturers do not like talking to each other. I have personally tried communicating with several cartridge manufacturers, being a disk mastering engineer myself, regard...

KA-Electronics introduces the “MTC-IFGO” Mastering Transfer Console Input-Gain-Filter-Output Board Available now: https://www.etsy.com/listing/586665655/mastering-transfer-console-input-gain http://www.ka-electronics.com/kaelectronics/MTC_IGFO/IGFO_Assembled_600.jpg Assembled PC board shown. The MT...

Wanted to let everyone know that boards are on order and that production quantities of the MTC-IGFO Input/Gain/Filter/Output board will be available for shipment around Thursday January 18th.

Wanted to let everyone know that production quantities of the MTC-IGFO Input/Gain/Filter/Output board will be available for shipment around Thursday January 18th.

Hi Trolls. wanted to make you guys aware of a new product in the pipeline. It's an MTC-1 front-end PC board minus source selection with: Balanced Input Left Mute, Right Mute, Stereo Mute 0 or +5 dB Gain Adjustable Gain from -5.5 to +5.5 dB in 0.5dB steps Four 12 dB/octave filter stages per channel w...

Hi Trolls. This thread describes a new Mastering Transfer Console input, filter and balanced output PC board that I've developed for simple vinyl transfer. It's basically the front-end of an MTC-1 without source selection. I've supplied several of these and will be ramping up production quantities....

I wanted to thank everyone that contacted me over the weekend regarding boards. Thanks to your support I'm pleased to report that the EEQ-12 boards have been placed on order and are expected around November 1st. Here's an EEQ-12 article I posted over in Circuits: https://www.lathetrolls.com/viewtop...

This is a highly appreciated piece from Wayne.

Thanks Peter!

Thanks petrolio! I noticed that the updated drawing's component designators didn't quite match the circuit descriptions. I missed the edit window to correct them. The Mid allpass filter is made up of IC5A/B and IC7A. The Side HP filter is IC6A/B and IC8A. The MS decoder is IC9 and IC10. IC7B and IC8...

A Second-Order 12dB/Octave Elliptic Equalizer Hi Trolls - it's been awhile. Around 2006 I introduced the Precision MS Matrix and a few years later the Stereo Width Controller. The question about how to implement Elliptic EQ with both of them comes up often. Until recently the answer has been to ins...

I wanted to drop back in with some test results based on a different nulling approach. Without going through all the details I figured out how to use one converter to record both the flat and analog EQ'd test signals simultaneously. (It's called mono. Should have thought about that originally :roll...

Hey Trolls it's been awhile. I wanted to share with you guys some work I've been doing comparing RIAA IIR Biquad plugins to analog RIAA EQ. After finding an accurate-sounding IIR vst plugin for Audacity (and a Nyquist RIAA coefficient tool) I was able to compare DSP IIR solutions directly to analog ...

I had the same download timeout issue with his links as well but eventually got them. I think his hosting provider is imposing file download size caps once he exceeds monthly bandwidth limitations. I brought it to Chris' attention and was told other people have reported that to him and that if I sen...

jesusfwrl Even if a manufacturer would be quite precise in informing you that a certain cartridge is designed to produce an output of 5mV for a peak recorded velocity of 7cm/s when terminated by a 47K load, you are still left with sample deviation between different samples of each cartridge. Thank y...

James you've outdone yourself.
This sounds awesome!

Took the liberty of doing an FFT on your tones. Very impressive. Nice even-order dominance.
The signature is very close to my STR-100 test record and S681.

When you spec 7 cm/second is that peak or RMS?

James this is very, very good.

Often an output level is quoted without any reverence to velocity.

I actually meant "reference." Too bad we can't correct typos but it made me laugh.

There may be an official Lathe Troll "Reference Level Thread" but after searching for a few minutes I haven't found one. I'm often asked to determine proper preamp gain based on vague phono cartridge level specifications. Often an output level is quoted without any reverence to velocity. "3.5 mV" d...