Audio Measurement Resources

[Echo North]

Great idea!

Here are a couple of great references I use all the time.

Rane Specs
http://www.rane.com/note145.html

AP Audio Measurement Handbook (bottom of page)
http://ap.com/download/whitepapers

Mike

 

[alexc]

Here's a link to Tektronix 'XYZ of Oscilloscopes' - a good primer for CRO usage

http://socrates.berkeley.edu/~phylabs/bsc/Supplementary/Lab1/xyz_scopes.pdf

 

[dio.pm]

Just a note to say that Mike's original links have been moved here:

https://www.ranecommercial.com/legacy/note145.html
https://www.ap.com/download/the-audio-measurement-handbook-2/

 

[JohnRoberts]

I made this a sticky...
===
I did co-author a book (with Larry Blakely) on performing audio measurements that we gave away free with the LOFTECH TS-1 audio test sets. Sorry I do not have a scan.

JR

 

[Audio1Man]

Hi John

I have the book, do you want to scan it?

 

[JohnRoberts]

not really...

It was mostly accurate, probably a few minor errors in it that I forgot about over the years.

[edit- I don't care if somebody else wants to share it, I just do not have a scan of that, and lots of my other old scribblings... /edit]

JR

 

[Whoops]

Hi John

I have the book, do you want to scan it?

As JR doesn't mind if it's shared could you please scan it and share it with us?

Thank you so much

 

[CJ]

What about a surface mount opamp in the tonearm, next to the cartridge? Probably been done already.

 

[JohnRoberts]

As JR doesn't mind if it's shared could you please scan it and share it with us?

Thank you so much

I do not care... I co-authored it with Larry Blakely (RIP, died back in August of this year) mostly to merchandise the Loftech TS-1 audio test set. It contained lots of basic procedures for things like setting up tape recorder bias and measuring frequency response.

What about a surface mount opamp in the tonearm, next to the cartridge? Probably been done already.

There is an incentive to not add excessive mass to the tone arm. A cartridge manufacturer could add discrete JFET source followers inside the cart without much weight/mass penalty, and phantom power the active JFETs through the existing wiring (like cheap microphone capsules do now).

This could pretty much negate cable capacitance and sundry termination effects, but I do not see enough market demand for developing a novel technology for such a mature product category. I am too lazy to do a patent search to see if anybody has already pursued this.

JR

 

[fragletrollet]

Just a note to say that Mike's original links have been moved here:

https://www.ranecommercial.com/legacy/note145.html
https://www.ap.com/download/the-audio-measurement-handbook-2/

Do I need to register to download?

Maybe someone could just upload the doc here

 

[Cqwet Dbdfte]

I do not care... I co-authored it with Larry Blakely (RIP, died back in August of this year) mostly to merchandise the Loftech TS-1 audio test set. It contained lots of basic procedures for things like setting up tape recorder bias and measuring frequency response.


There is an incentive to not add excessive mass to the tone arm. A cartridge manufacturer could add discrete JFET source followers inside the cart without much weight/mass penalty, and phantom power the active JFETs through the existing wiring (like cheap microphone capsules do now).

This could pretty much negate cable capacitance and sundry termination effects, but I do not see enough market demand for developing a novel technology for such a mature product category. I am too lazy to do a patent search to see if anybody has already pursued this.

JR

MC cartridges negate the cable capacitance issue, requires better low noise pre-amp, or a step-up transformer.
A
Phaedrus sells an active cartridge kit. Huge success?

 

[JohnRoberts]

MC cartridges negate the cable capacitance issue, requires better low noise pre-amp, or a step-up transformer.

yes but they deliver lower output.

I offered a MC version of my P-10 phono preamp kit back in the early 80s. For the MC version I used extremely low noise 2SB737s PNP transistors. These transistors were actually developed by a small Japanese company for MC head amps. ROHM bought that company and sold them in the US. IIRC these devices went EOL (end of life) around the turn of the century a couple decades ago.

A
Phaedrus sells an active cartridge kit. Huge success?

Who? I haven't followed the vinyl market for decades.

JR

PS: To expand upon what I already said, a SMD JFET buffer could be mounted inside the tone arm head shell and phantom powered. It would not add very much mass. One could co-locate the preamp providing the phantom power inside the base of the turntable to KISS. Cable capacitance is a real issue. I used to sell a small quad dip switch with polystyrene capacitors (24pF, 47pF, 100pF, and 200pF) to dial in total termination capacitance. If adding a hi impedance buffer to a typical MM cartridge it could be useful to terminate the cart first with the expected nominal termination (around 100pF-150pF and 47k ohms).