PPM driver

Does a PPM like a Sifam mechanical movement meter need a special driver or will a standard opamp buffer due? I read this EBU spec http://tech.ebu.ch/publications/tech3205 which made no mention of a specialized driver.

I just found this auction with a Sifam PPM and a driver board that looks very different from a simple opamp buffer. http://cgi.ebay.com/SIFAM-TWIN-MOVEMENT-STEREO-PMM-ALICE-DRIVER-BBC-SPEC_W0QQitemZ200311356534QQihZ010QQcategoryZ1504QQssPageNameZWD2VQQrdZ1QQcmdZViewItemQQ_trksidZp1638Q2em122

I just ordered some PPM's assuming I could just buffer them and go. Am I in for a world of hurt?

The PCB includes peak rectifier with suitable time constants + log converter. That is what you need to convert a moving coil meter into PPM.

Ohh, ooops. Are the time constants for a BBC scale meter different from and EBU scale meter?

Gold said:

Ohh, ooops. Are the time constants for a BBC scale meter different from and EBU scale meter?

Click to expand...

Take a look at this pdf

http://www.ibs.org.uk/public/lineuparchive/2008/115_Apr-May/10b_Audio_Waveforms_And_Meters_Extra.pdf

Thanks Rob. That's a great article. Mark Younge is the current chairman of the AES standards committee.

Anyone know of a supplier of PPM driver boards? Besides ebone

Gold said:

Are the time constants for a BBC scale meter different from and EBU scale meter?

Click to expand...

The differencies are minimal:
BBC: integration time 10ms, recovery 3s for 26dB
EBU: integration time 10ms, recovery 2.8s for 24dB

BBC to EBU scale conversion:
7 = +12dBu
6 = +8dBu
5 = +4dBu
4 = 0dBu
3 = -4dBu
2 = -8 dBu
1 = -12dBu

A Company with long experience of PPM driver design is Surrey Electronics, run by Trevor Brook, who has written articles for Wireless World - on many different subjects.

They now have a Web site (this is a recent venture - as I have often searched):

http://www.surreyelectronics.com/

They also make a thick film hybrid with all the 'complicated' bits in it for integrating into your own design - full details are on their site.

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Another source of driver cards, both mono and stereo - is Canford Audio:

www.canford.co.uk

Search for:

58-321 Mono PPM drive card
58-322 Stereo PPM drive card (this can be used for A/B or M/S indication)

Thanks. I contacted Sifam and they said Alice Broadcast also makes them. The Alice cards are the least expensive. Any reason not to get those?

I believe Alice stuff is decent. Otherwise, ask TSL. I use their meters every day, and they are very good.