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Old 20th May 2017, 12:17 am   #59
Catkins
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Join Date: Feb 2015
Location: Chepstow, Monmouthshire, UK.
Posts: 234
Default Re: Marconi 702 advice

Quote:
Originally Posted by dtvmcdonald View Post
I'm more interested in getting the sound working. I'll ask again ...
does anybody know the speaker impedance? It measures 3.7 ohms DC.
On the circuit diagram for the 702 sound unit (omnibus edition) it's listed as 4 ohms.

I don't have a 702 but the speaker for the HMV 900 is listed as 4 ohms too (and is presumably the same or a similar part number).

My HMV 900 speaker is currently out of the case (the HMV 900 is currently dismantled), and so it was easy to measure that.

Readings using Peak LCR45

5.750 ohms @ 15 kHz
1.970 ohms @ 1 kHz
26.84 ohms @ 200 kHz

DC resistance 1.52 ohms

My AVO DA116 gives the DC resistance as 1.8 ohms.

Hope that helps.

Catkins.
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