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 47 Ohm Speakers....
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 Return to top of page · Post #: 1 · Written at 3:23:37 PM on 20 March 2016.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 281

Hi everyone,

I have a couple of HMV 'Bahama' portable record players from the 1960's. Both of them have speakers blown and require replacements. Given the current speakers are 47 ohm, what would be the suggestion as for a replacement? I have looked wt getting the current ones rebuilt, but due to the odd value, no one can do them ...

Look forward to your assistance.

Cheers
Scott

Loudspeaker
Loudspeaker


 
 Return to top of page · Post #: 2 · Written at 4:09:08 PM on 20 March 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6014

47 ohms doesn't sound right to me. Are you sure it's not 4.7 ohms?

The only time I have come across 45 ohm speakers is in vintage office intercoms where the speaker doubles as a microphone.


 
 Return to top of page · Post #: 3 · Written at 4:17:22 PM on 20 March 2016.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1381

I've seen a 80 ohm speaker in a TV, so 47 might be correct.


 
 Return to top of page · Post #: 4 · Written at 4:19:09 PM on 20 March 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6014

Okay, I have found the schematic for model O3-8K and I note that it's a solid state circuit with transformerless output and 47 ohm speakers.

I don't like your chances of finding replacements other than in donor units, if you can find any.


 
 Return to top of page · Post #: 5 · Written at 7:39:31 PM on 20 March 2016.
Labrat's avatar
 Location: Penrith, NSW
 Member since 7 April 2012
 Member #: 1128
 Postcount: 292

Early transistorised amplifiers often had high impedance speakers.
I even have a radio with a centre tapped voice coil.

I can get, and do have numerous 45 ohm speakers, but they are tiny.
36mm diameter, height 5mm power 0.5W

Wayne.


 
 Return to top of page · Post #: 6 · Written at 11:36:14 PM on 20 March 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4348

The speakers were often in the collector of the OP transistor. The only other possible option is likely a transformer.

Marc


 
 Return to top of page · Post #: 7 · Written at 3:19:47 PM on 21 March 2016.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 281

Hi guys,

Thanks for the replies thus far. I have just emailed a couple of pics for loading on this topic that may assist. The size of the speakers are 10cm x 17.5cm

Any suggestions on a way to replace them is appreciated - the amp unit is an early simple sold state amp

Cheers
Scott


 
 Return to top of page · Post #: 8 · Written at 5:53:54 PM on 21 March 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6014

As Marc suggests, your best option may be to install output transformers in each channel so that you can use speakers with a commonly available impedance such as 8 ohms. Wattage handling is a consideration.

These may be suitable: https://www.edcorusa.com/com50-1

Schematic here: http://www.kevinchant.com/uploads/7/1/0/8/7108231/03-8k_t2-69.pdf


 
 Return to top of page · Post #: 9 · Written at 11:36:49 AM on 22 March 2016.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 281

Thats guys, The power handling is very low - I think it's only about 5Watts per channel.

cheers
Scott


 
 Return to top of page · Post #: 10 · Written at 8:43:35 PM on 22 March 2016.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6354

Photos uploaded.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
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