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Author Topic: Collins 75A4 Speaker  (Read 679 times)
AD4U
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Posts: 2543




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« on: April 10, 2019, 06:54:02 AM »

Several years I bought a Collins 75A4 receiver. I sent it to Howard Mills for a complete cosmetic and electrical restoration and updates. I have always used several speakers with this receiver - like a Heathkit SB-600, Drake MS4, Collins S Line speaker, Hammarland HQ-180A speaker, etc with great results.

Recently I found and bought a matching Collins 75A4 speaker enclosure. Before I bought it the seller told me that the original speaker had been replaced with a brand new 10 inch speaker. The speaker in the enclosure looks like a heavy duty woofer or a guitar speaker with a VERY LARGE magnet, a large voice coil, and with foam around the paper cone and with a 200+ watt rating.

When I use this speaker with the 75A4 I get some distortion on SSB and CW and some hum. When I use any of the other speakers I mentioned above, none of these issues are apparent.

I assume the original speaker in the Collins enclosure was a communication type speaker and not a Fi-Hi speaker.

I recently joined the Collins Collector Association but I have not received a reply.

I think my problem is obvious but before I try to find a suitable 10 inch communication type speaker to replace the 10 inch speaker in the enclosure, will the Fi-Hi speaker cause or amplify these  problems in a 75A4 receiver?

If I need to buy a communication speaker, where can I find one? I have looked on ebay and Amazon and the only 10 inch speakers I can find are the Fi-Hi type like the speaker is in the Collins enclosure.

Thanks

Dick AD4U
« Last Edit: April 10, 2019, 07:12:55 AM by AD4U » Logged
KD0REQ
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Posts: 2404




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« Reply #1 on: April 10, 2019, 09:22:22 AM »

no clue what the OEM speaker was, likely one of the mass producers like Oaktron, CTS, or Quam in business at that time.  closest thing to a "communications" speaker now would be a midrange 10-inch with a non-massive magnet. I'd look at the cheapest 10s at partsexpress.com for something without a whizzer cone and a narrow range.

if the non-original speaker is a Jensen or a Celestron, it's definitely a guitar amp speaker, and you might get some handy coin selling it.
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