Driving a 12inch speaker
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Location: Canberra, ACT
Member since 23 August 2012
Member #: 1208
Postcount: 587
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I have a large vintage (1960s) vented speaker enclosure, with a single 12" speaker. Its marked as Etone model 619, has a heavy cast aluminium frame, and also has 1982 on the frame (if this is the manufacturing date, then the speaker is not the original one).
On this thread http://www.guitargear.net.au/discussion/index.php?topic=30028.0. There are pictures of similar speakers, and information that suggests my 619 should be rated at 8ohms. I can't imagine it was rated for more than about 10watts RMS, but can't find the info. They are Australian and probably made in Sydney.
Originally, this enclosure was driven by a valve hi-fi amp built by Brian Cabena in Kew, Melbourne, about 1963. In the 1980s the valve amp was replaced by a solid-state amp (brand forgotten) from Kingston Hi-Fi in Canberra. Possibly, speaker replaced at same time? It performed very well (in my parents' house) with both amps.
I'd like to connect it to my Philips 123 Radioplayer, which quite happily drives a 10" 8ohm Rola external speaker.
When I connect the Etone, the output is very low, muffled and distorted.
Can I fix this with passive components, such as a transformer, or is the Etone in need of some kind of booster amp that I can connect without harming the Radioplayer?
Maven
[edited to correct the speaker size, after re-measuring]
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6821
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Etone is still around:
http://www.etonesound.com/.
If the speaker is in good condition, and the connections are good, then the radio should not sound muffled/distorted.
What is the DC resistance of the Etone's coil? An 8 ohm impedance should show about 6 ohms DC.
There is a danger in damaging speakers that are rated higher power than the audio source because the tendency is to wind up the source volume to the point where it clips and creates essentially square waves or pulsed DC which will quickly burn out a speaker coil.
It's safer to have a speaker that is rated lower power than the audio source as winding up the volume will cause distortion long before clipping occurs.
That said, a determined person can ruin a speaker under almost any conditions.
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Location: Canberra, ACT
Member since 23 August 2012
Member #: 1208
Postcount: 587
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DC resistance measures 6.9, speaker passes the "battery scratch" test. I'll try on another solid-state amp, but I still think there is some problem with the particular characteristics of the radio, which has several feedback tracks that seem affected by speaker performance. Puzzle continues..
Maven
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6821
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I'd like to connect it to my Philips 123 Radioplayer, which quite happily drives a 10" 8ohm Rola external speaker.
If it drives that speaker, then it should drive any other similar impedance speaker ... as long as the speaker and connections are good.
BTW: how long is the cable run between the radio and the external speaker and what gauge wire are you using?
Also, I trust that you are connecting directly to the Electone's voice coil and not via an additional impedance matching transformer on it? (I think I can guess your answer, but I had to ask to cover the bases.)
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Location: Canberra, ACT
Member since 23 August 2012
Member #: 1208
Postcount: 587
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I should have started in another place. I attached the speaker to another amp and found it had the same problem. Opened it up and found the foam surround had completey deteriorated and come away from the frame in a number of places.
Topic now moves to how to fix a speaker with this condition, which I believe is quite common. I see there are kits available to replace the foam surrounds. does anyone have experience with this method and is it worth the effort? I'd like to retain this Etone speaker if possible.
Maven
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5481
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I have not seen much in the way of adds for cones etc here. There are repairer adds in the HRSA mag.
There are a few in USA that advertise. try "tubesandmore.com", or perhaps Mouser, if you find nothing here.
Marc
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6821
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Location: Canberra, ACT
Member since 23 August 2012
Member #: 1208
Postcount: 587
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I phoned Etone and got a message in an interesting accent suggesting they were "on holiday until late January"! Not sure if that is last year's message or not.
Meanwhile I found this item available from USA
http://www.ebay.com.au/itm/370548392921?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649.
When measuring, I found what I needed was 12inch, not 15inch, and the only component needing replacement is this surround. So I'll see how the kit works when it arrives. Worth the risk at $20, including postage!
Maven
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5481
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Rather what I expected. The US & others seem to understand the meaning of "customer service" totally different attitude and it is amazing what they have.
Marc
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