OK, finally got around to pulling the second speaker apart and properly testing both drivers.
I must have mis-remembered, because it's clear that it's the RIGHT driver (the one in the same box as the amp) that's misbehaving, not the left. I tested both drivers on both channels, and every time the same driver is about half the volume and much scratchier than the other one. This is actually a surprising improvement, because in the past I could barely even hear it at full volume.
Either way, the drivers obviously need replacing. The board (while cheap and crummy) works.
That's a lot of good info, thanks!
Some of the stuff about modifying the vents etc. might be a bit above my head, but I'll keep it in mind.
Now I'm just torn as to whether I should try refurbishing the current board or replacing it with a brand new one. It looks like it might actually work out cheaper to replace the whole board! But staying with the current one would be less work and fiddling/adapting to fit.
Again, what is the size of the bolt circle on the 4”? Hole size? max vert height of the rebate.
The reason i ask is that the rebate is the shape of an FE103. The new one has a bit differetn bezel, but if the dimensions are close a vinatge FE103 might drop right in. If it nominally wants a bit bigger box you can then turn that to your adavatage by damping the port (stuff it with fluff.
dave
The reason i ask is that the rebate is the shape of an FE103. The new one has a bit differetn bezel, but if the dimensions are close a vinatge FE103 might drop right in. If it nominally wants a bit bigger box you can then turn that to your adavatage by damping the port (stuff it with fluff.
dave
Hole size is 104mm (~4.1''). Diagonal distance between the screws is 115mm (~4.5'')
Tweeter hole is 47mm(~1.85''), diag hole distance is 65mm (~2.6'')
My multimeter put them at 4 ohms. (Well, 4.5)
Here's some pics of the rectifier (it's separate to the board, attached to the back of the box):
Not sure how better to frame pictures of the board. What should I focus on in particular?
Your multimeter reads the DC Resistance of the driver. It's Nominal Impedance (opposition to AC) is around one third higher i.e. 4.5 + 1.5 = 6 ohm.
Focus on providing a sharp and larger (expandable) version of the attached photo that you posted earlier, which will allow us to see clearly down to individual component level.
Attachments
or a 3/4 view to see caps value... the metal thingy is a radiator fo an amplifier ic I surmise...
The red and green caps has to be keeped (film caps). The lytic long can caps are certainly good enough if less 20 years old... however if you see bumped top or leaks at the bases...think tpto a cap refurbishing... Very few thing to improve on the caps side but to avoid a futur refurbishing if you listen everyday... Sometimes some caps have a subjective better snap that can help those mini speakers but it mainly depends of the ic circuitry....
The red and green caps has to be keeped (film caps). The lytic long can caps are certainly good enough if less 20 years old... however if you see bumped top or leaks at the bases...think tpto a cap refurbishing... Very few thing to improve on the caps side but to avoid a futur refurbishing if you listen everyday... Sometimes some caps have a subjective better snap that can help those mini speakers but it mainly depends of the ic circuitry....
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Ah, thanks. Clears a few things up
OK, I've focussed a bit closer, specifically on the caps and labelled them. Are the tantalums of any importance?
The heat sink over the IC, by the way, is soldered on. Really solidly. Just how useful will it be to know what the IC is?
Oh, I think I meant polyester.
I've tracked down a few drivers on ebay.
4 inch:
4" inch 4Ohm 6Ohm 8Ohm 40W Speaker Woofer Subwoofer Audio Loudspeaker Bass #1 | eBay
2 inch (tweeters):
2pcs 2"inch 8ohm 8Ω 10W tweeter Speaker Neodymium paper cone Loudspeaker | eBay
Do these look like good choices? I'd prefer a source that isn't going to charge me a million dollars to post to Australia.
It's hard to find tweeters of the right dimensions. All I could find were 8ohm ones, but a bit of a google search seems to imply I can get away with this. Can anyone confirm? (Bearing in mind that at the price I don't really care if they add heaps to the sound - I'm half putting them in just for kicks, since there's a hole for them so why not? I just don't want them to make it sound worse.)
yes, the MKT will last more than you and us; keep them.
If the tweeters are working, why changing them ? Just change the falling unit and its cunterpart on the other cabinet.
No idea about the bass unit, Planet10 is the guy to follow for that.
Some rules matter : don't go bellow 6 ohms drivers, choose the wider bandwith in the low end and a low Vas (more or less box volume unit, idealy around 2 liters to 4 liters on the datasheet should work) as a not too high wattage because the little IC to hit the mak level the driver is able to !
And of course choose the driver as P10 said in order to fit on the screw pads and hole to keep it air proof.
look at Monacor. Peereless from Thymphany can be found in Oz shops! You may not have problem to find pc speaker drivers units. The one advised by P10 is of course if music matters and seems to look close as per his experience suggests.
If the tweeters are working, why changing them ? Just change the falling unit and its cunterpart on the other cabinet.
No idea about the bass unit, Planet10 is the guy to follow for that.
Some rules matter : don't go bellow 6 ohms drivers, choose the wider bandwith in the low end and a low Vas (more or less box volume unit, idealy around 2 liters to 4 liters on the datasheet should work) as a not too high wattage because the little IC to hit the mak level the driver is able to !
And of course choose the driver as P10 said in order to fit on the screw pads and hole to keep it air proof.
look at Monacor. Peereless from Thymphany can be found in Oz shops! You may not have problem to find pc speaker drivers units. The one advised by P10 is of course if music matters and seems to look close as per his experience suggests.
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Knowing what the chip is would just let us know the specifications and cabability of the amp, but there's no point in pursuing that any further.
I see no reason to change the electrolytic capacitors, or any other components for that matter.
Can you link the amp up to a spare pair of passive Hi-Fi speakers to gauge how well it performs?
If it performs well, then concentrate on replacing the drivers in the plastic cabinets.
P.S. I've just seen your latest post regarding the drivers you have tracked down.
I see no reason to change the electrolytic capacitors, or any other components for that matter.
Can you link the amp up to a spare pair of passive Hi-Fi speakers to gauge how well it performs?
If it performs well, then concentrate on replacing the drivers in the plastic cabinets.
P.S. I've just seen your latest post regarding the drivers you have tracked down.
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To clarify - there are currently no working tweeters in the plastic cabinets - just dummy, imitation ones.
Hummmm, why bother ? A full range is what one needs here!
I don't know if this one feets : https://www.parts-express.com/pedocs/specs/264-1062--tymphany-tc9fd18-08-spec-sheet.pdf
less than 10 usd at Part Express
easy to find anywhere on the planet.
btw , curently drinking a 14 yo Tormore
I don't know if this one feets : https://www.parts-express.com/pedocs/specs/264-1062--tymphany-tc9fd18-08-spec-sheet.pdf
less than 10 usd at Part Express
easy to find anywhere on the planet.
btw , curently drinking a 14 yo Tormore
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Because the current tweeters are literally blank hunks of plastic
Yes, that's been my main limiting factor in finding appropriate drivers. There's plenty of 4'' 6ohm speakers out there, but not many with the right shape/size footprint and screw hole locations.
Yeah, I thought they looked a bit expensive. But so far they're the least dicey looking ones I could find that would fit. I'll keep looking...
OK, to my surprise (and strangely disappointment), I did this and it actually sounded decent... at least to my inexperienced ears. A little bit thin perhaps, but I was just using a unit that's meant to be matched with a sub-woofer.
I was actually sort of looking forward to dropping in some nice audio grade capacitors haha! (But agreed - there's no point if it sounds fine as is)
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