Recently purchased 2x 1220c's and didnt realise the attenuators/crossovers had been removed and the pictured ones are not Goodmans........can anyone suggest a way of getting around this??
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Surrounds are sure original, have no idea about the x-overs though. Probably might be best to buy another pair and just duplicate the X-overs with todays components. They show up from time to time on eBay or other places. Even better would be to find single one that will be sure much cheaper than the nice pair.
xover is made with 1,5 mF cap and 0,18 mH air coil parallel connected.
today I just purchased 3 triaxioms with trebax units dismounted... I'm gonna cut the remaining felt off the whizzler cone, fit the 2,5" dustcap and voila. They are going to be just like Axioms 301s.
Next I'm gonna use the same cap and coil like in original crossover and match "301s" with Fountek Neo3.5H ribbon tweeter.
I'm kinda curious about the overall effect, because these Triaxioms I bought are 8 Ohm version and 301s that I had a chance to listen to are 15/16 Ohm.
Dan
Edit: for regulation of 'brilliance' there was a potentiometer which was 100Ohm and it was connected in 'counterphase' (I'm really missing a word here, I mean that minus was connected to plus and plus to minus in HF speaker circuit).
If there will be no regulation I think that original cap and coil will be enough. Constant level of 'brilliance' will satisfy me fully
today I just purchased 3 triaxioms with trebax units dismounted... I'm gonna cut the remaining felt off the whizzler cone, fit the 2,5" dustcap and voila. They are going to be just like Axioms 301s.
Next I'm gonna use the same cap and coil like in original crossover and match "301s" with Fountek Neo3.5H ribbon tweeter.
I'm kinda curious about the overall effect, because these Triaxioms I bought are 8 Ohm version and 301s that I had a chance to listen to are 15/16 Ohm.
Dan
Edit: for regulation of 'brilliance' there was a potentiometer which was 100Ohm and it was connected in 'counterphase' (I'm really missing a word here, I mean that minus was connected to plus and plus to minus in HF speaker circuit).
If there will be no regulation I think that original cap and coil will be enough. Constant level of 'brilliance' will satisfy me fully
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ARU was the 1st commercially available aperiodic “adaptation” to he loudspeaker. It was crude. One can easily replicate an improvemnet on the tech.
One also has to ask… over the years how have your driver’s aged. It is always a good idea to approach a vintage driver as some new entity (ie i have a 2 Axiom 8s that have drifted so far apart that i had to set them aside as they wer enot a pair).
dave
One also has to ask… over the years how have your driver’s aged. It is always a good idea to approach a vintage driver as some new entity (ie i have a 2 Axiom 8s that have drifted so far apart that i had to set them aside as they wer enot a pair).
dave
my general problem is, that my 1220C-s sounf very flat, the highs are weak - I think the trabak is running, but the overall sound is not good.
The mids and highs with my triaxioms are beautiful without any issues and there's plenty of bass depending on the room. They're my main speakers after building the enclosures in 2012. I've got the issue with one speaker, where the voice coil scratched at medium volume. This was probably caused by shipping. After two months the voice coil has centered itself and this issue had gone. I found, that the high mids weren't as good as the rest. The original cross-over is calculated around 5 - 7 kHz. I've replaced the original capacitor with a lower value (1 mF) and bypassed the coil and the variable resistor. The 'Trebax', which is connected with inverted polarity, is now an auxiliary tweeter and the woofer works as fullrange. The volume of the enclosure is 10 % smaller than recommended (with ARU 172) and the baffle is also less wide.
The walls inside are covered with felt and I've installed 2 curtains with thin felt as proposed in original drawings. Recently I've checked out a modification with a kind of transmission line in one cabinet and measured with the audio analizer of my smartphone a little difference, in my view an improvement in bass response. My amp is a 2A3 PP triode amp (ai faa) and the speakers are connected to the 16 Ohms tab. This combination works great. With my ACA amp, the bass response is weak and overall it looks to be stressed to much, probably because of the speaker load at the low end.
