DSJR
Major Contributor
Drifting even more off topic, but the content below does kind-of show what was used in UK broadcast editing suites with later BBC-style monitors.Apologies for the thread drift, but I wonder why you say this, as there's nothing in the 303's specification or measurements that would account for it provided it's used within its specification. That means a minimum load of 4 ohms. If using loudspeakers where the impedance drops below that, then the amp is being used outside its design specification.
S.
I have a motley collection of old Crown prosumer power amps which broadly all 'sound the same' to me as indeed they should (taut and lean in audiophool language, although they do change 'sound' to a degree with the programme material played so pretty transparent still I think). The HH VX300 is a touch different in a slight way as it has extensive filtering below 20Hz apparently and the hf over 20kHz also appears tightly rolled off. What comes out is an amplified only version of what goes in and with the speakers I currently use, perfect for the job!
My rebuilt Quad II's and working 303 also 'sound the same' as each other, confirming Quad's rather sniffy claim forty odd years ago that all 'their' amps sounded the same, but the sonic 'flavour' into my speakers is softer, warmer, 'nicer' and absolutely charming into my Spendors and Harbeths at the modest volumes I play at. I also have a 'virgin' 303 which blew up a few years ago and it was donated to me to see what I could do with it. It's in too good a condition for my clumsy mitts to want to try to repair (I did replace an output transistor like for like but the fault is deeper and maybe on the supply board for which I have a replacement). I'm not geared up for soldering any more and have lost any remaining confidence in my skills anyway in recent times, so have left it, although there's a gent on eBay UK supplying nicely made replacement boards as per original design, who will service and repair it for not too much - I intend to send it to him for repair at some point.
Kind-of coming back on topic, the LS5/9's I had for a goodly while came out of an editing suite, their intentionally scooped out upper mids working well in a nearfield situation for the editing staff I gather. These are incredibly strange speakers as I've NEVER heard a speaker change its sonic 'perspectives' in different rooms the way these LS5/9's did, going from a stark balance with deep perceived sound-field to a heavy dull balance with crashing top (I hesitate to say 'tinsel' again) but a perfect reason to want honest 'neutral balance' speakers/monitors today. The VX300 was the amp driving them for years and you can see the life this old warhorse has had, decals rubbed off the now unobtainable front panel, slightly iffy Noble attenuators around the half way point and heat marks on the main circuit board from I suspect 24/7 use for years in its rack - I fixed an open circuit bias resistor and offsets are around 5mV each side as recommended in the service info I have and it gets fairly warm/hot on both heatsinks now - I still fetch it out to use from time to time, but the old D-150 does seem to tell me more about the music I play (yes, a subjective emotional vibe, but there ya go!). A sister suite at the same facility used the same type speakers and a Quad 520 power amp which I lusted after having seen it
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