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Junior Varsity
Question about headroom with dj mixers
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<blockquote data-quote="John Roberts" data-source="post: 43123" data-attributes="member: 126"><p>Re: Question about headroom with dj mixers</p><p></p><p></p><p>There was a recent thread here or somewhere about low vs mid frequency power output. At <<120 Hz, capacitor size and therefore PS ripple voltage can make a few volt difference to peak output. So for bass frequency PS cap size matters. </p><p></p><p>The typical constraints imposed by transformers are #1 Unloaded PS rail current/voltage (limited by design, ie turns ratio and core size) , and #2 continuous power, limited by heat dissipation and internal insulation resistance in the face of temperature rise due to IxR losses. Some value amps, use circuit breakers to protect undersized transformers from overheating, by shutting down the amp before the internal one-shot thermal fuse opens. </p><p></p><p>HF switching supply transformers have a huge thermal advantage from passing smaller amounts of current many times per second, instead of large current pulses, at the much slower mains frequency. But there is a cost for this higher technology so generally all things equal the higher technology approach has to cut some corner somewhere to match price. </p><p></p><p>It is only a very recent trend where the switching and class D technology has matured to the point that the material savings from smaller iron and smaller heat sink can actually translate to lower cost over all, even with the higher inherent complexity. </p><p></p><p></p><p>Talk is cheap... these are all constraints within the purview of competent design engineers. The are high and low performance amps in any technology. </p><p></p><p>The reality is a modern "value" amp will generally be designed to a lower performance standard than an older not-value amp. So in street dollars you could get more actual amp for less money by buying old, but this is not related to the technology used per se. More influenced by market trends toward cheaper and cheaper power amps. I recall when $1/watt was a cheap amp... today that is expensive. Note my idea and yours about "old" may vary some too. </p><p></p><p>JR</p><p></p><p>PS: regarding pulling more power from the wall, only the premium PFC (power factor correction) and better yet PFC+ regulated PS voltage amps can pull demonstrably more power from a given mains distribution. You will not find to many cheap PFC amps.</p></blockquote><p></p>
[QUOTE="John Roberts, post: 43123, member: 126"] Re: Question about headroom with dj mixers There was a recent thread here or somewhere about low vs mid frequency power output. At <<120 Hz, capacitor size and therefore PS ripple voltage can make a few volt difference to peak output. So for bass frequency PS cap size matters. The typical constraints imposed by transformers are #1 Unloaded PS rail current/voltage (limited by design, ie turns ratio and core size) , and #2 continuous power, limited by heat dissipation and internal insulation resistance in the face of temperature rise due to IxR losses. Some value amps, use circuit breakers to protect undersized transformers from overheating, by shutting down the amp before the internal one-shot thermal fuse opens. HF switching supply transformers have a huge thermal advantage from passing smaller amounts of current many times per second, instead of large current pulses, at the much slower mains frequency. But there is a cost for this higher technology so generally all things equal the higher technology approach has to cut some corner somewhere to match price. It is only a very recent trend where the switching and class D technology has matured to the point that the material savings from smaller iron and smaller heat sink can actually translate to lower cost over all, even with the higher inherent complexity. Talk is cheap... these are all constraints within the purview of competent design engineers. The are high and low performance amps in any technology. The reality is a modern "value" amp will generally be designed to a lower performance standard than an older not-value amp. So in street dollars you could get more actual amp for less money by buying old, but this is not related to the technology used per se. More influenced by market trends toward cheaper and cheaper power amps. I recall when $1/watt was a cheap amp... today that is expensive. Note my idea and yours about "old" may vary some too. JR PS: regarding pulling more power from the wall, only the premium PFC (power factor correction) and better yet PFC+ regulated PS voltage amps can pull demonstrably more power from a given mains distribution. You will not find to many cheap PFC amps. [/QUOTE]
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