LM317/337 regs are superior to their 78xx/79xx competition in almost every spec.
tubologic said:The (Linear Technology) LT1086 (positive) and LT1033 (negative) are much better regulators
jdbakker said:tubologic said:The (Linear Technology) LT1086 (positive) and LT1033 (negative) are much better regulators
Judged by what? Noise specs for the LT1086 and the 317 are equal, the LT part has ~6dB worse ripple rejection than the 317. The LT1086 has a low dropout voltage, but that's almost never relevant in audio applications. Output voltage accuracy is better (2% vs 4%), but that too has little impact. The LT1033 has a higher max current spec than the LM337, but you'll hit package dissipation limits before that gets relevant. For both the LT1086 and the LT1033 the max input-output voltage is lower than for the generic ones.
LT has nice parts, but in typical audio work these don't seem worth paying 3-5x the price of a more traditional LM317/337.
JDB.
[in my book, picking a single-sourced part over a multi-sourced industry standard had better have a damned good reason]
tubologic said:I didn't measured the noise spec's of a LM317 vs LT1086 but actually compared how they perform in a very critical audio circuit (AC701 heater supply for a tube Mic.) Believe me or not,the AUDIBLE and MEASURABLE differences were not marginal or subjective: the LT powered Mic had a 6 to 8 dB lower wideband hum & noise than the LM version. To get the same results with a generic LM317 a 10,000 µF capacitor was required at his output,which is not recommended and partially defeat the purpose of the regulator.
If it is a KM5x microphone, the bias voltage is directly derived from the heater voltage, so any noise in the heater supply is transferred to the output at full gain.Michael Tibes said:Sorry if this is getting OT, but you really had a 6 dB higher noise floor with a LM317 regulated heater supply? I didn't expect the heater supply to have such a huge effect on the noise floor, but it would definitely be worth trying it. I always believed that the effect of the heater supply cleaning was negligible as long as it's 'relatively clean'?tubologic said:I didn't measured the noise spec's of a LM317 vs LT1086 but actually compared how they perform in a very critical audio circuit (AC701 heater supply for a tube Mic.) Believe me or not,the AUDIBLE and MEASURABLE differences were not marginal or subjective: the LT powered Mic had a 6 to 8 dB lower wideband hum & noise than the LM version. To get the same results with a generic LM317 a 10,000 µF capacitor was required at his output,which is not recommended and partially defeat the purpose of the regulator.
Michael
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