I want to change the voltage regulators in my Classé preamp, they dont seem to be of the best kind.
It uses L7815CV (+15V 1.5Amax) and a L7915CV (-15v 1.5Amax).
The powersupply supplies +-25V to the regulators.
What regulators should i look at?
Im really intrested in those sulzer types, anyone with schematics and layout?
Nothing is overkill =D
regards - kasra
It uses L7815CV (+15V 1.5Amax) and a L7915CV (-15v 1.5Amax).
The powersupply supplies +-25V to the regulators.
What regulators should i look at?
Im really intrested in those sulzer types, anyone with schematics and layout?
Nothing is overkill =D
regards - kasra
kasra said:
Kasra, we have had a discussion privately but you seem not be satisfied with my answers.
First of all: what is the main goal? The main goal is to create a stable DC-wise and AC-wise voltage source. You want also little noise = low internal impedance at all frequencies
What is "bad" with the 78xx and 79xx? Rather high internal current consumption, not so fast, high drop-out voltage, not very stable voltage reference.
For preamps with rather constant current consumption the important parameters are rejection of incoming disturbance, low noise output. The easiest way to achieve this (in a already built amp) is to add passive components before and after the regulator. You will get the best effect if the components are added after. Decouple every opamp locally with 10-100 ohms in series plus 100-470 µF maybe also add 10-100 nF small polyester or ceramic cap bown to signal ground.
If the pre amp is opamp based the importance of clean voltage is less than if the amp is made by descrete parts, check for intance Pass Lab's RIAA amp with FET's.
Before you ruin your fine Classé amp totally (I've seem the pictures), maybe the amp design is wrong? The voltage is maybe alright? You are digging in the wrong end? Maybe you should design your own amp in order to get satisfied?
Per,
You have stated my goals.
However dont like to mess around with the existing design by adding / removing components due to little knowledge about the design. I have no own experiences from changeing 78xx and 79xx but there are som many things thats pointing on them and their implements to partly be the bottleneck in this design.
If i was going to change the regulators to 108x or 337 or others which are proved better, i still would need to change some components, and add some, on the board which im not found of - just to get them optimized..
The best / easiest? thing would be to simply build a new powersupply, perhaps external.
>Decouple every opamp locally with 10-100 ohms in series plus >100-470 µF maybe also add 10-100 nF small polyester or >ceramic cap bown to signal ground.
These things you mention about optimizing the opamp are all partly done, they all made the preamp better.
However i still feel the sence that i have some HF-noise and "övertoner(=D)" from the supply, which from what i know all partly points to the regulators
As you mention, the single best thing would be to build a completely new unit. Unfortunately i dont have the time to do that. Perhaps sometime in future i will.
best regards - kasra
You have stated my goals.
However dont like to mess around with the existing design by adding / removing components due to little knowledge about the design. I have no own experiences from changeing 78xx and 79xx but there are som many things thats pointing on them and their implements to partly be the bottleneck in this design.
If i was going to change the regulators to 108x or 337 or others which are proved better, i still would need to change some components, and add some, on the board which im not found of - just to get them optimized..
The best / easiest? thing would be to simply build a new powersupply, perhaps external.
>Decouple every opamp locally with 10-100 ohms in series plus >100-470 µF maybe also add 10-100 nF small polyester or >ceramic cap bown to signal ground.
These things you mention about optimizing the opamp are all partly done, they all made the preamp better.
However i still feel the sence that i have some HF-noise and "övertoner(=D)" from the supply, which from what i know all partly points to the regulators
As you mention, the single best thing would be to build a completely new unit. Unfortunately i dont have the time to do that. Perhaps sometime in future i will.
best regards - kasra
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