Thread: Preamps
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Bret L Bret L is offline
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Default Preamps

On Jul 30, 4:40*pm, "Trevor Wilson" wrote:
"Bret L" wrote in message

...

The best preamp is no preamp. In the case of CD players, DACs, and
tuners there is no reason to have a preamp but for the intransigence
of the makers who refuse to put convenient volume controls on them.


**There's more. Very few source manufacturers build products with suitably
low output impedance figures, such that long interconnects may be used.



They don't build the preamps any different than the CD players in
many instances. Same chips. Same topology.
Are both inadequate? Yes, but that's another story.

However, to provide for volume control, tone controls, switching of
units without moving cables and for phono sections (you could put it
in the turntable, but nooo) you need a preamp.


An ideal preamp should provide for:


1. A stepped precision attenuator so precise and repeatable level
settings may be made.


**Provided there are AT LEAST 100+ steps, Anything less results in poor
resolution of absolute volume levels.



2. Internal provisions for balanced and unbalanced output with a
replaceable connector field panel. If transformers are to be used for
balanced output they should be plug-in style so they can be purchased
later and easily fitted.


**Why? The need for balanced outputs is so incredibly rare, that it barely
rates a mention. For extremely electrically noisy environments, it is
helpful. Those situations normally involve long audio cables (20 Metres)
mounted close to power cables, typically carrying energy from TRIAC
controlled lighting systems. Under these cicumstances, balanced lines can be
helpful. Such conditions are rare or non-existent in domestic situations.



3. Provision should be made for internal mounting of phono input
transformers for users of low output MC carts.


**Agreed.



4. Low or high output, a balanced input should be provided for with
either a transformer or active internal electronics. This should have
a rational kind of four conductor connector. No attempt to utilize RCA
connectors for balanced connections should ever be made.


**Of course, but balanced systems are unnecessary.


If you want to interface to the pro recording and sound reinforcement
world they are. That is necessary more than you would think.