DIY Newbie...Passive Preamp question.

Hello.
I'm new here and would like to learn a little about electronics. A new tube amp built by a small company that specializes in Dynaco type ams is being delivered tomorrow. The builder is installing stepped attenuator on the amp that I can use if I'm connecting just one sound source on the amp.

I'm trying to build up the courage to build one of his other kit amps but before I do I thought perhaps something such as a passive preamp may be something simpler that I could try out.

I've been a mechanical engineer, tool designer and CNC programmer all my life and really have a very basic knowledge of electronics.

The passive preamp that caught my eye and seems simple to build was one being marketed as a Polish built preamp by Akustyk.

To me it looks like its sorta like B1 preamp being sold in the DIY store. Is it?
Can someone help get me started with the other components I would need such as the attenuator and source selector and perhaps schematics that will help me understand how it all goes together.

Perhaps this request is way beneath others here and if so i won't be offended if I'm told that. But if someone could help I'd appreciate it.

Thank you...Blake
 
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The passive preamp that caught my eye and seems simple to build was one being marketed as a Polish built preamp by Akustyk.

To me it looks like its sorta like B1 preamp being sold in the DIY store. .................
If the attenuator has active electronics associated with it then it is not a passive pre-amplifier.

A passive pre-amplifier is simply a mechanical assembly of resistor/s to attenuate the signal.

The advantage of apssive is ti's simplicity and how little it affects the signal passing through it.

The disadvantage of passive is the output impedance.
This output impedance generally cannot drive cables and the Rin/Zin of the receiver.

Adding a buffer (B1) after the attenuator allows the pre to drive a cable and Zin.
 
If your amp already has an input attenuator, your "passive preamp" might be nothing more than a selector switch for different inputs.

IMO, most preamps with active output stages have way too much gain and the output stage is rarely necessary, at least not one with gain. I've been very happy with passive preamps having no buffer at all. If you have a turntable you'll need an active RIAA stage in there too.
 
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