What Pre Amp to go for?

[mikeyb]

Hi,

I am on the lookout for a Pre Amp to go with my EWA M-50 Power Amp. I am currently using Ali's Slagle Passive Pre which is superb, and I can keep as long as I like with the probability of purchase, but I'm wondering if there is anything out there that isn't too expensive ( under £1000 S/H ) that would compete with it, or possibly better it ( not easy I bet ).

Would need to include a minimum of 3 inputs, Headphone out and remote control ( no line of site )

The Croft Epoch I had a short time ago was nice, but the gain was all wrong, I think the M-50 needs 22k rather than 47k, is that right?

Jerry's Bel Canto Pre3 looks good but it has green led screen, but I'm not keen on green lol.

I wonder if it would easier to connect a headphone amp to the Slagle output? Then forget about the remote?

Your thoughts, recommendations much appreciated.

Mike.

[walpurgis]

Why not ask Colin for recommendations?

[mikeyb]

Why not ask Colin for recommendations?

I've heard his Q20 Pre and it's excellent but over my budget. I just wanted to pick a few brains in here, sitting here bored watching the rain and thought I'd ask 😊

[RothwellAudio]

The Croft Epoch I had a short time ago was nice, but the gain was all wrong, I think the M-50 needs 22k rather than 47k, is that right?

I'm not sure what you mean by that. Can you elaborate?

[mikeyb]

I'm not sure what you mean by that. Can you elaborate?

Not really cos I don't understand it, Colin mentioned a figure of 22 when I said the Croft had to be turned almost all the way up to get to semi decent volume, I think he said the M50 likes to see 22 or something, seeing as I don't understand this sort of thing I might be completely wrong lol

[WESTLOWER]

Hi Mike
give David a shout at AD Audio (in the trade section) he is building some serious Pre amps, and you won't find better for the money.
He is very flexible to ones needs and budget. You won't be disappointed.

[Simon_LDT]

I think the 22k figure is the input impedance (going by the specs I see on the EWA site). What are your sources (solid state/tube)? Maybe try a passive?

[Light Dependant Resistor]

I think the 22k figure is the input impedance (going by the specs I see on the EWA site). What are your sources (solid state/tube)? Maybe try a passive?

With passive attenuators, the figure of merit is what is called true impedance,
usually occurring close to half volume which is where the resistance from the
source greets the resistance to ground. Where they intersect and the resulting
resistance is the same, is the passives true impedance.

This describes the most common form of Pad circuit which is a L pad
namely a series resistance connects the source to the output, and a
shunt resistance connects the output to ground,

As with anything there are variations, and the terms linear and log
can provide - in the case of log a steeper entry curve ie volume not
commencing straight away. If it is your preference for volume to
commence as near as practicable to off, then a linear response
may be preferable to log.

To save much forum research, 15k is generally agreed to be the
preferred true impedance. ( DIY audio forum ). But 18k to 20k is also
very good as well. Anything lower like 10k will start to change
the dynamics of audio, and may appear a bit too dynamic suiting
some music but not others. Hence slightly higher usually is preferable.

While I am here, a common curly question is what is a passives output impedance ?
The output impedance at best, is its true impedance, however if volume is
placed at maximum then it will achieve connection from the source to the
output with effectively no loss. Output impedance applying to passives
is a misnomer, as they are not an active device.




Hope this assists

[RothwellAudio]

With passive attenuators, the figure of merit is what is called true impedance, usually occurring close to half volume which is where the resistance from the source greets the resistance to ground. Where they intersect and the resulting resistance is the same, is the passives true impedance.

This is so far off standard electronic theory, accepted wisdom, and common usage that I urge anyone reading it to take it with very large pinch of salt.

[Light Dependant Resistor]

This is so far off standard electronic theory, accepted wisdom, and common usage that I urge anyone reading it to take it with very large pinch of salt.

Its easy, just find a multimeter and measure without any signal leads connected, from input to output
then output to ground, where the resistances greet each other - the resistance measurement then shown
is the passive devices, true impedance. Each channel Left and Right should ideally be the same.

Where you may be confused is then attaching signal leads, but a passives true impedance is quite simple
reflective of its L pad resistances intersecting, It is after all a resistive divider, in this case variable.
Noting variations occur where they intersect with log or linear types, but at some point they indeed intersect.