Mods to lower output impedance?

[greg788]

Probably a dumb question (which I'm good for), but are there any simple mods that would lower the output impedance? I'm trying out an amp whose input impedance is only in the 4K range. My speakers are "bass light" sealed boxes so I honestly don't notice a difference versus my standard amp, which has a 47K input impedance. But I'm sure a swap to a reflex and/or larger speaker down the road would make the lack of bass due to the impedance mismatch apparent. This amp with the 4K input impedance is sonically a "keeper" needless to say

[Paul Joppa]

For what it's worth, the Moreplay output impedance is low at low settings of the volume control. Below the midpoint (about 12:00) it's less than 1K.

[greg788]

Does the impedance rise (presumably logarithmically) as volume is increased from zero with volume at zero? Or linearly? If logartithmically, is there a range (like 8-10am) where increase is most dramatic/significant?

[Paul Joppa]

Volume controls are usually two linear segments approximating a log function; the first half covers 0 to 1K ohms; the second half 1K to 10K but is complicated by the tube's internal impedance (a few Kohms, but I haven't measured it - maybe PB has?). So yes, there is a fairly abrupt rise above the 12:00 setting.

[Paul Birkeland]

It was definitely tricky to figure out how to produce a specification for the Moreplay output impedance.  The BeePre with both upgrades would be the optimal preamp to use with an amplifier that has such a low input impedance, or you could use one of our headphone amps as well.

[greg788]

Can the Crack with Speedball be reconfigured to use as a preamp, either by replacing the headphone jack or adding RCAs with a switch or something?

[Paul Birkeland]

Just use a 1/4" to RCA adapter in the headphone jack.

[greg788]

I think I know the answer, but how would the Crack with Speedball upgrade compare sonically to a Moreplay?

[Paul Birkeland]

I have not done that comparison, let us know what you observe!