Output impedance of stock Quickie?

[Sonido]

Anyone know the exact or ballpark number of ohms the output impedance of the stock Quickie? Adding the PJCCS upgrade increases this? If so, to how many ohms?

Thanks

[Paul Birkeland]

2K stock, 4K with PJCCS.

[Sonido]

Thanks. Now as far as pairing with an amplifier's input impedance, such as following the 8x rule, is that just for noise floor problems, or also damping factor? Damping factor seems to be more about the multiplier of impedance between amp and speaker because it causes problems with how the diaphragm of the speaker moves, creating problems in the bass, if I'm not mistaken. So the impedance matching between the preamp and the amp shouldn't cause any damping factor issues, only noise floor, right?

[Paul Birkeland]

There are a few reasons to follow the 10X rule. 

The first, and most important, is that if you impose a very low load on the Quickie, it will change the actual operation of the 3S4 in a way that drives up distortion and mucks up the sound a bit.  If you are 10X over the output impedance, the 3S4 in the Quickie will be gently loaded and perform very well.

Along with the first reason, the low loading will decrease the apparent gain of the circuit (it actually decreases the available voltage at the output), so you will have to push the preamp even harder to get the output voltage that you need. 

Along with these two, there are coupling capacitors at the output of the Quickie that are sized for loads that are 40K or greater.  As you dip below 40K, the lowest bass will begin to roll off slightly, and when you get to 10K, you may notice a few dB of bass loss at the lowest frequencies.

[polyghan]

There are a few reasons to follow the 10X rule. 

The first, and most important, is that if you impose a very low load on the Quickie, it will change the actual operation of the 3S4 in a way that drives up distortion and mucks up the sound a bit.  If you are 10X over the output impedance, the 3S4 in the Quickie will be gently loaded and perform very well.

Along with the first reason, the low loading will decrease the apparent gain of the circuit (it actually decreases the available voltage at the output), so you will have to push the preamp even harder to get the output voltage that you need. 

Along with these two, there are coupling capacitors at the output of the Quickie that are sized for loads that are 40K or greater.  As you dip below 40K, the lowest bass will begin to roll off slightly, and when you get to 10K, you may notice a few dB of bass loss at the lowest frequencies.

So is the 10x rule "over 10x" or "under 10x" for best performance? My current amp has a 47k input impedance, would there be any issues with the quickie stock (without PJCCS)?

[Paul Birkeland]

10X or over. 

47K is a great load for the stock Quickie or PJCCS'd Quickie.