pass labs x350.5 and arc ref 5se - impedence mismatch?


any experience from you guys? thks so much
chainsdb
Why do you ask? Are you having an issue?

ARC Ref5se - output impedance = 600/300 ohms bal/se

Pass 350.5 - input impedance = 30/20 Kohm bal/se

Seem OK.

The X350.5 has specified input impedances of 30K unbalanced and 20K balanced, as indicated under "Technical Specifications" here, although I suspect those numbers have been mistakenly interchanged. As with many ARC line stages and preamps ARC recommends a minimum load of 20K for the Ref 5se, although it isn’t made clear if that applies to the balanced outputs or the unbalanced outputs or both. The reason 20K or more is recommended is presumably because the output impedance of the Ref 5se and many other ARC line stages and preamps rises to considerably higher values at deep bass frequencies than its specified value, which is presumably based on a mid frequency such as 1 kHz.

Those numbers suggest that impedance compatibility between the two components would be marginal at best. However Stereophile’s measurements of the Ref 5se’s output impedance were as follows:
At high and middle frequencies the Ref 5’s output impedance was slightly higher than specified, at 628 rather than 600 ohms balanced and 322 rather than 300 ohms unbalanced. However, at 20Hz the impedance rose to 1447 ohms balanced and 637 ohms unbalanced, which, with an extremely low load impedance of 600 ohms, rolls off the low bass by 3dB at 15Hz.
(Although that paragraph refers to the "Ref 5" the review and the measurements were of the Ref 5se).

1447 ohms seems comfortable relative to a load impedance of 20K or more.

Regards,
-- Al



Thks guys asking because my slp98 seems to provide tighter bass as opposed to the ref 5se....
the Cary SLP 94 and 98 were always sleepers and punch way above their price.
Is the REF 5SE and X350.5 a bad match? Has anyone checked this out?
I am currently using an ARC Ref 5 with a pair of Pass Labs XA-100.5 mono-block amps with very good results.