The new Coda S5.5 amplifier: It's a "Petite Beast"!

@firefly627s

Im currently using a Coda CB preamp with the No.8. It sounds good but its very neutral in my opinion.

My goal was to get a neutral power amp and let the speakers do their thing and tweek the sound via preamp. My goal was to find a truly balanced tube preamp preamp to pair with the No.8. But with the No.8 having only 10k input impedance balanced. I’ve been having a really hard time finding something to match. I recently came across another low key brand. Backert Labs Rhumba. Made in USA. He has three preamps.. balanced and all three have an output impedance of <75.

. I believe the price ranges from 4000-12000. But you’d have to check his site. Either way.. if you already have a tube preamp that you want to try with whichever amp you decide on..it can’t hurt to try. Doug did say he builds his amps with balanced in mind.. but I’m sure using the single ended is just as good.

Im curious to know why Doug’s amps have such a low input impedance..when using balanced. I guess it doesn’t matter when using a solid state pre amp.. But I’d still be curious to know why. I just don’t see it on other amplifiers.

Sounds like you can’t go wrong with either amp. I’d trust his judgment..I’m wondering why Doug is steering you to the No.8 though. 

As far as I have been able to discern, the general rule of thumb for proper impedance component matching is that the input impedance should be at least 10x higher than the output impedance. Given that the input impedance of the Coda S5.5 is 10K ohms, then one could at least theoretically have a preamp with an output impedance of up to 1K ohms and still be okay. Have people found this to be true or should one strive for even lower output impedances, like 20x or more?

As an example, I noticed that the Atmas-Sphere Class D amps have an input impedance of 100K ohms while their tube preamps have an output impedance of 250 ohms. That's quite a "cushion"!

@vthokie83  I too am interested in your comments on the Caladan / s5.5 pairing. I have Caladans. Currently a pair of AGD Tempo’s as mono blocks, using one channel of each amp - not bridged (don’t ask ;-). 

Regarding tube preamps, I have a Backert Labs Rhythm 1.3 which has an output impedance of < 80 per their specs. Doug at Coda said they would play well together.

There is absolutely nothing wrong with the AGD / Caladan pairing, but sometimes you don’t know what you are missing until you aren’t. Call it curiosity on my part. Or neurosis if you wish.

Markmuse, I never did see anywhere that you posted your opinions on the Caladans since you got them.....I'd love to hear from you on them. Send a private message if you don't want to hijack this thread.

I loved the Backert Labs Rhythm 1.4s that I test drove a few weeks ago, it came down to those and the Aric Audio Motherlode XL for me.....but the Backert was absolutely terrific.

I'll try to get some thoughts together on the CODA/Caladan pairing, but it's 73 degrees and sunny here in Chicago today....and my wife has me cleaning up around the house today (and basement). She's definitely putting a "hitch in my getalong"....but she never complained about buying the Caladans/CODA/Aric Audio, so I owe her.