Matching it with a tube preamp in balanced mode could be an issue with some, since the balanced input impedance is only 10k ohms.
The new Coda S5.5 amplifier: It's a "Petite Beast"!
I have in-house the New Coda Technologies S5.5 amplifier for review for Stereo Times website. It will be awhile before I write the review. However, I'm so impressed by the performance of this petite amplifier, it only weights 45 pounds, that I wanted to give a heads up to you GON members if you are in the market for a balanced pure class A amplifier, delivers 50 watts @ 8 Ohms, and can drop 100 Amperes of current on a peak!
The world class build quality of Coda amplifiers is on display with the S5.5, along with the most beautiful purity of tonality, precise sound-staging, complete liquidity offered by pure class A design, and what might be the best top end regarding details, decays, and a natural shimmering without brightness or any edge at all.
The S5.5 uses extremely wide bandwidth output transistors instead of the usual TO3 devices used in most transistor designs. I own the Coda #16, which is great, but the midrange/high end is taken to another level of musical enjoyment with the S5.5. The S5.5 has a sense of speed/aliveness that is exciting to listen to that you experience in live music. The amp is dynamic as hell, has driven with ease any speaker I have tried it with, hence my nickname of the "Petite Beast". Remember, 50 watts pure class A, can drop 100 amperes of current and only weights 45 pounds.
Teajay (Terry London)
Showing 8 responses by grk
@audioman has a point...the left and right channels are reversed from most amps! I don't recall having seen that before. It's shown not only in the diagram but also in a picture on their website. The channels should be labeled as such when one is facing the front of the amp.Wonder why they did that? It may not ultimately matter, but it does seem rather odd. |
"I find the comments regarding Class D amps lacking “soul” very interesting when compared to good Class A or AB SS amps and tube amps. I recently purchased some Class D mono blocks to be used in lieu of tubes during the summer and could not describe the difference any better. I think Class D have come a long way in the last few years, but also feel they have a ways to go." Well if one is willing to pay quite a bit more, it looks like the newest AGD Duet amps have achieved quite a lot! "The AGD DUETs anchored a truly stunning aural experience, retaining perfect control of image and musical energy regardless of amplitude through continued listening sessions. In essence, and with every reference example, I found the DUETs to be a key conduit to the soul of the recorded musician." So much for the amps lacking "soul"! |
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"! |
@irave Don't do it...the amp will explode! 😉 If it is a truly balanced design, that should not be an issue. I have a SPL Performer S1200 amp with both balanced and RCA inputs. I also use a tubed preamp with balanced and RCA outputs. (Some preamps and amps run the RCA and XLR inputs parallel, so they are not truly balanced) I use the preamp and amp balanced connections for LP and CD listening and bypass the preamp using the RCA connections while listening to internet radio running directly into the amp. Since I tend to have the tuner on for at least 2-3 hours a day (for background music), it saves wear and tear on the preamp tubes. There is an input switch on the back of the amp for both inputs making the change easy. It appears the Coda has an input switch on the front.
|