Why not ? Fundamental in these cases is, imho:
- following Spectral recommendations about MIT cabling just to avoid the risk of fluctuations that can be damage the power amp
- avoid old equipment
in the past, during a transition phase, my preamplifier was a Mc C2500 - pure plasphemy - ...not bad.
I believe all Spectral amps have an input impedance of 10K ohms. Accordingly, only preamps with a low output impedance are potentially suitable for Spectral amps. The Nagra preamp output impedance of 50 ohms should be a good fit as long as you use MIT interconnects and speaker cables .
I discuss the issues of non-Sprectral pre-amp compatibility with Spectral amps in more detail here:
But to save you time, Spectral has gone back and forth on their insistence to use only Spectral pre-amps with the amps. My Spectral 400 manual clearly states only that you should use a preamp of low output impedance, but that was about 2 years ago. I'm now told they will not let dealers sell their amps unless the customer also uses a Spectral pre-amp. If that is indeed the case, you may wish to reconsider using a Spectral amp with the Nagra. I can tell you that the Spectral universe is not unlike the world Ayn Rand abhors, and that you might just find that there is considerable sonic joy and magic if you can free yourself from the Spectral shackles and use a tube preamp of your liking with good compatibility. Yes, there may be some risk, but in my view, it is nominal. What I and others have discovered is that some tube preamps and Spectral amps make wonderful bedfellows.
Thanks for your reply! The Nagra Jazz is like new and my cables are the MIT Oracle MA-X2...love them!
Thanks Marty! I have been told by my audio dealer that the Nagra Jazz and Spectral power amp would cause no trouble. One final problem for me to fix is an interlink between the CDP- cd-player and the Nagra Jazz. I can buy an older type MIT Oracle 350 but it has a fixed low impedance (meant for spectral). However, the input impedance of the Jazz is > 75 k Ohms...is this a big problem?
Preamp input impedance has no bearing to the discussion; it's the output impedance that has to be low (e.g. 100 ohms).
Are you sure Ack? The proper impedance setting is determined by the input impedance of the component that is at the delivery end of the signal, so I have always been told. But since this is just a temporary solution (until I can buy a used MA-X, my only real concern is if a wrong impedance setting can damage my equipment.
And FWIW, 75K input impedance is too high, so be careful matching sources and preamp...
Yes,,, the pre amp to amp is no problem: I use MIT MA-X proline set on "low" to feed the Spectral 360. The remaining question: is it safe to use a Oracle 350 with low impedance between the NagraCDP and Nagra Jazz pre (input > 75K)? Or is this a big NO? I have never heard about a wrong impedance choice of an MIT in a NON SPECTRAL SET UP to damage equipment...
The Nagra preamps (Jazz and PL-L) are only coupled by a transformer if the unit was ordered with them as they are optional. The output impedance for the single ended outputs is actually lower than the XLR transformer balanced outputs. I have a PL-L and the single ended outputs were measured by stereophile. "The unbalanced output impedance was 36 ohms across most of the audioband, this increasing slightly to 125 ohms at 20Hz. The balanced figures, from the optional transformer-coupled XLR output, were 63 ohms at 1kHz, 66 ohms at 20kHz, and 158 ohms at 20kHz." They should work fine especially with the MIT interconnects.
It's not a matter of blowing up equipment, it's about optimal operation. And you would need a high impedance version of the cables for the sources. WRT the amps the impedances may be compatible but also keep in mind they need 100-200mA of current to be driven properly. This has been discussed numerous times before.
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