What’s AV bypass mode?
AV bypass mode is where one of the inputs has unity gain and bypasses the volume control. It’s useful for integrating a 2 channel pre-/power or integrated amp into a multichannel or HT system.
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AV bypass mode does come with a health warning. If engaged just make sure you don’t put a regular source into it. Without the volume pot to calm things, the sound will be somewhat loud. Albeit only for a short period.
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I went from 252/ 250 to Ear 912/ 250 with great success. A better sound, with no loose on Prat, and a great phono stage inside. Same price as 252 , with a 3k phono as a bonus.
Hifi plus in 2005 tried a Macintosh pre with Nap 300 and found the combo very satisfying.
Martin Colloms uses a Townsend pre with a 300 dr.
But sometimes the match is not good, as with Conrad Johnson pre.
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Thanks for clearing that up JJL nothing technical required with that answer.
However a little more insight into the actual specifics of the Naim Amp and also for
one of the Pre Amps used will allow people more idea of what is possible should they
need to go there, and also allow the Experts to comment on compatibility we don’t
want to blow some ones stuff up with out them being informed.
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Just curious Valve preamps seem to have something going for them does this design render them more compatible with Transistor Amps making them a easier match up than
Transistor ones.
Should I buy a new supercap or go directly to ex demo 552?
if you can afford it, the 552 is the way to go. Having said that, 282/Supecap with the 300 is a great match as well.
282/Hicap is a little under-preamplified for the 300, IMHO.
282/hicap/250 or 282/super/250
282/supercap/300, 252/supercap/300 are all good combos.
I ran the 552/300 for many years. If you like the 300, the 552/300 is great!
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Yes sometimes it does match very well, but not all tubes pre can match. Conrad Johnson for instance.
Unfortunately I own Alibaba stock so this is mostly hypothetical. Probably need to pawn the hifi tomorrow for my weekly margin call. It is nice to dream though… without hifi most my dreams relate to wishing I didn’t own Alibaba stock. Which doesn’t make sense when you consider how undervalued it is. Every day it gets more undervalued which, apparently, makes it even more attractive. Also I’ve never owned a thing that was capable of producing the profound feeling of impending doom I experience every morning thanks to BABA. So… it’s not all bad…
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Yes. i was thinking i read something here along the lines of unlimited Bandwidth Pre Amps
being clearly not suitable partners for Naim Amps. And weather or not Valve Amps would
also be made with such Bandwidth among other unknowns, it seems the Experts have
gone for coffee.
@Katzky2021, way off-topic and removed; probably best on a different dedicated thread please. Thank you.
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Hi Chaps, I am no expert, but I do own a valve Pre amp and being equipped with substantial iron cored output transformers I strongly suspect that it is bandwidth limited. It certainly didn’t cause the NAP 300DR any problems that I could measure.
At line level signal amplitudes, the type of device, solid-state or thermionic valve is not the main factor, both are capable of Mhz performance way above audio signal frequencies, it is the amplifier circuit configuration that affects the frequency limitation, preferred by Naim.
I have tried a bundle of different devices acting as pre amps with my NAP 300DR (most just for the fun of it!) and I have not seen any hint of stability issues in the Naim Power amp, but that is not to say that some pre amps might not cause this problem.
Quite a few valve pre amps have relatively high output impedance, and when used to drive power amplifiers which have a low input impedance this can cause a reduction of signal amplitude transferred to the power amp and a reduction, or roll off in low frequencies. You could say that they are mismatched. Valve pre amps which are coupled to power amps which have very high input impedance are unlikely to have this problem.
Naim pre amps have a comparatively low output impedance.
OK, I (finally) agree. One quick look at what is available on the market is enough.
The closest I get is Lejonklou Sagatun which is 4-input but a switch at the back that turns it into single source (bypassing the select block) with a slightly improved SQ.
My view is that if you have some kind of digital source you should have a separately boxed analog preamp with an analog volume control. I dont think a digital volume control that late in the chain is compatible with the various noise shaped dithers often applied at the mastering stage.
Also separating the boxes of a mainly digital device like a streamer/DAC and the analog electronics in a pre seems like a good idea.
And there are some manufacturers who, like Naim, make matched pre/poweramps. This doesnt mean you cant find mixed makes that sound good. But you can save a lot of hours taking advantage of this by buying a Naim pre with a Naim power.
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Ear 912 measurements, from Stereophile:
“
The line-stage output impedance was a suitably low 32 ohms balanced and 39 ohms unbalanced across most of the audioband, rising at 20kHz to still-low values of 65 ohms and 87 ohms, respectively. The front-panel VU meters were calibrated for an input of 775mV = 0dB (equivalent to a level of 1mW into 600 ohms), while the unity-gain setting of the Volume control was 2:00. The Volume control also showed excellent channel matching at all settings.”
Naim NAC 252:
AUDIO OUTPUTS
Analogue Outputs
1 x variable, 3 x fixed (DIN)
Line Outputs Fixed (level)
75mV, 600Ω
Line Outputs Variable (level)
775mV
Output Impedance
<50Ω
Load Impedance
10kΩ (min.)
The Ear is 35 ohm, the Naim is inferior to 50.
I wouldn’t get too hung up over absolute figures FR, you are right, 35 ohms is low, especial for many valve preamps, I recall my SuperUniti is <20 ohms and some Chord DACs are <1 ohm but that doesn’t make it better. It’s just one consideration, but one which can cause a mismatch between some valve pre amps and the power amp of choice.
As a rough rule of thumb some say that the output impedance of the pre amp should be at least 10 times lower than the input impedance of the power amp, others say 20 times is a safer figure. On that basis, anything less than 900 ohms should work with a NAP 300 for instance, but this is just one parameter to consider, but a fairly significant one.
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Ah ok Roog, didn’t knew that. So the output impedance is not enough to see if a non Naim pre can match a Naim amp?
Absolutely right, it is just one thing you should try to get right. 35 ohms is ‘quids in’ (sorry just a little light hearted UK expression.)
I tried a Chord TT2 (output impedance less than 1 ohm by quite a lot), direct into my NAP 300DR and I wasn’t convinced by the sound, but it had no problems driving the power amp. The sound to my ears was very clean though, perhaps I should have given it a little longer than the 2 day demo that I had with it?
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