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  1. #1
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    Tube Preamp for NAD C370 Amp, please

    Hi, I need your suggestions for a good tube preamp for teaming up with my NAD C370 Amp. I like to have a warm,soft ,full-bodied,and GOOD bass sounding preamp at around
    $1600
    Thanks in advance
    Simon

  2. #2
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    Quote Originally Posted by simonleemd
    Hi, I need your suggestions for a good tube preamp for teaming up with my NAD C370 Amp. I like to have a warm,soft ,full-bodied,and GOOD bass sounding preamp at around
    $1600
    Thanks in advance
    Simon

    Why not just place a 1/2 ohm to 1 ohm resistor in each leg of the amp output and you are set for that warm sound. Certainly will be less than $1600.
    mtrycrafts

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    How to do it properly,please

    Thanks mtrycraft for your suggestion,but its too simple for me to comphrehen your suggestions,please explain in more detail ,so that I can follow your instruction and do it in justice? Thanks
    Simon

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    Quote Originally Posted by simonleemd
    Thanks mtrycraft for your suggestion,but its too simple for me to comphrehen your suggestions,please explain in more detail ,so that I can follow your instruction and do it in justice? Thanks
    Simon
    I am sorry abpout not explaining it enough.

    A 1/2 ohm or 1 ohm resistor in the red terminal of the amp to each channel in series with the speaker cable, left and right, 2 resistors, will give you the same effect as a tubed amp you are looking for, a mellowed upper end. Or, you could even experiment with the high frequency tone control bu rolling it off. That will do similar effect.
    mtrycrafts

  5. #5
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    Quote Originally Posted by mtrycraft
    I am sorry abpout not explaining it enough.

    A 1/2 ohm or 1 ohm resistor in the red terminal of the amp to each channel in series with the speaker cable, left and right, 2 resistors, will give you the same effect as a tubed amp you are looking for, a mellowed upper end. Or, you could even experiment with the high frequency tone control bu rolling it off. That will do similar effect.
    Of course, if he wants to replicate the sound of a SET tube amp, this might not cut it. Any ideas on how to induce 3-5% even ordered THD easily? :-)

    As for resistors, I dont know of any cheap non-inductive resistors rated at adequate power for a typical amp(50-100watts/channel). I would recommend using Dayton generic non-inductive resistors; parralelling the units to equal the desired resistance but at a reasonable power rating(ideally equal to amp's rating). If he has a 50 wattt amplifier, 5 parralelled 5 ohm resistors(10 watts per unit rating) per channel will be ideal. The 10watt resistors at the following address are only $0.98 each when you buy 4 or more:

    http://www.partsexpress.com/webpage....ctGroup_ID=345

    -Chris

  6. #6
    RGA
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    I find it odd that people are making certain assumptions about tube preamps. Stereophile reviewed one that supposedly measured flatter than any opther preamp of any design going if memory serves - even getting the anal Measurer to want one.

    SOME tube preamps roll off highs, SOME tube amps require a healthy warm up...MOST are ready to go within 10 seconds of being turned on many extend out 100khz and dig down to well under 15hz...are more linear and have better "types" of distortion. Add to this a whopping 200watts per channel from some of them - the myth of tubes today is rolled off highs and flabby bass...you can certainly find ones that still do that...but not as many. Best of all the tube amps are starting relatively cheap when you consider the build quality is about 10 times that of the plastic piece of crap receivers they dole out for $3,000.00.

    Be sure though that you're not buying tubes JUST because they look cool. Certain tube amp makers still make tubes with that softer sound so be sure that you're going to like it long term. Some of them seem to add a bit of emphasis to the midband (to a tube fan they view it as digital sucking the life out of the midband). Since reproducing live is impossible and there is no such thing as perfectly accurately you can A try and get close or B find somehting most pleasing. Occasionally that is tubes occasionally it is SS. I tried the resistor and it sounded nothing like a tube amp...though I have not heard tube amps from the 1940s and 1950s - I have heard ones today...even SETs that with matching speakers no one hear would be able to tell that the bass wasn't being run off ss krell and there was no hum or any noise and extension was well beyond my hearing.

    But then perhaps some poeple know hoiw to do SET and some don't.

  7. #7
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    Blue Circle BC21 @$1600
    Rogue Audio 66LSR @$1400
    Remember, different isn't always better, but it is different.
    Keep things as simple as possible, but not too simple.
    Let your ears decide for you!

  8. #8
    DMK
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    The old Dynaco's rolled off the highs and flabbed out the bass. Some more modern ones do as well. Those are the crappy tube amps, IMHO. the good ones bring the live event closer to my listening room and have more detail than SS. Less grain and a more natural sound. And since we're talking preamps and not power amps:

    try www.audioelectronicsupply.com. Made by Cary, a well known and respected tube amp and preamp maker. Antique Sound Lab makes some nice tubed pres at your price point and less. The Conrad-Johnson PV-10A was ok but a little too much like what the folks above criticized - a little sluggish and mushy sounding. But it may be what you're looking for to fatten up your sound. That's about all the experience I have with tubed pres in your range except my first one, the Anthem Pre 1L made by Sonic Frontiers, was a great one at $1000 retail. If you could find a used one, it'll fit the bill nicely for you and it will go great with the NAD.

  9. #9
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    Quote Originally Posted by RGA
    I find it odd that people are making certain assumptions about tube preamps. Stereophile reviewed one that supposedly measured flatter than any opther preamp of any design going if memory serves - even getting the anal Measurer to want one.

    SOME tube preamps roll off highs, SOME tube amps require a healthy warm up...MOST are ready to go within 10 seconds of being turned on many extend out 100khz and dig down to well under 15hz...are more linear and have better "types" of distortion. Add to this a whopping 200watts per channel from some of them - the myth of tubes today is rolled off highs and flabby bass...you can certainly find ones that still do that...but not as many. Best of all the tube amps are starting relatively cheap when you consider the build quality is about 10 times that of the plastic piece of crap receivers they dole out for $3,000.00.

    Be sure though that you're not buying tubes JUST because they look cool. Certain tube amp makers still make tubes with that softer sound so be sure that you're going to like it long term. Some of them seem to add a bit of emphasis to the midband (to a tube fan they view it as digital sucking the life out of the midband). Since reproducing live is impossible and there is no such thing as perfectly accurately you can A try and get close or B find somehting most pleasing. Occasionally that is tubes occasionally it is SS. I tried the resistor and it sounded nothing like a tube amp...though I have not heard tube amps from the 1940s and 1950s - I have heard ones today...even SETs that with matching speakers no one hear would be able to tell that the bass wasn't being run off ss krell and there was no hum or any noise and extension was well beyond my hearing.

    But then perhaps some poeple know hoiw to do SET and some don't.
    Well, it that is the case, why is he looking for such an expensive tube pre in th efirst place? Use what he has now.

    There is only so much you can do with a SET amp, which is not much. Here, the car analysis is perfect, such as a very simple design costing a fortune. What a sorry excuse for an amp.
    mtrycrafts

  10. #10
    RGA
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    Quote Originally Posted by mtrycraft
    Well, it that is the case, why is he looking for such an expensive tube pre in th efirst place? Use what he has now.

    There is only so much you can do with a SET amp, which is not much. Here, the car analysis is perfect, such as a very simple design costing a fortune. What a sorry excuse for an amp.
    Some companies do a lot with SET amps. 30 watts too.

  11. #11
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    Quote Originally Posted by RGA
    Some companies do a lot with SET amps. 30 watts too.

    And it will still remaine a SET amp, too simple for a complex job.
    mtrycrafts

  12. #12
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    Quote Originally Posted by simonleemd
    Hi, I need your suggestions for a good tube preamp for teaming up with my NAD C370 Amp. I like to have a warm,soft ,full-bodied,and GOOD bass sounding preamp at around
    $1600
    Thanks in advance
    Simon
    Isn't the NAD C370 an integrated amp, which already has a built-in preamp? Although I like tubes, I would question spending three or four times what the C370 is worth for an additional preamp, unless I planned to eventually upgrade the amp.

  13. #13
    RGA
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    Quote Originally Posted by mtrycraft
    And it will still remaine a SET amp, too simple for a complex job.
    Another duped by the manufacturer's jargon. I suppose a DBT proves that no-one in the world would take SET?

    SET is linear - SS is not. Interestingly the coveted THD doesn't seem to impact the listening either...coincidence I think not. Though I have only heard two SET amps...the second until they told me it was a SET I may as well have been listening to a Bryston - except with the etch.

  14. #14
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    Quote Originally Posted by RGA
    Another duped by the manufacturer's jargon. I suppose a DBT proves that no-one in the world would take SET?

    SET is linear - SS is not. Interestingly the coveted THD doesn't seem to impact the listening either...coincidence I think not. Though I have only heard two SET amps...the second until they told me it was a SET I may as well have been listening to a Bryston - except with the etch.

    Not at all. Set has a mellow sound that some do like, just like daydreaming.
    Set linear? Hardly with all the distortion and FR irregularity.
    mtrycrafts

  15. #15
    RGA
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    Wow which SET did you test that sounds mellow...with every speaker available? No exceptions? http://usuarios.uninet.com.br/~edelima/REASONS.htm

  16. #16
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    Quote Originally Posted by RGA
    Wow which SET did you test that sounds mellow...with every speaker available? No exceptions? http://usuarios.uninet.com.br/~edelima/REASONS.htm

    Why test? It is a given. One only has to look at the specs.

    Plus, let's not forget what the output transformer does to frequency response and how much it follows the speakers FR due to that output impedance.
    mtrycrafts

  17. #17
    RGA
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    Interesting Stereophile just did a review of tube amp with a dead flat frequency response throughout and beyond the audible range.

    Integrated SE tube amps from ASL are 23Hz-27000Hz 1dB - and this is not a particularly high end make under $1k. Distortion is typically high for SET rated <2.5% at 1watt and rising to <5% at full power. Of course most speakers and rooms will dwarf those figures - and it matters what kind of distrtion...the pleasing to the ear kind or the kind that SS doles out

  18. #18
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    I recently added a tubed preamp to my system, paired up with none other than the C370.

    Tubes do more than just make a "warmer" sound. IMO they bring life into the music, something no resistor would ever do all the resistor does is take something from the music not make whats there BETTER. The preamp i have is the Bottlehead Foreplay, its a kit that you have to build, or you can buy one and have it built for you for an added 250 bucks. the base kit price is 150, which is a lot less than what your willing to spend, but does really add something to the 370 that the internal preamp lacks. rolled off highs and flabby bass is about the furthest thing from what i have with adding tubes to the NAD.

  19. #19
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    Quote Originally Posted by RGA
    Interesting Stereophile just did a review of tube amp with a dead flat frequency response throughout and beyond the audible range.

    Integrated SE tube amps from ASL are 23Hz-27000Hz 1dB - and this is not a particularly high end make under $1k. Distortion is typically high for SET rated <2.5% at 1watt and rising to <5% at full power. Of course most speakers and rooms will dwarf those figures - and it matters what kind of distrtion...the pleasing to the ear kind or the kind that SS doles out

    +/- 1 dB? Yep that is somewhat flat. What happens when you ad a speaker to it?

    Now why would a speaker distort 2% with 1 wats of power? You need to find better speakers. Not even the Velo suns do that poorly with 1 watts. Typically franctional levels as with speakers.
    Now, when you add lots of power, then it is a different story with speakers., 1 watt is nothing.
    mtrycrafts

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