Hello,
I'm new here and would like very much to add my experience on this subject.
For 15 years, I had a variety of powerful, well-maintained high-end vintage SS receivers (marantz, denon, akai) hooked up to my PMC DB1 speakers and my SVS SB1000 subwoofer. Music was played out of the 3.5 mm line out headphone jack on a mac mini. I thought the sound was really good, but never great.
For reasons unimportant to the discussion, I decided to sell my vintage SS receivers and purchased an NAD C268 power amplifier. Again, I played music out of the headphone jack of the mac mini. No preamp. I WAS ASTOUNDED BY THE QUALITY OF THE SOUND. Literally speechless. I had NEVER heard anything like it, and I have been around a long time. I heard so much in songs i had played for years and never heard. Not only was I impressed by what I had never heard before, but I was completely impressed at all the nuance that was in many recordings. I can't impress enough at how astounding the sound is.
I thought to myself immediately, there is no way I can better this sound! But, then I said to myself "maybe i CAN better the sound"! I thought that I might be able to better my sound with a quality preamp and a DAC. So I spent weeks reading, much of it on this site.
I decided to buy the NAD C 165BEE preamp for $1000. I thought it would pair nicely with my new NAD amplifier. In short, the sound degraded considerably and went from astounding to good/muddy, just like my SS vintage receivers. I really wanted to spend the extra dollars for the preamp and looking for any excuse. I packed it up and sent it back THAT DAY. There was simply no comparison whatsover. Many songs told the difference. The bass at the intro of "Baby did a bad bad thing" by Chris Isaak was so ill defined compared to without the preamp as well as the highs and cymbal sounds and crashes. SO, I have no idea of the voltage of the mac mini's 3.5 mm line out or impedance, but it is MAGICAL straight into the power amp without preamp.
Next, I thought maybe an outboard DAC would improve the Apple mac mini DAC. After reading, I went with the Behringer DAC and the Schit Modi 2 and tried both, again, straight into the power amp without preamp, and bypassing the mac mini DAC. Both were hooked up via USB. Immediately, I heard a sound difference with both DACs. The highs were more separated an emphasized with both DACs, but the sound was harsh and artificial and the mids and full natural sound were missing! The mac minis DAC was indeed spectacular in the extremely listenable natural, yet full sound coming out of it. Both DACs were returned that day. I believe that DACs that "enhance" the sound do so at their own peril. I want no coloration and my guess is that that is exactly what the apple mac mini DAC provides.
So, for me anyway, whether it was the luck of my particular setup or what have you, a preamp took me from magical sound to good and remarkably mediocre sound compared to straight to the amplifier and the sound difference degradation is HUGE and easily verifiable. Lastly, a DAC worsened my sound by making it harsh and grating, by emphasizing the highs probably at the expense of the mids (sort of like when I used to turn up the high freqs on my equalizer when I was a teen), losing the natural and gentle sound that came from the mac mini DAC. Many will say that the DACs I chose were not expensive, but the Behringer has been compared favorably with the Benchmark DAC by a very experienced engineer. But, maybe a $2,999 DAC would do the trick, but I highly doubt it and I don't want coloration to my music anyway, I want faithful reproduction.
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I use a passive attenuator. I see George saying what matches well with such a control in a system. I would like to say that I think in my system I benefited from a source that has a more robust power supply in it. Not more volts output, but a larger supply. But I don't know why. But it sounds better than a very similar (moon d100 v moon d300) source with a smaller power supply. I can't say for sure but I think the power supply might be largely responsible for a more natural, noticeably fuller, less lean sound. It has me thinking that everything in a system effects how that passive works out well or not. To a larger degree than a system with a active. So maybe after you get the full signal to the amp with the least amount of electronics in the path of it, it can show it's magic. |
every time I have tried a Dac with a volume control, it did not sound as good as having an actual preamp in the system. Granted, I have only tried it twice, but as others have said it would depend on the system. of course these days there is DAC/peramps and Preamps with built in DAC, Intergrateds with DAs ect.. Lots of options and many ways to get the sound you want. |
We really ask alot of that litle potentiometer in that preamp of ours. We put the whole audio signal through it and ask it to attenutate just what we want, just the way we want it too. We want it to bring us the emotion, without any distortion. We want to be able to hear the quiet, and unravel the loud. That is a tall order and you really (REALLY) need a higly resolving preamplifier (unless you have an aeris, etc, ie a dac that has some real archectecture behind the volume control)to pull it off. Some live perfomrances can benefit from a good preamp. |
YES it is the heart of your system |
Any input impedance is "compatible" ie it will work. Its more a question of how well. The 10X rule is commonly cited. That's a reasonable approach, the challenge being that impedance can vary widely at different frequencies and a single output impedance rating may not reflect the worst case, so I think it best to include some tolerance as an insurance policy whenever in doubt.
47Kohms is most likely a good match in general. I would not be concerned at all if everything else looks good. I cite 60kohm merely as a very safe number to go by in most any case based on what the vendors seem to commonly go for when designing towards the goal of compatibility with tube pre-amp gear. Higher input impedance is pretty much always as good or better for best results in regards to low distortion, detail and dynamics. |
Mapman, then does that mean if my solid state amp has an unblanced input impedance of 47K ohms that it is not compatible with a tube preamp? |
When researching SS amps to go with my current ARC tube pre-amp, I found a surprising # of leading contenders otherwise with 10Kohm input impedance or not much higher, especially older models. The trend in more recent years might be different,perhaps due to popularity of tube pre-amps with audiophiles.
Most that mentioned design for use with tube pre-amps tended to be in 60-100kohm range, unbalanced, double that for balanced. |
Yes, George, John may well have stated that. I gave up believing everything I read in Stereophile decades ago. If a tube amp the input impedance can be set almost arbitrarily but most manufacturers go with 100K and I have seen some that are as high as 1 Megohm.
For solid state, 10K is usually the bottom end of the range and 100K is the highest, most likely an amplifier with FET input. Dynaco built their PAS3x to be able to work with 10K. ARC OTOH does not expect to see less than 30K with their preamps. We build our 2 bigger preamps to be OK with 600 ohms and our smaller preamp is good down to 10K.
Bottom line is its all over the map, Stereophile notwithstanding. |
I do have to say I have purposely picked out matching components that support and complement my system with a passive attenuator. We can't get away from things being system dependent I don't think. I have heard some great sounding systems with active pre.'s. It seems to me I can hear extra electronics in my system when I put in more that I have. I am probably delusional but that's ok with me. I like the less is more if I can make it work. And it has worked really well for me. |
For years I used a Preamp. Once I bought the PS Audio Direct Stream Dac and sent the output to my BSG QOL and then to my Amp, I sold my Preamp. |
I believe even in Stereophile John Atkinson states 47k-51k input impedance has been an unofficial input impedance standard now for over 50 years for most home audio S/S products input resistances. Since it was made the standard for MM cartridge loading way back and they followed suit with preamp and poweramps at 47k-51k.
Tube amps have even higher up to and higher than 100kohm which is even better for higher value passives like 20kohm ones.
As for the very few amps that are 10k that many tube preamps won't drive, they constitute probably less than 1%
of the market share.
Cheers George |
Marqmike, I would think first your power amp has enough gain
for a passive preamp to work very well, this would be a very
important thing. Second you must have a very good quality
passive preamp, passive preamps like active are not all
created equal. I have had high quality amplifiers that they
could carry an inferior preamp and vice a versa. Get both
right and your in for a treat. A few years ago I owned a
McCormack DNA-1 with a revision A which had plenty of gain
for a passive preamp coupled with an upgraded McCormack
passive preamp. It sounded heavenly, there was no lack of
dynamics, it was refined and transparent as hell. I miss
that combination terribly because I never thought of looking
at another active preamp with this combination. |
"I really do as it sounds much better if you have a great preamp as i do."
OK, I will ask: Ebm, what preamp do you have? |
Out of a 4V source, I have heard a Goldpoint resistor type passive preamp sound pretty good into Class A, SS monos with 100K ohm input, but still lacking depth and dynamics compared to the same amps played through my preamp, which is buffered with no gain. Into NC1200 Class D amps, the passive preamp sounds very clean, and delivers close to the same level of dynamics as I achieve through my buffered preamp. However, through my Class AB SS stereo amp with 10K ohm input, the passive preamp sounds terrible.
I also have a pair of balanced Endler attenuators, which connect directly to the amplifiers so there are no cables required after the attenuators. I cannot discern any significant difference in dynamics between those and the Goldpoint passive, from which I use a1M cable into the amps. |
George is mostly correct here, just watch out that some solid state amps have a 10K input. 47K is not a standard. |
Mapman is right with proper mating with passives. And as I have stated many times. If you decide to give a 10kohm passive a try, such as the very affordable $49.00 Schitt SYS passive pre. http://schiit.com/products/sys-passive-preamp, the only proviso to look for to give them a great match are. 1: Interconnect to power amp to be low capacitance (<100pf per foot) which most good quality one are, and 3mts or less long. 2: Tube output sources can be a problem if higher than 1kohm output impedance, solid state sources are normally never a problem. 3: Input impedance of the power amp should be 33kohm or higher, which most are (47kohm being the standard). If you have these, which 99% of systems are, then you can reap the benefits of the transparency and dynamics that a passive will bring to your system. Cheers George |
The problem you are usually facing with passive controls is the interconnect cable. An active line stage will usually be less sensitive to the cable. In fact if done right, the active line section will control the cable so well that it will have no sonic effect at all.
Passives OTOH require that one be very careful about the cable. Some passives are lower values, such as 10K, which make them less cable sensitive but then you have the problem that not all sources can drive the 10K properly.
I have presented some of the math about why passives can put you at a disadvantage elsewhere on this site, and the math shows that the quality of the control has nothing to do with it.
This is not to say you can't get a passive to work quite well, just that you do have to be careful and results vary quite a lot. Generally speaking though, it means short cable runs.
'Just get it right' is indeed excellent advice. |
Its all about synergy as usual I think. Passives make sense to me if properly mated to suitable sources electronically. That might even be one of the best ways to go if done right, at least from the "purist" point of view, a simple signal path that mates well to gear upstream.
What's not to like?
Mating of active pre-amps, especially tube gear, opens up a similar but different can of electronic mating issues to address. Plus the preamp itself becomes more of a potential sound tweak.
There are so many ways to tweak and do it right. Active/passive, who cares really? Just choose your paradigm and do it right! Passive pre-amps offer a different way to do things. Options are good. Just get it right. |
Marqmike, I have always seen it as a statement of how bad many active line stages must be for a passive to beat them. I can't use a passive in my system- the result would sound broken- no bass, no impact. The active preamp I use has more detail as well.
So much depends on setup! My interconnect cables are fairly long, something that is not a good idea with a passive. I find though that by keeping the amps by the speakers and the speaker cables short that I get a lot more resolution. The front end equipment- preamp, tt and digital, reside on an equipment stand that is located in a room nadir where there is the least bass. It is also not too far from my listening chair. |
I use a passive and have for about 25 yrs. I have never really wondered much why it sounds good to me. I have had and listened to new and older ss and tube pres in the 2000-8000 range. And I always go back to a passive. I have heard systems with passives sound really bad, much like has been described by others. I just had a thought and maybe this has been considered before. I know the passive does not introduce much of a coloration but because of its lack of a gain stage it may lack some control over the signal which could and probably does effect the sound. But I think more than that the passive seems to revel what else is in your system. Before and after it. And when a passive is introduced and the sound leans out or is to clean or other negative traits it maybe that the equipment it is put in the system with may not be up to working well together. If you could begin by getting the amp and/or speakers and/or cables or whatever that plays well with a passive or in other words with a component that logically couldn't do much harm to a signal but rather complement its sound you could really enjoy a passive in that system. And then that begs the question- Because a passive really doesn't do much to a signal is a lot of the equipment that is in our systems not very good sounding on its own? Not to be controversial, but I do wonder. |
the budget inclined may still want midrange ;) |
Even with a DAC capable of 10V output, in my system a preamp provides more bass power, dynamics, and detail. Up until a month ago, I've found that passives may be cleaner than actives, but to varying degrees lean the sound and lose some of the power of deep bass.
That was until I tried the Tortuga LDRxB preamp. It uses light dependent resistors (LDRs) to both switch between inputs and to provide attenuation. It has all the deep bass, power, dynamics, as well as delicacy in the mid/treble of the best active preamps I've heard. It also has a self-calibration feature that the user can run to maintain long term impedance tracking channel.
A Constellation active preamp that uses LDRs for input switching and volume control sells for $65K. The Tortugas are $1500 or $2400 for the SE or balanced versions. |
you can find great sound with either methods . For the budget inclined it is not necessary . Just do not need to get newcomers to this hobby thinking that they need to spend huge amounts of money on a preamp to get great sound. |
When I mentioned to my dealer that I would try my CD player preampless into my amps, he told me I would probably lose a little midrange. 2 years after living with a preampless system, I added a preamp. Dealer was right. I was robbing myself of some pretty sweet (missing) midrange. I dont think anyone should make the decision to go w/o a pramp w/o trying a preamp. |
Robcentola hi,
Almarg (Al) is correct, technically, going direct and using the built in digital volume control of your Dac2, in my opinion will be the most transparent/dynamic way of getting the sound from your source to your speakers, without added colourations of a preamp.
If you find after doing it you would like to "voice " that sound a little, then for no cost you can position your speaker a touch differently
eg: toe them in or out a little, or move them closer or further from the back wall.
Or for some cost you can try different interconnects or speaker cable.
These suggestions are far cheaper than taking a punt on a preamp that costs $K's in the hope it has the right set of colourations for you, as they do all sound different to each other, because they all have their own set of colourations.
Cheers George |
I have generally found that a good active, well matched preamp can provide the drive a amplifier needs to show off its capabilities, not to mention you have the ability to switch between sources.
For an exception and laughs I purchased a Lepai Class D integrated amp (can be held in the palm of your hand) rated at 100 watts per channel, it uses a passive preamp and costs just over one hundred dollars new. After 400 hours of break-in it was astonishing how good it sounded and transformed itself. I thought it compared very well to some far more expensive components I own and I'm no longer laughing.
It is then 95% possible that the Benchmark DAC2 can be all you need, bypassing the preamp all together. |
In this particular case, given the relatively low output impedance of the DAC2 series, and given the 32 bit processing that is utilized in the digital part of its "hybrid gain control" mechanism, and provided that none of your sources are phono cartridge/phono stage combinations providing particularly low output (gain does not appear to be specified for the analog inputs of those DAC2 models which provide analog inputs), you don't "need" a preamp, at least from a technical standpoint.
As many of the others have indicated, though, whether or not you would find incorporating a preamp in the signal path to be sonically preferable is not predictable with any certainty, as it is system dependent, listener dependent, and perhaps even recording dependent. It might even be dependent (in unpredictable ways) on whether or not the power amp you settle on would be driven by the DAC2's balanced or unbalanced outputs.
Personally, my instinct is to place the burden of proof on adding anything to the signal path that might not be necessary. And my suspicion is that while a high quality active preamp, especially one that is tube-based, would more likely than not enhance the sound quality of your system, obtaining that enhancement to a meaningful degree, and without introducing unwanted side-effects, is likely to cost significantly more than the sub-$2K price you will be paying for the DAC2 itself.
Good luck, however you decide to proceed. Regards,
-- Al
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How can a preamp better the input signal from a DAC or anything else? Wouldn't this be classified as "Coloration" since it must alter the original sound to be "Better?" Of course better is in the ears of the beholder.
I use a Benchmark DAC 2 HGC running balanced Audioquest Sky cables.
I also have another pair of Sky so I could experiment with this very thing.
I think going through an extra set of interconnects affects the sound in and of itself. My reference is taking the DAC straight into an Aesthetix Atlas driving a pair of Vandersteen Quatro CT's. I have tried the ARC REF 5 (my normal preamp before this computer audio experiment) and there's a slight decrease in resolution with a slight added tube coloration when it is in the loop. Some would probably call this better sound but it is a definite coloration to me. Guess you go with your own ears but just my take. |
What about the recording engineers of the world? Should they be eliminating gain stages? They in fact use them right? Fact is eliminating these gain stages does impact dynamics. High frequencies compress all together so you can hear everything at the same level. The background noise is just as loud as the voice etc...This is just an example of properly executed gain stages a their importance.
I have found the same to be true in a high end playback system. I have also heard playback systems without an active preamp that sounded good .... Just not as good to this set of ears. It is certainly subjective. |
grannyring
there will be pre gain stages on mics, guitar amps , ect. Not on the playback system |
Go into a studio and see they always have a pre gain stage ,..... Always.
Can certainly get good sound with a passive, no doubt. All about
preferences. No need for the active to be tube....just my preference. |
Another interesting amp to check into is the new Ampzilla from Wyred 4 Sound who bought the rights from Spread Spectrum Technologies. I believe it lists for $3000 |
Robcentola. I agree that it all depends on the system and equipment used and it is also personal taste at times.
Besides the Dsonic you should check out the new amps at NAD and Merrill Audio. One is $3,000 the other is $2,500 I believe, encase you are not aware of them. They both look interesting for the money IMHO.
Oh, I use my Veritas monos direct. But if I spent a lot of money (at least $8,000 and up) on the right preamp I could see were it might bring added enjoyment. |
I have found it is alot easier incorporating a passive volume control than it is to match a preamp to one's system .To say you need one to get great sound is ridiculous . Go into any recording studio and ask them what preamp are they using and the will show you a microphone preamp. Then you say no i mean the preamp . and they will look at you puzzled . A volume control is all that is needed . There are several on the pro market at all costs . Shiit Audio has one for $50 also . |
Interesting question. I'm a reviewer for stereotimes.com and I've been looking at the recent Benchmark gear. I requested their new AHB2 amplifier for reveiw which was developed in collaboration with THX. It puts out 100Wpc @ 8ohms and 190Wpc into 4ohms and has some of the lowest noise and distortion figures I've ever encountered for an amplifier. It is small and weighs 12.5 pounds (I think) but it is an analog amplifier although it uses a sophisticated switching power supply.
I plan on comparing it to my Rogue Medusa Class-D tube hybrid and my modified Dignity Audio 300B mono amps in another system.
The AHB2 has both standard binding posts and lower noise SpeakON speaker terminals. So I requested that Benchmark send a pair of SpeakON cables so I can hear them too.
Benchmark then volunteered to send their DAC2 HGC because of its very low distortion and because they know it mates well with their AHB2 amplifier. The DAC2 HGC is a small full featured DAC and preamp that features 5 digital inputs and 2 pair of RCA analog inputs as well as 3 analog outputs and a high performance headphone amplifier with 2 volume controlled outputs. It's quite a piece.
All this Benchmark gear is currently being shipped to me and I should have it in my house by the end of the coming week (although the review will take a couple of months to be written and published). I'm very much looking forward to my evaluation of the AHB2 amplifier. It may turn into a joint review with their DAC2. We'll see.
One thing is crystal clear: for the lowest distortion and lowest noise signal path possible the combination of the Benchmark AHB2 amplifier and their DAC2 HGC DSD processor/preamp will be difficult for any other company to match. |
Agree with Charles and Granny above (though not necessarily the 'tube' part). ;)
*Having tried few current most highly touted SOTA volume equipped DACs in my, and friends' systems, no matter their stratospheric costs, still clearly benefit from having a 'great' pre inserted in the chain. |
"It depends" is the best answer because it involves a lot of
factors including personal preference. Mentioned class D amps are in big
part based on modules that have low input impedance (for many Icepower
modules it is 10k). My class D power amp has additional input stage
increasing input impedance from 10k to 40k. I use it with Benchmark DAC1
direct, with great sound. I believe that additional component in the signal
path will always cause some loss of transparency but often can change
sound to your liking (in addition to impedance matching). No right or
wrong here |
You will have to listen yourself my audio friend. For me a great tube preamp is an absolute must and sets the stage for the whole system and experience. A preamp is not needed in terms of getting sound out of your system, but for many, a preamp is a sound quality must. |
Wondering this same thing myself as the benchmark and oppo have pre amp capabilities.
I had to sell my rig because of financial reasons and when I rebuild, I'd like to bypass a dedicated pre amp if possible.
On a side note, my last pre amp was a lightspeed attenuator which I loved very much. It's for sale at tmraudio.com if someone wants one for $200 off and no wait time. No affiliation btw, just tryin to hook up fellow a-gon'ers. |
Hi Robcentola,
Welcome to this site. You may not be aware that audiogon has a vast archive section. I suggest you type in active preamp vs passive and/or active preamp ve direct source connection. Rob , this topic has been discussed hundreds of times (or close to it) and you will get the same answers from both sides (you'll see). It will depend on the quality the given preamp and other system components. It will also depend on what type of sound you're seeking. There's no one best answer, you'll just have to actually "listen" and decide. Some active preamps are superb and will be an improvement and some will degrade your sound compared to direct connection. It just depends.
Good luck, |
I really do as it sounds much better if you have a great preamp as i do. |
The Ncore NC1200 Class D amps were the first I heard that sounded anywhere close to as good through a passive preamp as through an active or buffered preamp. With the D-Sonic you may meet your goals without a preamp. If you already own the preamp I would definitely try it both ways.
BTW, if your source is a computer, you can do room correction through your player, probably as a plug-in. |
As long as you don't need analog inputs or anything like DSP or room correction, you should be able to do this. I know that when I direct connected my Oppo BDP-93 to my power amp it sounded very good indeed... |
In terms of gain you don't need one. And having no preamp will make your stereo sound more lively but only a touch. What a tube preamp does really well amongst other things is allow you to voice your system. If your speakers have a benign impedance curve (if they're 8ohms nominal they probably do) the linestage in your preamp will have the greatest influence on the overall sound which is really handy; you can swap out relatively inexpensive nos tubes instead of endlessly buying new speakers, amps or sources trying to get the sound you're after. I try to get everything as neutral as possible apart from the preamp's linestage. So yeah, chalk me up one vote for a tube pre. |
In terms of gain you don't need one. And having no preamp will make your stereo sound more lively but only a touch. What a tube preamp does really well amongst other things is allow you to voice your system. If your speakers have a benign impedance curve (if they're 8ohms nominal they probably do) the linestage in your preamp will have the greatest influence on the overall sound which is really handy; you can swap out relatively inexpensive nos tubes instead of endlessly buying new speakers, amps or sources trying to get the sound you're after. I try to get everything as neutral as possible apart from the preamp's linestage. So yeah, chalk me up one vote for a tube pre. |
