Should I eliminate my preamp?

Many owners have complained about the sound of the Oppo’s balanced or SE output I can’t remember which it was.
But technically the ESS dac chip having a balanced output, would say to me that balanced should be the superior output, as to have a SE output another summing opamp would have to be introduced to change balanced back into single ended.

Cheers George

@elf1   I have been using my Audio Research tube preamp and Bryston amp to drive Magnepan speakers for years. Recently I added a Oppo blue ray player to my system and connected directly to my amp using the balance cables. The reason was to eliminate the signal having to go through another piece of equipment before it hits the amp. Am I wrong or what am I missing?

I am curious what you heard in this experiment? Whats missing is what you heard.!

I went from a tube pre to a passive to a direct connection.  The passive had more detail than the tube pre but sucked the life out of my system.  When I eliminated the passive (and the additional interconnect) the direct connection maintained the detail of the passive but had much greater dynamics and it was as though I removed multiple blankets from the front of my speakers.  I then changed my interconnects to unshielded and the sound further improved.  My tech recommended a "current amp" (actually a 0 gain custom built active preamp) - haven't tried it and not sure what that is...

marqmike529 posts04-09-2018 1:20amThat is real possible. Thanks

If you look at it technically, the VH 1st interconnect has not only capacitance, but resistance (very little, except for the Carbon they once had) and also inductance.
These three parameters "capacitance, resistance and inductance" are the three component (parameters)  that make up for the "crossover filters"  in speakers.
And by halving the length of your VH 1st to 1/2mt you've changed all three parameters from what they were at 1mt.

This could be the difference you heard??

Cheers George 

Just to update my own experimentation...I found happiness with an ARC REF 3 linestage, but only after I replaced the tubes with a spare set of new Sovteks that came with it.  The existing tubes were well within their life-cycle, but I did noticed it had the SED Winged C 6550 in the power supply, and there has been some reporting that the original ARC Sovtek 6550 sounds better, so maybe that was the difference.  I notice some good prices on Ref 3's, so I'm passing on my experience.

It was an educational process.  I came to realize how important words are to me, and I get deep joy in hearing the nuance in how an artist delivers the words.  That was the attribute that was so hard to find in swapping equipment, and what was lost in my specific instance when using DAC-direct or the solid state linestage that I tried.

Someone like Joni Mitchell can sound exceeding pure on many systems, but I can now hear how flawed she is, which let's me rejoice in her brilliance and humanness.  Of course, someone like Dylan can be endlessly appreciated in his voicing, inflection and phrasing, and my audiophile satisfaction is directly related to the degree to which it is revealed as a human voice in the room.

So the hunt for what a linestage can do was rewarding and recommended.

Cheers!

Elf1: "Most" balanced outputs almost always double the output voltage.  This is a good thing. Eliminating your preamp, if the preamp is in good internal condition, will sometimes make the final sound leaner and thinner. I would invest in a comparable preamp with balanced connectors. I think u will hear an improvement in your sound, i.e., a fuller more gutsy  sound,  while having more diversification at the same time. 

I do have a question regarding passives . The pot used in the SM Pro Nano patch I use I assume costs a few bucks . Would say a Alps volume pot have a different sound ? I would assume all passives should have a similar sound . Is there a way to alter the sound with a passive be it with different interconnects or like I mentioned different brands of pots?

@maplegrovemusic

The interconnect cable is going to make a bigger difference than the pot that is used. However, as the value of the pot used is increased, its quality becomes more audible. If using a 10K pot, the ALPs will work fine. You might want to run a nicer part if using a 100K part.

If your source is solid state, 10K is probably a safe value. If using tubes, check with the manufacturer, but often 50K will do the job.

I have two different Stax Electrostatic headphone systems.  My Stax SRD7SB/Lambda system is driven directly by my Rega Osiris integrated using an OPPO 205 by a half meter pair of MG Audio Design ballanced interconnects.  I have also added a one foot pair of MG Audio Design speaker wires between the Rega Osiris and the connecting wires of the Stax SDR7SB box for added fidelity.  My other Stax system is an SMR1-MKII/Lambda hooked up by again MG Audio Desgn single ended interconnects to the record out single ended outputs of my Audio Research LS 27 preamp.  Bothe systems, even though the Stax units are all about 35 years old but I have a sound reproduction from both of them can compete favoribly with much of these current top end regular headphone based systems.  Of course if I had the latest top of the line Stax headphone system and could run them into my LS27 ballanced it would be another story.  Oh yes, I use an OPPO 105 for my Audio Research LS27 system, which I use on my Martin/Logan speaker system.  The Audio Research/Stax SMR1-MKII total tube headphone system verses the complete solid based Rega Orisis.Stax SRD7SB systems both have different pluses and minuses>  Overall I prefer solid state 160 watts per channel Stax/Rega sytem for rock and roll, with the tube based Audio Research/tube based Stax system for everything else.  

That is real possible. Thanks

They do say the VH First has a sound of it's own, and is not neutral. Maybe what you heard is just that with the 1/2mt, less of it's house sound getting closer to neutral.

Cheers George

Nice post George.  You figured out all the specs of my system. And as I put my system together I tried to do as much of that as I could.  I wondered about capacitance of my cables, input sensitivity of my amp and so on. I think it payed off.
The dac I use in my main system is a moon 300d. It has a bigger power supply than the 100d I use to use. I did not have that on my virtual system. I just went on their and updated it since you mentioned it. Thanks.
Now the sound I hear is not a night and day difference. But easily noticeable for me, which means it may not be for someone else not familiar with my system. The difference for me was in not just hearing the music but feeling it a little more. I think it is the actual air pressure. Like when a vocalist gets their mouth close to a mic and you feel the air pressure of their voice a little more through the sound system that is being used. And I am talking about just a little more. Anyway I think people would enjoy a passive more if they make a passive friendly system.  Maybe my experience doing this help's someone a little.

chuckjonez19 posts04-05-2018 10:55pmThe first truly high end piece of gear I bought was a pre-amp. I couldn’t believe that change it made in my system. Without changing my midfi CD player or power amp, I was hearing a 3 dimensional sound stage for the first time, and a less brittle, much warmer and rounder sound. It excited me so much I rushed to purchase a high end power amp. It added bass authority and an even rounder more musical sound, but the soundstage magic was still a product of the preamp. I’ve been a preamp believer ever since, and would not consider using only a DAC with a volume control. That’s my limited experience.

Direct vs. Preamp - the basic question.  Seems to me that checkjonez figured out what he prefers and that is all that matters.  No one person here can say for sure as each system has many variables.  You can change the sound of any piece of equipment CDP, pre, amp by simply changing resistors, caps, etc.  You don't always have to chase a higher priced component.

I prefer a preamp, some may not.  To me it does not depend on the quality of the source, direct has a different presentation than a tube preamp IMO and in my system.  Which is closer to being real - that depends on what you prefer with your own ears.  I understand what checkjonez is saying.  Soundstage magic with his tube preamp.

Happy Listening.  

Since I've gone from tube integrated, to direct-from-DAC to tube amp, to solid state linestage, to classis ARC tube pre-amp, to newer ARC tube linestage, I've decided that....it depends. I have some speculations and experiences but few technical chops.

I do think a lot of linestages are tone controls that shape the sound, which is fine.  In that vain, I think Mark Levinson had it right with the Cello Palette, which allowed the listener to shape for speakers, room, and personal preference.  Someone should make a great modern version of this where you can store a few profiles.  Sometimes you need more cowbell, and sometimes you need Big Bottom.

But I'm still haunted by how alive the tricked out SP3a sounds and plan to give it another go.  Once you hear it, others seem veiled and more "recorded."  Less involving. I also think tube pre's can add pleasing even harmonics that is just nice to listen to.

It also seems that some tubed units create faster swings from soft-to-loud and a sound stops faster, producing more nuanced, lifelike vocals.  My hunch is that this relates to very good power supplies and associated circuits.

I'm still not satisfied, and may try Backert or Sachs, since I want those lifelike vocals without softening the bass.

Its always best for sound to have a preamp keep it and enjoy.

Your SP6 is not a very good preamp. My advice is to get a good more current preamp, something from at least the mid ninties as preamp quality took a giant leap at that time. As a general rule using a preamp is better than eliminating it even though this seems counterintuitive. If using a cheap preamp, eliminating one could produce better sound in some aspects but a good preamp will almost always be the route to better sound rather than eliminating one or for that matter using a passive one.

It really depends on how well the line out is on a unit. My Esoteric K-01 using the line out function is superb. It really shows how good the K01 is. But I need the preamp to power my sub which I cannot do without it. So a preamp gives you lots of flexibility, if I did not need that I could leave with the K-01 directly to my amp. In fact if I had full range speakers I would not need the sub and I would use the line out of the K-01. It's world  class. 

Looking at your very nice system
https://systems.audiogon.com/systems/2186

Your D100 dac is no problem at 2v and 100ohms into the Lightspeed. And that at 2.5kohms using the 1mt of VH First at  61pF/mt is -3db at 1mhz!!. And your Belles Ref 150A needs only 1.4v in for full output at 100kohm input impedance which is no problem.

Looking at all this you have a prefect match up I can't see how there can be a difference between 1m or 1/2m of the VH First???

Cheers George

Using a passive I know in my case that there is a real noticeable difference when I go from a 1 meter cable to a half of meter cable.

If you hear this difference in length, either your interconnects are high capacitance or your passive or source is high output impedance.

Cheers George

Using a passive I know in my case that there is a real noticeable difference when I go from a 1 meter cable to a half of meter cable. I has a fuller more complete sound when I use a half a meter cable no matter which the five brands I have to try.

I switched from using a DAC direct to my power amplifiers to a preamp and never looked back. The addition of a preamp substantially improved my sound quality st all levels. It was a “huge improvement”. 

However, as was stated above, it is possible that going direct maybe thd best but I do not know your system.  All my testing proved to me that a preamp, in my system, produced the best sound by a huge margin. You might have to test some combinations in your system to see what you like.

As as you can see from the above posts, everyone, it seems, has a different opinion.  If possible, j suggest you demo with and without a preamp and see what you like.  I did this testing and purchased a preamp. 

One last thing . I have had 30 pairs of speakers in the last 5 years and have noticed if a duller sounding speaker gets used with the passive it will sound dull . Add a active pre and that speaker wakes up a little . This might be why people prefer the active with their speakers . When Using a passive with higher energy speakers in the upper mids and treble and those speakers did not sound sterile or dull . All system dependent .

I do have a question regarding passives . The pot used in the SM Pro Nano patch I use I assume costs a few bucks . Would say a Alps volume pot have a different sound ? I would assume all passives should have a similar sound . Is there a way to alter the sound with a passive be it with different interconnects or like I mentioned different brands of pots?  

I go back and forth with passive and active .One thing I have noticed using a $60 SMPro Nano patch volume controller with my all digital library is no recordings have that drive your ears to bleed like active preamps can have . Must have had a dozen or so actives in recent years , Certain recordings were improved with added bass and treble from a active , but more recordings sounded bright . Used to think it was the recordings when in fact it was the preamp causing the problems. I still am bringing in active preamps as it is part of my hobby and is fun . It is nice to have another method to try that can sit in a closet and not worry about the price while its not being used .

alfa10069 posts04-07-2018 8:01amI do not have a preamp. MSB DAC direct into Pass Labs power amp. Previously it was Wadia DAC direct into Pass Labs power amp. Tried many preamps and always preferred no preamp.

Yes if you have a great source/s as you have had, this always seems to be the outcome.

If your source is not so great and needs some sort of colouration’s (tonal changes) to make it listenable, then a band-aid fix with a preamp can make things better, but picking the preamp with the right tonal colouration’s to fix the source is always a mine field, as all preamps sound different.

In my view it’s best to fix the problem (source), not to throw a band-aid on it.

Cheers George

I do not have a preamp.   MSB DAC direct into Pass Labs power amp.   Previously it was Wadia DAC direct into Pass Labs power amp.  Tried many preamps and always preferred no preamp.   

It also explains why some folks report that using different interconnects makes a big difference in sound quality while others don’t hear a difference.

You welcome, and correct, always use quality low capacitance interconnects, with passives and you’ll get the closest to the proverbial  "The best preamp should sound like a piece of wire" sound.

Cheers George

George, Ralph, thank you both for taking the time to explain the math. I had to read them twice to understand the details but it does make a lot of sense. It also explains why some folks report that using different interconnects makes a big difference in sound quality while others don't hear a difference.

What Ralph mentioned about coupling caps above is not relevant these days, as nearly all solid state sources have been direct-coupled for years,

This statement is false, on account of the fact that a lot of solid state equipment does use coupling caps. Some does not- and then your chances of successful passive operation improve.

It's always been said by audio designers as a gauge of how good a preamp is since the mid 1900's, when separates (preamp & poweramp) entered into audio, that saying is:
 
"The best preamp should sound like a piece of wire"
 
ie: a like a direct source to amp connection.  

Just because one might want it to seem that way does not mean that is what it should be. Interconnect control is why so many people on this thread have had success with active line sections.

The bottom line is care and audition is imperative if you want the best out of the investment dollar in your equipment!

Never get rid of your pre amp , You want the best ? Go with BAT Balanced Audio Tech.

The advice given is good.   If your inputs are limited to one and that is the digital input with variable output, you have nothing to lose by using it instead of a preamp, unless the digital volume control were noisy for some reason.

I have one preamp, original cost $5000 (which would be around $10K today) sitting in a third system, just because it has a very good dual volume control with discrete high quality resistors and a switch. The fancy dual phono stages etc. remain unused.

Wonder if someone has done an A/B between something like that and a CD player digital volume control.......

Why not go to a high quality integrated amp and forget this whole discussion?  I went to a 300B amp and I've been very happy with the results.  Before that I had Maggy 20.1 panels, Manley Neo Classic 250 tube amps, and a Prima Luna Dialogue tube preaamp.  My source was a Berkeley DAC (with volume control). For grins I connected my Berkeley DAC directly to the Manleys and I was shocked that I preferred that sound to the preamp!  But I like the 300B sound even better.

It's always been said by audio designers as a gauge of how good a preamp is since the mid 1900's, when separates (preamp & poweramp)  entered into audio, that saying is:
  
"The best preamp should sound like a piece of wire"
  
ie: a like a direct source to amp connection.  


Cheers George   

As a long time (>20 year) user of and believer in passive line stages / removing active line stages, the answer is a big "it depends."   I.e., it depends on the output impedance of your source, the overall quality of the output stage (including both volume control mechanism and current delivery) of your source, the capacitance of your interconnects, the input impedance and sensitivity of your amplifier, and (of lesser importance) the sensitivity of your speakers.  Beyond that, I don't see enough information about your components and system to give a more definite recommendation.  I own an older Oppo (BDP-83se), but don't believe it has output volume control; however, my general impression is that I don't think the output stage is of the quality that I would necessarily prefer a direct drive sound.  By contrast, some of the aftermarket Oppos that significantly upgrade the output stage are suitable candidates for direct drive to the amplifier.

I most certanly prefer my Audio Research LS27 to no preamplifier by far.  In fact if I play my 35 year old or so Stax headphone system thru the record out of mt LS27 instead of the audio source directly in the audio reproduction is extremely better thru the tube LS27.  It is not just a minor improvement in sound quality.  Whatever audio source is used, say even my OPPO 205 as well as 105, the addition of a fairly recent Audio Research tube preamp will be the best choice.  By doing so a quality close to40 year old Stax headphone system can actually compete favorably to some of the recent expensive planer magnetic headphones of today.  For a fraction of the cost.  That is what a true quality tube preampkifier can do for an audio system.  It is simply someting one has to try out for themself.  Recently Paul McGowan of PS Audio said the same on his own current top audio systems.

The first truly high end piece of gear I bought was a pre-amp. I couldn’t believe that change it made in my system. Without changing my midfi CD player or power amp, I was hearing a 3 dimensional sound stage for the first time, and a less brittle, much warmer and rounder sound. It excited me so much I rushed to purchase a high end power amp. It added bass authority and an even rounder more musical sound, but the soundstage magic was still a product of the preamp. I’ve been a preamp believer ever since, and would not consider using only a DAC with a volume control. That’s my limited experience. 

You may think at first that you're hearing a more transparent signal but a preamp properly matches the impedance between stages and provides more muscle (better dynamics) in the long run if it's a fairly good pre which it sounds like you have. You will get more dynamics and you won't be as susceptible to roll-off of high frequencies. The pre-amp is more than just a handy switching device, it provides an easy load for whatever you plug into it and outputs a lower impedance which will make the amplifier happier than if you just plug in a source device.

Willemj- how do you know what an album is supposed to sound like? Are you telling me by bypassing a preamp you are closer to the master? If you like vinyl these guys will tell you their master is more realistic. 
There are many reasons to go thru a preamp:
1) if your dac/cd player is solid state, you might want to go thru a tube preamp that front end solid state amps
2) you might want to upgrade to an external dac, add a tuner, turntable phono preamp, etc...

Bring home a couple of good preamps and compare them to your direct connect setup

If you have a solid state source like a CD player, quite often it has a coupling cap at its output

What Ralph mentioned about coupling caps above is not relevant these days, as nearly all solid state sources have been direct-coupled for years, only tubed sources may have this problem as they have a caps on the output.
But below tubed preamps have this problem at the other end of the system with some of today's low input impedance amps.  

All is not good a match with 99% of tube preamps with  low input impedance amps these days, many Class-D's, some First Watt's, some Pass Lab's and many others.

The coupling cap that's needed on the output of 99% of tube preamps can be too small for these amps I mentioned, which can be as low as 10kohm input impedance. 

This is not a good match and will roll off the bass very early, to the point of owners saying this "tube pre has little or no bass".
  
To fix this one can change the cap for a much larger uF one which can be a fitting issue in itself or revert to a not so good sounding bi-polar electrolytic cap which will be small

Cheers George 

Yes, but the OP asked about using a DAC with volume control as a low impedance source to drive the interconnect to the amplifier. There is no passive attenuator in this scenario, and from an engineering standpoint no need for the preamp. The people arguing for retaining a preamp are arguing that they prefer the sound of the preamp. That may well be, but it is not more electrically accurate. The preamp is providing a subtle distortion that sounds pleasing to them. 

"I can give you the maths if you want."

An offer that is hard to refuse, if not too complicated for my pay grade...

Here is some additional math:

With a 10K pot in series with the output coupling cap, a timing constant is introduced.

The formula for a timing constant is this:
1,000,000/Resistance x capacitance x 6.28 = F

Resistance is in ohms, capacitance in microfarads, F is frequency in Hertz and 6.28 is Pi x 2.

If you have a solid state source like a CD player, quite often it has a coupling cap at its output (probably an electrolytic capacitor). Depending on the designer's expectations, the cap is probably between 1uf and 10uf. But without knowing that, if we do know the amplifier's input impedance which has to be included, we have enough information to draw some conclusions.

If the amplifier input impedance is 10K (worst case scenario) we can see that the timing constant is raised an octave if the volume is all the way up. Depending on the design, this can introduce phase shift in the lower frequencies, which is perceived as reduced impact.

At volume control settings at less than full volume, a series resistance is introduced by the control. This effectively raises the output impedance of the source as far as the amplifier is concerned. To reduce the volume by 6 db, the control is at mid position, with 5K driving the output and 5K to ground. The series resistance thus introduced with such a low impedance load of 10K at the input of the amplifier can be audible as a reduction of dynamic punch at all frequencies.

Now the reason I mentioned the formula is that with different controls, the timing constants are different. Sometimes it works out well and sometimes it does not. But in all cases the interconnect cable is uncontrolled by such a high output impedance so its artifacts will be much more audible than if driven by a lower source impedance.

So audition is important- and its important to remember that while it might sound alright with a passive, it could well sound better (less colored for the reasons stated above) with an active. If you spent some money on the amps and speakers, it seems a shame to me to not get the most out of them.

This is an example of you get what you pay for. 

A good preamp as DSP? A joke.

I like 10kohm pots as passives, as the can be driven by just about any solid state source, just some high impedance tube sources have trouble, and being 10kohm as a voltage divider passive they have the lowest output impedance at worst (mid possition) around 2.5kohm.

With 2mt of poor quality interconnect with high capacitance at (100pf picofarad per ft) that 2mt is approx 650pf total

6.28 (2 pie) x 2500ohms (2.5k) x 650 (650pF) ee to the -12 1/x = gives a very respectable -3db point at 98khz! and this is the worst interconnect at 2mt at the worst mid volume setting.

So as you can see driving the capacitance of poor quality 2mt interconnects with a 10kohm passive at worst volume mid position of 2.5kohm Z is not an issue at all as we are at only -3db at a still very high 98khz!

With one meter of that same interconnect, it becomes -3db at 196khz!!

With one meter of better quality interconnect which has only 50pf per foot then the -3db is at 392khz!!!!   

Cheers George

"I can give you the maths if you want."

An offer that is hard to refuse, if not too complicated for my pay grade... 

The OP was asking about getting rid of the preamp in the case when the DAC has a volume control. In that case, there is no downstream volume control, and no need to provide a low impedance buffer for the interconnect, as the amplifier will take care of that.

This is correct, and the source having a digital domain VC it will have a low impedance output, probably lower than many preamps especially tube ones, and it will drive any interconnect just as well if not better.
Besides, driving interconnects with a 10kohm passive is not an issue either, unless the interconnects are"low quality high capacitance" and are 3mt or more long. I can give you the maths if you want. 

Cheers George

The OP was asking about getting rid of the preamp in the case when the DAC has a volume control. In that case, there is no downstream volume control, and no need to provide a low impedance buffer for the interconnect, as the amplifier will take care of that.

Any preamp will add frequency response anomalies and distortion. You may prefer that sound to the unmodified signal, but it is good to be honest (as most of the posters in this thread have been) about what is actually going on.

One of the most misunderstood tasks of any good preamp line section is to control the interconnect cable. This reduces coloration, which is often heard as an overall thinness and loss of bass impact.

Passive controls often have the issue of effectively raising the impedance of the source by putting a resistance in series with that source. This can often have the effect of acting as if a smaller coupling cap is used in that source, causing a loss of bass impact.

A buffer for the volume control (at the very least) is required; that buffer also has to control the interconnect cable, so in practice many preamps reduce the colorations described in several previous posts, with a much smaller coloration introduced by the line stage- a net improvement overall.

Although I've been rationally inclined towards simplifying a system as much as possible for the "purest" sound, personal experience has shown me that inserting a GOOD preamp between a source (w/volume control) and the amp often resulted in better sound. 
Since I listen to music instead of theory, measurements or specs, I keep the preamp in the system.

Any DAC or digital front end I've ever used as volume control simply,and I've owned some expensive ones,doesn't have the rich fullness of a top tier tube pre amp.

phomchick

Any preamp will add frequency response anomalies and distortion

Quite so. But with the best preamps, those levels are far below the threshold of audibility.

The theory is correct. Any preamp will add frequency response anomalies and distortion. You may prefer that sound to the unmodified signal, but it is good to be honest (as most of the posters in this thread have been) about what is actually going on. Sometimes I enjoy the listening to different DSP settings in my Yamaha A/V receiver  :-)