Passive Pre Amps Are More Detailed Than Active: Or Truisms We Use In Audio

Folks like things in nice easy to digest packages, and prefer orderly generalizations that explain the world for them.

In audio we say things like

Class A SS is more detailed than Class AB

Tubes Are Warm, SS has stronger bass response

CD's/Digital files have greater dynamic range than vinyl

The one that is often used is passive pre amps and transformer based volume controls are more transparent than active pre amps.

Well like in anything in audio , it depends....in part on what amp is used...and what source is used.

For instance I recently acquired an H2O Ausio 250 Signature amp, and I have found it to be the equal or better of many a fine Class A or tube amp. It is special. However the designer recommends an active pre amp with it. So I tried a few, and have settled on a Plinius Tautoro. What I am finding is that I have a level of detail that has eclipsed any previous amp/pre combo I have owned. You cn hear so far into the recording, that subtle stylized embellishments to the playing can easily be heard, that vocal nuances are readily apparent, that note decay and attack sound far more natural than ever before, sticks on cymbals are distinct, and the silence between notes becomes part of the composition. In short, I have never had a passive pre and amp combo that is designed to work together give results as good as this.

I will say the Tautoro is a mighty fine pre amp, not sure if its world class, but it is a refined thoroughbred. This amp and pre amp combo is as fine as I have heard, and I continue to be tickled with what I hear as I move through my music collection. This amp and pre is a reference pairing for me, and I plan on keeping this around for a good long while.

Perhaps an active pre amp is not limited in the ways most of us think they are. But it can be funny ohwo things work out. I once had a Rowland Model 5 amp and Consummate pre amp combo. I compared an Electra Print PVA Audio transformer based pre to the Consummate, the PVA is a passive I have used with great success in many systems. I found no difference between the Consummate and the PVA, and that Rowland Pre sold for $5K new. Audio sure can be funny about how things work out.

Cheers
Mister Pig

 

I suspect the demands from a particular loudspeaker has much to do with the effectiveness of a passive switcher.

 

And how would that be? A bit more detail please ad i have not heard of anyone discusding pre amp and speaker matching.

Cheers
Mister Pig

 

The thread title presents this as an absolute whereas there are almost no absolutes in something as personal as hifi. So many variables between passives & actives that it is impossible to generalise like this & personal preference plays a big part. I have a passive/active combo that sounds exceptional....




-.....but perhaps only to my own listening preferences?

 

Passive preamp will work well if it uses a low resistance (10KOhm or less) pot, and the source component feeding it has a robust output stage. Also low capacitance cables, and/or really short runs, are needed on the preamp output. In this case, it's distortion free.

 

It may be efficiency or other factors. The added gain of many active pre's can bring noise and veiling with high efficiency speakers. In fact, recently Schiit has stated that the Saga could be a better match with high efficiency speakers than the more expensive Freya for that very reason.

 

I must have built dozens of passives.
They can deliver superb sound quality.
Without getting technical you have to match the pot to the power amp
In addition the source output impedance
Should be lower than the pot
Problem i found was, that my cd player and phono stage differed in output impedances, so performance varied.
All the same a very high standard.
Most active preamps are poor.
The Croft Vitale i am presently using
Outperforms the passive preamp
Comfortably.
There is no gain on line level. The tube

Acting as a buffer which matches output impedance
On reflection passive is a better option
Unless you find a true hi fidelity preamp

 

I have owned a few good passives, such as the Pass B1 and the Electra Print PVA, and given the right amp they work fine. However, the amp I have here has an input impedance of 8,000 ohms, and requires some gain. The designer states that an active pre amp is preferred, and from what I have heard I can believe that.

What I have found with the Tautoro is that this combo provides a sound quality that out distances many an amp/pre combo with passives that are designed to work together. Such as the PVA and 300DRD amps, or the B1 and F7.

In this case an active pre amp excels, and the sound quality in this pairing is better than what I have heard in many good passives.

Now I was an advocate of passive pre amps, following the accepted mantra of my amps needing only 2 volts of output to reach maximum output, of impedance buffering from transformers or active circuit, and my sources having low output impedance and 2 to 4 volts of output. Along with low capacitance cables. I checked all the boxes.

With that said, this active has every bit of resolution and clarity, has nuetral tonal balance, and does macro dynamic swings far better than the passives so.

Every system is different and has different requirements. For this one an active pre amp is the better choice, and that is the point of the title...that the truisms we often use to compartmentalize our hobby do not always hold true.

Cheers
Mister Pig

 

Yes! It's hardly that simple. Another example of a generalization is that DAC chip X will always "sound" a certain way. This ignores the importance of implementation, including the power supply, clock, & audio stages.

We are not buying tubes, transistors, or chips -- we are buying audio components, which we assemble into a system. Of paramount importance is the engineering quality of each component and their compatibility.

Thanks for bringing this up again, Mr. Pig.

 

Some of us building our own equipment are actually buying these things.

 

Well spoken.when i heard the Croft coupled to my Leak i know exactly what you mean and experienced the same as you.
I know a passive CANNOT add anything
So therefore must be linear the superiority of the active in THIS CASE cannot be denied.

 

In my experience a well matched passive preamp, is the most transparent option short of having no preamp at all. But being the most transparent does not necessarily equal the most detailed (or subjectively the "best" sounding inside of a given system). I am of the opinion that just as a good tube preamp can add a little lushness to the sound, that likewise some really good SS designs can sometimes exaggerate detail just in a way similar to how some high-res digital cameras can sometimes produce that "shaper than life" effect. And if you enjoy that effect (just as I enjoy my tubes), then go with it!

 

I had no idea there was a truism that passives are more transparent (whatever that means) than active linestages or preamps. I generally do not isolate particular qualities when I am listening to different gear so it is more a case of I prefer this or that and I take note of what my favored item does better. I've heard different types of passives, resistor passives, light dependent resistor passives, transformer volume controls and autoformer volume controls. Most of them sounded very good, but I would not say that any really stood out as being much better than well implemented active alternatives.

In a direct comparison of the Placette active (zero gain, includes a unity buffer) to the Placette passive linestage (same 126 step resistor ladder attenuator astheir active linestage) I preferred the active because it sounded more lively; I bought the active linestage.

A friend had a light dependent resistor passive linestage which sounded quite good in his very dynamic sounding system. Just for fun, we substituted a nice tube-based linestage (310 tube) and even the proud owner of the passive linestage was surprised at how much he liked the tube unit (very dynamic while still sounding smooth and musical).

I have not heard transformer-based or autoformer-based volume controls in any kind of comparison. But, in the systems I've heard these types in, I really liked the sound. The sound I heard was very dynamic and open, even at the lower volume settings. My issue with the transformer-based volume controls had to do with the limited number of steps available; the setting I wanted seemed to almost always be between the available steps. Also, very few transformer-based volume controls come with remote adjustment capability. The autoformer volume control had MANY steps, allowed for balance adjustment AND it was remotely controlled (from MyEmia).

In the realm of high end linestage/preamps, I am more inclined to go with active, tube-based units, and I am particularly fond of units that utilize output transformers instead of coupling capacitors (this does, ideally, require the use of an amp with complementary input transformers).

 

I have an Intact Audio (Dave Slagle) autoformer that sounds excellent in my system. And it has 1.25db steps so there’s never a problem wanting to find a level in between two steps. From strictly a sound quality perspective, I have to say I prefer the sound of my Emotive Audio Epifania which is an active tube linestage. It has just a slight bit more nuance and subtlety in the upper midrange and highs. But they sound surprisingly similar, so close that I usually use the AVC just for the simplicity.

Like most things audio, there are no hard and fast rules here. The particulars of a given system, and the sonic priorities of the listener, will give different results.

 

I have had the Tautoro powered up for 4 days now, and I noticed on day 3 that this pre amp settled in. What I have found at day 4 is that the sound has stabilized, and is not going through any changes. So I think I now have a complete understanding of what this pre amp does in my system. I know there are folks who think warm up occurs in an hour, or maybe a day, but from what I have heard with this pre amp is that its a few day process.

I know solid state electronics are boring to talk about, they are just a collection of resistors, caps, IC's, and circuit boards. They do not have the allure of glowing tubes, the joy of tube rolling, or heated debates on capacitors, the types of output transformers being used, or types of resistors being selected, and so on and so forth. Lets be honest, SS is drab, and there is not much to do with it but perhaps change cabling to it.

But the longer I listen to this pre amp, the more I appreciate it. Tonally its well balanced, its expressive in micro and macro dynamics, it gets overtones right, it gets space right. Perhaps the only thing I can quibble about is that the sound stage does not extend quite as far into the room as my previous integrated did. And perhaps this can be argued as an aberration. This replaced a Musical Fidelity NuVista M3 integrated, which was quite nice in its own right. But I find this combo of Tautoro pre-amp and 250 Signature amplifier to have better tonal balance, better low level detail, and less of an imprint on the music.

I am currently listening to a record from the Boarding Party, which is an old album from the late 60's. One thing that struck me is that I can hear tape print through, and with the same phono stage/table/cartridge I could not hear that with the Musical Fidelity. I could not even here this with the 250 Signature amp and an Edge SI-1M pre amp. Yet here it is with the Tautoro in the system. But the important part is the voices sound so real, the performers so expressive, and the music is engaging. I spent over a decade doing SET tube amplification and high efficiency speakers, yet this has more honesty in presentation than anything I put together during that time period. Now several of those rigs sounded good, and I enjoyed them, but this is simply closer to real and authentic sounding.

Cheers
Mister Pig

 

It has been my personal experience that most of the very best SS gear I have ever heard takes FOREVER to warm-up fully. Yes it all power on in an instant, but the sound can change for a day or more before it stabilizes. With such warmup sensitive gear, running it 24/7 is about the only viable option.

FWIW: I have found with my tube gear that I need to turn my preamps on a minimum of an hour before listening, and about 15 minutes for any of my amps to get the full sonic experience that I desire.

 

There are some interesting comments posted above. Salectric compared the Epifania linestage to Dave Slagle's autoformer volume control. I mentioned an autoformer volume control from MyEmia, but, I sometimes confuse their stuff with other items from Dave Slagle because of his involvement with MyEmia. I probably heard the same autoformer volume control as Salectric described. It is also interesting that he compared it to the Epifania because I own an Epifania too. I have a version of the Epifania that includes a remotely controlled stepped attenuator. I like the Epifania's sound--it is very vivid and lively sounding. I currently run a different tube linestage; I would not say one is better than the other because they have a different sound and different strengths. I prefer both to my other linestage/preamp, which is a solid state Levinson No. 32. The Levinson is an extremely versatile and flexible preamp, but, by comparison to the two tube units I own, it is a touch too much on the "polite" side (slightly less lively sounding); still, it is a great component in its own right.

I agree with the OP that solid state gear takes forever to warm up. That is why I keep solid state stuff on all the time (my music server/DAC is solid state). At least solid state stuff does not suffer as much from being kept on all the time as would tube gear. I would never keep tube gear on when not in use, but, the good news for tube users is that tube gear does warm up faster.

 

Larry,

My AVC uses the same autoformers that are in the MyEmia AVC (copper version) but are in a DIY case rather than the nice looking MyEmia enclosure. One advantage of that is mine is a hotrod version with no switching—just a single pair of inputs, the AVC, and a single pair of outputs.

 

Salectric,

I was sort of interested in the version that is just the "guts"--the autoformer, the remove control receiver, the switching, the logic controls, etc.--and I wondered if that could be incorporated into my linestage as a replacement for the motorized volume pot and the two Davin controls for manual channel balancing. I don't know about the specifics of the circuitry of my linestage, impedance of the existing pot, etc., so it would have to be someone else who would do the Frankenstein surgery; I am not technically inclined.

I do wonder how that might change the sound. I like the idea that transformers and autoformers convert voltage to current when increasing attenuation, instead of just throwing away the signal as heat, which might help with maintaining "drive" at lower volume levels (my system is good at lower volume as it is, but still...).

 

Larry,

You need to talk to Fred Volz about that. A few years ago he mentioned that he had built an Epifania with a remote control Slagle AVC and it was the best sounding Epifania yet. As I recall he said he installed the AVC on the output, not the input like a normal volume control.