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Are passive preamps bad?

Neither the Topping E30 nor the E30 II have a preamplifier stage and do not have any components for one.
If you use the volume reduction function of these devices, I recommend taking additional precautions to avoid permanent damage to speakers, headphones and your hearing.
Sorry, I meant the L30/L30 II. A little ditzy today.
 
so-called "passive preamps" are fine as long as no gain nor impedance matching/buffering is required.
I used a passive transformer volume control with source selector for years before very recently switching (no pun intended) to a quite modern active preamp.







My SE 2A3 amp benefits from a little more oompf (drive) delivered to its voltage amplifier stage.

 
Sorry, I meant the L30/L30 II. A little ditzy today.
Both are well-functioning preamplifiers, although I would recommend the Sabaj A10h. Half the price (e.g. HiFi-Express) with absolutely channel-identical relay-based volume control, display and remote control.
Together with a manual input selector switch, the cheapest preamplifier with absolutely channel-identical relay-based volume control. The extra cost for this type of volume control alone is x times more expensive for most manufacturers.
 
Who needs a preamp these days? just a switch box will do for most. ;)
I like having a physical volume control. I was just using the volume control on my squeezebox touch and when I just clicked on an open browser window that had previously set the volume at 100% for that player it grabbed control and went full volume for a couple seconds.
 
With things like the JDS or Sabaj preamps, especially with switched volume levels on the A10H, I don't know it is worth doing your own passive. The price on these is so low, and they are never going to color the signal. I've made some passives with extremely small switched steps for precise volume matching. But in normal preamp use for music you don't need that.
 
“ back in the day” I tried passive preamp occasionally in my system. My totally old-school audiophile sighted listening results were always: the passive preamps tended to sound a bit cleaner and more transparent (I was often comparing them to tube preamps).
But there was sort of lack of balls to the sound, a lack of density power and oomph, like my system had become slightly underpowered. I always went back to active preamps. I’m sure passive preamp can work just fine in the right system.
 
I'm considering this preamp: https://www.schiit.com/products/saga_2 . It's reasonably inexpensive at 279USD and has 4 inputs. It doesn't have a balanced input, but it does have both single ended and balanced output in case you are using a pro/xlr input amplifier. It has a relay volume control and discreet circuitry, if that matters to you. It also has a basic headphone amp. I've tried headphone amps that also have preamp capabilities and they can work fine if you don't need switching for multiple inputs.
 
“ back in the day” I tried passive preamp occasionally in my system. My totally old-school audiophile sighted listening results were always: the passive preamps tended to sound a bit cleaner and more transparent (I was often comparing them to tube preamps).
But there was sort of lack of balls to the sound, a lack of density power and oomph, like my system had become slightly underpowered. I always went back to active preamps. I’m sure passive preamp can work just fine in the right system.
I agree that was common. I usually used 1/2 meter interconnects at the output (input side interconnects can be long). That usually helped with what you are describing. I also mostly used switched units and could keep the impedance under more control. Best was when I built a couple small boxes that had an RCA plug made into the box and it plugged right onto the back of the amp. I put on a longer shaft to work the switch so it stuck up enough to reach easily.
 
Hello,

In a discussion on one of my previous post the topic of pasive preamp stages came up. This person claimed that they were not ideal and should be avoided.

I didn't follow up why that was because I didn't want to go to much off topic.
But I want to ask the question now.

Why or if they should be avoided?

In my mind they make sense.
The dac plays it's full range signal that I would believe is it's optimal ouput level.
There is no processing needed in your dac/streamer.
No circuits to that can add distortion and/or noise.
You lower the noise comming in from the input device.

It's an input selector with a potentiometer in a box. What could go wrong
If the output of the DAC is high, and the listening is low, then the passive-pre has a lot of attenuation.
Let’s say maybe 30-40 dB.
Let’s say it is 1k ohm output impedance… Then you have 10000:1 attenuation, and now the output impedance is 1M ohm.
30dB would be 100k (maybe I am in voltage rather than power, but you should get the point.)

If you are driving an IC which is long and the input impedance of the amps is low then the you can get a coloured system, because the driving end has a loose grip on the cable. And you end up in a situation where every IC you try can be heard as affecting the colouration of the system.
And might go down the rabbit hole of trying cables.

The only reason I can think of to avoide them is the non linearity of the potentiometer channels.

Am I missing something here?
Ideally a passive-pre would be using a transformer rather than a potentiometer, and the output impedance would be less affected.
Running it wide open would be fine though… a that point it is just a wire.

I think you would want to have your DAC set to the lowest output voltage, and if the amp is selectable, then use the lowest gain.

So the worst case is a high output selection on the DAC, some sensitive horns that require massive attenuation, long ICs which have high inducance and/or capacitance, AND a low listening volume.

A preamp which has a constant output impedance allows for listening to it loud or quiet, and usually has noise that is below the threshold, and distortion that well below what the speakers have.
The problem is that having no other source devices that need to be switched in, it is easy to want a passive pre.
 
With things like the JDS or Sabaj preamps, especially with switched volume levels on the A10H, I don't know it is worth doing your own passive. The price on these is so low, and they are never going to color the signal. I've made some passives with extremely small switched steps for precise volume matching. But in normal preamp use for music you don't need that.
We once tested with experienced and inexperienced HiFi enthusiasts how finely and in how many steps a potentiometer on a headphone amplifier can be moved manually from start to finish. It was between 25 and 33 steps.
With a good logarithmic gradation, anything over 64 steps is pointless and only good for marketing bla bla. Unless a finer control is required for special reasons.
Even these potentiometers equipped with SMD resistors for €8-16 with 21 or 22 steps are easily sufficient in reality. For me, not only the cheapest solution, but also the one with the least influence and the best channel equality. Also ideal as a replacement for quad potentiometers with large channel inequality, e.g. in the Singxer SA-1 for less than €30-40 material.
 
We once tested with experienced and inexperienced HiFi enthusiasts how finely and in how many steps a potentiometer on a headphone amplifier can be moved manually from start to finish. It was between 25 and 33 steps.
With a good logarithmic gradation, anything over 64 steps is pointless and only good for marketing bla bla. Unless a finer control is required for special reasons.
Even these potentiometers equipped with SMD resistors for €8-16 with 21 or 22 steps are easily sufficient in reality. For me, not only the cheapest solution, but also the one with the least influence and the best channel equality. Also ideal as a replacement for quad potentiometers with large channel inequality, e.g. in the Singxer SA-1 for less than €30-40 material.
I had experimented with how many steps for myself and friends. I found 1 db steps were close enough to infinite resolution you didn't need any finer steps for volume control. You might possibly switch between those two steps and barely hear a difference, but you never found yourself wanting a smaller step in between. Later I put together some that were setup similar to R to R ladder dacs. So I had 128 positions with 7 switches. Sort of like picking bits. It didn't take long for me to get used to it so I could quickly switch volume like I wanted making very small steps (smaller than needed) if I wanted to do so. Not sure many people would have cared for that arrangement. Of course with ICs one could have that done by a rotary encoder now.
 
Let’s say maybe 30-40 dB.
Let’s say it is 1k ohm output impedance… Then you have 10000:1 attenuation, and now the output impedance is 1M ohm.
30dB would be 100k (maybe I am in voltage rather than power, but you should get the point.)
Unless I misunderstand you on this, that is not how it works. Firstly 40 db is only 100:1 attenuation in voltage terms. That does not have a multiplying effect on the output impedance. Your highest output impedance will be at -6 db. If you are using a pot, then at that point output impedance is half the value of the pot. 5 k ohms for a 10 k ohm pot. All other settings will have less output impedance. If one uses switched resistor pairs one can reduce the change in output impedance by using a pair optimized for each switch position.
 
Bad....probably not, if it works for you with your gear....

Can't imagine bothering myself.
 
I have something like this. Four switchable inputs an volume control.

Can somebody tell me, what this is?

Also it has two outputs which are active at the same time. Can I understand them as an y cable?
 

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so-called "passive preamps" are fine as long as no gain nor impedance matching/buffering is required.
I used a passive transformer volume control with source selector for years before very recently switching (no pun intended) to a quite modern active preamp.







My SE 2A3 amp benefits from a little more oompf (drive) delivered to its voltage amplifier stage.


Peel the protective plastic off the Sangean display. :)
 
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Peel the protective plastic off the Sangean display. :)
It's probably molecularly bonded at this point! ;)

PS I bought that tuner used. ;)
PPS We have an HP multifunction printer that I bought when I retired and started my consultancy (11 years ago) -- I still keep finding little strips of static-adhered protective plastic sheeting adhered to it. :facepalm: HP stuck the stuff everywhere.

I have something like this. Four switchable inputs an volume control.

Can somebody tell me, what this is?

Also it has two outputs which are active at the same time. Can I understand them as an y cable?
Probably.
It is testable. :)

The above-mentioned TVC/switchbox has paralleled outputs, visible on the right in the photo I posted. I used them for years to "interface" an active subwoofer (top pair of OUTPUTS) in parallel to the power amp (bottom pair).
 
I have something like this. Four switchable inputs an volume control.

Can somebody tell me, what this is?

Also it has two outputs which are active at the same time. Can I understand them as an y cable?
Possibly a transformer-based passive "preamp". Are there any labels to help identify the manufacturer (though it looks rather homebrew)?
 
I ran a home made one using an Alps pot back in the early 80s, then a Mod Squad passive in my 2ch rig for decades and it functioned perfectly.
As @Blumlein 88 and others have mentioned you do have to be aware of the input and output impedances involved and cabling.
When done right, IMHO there is nothing better.
Besides what's available new today, used models are out there, with little worries involved since there's little to fail. Only switches and
pots that can get dirty or noisy, usually fixed with a shot or 2 of deoxit contact cleaner. The pots and switches on my unit were still completely
quiet when I sold it after 3+ decades and I had never cleaned them.
These units were made under the eye of an engineer name Steve McCormack and marketed under the name Mod-Squad and McCormack Line Drive
Later units included buffering circuits to handle impedance issues ?
Just a thought.
 
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