Passive Preamplifier? Enlighten me... :)

[rohitmusic]

Came across this new term today

How it is different than a normal pre amplifier? Pros/cons?

Please enlighten me.

Thanks!

 

[doors666]

search......

 

[rohitmusic]

Already read some stuff..

Would prefer on hand experiences from forum members and popular options on this forum

 

[Divakar7]

Share what you have learnt so far from your search. That may be a good start to get a discussion going..

 

[msagar]

Passive preamp will not have signal amplifying circuit (gain) to drive most of the amplifiers. Your system matching will not be easy. With the passive preamp you can not run longer interconnects.


Active preamp will have signal amplifying circuit and system matching would be easy.


Though the passive pre amps sound better (couple of my friends still use them). Due to system matching issues I gave up my prometheus pre.

 

[rohitmusic]

Passive preamp will not have signal amplifying circuit (gain) to drive most of the amplifiers. Your system matching will not be easy. With the passive preamp you can not run longer interconnects.


Active preamp will have signal amplifying circuit and system matching would be easy.


Though the passive pre amps sound better (couple of my friends still use them). Due to system matching issues I gave up my prometheus pre.

Thanks!
Following is what I get based on reading:
- They work on the principle by assuming the source signal (from CD,etc) i sufficient to be supplied to the power amplifier.
- They don't have any gain control
- SQ is equivalent/bettered as compared to equivalent or even better dedicated preamplifiers
- Sound is very detailed true to source

I have read some rave reviews of passive pres.

Thanks again for the inputs, it helps

 

[Audiodoc]

A active preamplifier is definitely better for signal matching although if your source voltage is high enough you can set your active preamplifier to unity gain (like the pass B1). Technically a passive preamp is a potentiometer and nothing else.

 

[TerryO]

The idea of a passive preamp covers a lot of variations. It starts with a simple 2 channel potentometer in series with the source and can, depending on how liberal you are with definitions, lead to a unity gain circuit or even a transformer or autoformer volume control.

A simple 2-channel ganged pot works surprisingly well and depending on what you already have for a base-line comparison, it may be seen as a definate step upward!

Best Regards,
TerryO

 

[2chFreak]

? Your SOURCE device will govern the drive of the entire system's overall Gain structure and how successfully you're able to implement a Passive in the system.

? Usually, source impedance of the Drive device should be as low as possible, preferably less than 100 ohms.

? The voltage output from the SOURCE device should be as high as possible, preferably above 2.0 volts, and the higher the better.

? The Sensitivity of the Power Amplifier's input should be 1.0 volts or lower, preferably the lower the better.

? The Input impedance of the Power Amplifier should be as high as possible, preferably 47k ohms. [ It is possible to tackle input imp as low as 10k ohms also but only with a very strong & very low imp drive from the source ].

? The Interconnecting cable between the Passive's outputs and the power amplifier's inputs should be restricted to 0.5 metres of a very low capacitance type in order to arrest high frequency roll-off.

IF & ONLY you're able to address most of the above properly, only then should you consider a Passive device.

Passive devices can be of 2 Types : Resistor based or Transformer based TVC. Both are successful and work well.

Finally, a well setup passive in a system is one wherein your playback is conducted between 10 o'clock to 2 o'clock Volume Level position.

If you're able to adhere to the above, you will be well rewarded with a clean, detailed, ultra low-noise sound that the passives are supposed to.

 

[sachu888]

I have tried Active SSP B1 and Passive Lightspeed Attenuator B1 and SSP are the best active preamps I have ever heard and LSA can be used as a volume control in either preamp.I did not try LSA as a standalone preamp though.

Regards,
Sachin

 

[vin_eme]

+1.

SSP + LSA the killer combination. Sonically excellent!


__________________________________________
*****Wirelessly posted using an android device*****

 

[reignofchaos]

Got a preowned Mccormack TLC-1 recently. This has both passive and buffered outputs. The passive output just sounds incredible - it is clean - squeaky clean with jet black backgrounds. It really has no drawbacks I can think of - its noise floor is so low, even if you put your ear beside the tweeter with no music playing, you can hear nothing. There's an incredible amount of detail and a massive soundstage, it sounds like the source sounds - there's nothing extra added, nothing subtracted. Also there is no grain or harshness that is typically associated with solid state preamps. It is as refined and polite as the best tube preamps I've heard. My jaw dropped on the floor when it was first connected to my system. No wonder this was a Stereophile Class A preamp during its days.

Overall it is the best match for my system after hearing a variety of preamps - the lack of gain is really not a problem as it perfectly matches with my DNA-125. Also the fact that my cd player/dac has a slightly higher than normal drive means a passive works beautifully with none of the usual drawbacks associated with passive (thin sound with lack of bottom end).

 

[reubensm]

Do the NAD C320 and C326 BEE amps have passive preamps? Went through their circuit schematics and noticed that they do not have amplification in the preamp stages. The tone controls are also passive.

 

[doors666]

Earlier I was not using a preamp (equiv to a passive pre). Then I added the pass b1. I saw improvements in the imaging, clarity, separation of instruments etc. So the argument that passives are better doesnt hold much water for me atleast. There was no impedance issue earlier also, pre wasnt really required.

 

[omishra]

Earlier I was not using a preamp (equiv to a passive pre). Then I added the pass b1. I saw improvements in the imaging, clarity, separation of instruments etc. So the argument that passives are better doesnt hold much water for me atleast. There was no impedance issue earlier also, pre wasnt really required.

Pass B1 already discussed a lot in Pune HFV Meet thread. See last few pages of it after 2nd Dec. There people experienced how details of music preserved by passive pre like Pass B1.

 

[reignofchaos]

Earlier I was not using a preamp (equiv to a passive pre). Then I added the pass b1. I saw improvements in the imaging, clarity, separation of instruments etc. So the argument that passives are better doesnt hold much water for me atleast. There was no impedance issue earlier also, pre wasnt really required.

I thought Pass B1 was just a buffered passive with unity gain.

 

[omishra]

I thought Pass B1 was just a buffered passive with unity gain.

You are still correct. It is no gain/unity gain buffer which makes large input impedance and low output impedance. So sources are not strained and power amps are driven in full faith.

 

[iaudio]

I think that's what doors is trying to tell us. When he had no pre( which he equates to passive pre) the sound was not as good as it is, when he started using Pass B1 pre amp.

 

[doors666]

I think that's what doors is trying to tell us. When he had no pre( which he equates to passive pre) the sound was not as good as it is, when he started using Pass B1 pre amp.

thats correct, b1 improved sound a lot over passive pre (essence feeding the amp directly).
B1 is not a passive pre. its a pre without gain. a passive pre is without power. pot with input and output connectors and an input selector.

 

[sachu888]

thats correct, b1 improved sound a lot over passive pre (essence feeding the amp directly).
B1 is not a passive pre. its a pre without gain. a passive pre is without power. pot with input and output connectors and an input selector.

Yes,B1 is active buffer with unity gain.

Regards,
Sachin