Handmade Passive Preamplifier

[AudioLover525]

I of course understand what a passive pre-amp is, I currently use one and have had others. However, when you state that it adds gain, guess what, it is no longer a passive pre-amp. Any kind of gain stage makes it into a standard active pre-amp and no longer a passive. If you are using it without gain you are using it passive.

To quote Arek Kallas, one of the true expert designers in the field, offering some of the best passive pre-amps and attenuators in the world, when you add a gain stage, "In fact it will be an active preamp".

Further more, to add gain does require some type of power. It can't add gain (amplification) without it. So in passive mode it is basically an attenuator and to add gain requires some kind of power (it cannot get louder without a power source). Therefore what is being referred to as gain is in fact more attenuation. With a pure passive, at no attenuation the full input signal is being passed to the amplifier, attenuation actually cuts this signal back to control the volume you hear. Usually with some type of resistors put in line. Less volume equates to larger attenuation resistors. The volume control actually moves different resistors in and out of line with the source signal.

To summarize, you cannot add gain (amplification) without power and adding true gain in fact changes the pre-amp to an active pre-amp, no longer a passive. This has been fully described to me by two of the foremost experts in the field; Arek Kallas, owner of Hattor Audio and Khozma Acoustic and my personal friend EJ Sarmento, owner of Wyred 4 Sound (designer and builder of the world renowned STP-SE Stage 2), SST, Carver and others.

First of all, if we talk about the gain, I would like to stress that the gain mentioned in my work is VOLTAGE gain but not power gain. We have definitions to define whether this is active or passive. To quote, "A passive component, depending on field, may be either a component that consumes but does not produce energy (thermodynamic passivity) or a component that is incapable of power gain (incremental passivity).", see on wikipedia. No active component involved. This is definitely a passive preamplifier.

Adding power gain does require power, while adding voltage or current gain might not. We could do energy transfer to add voltage or current gain without power, one of the examples is phono MC transformer preamplifier. It added voltage gain by using a MC transformer to do energy transfer, which does not require power. This is exactly what the case in my work.

 

[AudioLover525]

I thought that the schematic in post #1 looked strange.
It seems that the unit is not a passive pre-amp, that is an input selector and volume control. But rather it's a euphoric effects generator.

To be more accurate, I would say that this is a passive preamplifier with input selector and volume control. For the reasons, see my previous comments:

"We have definitions to define whether this is active or passive. To quote, "A passive component, depending on field, may be either a component that consumes but does not produce energy (thermodynamic passivity) or a component that is incapable of power gain (incremental passivity).", see on wikipedia. No active component involved. This is definitely a passive preamplifier."

Have you ever seen a euphoric effects generator could obtain voltage gain selections from 1X, 3X, 5X to 10X?:rofl:

 

[AudioLover525]

Again, I agree. It looks like a nice unit but it certainly is not a passive pre-amp.

"successfully amplifying and tuning sound quality", and "with 1X, 3X, 5X and 10X gain options", I also have an issue with this, it cannot amplify the sound without a power source. Passive pre-amps attenuate the sound by putting various resistors in the signal path. Adding "gain" amplifies the signal and this requires a power source, and also would make it not be a passive pre-amp. Maybe he is confusing a lesser amount of attenuation as being gain?

I think I've explained this part. We can amplify without a power source, if we talk about VOLTAGE amplifying.

"This is a passive preamplifier but not a volume control", excuse me.... to be a passive pre-amp it has to be a volume control... that is exactly what attenuation does.

"Plus, a 59 steps mechanical volume switch is used", ok, so now I am very confused, not a volume control and a couple sentences later 59 step mechanical volume switch is used??? Huh?

This is a passive preamplifier with 59 steps mechanical volume control, but not either one, to be a more accurate speaking.

With 1V input, we have 10V output. With 0.1V input, we have 1V output. This is the fact. How could you say that this is not the case, huh?

 

[Speedskater]

Yes a transformer can increase output voltage, but at the cost of lowering it's input impedance. There are no free lunches with transformers.
Not sure that lower impedance's are a good idea with passive components.

 

[Randy Myers]

Also, we are talking about the accepted terms in the audio world. A preamplifier controls volume output to an amplifier and selects inputs from music sources. A passive preamplifier does not add any gain but instead passes the signal through and controls volume more often then not by utilizing some sort of inline resistors to attenuate the signal.

When I added the tube stage to my preamplifier yesterday it was no longer a passive preamp but instead became an active pre. I can actually selected which manner I would like to run it, either passive or active from a switch on the front panel. To add gain/amplification to the signal does indeed require a power source.

The device you built, which looks interesting and appears that you did a good job on it, does not seem to be a passive preamplifier as the terms are used in the audio world. There is not input selection, but instead you can switch connected sources to change the voltages (as you described it) which of course does change the impedance.

Cool looking device but certainly not what I would refer to as a passive preamplifier.

 

[AudioLover525]

Also, we are talking about the accepted terms in the audio world. A preamplifier controls volume output to an amplifier and selects inputs from music sources. A passive preamplifier does not add any gain but instead passes the signal through and controls volume more often then not by utilizing some sort of inline resistors to attenuate the signal.

When I added the tube stage to my preamplifier yesterday it was no longer a passive preamp but instead became an active pre. I can actually selected which manner I would like to run it, either passive or active from a switch on the front panel. To add gain/amplification to the signal does indeed require a power source.

The device you built, which looks interesting and appears that you did a good job on it, does not seem to be a passive preamplifier as the terms are used in the audio world. There is not input selection, but instead you can switch connected sources to change the voltages (as you described it) which of course does change the impedance.

Cool looking device but certainly not what I would refer to as a passive preamplifier.

First of all, those accepted terms you stated are lack of concrete evidence, at least I don't agree. For mine is supported by the Wikipedia, which is accepted by the worldwide.

Secondly, when we input 0.2V would output 2V(10 times gain, +20dB). That's why I called it an amplifier.

Thirdly, our preamp does not require any power sources and uses all passive components. That's why I called it a passive preamp.

Fourthly, all preamp are with volume. So according to your theory, all preamp should be called as volume right?

Finally, what you previously argued so far is meaningless.

 

[AudioLover525]

Yes a transformer can increase output voltage, but at the cost of lowering it's input impedance. There are no free lunches with transformers.
Not sure that lower impedance's are a good idea with passive components.

Certainly. Input impedance will surely be lowered, however all CD network players and DAC support that.

 

[Randy Myers]

our preamp

Hmmmm.....

For mine is supported by the Wikipedia, which is accepted by the worldwide.

Wikipedia is not an authoritative source and you do know you are posting on an Audio Forum where we discuss things in audio terms, right?

Secondly, when we input 0.2V would output 2V(10 times gain, +20dB). That's why I called it an amplifier.

An amplifier amplifies the audio signal and does not simply play with voltage.

Thirdly, our preamp does not require any power sources and uses all passive components. That's why I called it a passive preamp.

You can't really call it a preamp if if does not have an input source selector and a volume control can you?

Fourthly, all preamp are with volume. So according to your theory, all preamp should be called as volume right?

That is just plain putting words in my mouth. No one said a preamp should be called volume, however a volume control is a major function of any preamplifier. Besides being wrong it is also extremely rude. I know you are not used to a forum like Audio Shark where people are friendly and treat others respectfully, but that is how we operate here.

Finally, what you previously argued so far is meaningless.

And again another rude statement.


And there you have it. A shill for a company trying to drum up business.

Just give it up please...Your arguments makes no sense and it just goes round and round. With each post you are sounding less and less credible so please just stop.

Definitely have had enough of this thread.

 

[Speedskater]

Your unit has qualities that are almost opposite of the qualities desired by audiophiles that chose passive pre-amps.
Those audiophiles chose passive pre-amps because they feel that an active stage might change the signal in some small way.
Your unit intentionally changes the signal.
Why not call it "Not a Passive Pre-amp" ?

 

[AudioLover525]

Wikipedia is not an authoritative source and you do know you are posting on an Audio Forum where we discuss things in audio terms, right?

Wikipedia is monitored by many professional and discerning people, which is trustful. Otherwise what other platforms could you provide?

An amplifier amplifies the audio signal and does not simply play with voltage.

I'm talking about 20Hz - 20kHz audio signal from 0.2V to 2V. If I'm not talking about audio signal, what else could I refer to?

You can't really call it a preamp if if does not have an input source selector and a volume control can you?

You're wrong again. So you're talking about those so-called "definitions" again right? We do have a volume control with 59 steps mechanical control. I intentionally not to put on the input selector as there is only need to use one sourcing which I aimed to ensure a more pure sound quality.

That is just plain putting words in my mouth. No one said a preamp should be called volume, however a volume control is a major function of any preamplifier. Besides being wrong it is also extremely rude. I know you are not used to a forum like Audio Shark where people are friendly and treat others respectfully, but that is how we operate here.

And again another rude statement.

And there you have it. A shill for a company trying to drum up business.

Just give it up please...Your arguments makes no sense and it just goes round and round. With each post you are sounding less and less credible so please just stop.

Definitely have had enough of this thread.

I couldn't feel how nice or friendly you've been so far. From time to time you keep on arguing what a preamplifier is, what means by active or passive...What I've received are those rude saying either, that's why I talk to you in this way. I agree that this forum is a place with many good people, but you might not be one of them.

 

[AudioLover525]

Your unit has qualities that are almost opposite of the qualities desired by audiophiles that chose passive pre-amps.
Those audiophiles chose passive pre-amps because they feel that an active stage might change the signal in some small way.
Your unit intentionally changes the signal.
Why not call it "Not a Passive Pre-amp" ?

Yes because this is a new concept and that's why you feel some kind of opposite qualities. This unit really changes the signal, by passive components, like what an active stage does as usual. In fact, there is also an 1X gain option in the unit which could attain signal changing in a small way, I think that's what you and other music lovers look for. Only passive components are used so it definitely called "a Passive Pre-amp" but not a "Not a Passive Pre-amp".

 

[Randy Myers]

I agree that this forum is a place with many good people, but you might not be one of them.

Wow from someone who has 25 posts all in this one thread where you are trying to gain support for a product you are trying to push, versus someone who has over 4500 posts and has been involved in this forums for years... yea that makes sense to me...

Don't bother responding...

 

[Speedskater]

Secondly, when we input 0.2V would output 2V(10 times gain, +20dB). That's why I called it an amplifier.

I doubt that there are many high fidelity products that have a fixed output of only 0.2V.
And other portable products with a 0.2V fixed output, won't have a low enough output impedance to be suitable for transformer voltage amplification.

 

[AudioLover525]

Secondly, when we input 0.2V would output 2V(10 times gain, +20dB). That's why I called it an amplifier.

I doubt that there are many high fidelity products that have a fixed output of only 0.2V.
And other portable products with a 0.2V fixed output, won't have a low enough output impedance to be suitable for transformer voltage amplification.

I understand that there are few products have a low fixed output. The number is in fact an example which just to explain the ratio of amplifying as 10 times. I could tell when we input 5V then output 50V(still 10 times gain, +20dB), just a numerical example.

 

[OliviaVis]

New comer here. Just looking for its price on eBay... but couldn’t find the product.

 

[Speedskater]

The web-page seems to have more info and prices than I remember seeing 2 weeks ago.
http://www.designbymrk.com/

 

[Randy Myers]

The webpage actually shows it with a volume control (volume etched on it), and an input selector (3 RCA inputs) beside that weird gain control thingy. Obviously the OP did not build it as it was intended to be built.

Honestly, in my view I would stick with either the Khozma Acoustic or Hattor Audio passive pre-amplifiers. In my view they are using a higher quality level of parts. I can tell you from personal experience the Hattor is amazing. Also, adding the Hattor optional Tube Active Stage is fantastic and it can be used either passive or active!

The Khozma offers a superior attenuator if someone is a DIY person and is building their own unit. He also offers input boards and remote control capacity if that is something you feel like adding to your home made project.

Here is how it is designed, with a selector to choice the input and a separate control for the gain thing:

 

[Speedskater]

Yep, the OP's schematic in post #1 is strange to say the least.

 

[CPP]

Yep, the OP's schematic in post #1 is strange to say the least.

sure is

 

[AudioLover525]

New comer here. Just looking for its price on eBay... but couldn’t find the product.

Welcome:wave:You could search "59 steps attenuator" for the whole set of attenuator and transformer. But for the full kit of passive preamp, I'm not sure. Anyone could tell if you know.