Douk Audio/Nobsound V1 XLR Passive Preamp......impressive!

[Schlippwhip68]

Nobsound VOL-3/V1-XLR HiFi Passive Preamp Variable Audio Attenuator RC

Warm tips 1.Available in RCA and XLR Versions: Please choose the appropriate version based on your audio setup. 2.Please use high-quality cables with good shielding performance, otherwise there will be noise. 3.With no gain, no any amplification, only control the signal from the audio source...

doukaudio.com

This is somewhat a fresh break from active pre amps. As many (do and don't) on ASR, I have been tinkering with op amp/valve/power supply rolling in anything and everything where it was, is and will be possible also with great results here and there. This example from Douk Audio arrived today to serve the very opposite of those endeavour's and initial impressions....are very, very good!


The Nobsound V1 XLR offers a good solid weight to the unit, I was hoping this would be the case as to avoid the dreaded 'Mexican Wheelie' which is a bane of smaller hifi gear universally. Cable weight is very nicely counter balanced with this unit, so no lift at the front end.

A very nice Matt black finish to the unit which has a feel of durability to it (sandblasted?) rather than a thin painted finish, it also happens to match my Audiolab M-PWR colour/finish too.
The Alps potentiometer is super smooth to turn with a small amount of resistance and the nob itself is a good solid piece of aluminium. Volume increase/decrease is very gradual and again smooth with no sudden jumping at any given point, excellent performance! As far as any colouration of the sound goes then the purpose of this passive pre amp or any for that matter, is not to allow any sonic influence and the Nobsound V1 delivers exactly that.
The entire sound signature from my test dac comes through unadulterated and I simply have nothing else to need of it, very well executed. The Bass, mids and highs are as close to the original sound as the dac can deliver, no influences from second stage resistor's, op amps, valves, power supplies and so on. The fitting of my Neutrik XLR plugs are flush with no play once they are plugged in, a nice tight fit.

I have still have time for my active pre amps with my op amp and valves of choice because there are times when a switch to such are welcome but here I am talking zero colour and zero dilution of the sound of whatever is being streamed into the dac with the Nobsound V1 XLR.

Value for money is exceptional to be fair and this is a solid unit from Douk which I fully recommend to any one wanting to clear out any powered stage between the dac and power amp. If you dac has volume control then maybe this will not matter but for those who dont then this is an excellent solution.

Douk Audio have over the last 18 months released some commendable products imo. I have there U2 Pro (2025), the P7 Pre amp, the A5 mini amp and now the V1 passive pre amp. The quality of the build and parts have not brought question most of the time, well once where I received a slightly damaged Capacitor but negligible and after sales service do listen. The P7 performs blisteringly well and now after a few months use, the valve upgrade and yes, op amp too, has 'settled into the road' and sounds great! Douk's flagship amp the G7 looks like a very capable unit to and some reviews are starting to surface on YouTube, I would take a look at that amp if you are looking. The A5 is by far my favourite amp of 2025 in regard to design and the TI3255 sound and again imo surpassed Aiyima last year regardless.

The Nobsound V1 XLR Passive Preamp, its a winner!

 

[EERecordist]

The only passive preamp I'm aware of is a transformer.

I don't think the title is correct. I don't understand the design philosophy of the product.

 

[john61ct]

Yes it would be more clear to call it a passive volume attenuator

However "a preamp" these days can even be just a passive source selector.

Volume attenuation on its own qualifies as well IMO, including passive without any transformer, signal conversion etc.

Saying "this does no active signal boosting" is not useful when no such functionality was ever claimed.

What is the practical difference between a passive preamp and an active one?

I've googled this and the active one can add gain, the passive cannot, is that about right? Would that mean in practical terms an active one can be louder? Would be great if someone could shed some light on this because im not really sure :)

www.audiosciencereview.com

 

[Schlippwhip68]

Yes it would be more clear to call it a passive volume attenuator

However "a preamp" these days can even be just a passive source selector.

Volume attenuation on its own qualifies as well IMO, including passive without any transformer, signal conversion etc.

Saying "this does no active signal boosting" is not useful when no such functionality was ever claimed.

What is the practical difference between a passive preamp and an active one?

I've googled this and the active one can add gain, the passive cannot, is that about right? Would that mean in practical terms an active one can be louder? Would be great if someone could shed some light on this because im not really sure :)

www.audiosciencereview.com

‘A Passive Volume Attenuator’, agreed and point taken.

 

[john61ct]

Looking for something unpowered and inexpensive like this, but capable of accepting XLR balanced input (any flavour of "balanced")

and putting out SE via RCA downstream.

The passive attenuator alone used for optimising the gain level, not looking for extra internal electronics to step voltage down.

I guess a -6dB level drop happens anyway as a result of the bal-->SE conversion?

 

[Schlippwhip68]

Do you mean something like this:

https://ebay.us/m/JxMnhL

 

[Redacted]

Is it not "a buffer with a volume knob"? Rather than "a volume knob" (aka pot)
I'm struggling with how op-amps or whatever used, are called passive, irrespective of unity (or other) gain.
It must be a new marketing thing designed to confuse old errr, buffers like me.

It absolutely is useful though.

 

[Schlippwhip68]

Just read that this is active and not passive. There is no mention of op amps.

• Bi-Directional RCA & XLR Converter: Seamlessly transforms RCA (unbalanced) to XLR (balanced) and XLR to RCA. It's the perfect solution for bridging consumer Hi-Fi gear with professional audio equipment, in either direction.
• True Balanced Circuitry for Pristine Sound: Upgrades your RCA signal to true balanced XLR. It eliminates unwanted electrical hum, buzz, and ground loop noise that contaminates your sound. Enjoy a cleaner, more detailed sound with improved signal integrity.
• Dual-Path with Independent Control: The two conversion paths are fully independent and can operate simultaneously without interference. Each features its own volume knob, acting as a mini-preamp for precise level matching between your components.
• Complete Audio Compatibility: Effortlessly integrate devices such as mixers, audio interfaces, active studio monitors, power amplifiers, DACs etc., ensuring stable, high-quality signal transmission for both home stereo setups and advanced audio systems.
• Premium Aluminum Build: Crafted from a solid, compact aluminum chassis, the NS-05P PRO not only fits your desk but also provides robust shielding. It effectively blocks external interference, guaranteeing pure signal for Hi-Fi listening.

---

Q: Is the RCA-to-XLR conversion on the NS-05P PRO a true balanced output?
A: Yes. The NS-05P PRO features a fully differential design, delivering a true balanced signal when converting from RCA to XLR.

Q: Can the NS-05P PRO operate both RCA-to-XLR and XLR-to-RCA paths simultaneously?
A: Yes. The two signal paths are fully independent, allowing both conversions to function at the same time without interference.

Q: Why is the NS-05P PRO not working?
A: 1. The NS-05P PRO is an active converter and requires a DC 5V (≥1A) power supply to function properly. Please check if the power supply work well.
2. Please ensure the RCA and XLR ports are connected correctly:
Left half: RCA input → XLR output; Right half: XLR input → RCA output. The NS-05P PRO does not support RCA-to-RCA or XLR-to-XLR connections. Incorrect connections will result in no signal output.

Q: Why does the output volume of NS-05P PRO differ in RCA-to-XLR and XLR-to-RCA modes?
A: When the volume knob is turned to maximum, XLR-to-RCA mode provides the maximum gain of +5dB, resulting in a louder output. In RCA-to-XLR mode, the maximum gain is 0 dB.

Q: What should I do if I hear hum or background noise when using the NS-05P PRO?
A: Please use a wire to connect the GND on the NS-05P PRO to a real earth ground or to the metal chassis of another equipment. If the issue persists, please contact us for further assistance

 

[LTig]

The only passive preamp I'm aware of is a transformer.

It's common to name preamps without active amplification stage passive preamps. However, a preamp also has switchable inputs, what this device is lacking.

I don't think the title is correct. I don't understand the design philosophy of the product.

Put it between a source without volume control and a power amp without volume control.

 

[john61ct]

Passive simply means no external power is drawn.

Therefore does not actually amplify the signal.

Thus more accurate (for sticklers) to call it a volume attenuator.

The next most common "preamp" function is to allow switching between sources, that also requires no active power

but a device can be called a preamp without that function.

Is it not "a buffer with a volume knob"? Rather than "a volume knob" (aka pot)
I'm struggling with how op-amps or whatever used, are called passive, irrespective of unity (or other) gain.
It must be a new marketing thing designed to confuse old errr, buffers like me.

It absolutely is useful though.

 

[john61ct]

Just read that this is active and not passive.

Yes, that is required to go from SE (consumer RCA) signal level up to balanced (pro, XLR)

which I don't need.

But if it does clean conversion, that price is great!

Passive is much more likely to be clean without having to wait for @amirm to test it.

 

[ManuMaker]

Hello! I let me going with IA and make me buy this nobsound, got a topping d50 iii and i will recieve a buckeye ncx252mp im using a aiyima a20 passtrought, sometimes got to go like -16 -20db, so this looks like a solution to hear my linton 85, now ia (cloude) tells me that theres no measurements and i be better only using the topping as a preamp, jejejeje, what should i do? Thanks!
Sorry bad english. And for de 2-1

 

[john61ct]

wut

 

[ManuMaker]

Hi! I ended up going with AI advice and it made me buy this Nobsound. I already have a Topping D50 III and I’m about to receive a Buckeye NCX252MP. I’m using an Aiyima A20 in passthrough mode, and sometimes I have to bring the volume down to as low as -16/-20dB. The D50 III’s volume control is digital, so I’m worried about bit depth loss (bit truncation) at such low digital volume levels.
The idea was to use the Nobsound purely as a passive analog volume attenuator in the chain — not as a DAC or amp — so I could keep the D50 III’s digital volume closer to unity gain and avoid bit truncation.
Since the Buckeye NCX252MP has almost double the power output, I’m also concerned I’ll have to lower the volume even further to compensate, which is exactly why I wanted the attenuator.
However, the AI (Claude) told me there are no real/independent measurements available for the Nobsound attenuator, and that because of this lack of verified data, it would actually be riskier (in terms of potential quality issues, like poor channel matching or added noise) to insert the Nobsound into the chain than to simply use the D50 III’s own volume as a preamp instead — since the D50 III at least has known, published measurements.
So what should I do? Should I skip the Nobsound attenuator altogether and just rely on the D50 III’s digital volume as a preamp into the Aiyima A20/Buckeye chain, or is there a better way to solve the digital volume/bit truncation concern without introducing an unmeasured passive attenuator?
Thanks! Sorry for my English, it’s not great.”

 

[john61ct]

OK, I'm no expert, but my human understanding is

If you want to optimise, the process is to put out the maximum line level voltage at each stage so long as well below where clipping starts for the next input.

Then attenuate only with your pasive at the end, just before feeding the power amp.

With a passive analog volume control, there is nothing to measure, in a good sense there should be no effect at all on the signal. Use your ears, if there is something wrong you'll hear it.

> I'm worried about bit depth loss (bit truncation) at such low digital volume levels

With modern digitally transparent gear, you do not need to worry so much about this issue as in the past.

To get "fuller range" (finer control) use of the last passive knob, feel free to lower the line level using the previous control in the chain

 

[ManuMaker]

Thanks! D50 iii got 4v and 5v output on xlr, i put it on 5v?