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The Truth Pre Amp Review

Stokdoof

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This preamp with the input controls not aligned horizontally and the output labelling done by hand is even worse then when I would personally make such an amp in a casing, and trust me, like we say in Dutch, “I have 2 left hands“ when it comes to DIY work.
 

YSC

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This is a review and detailed measurements of The Truth Pre Amp (its real name). It was kindly sent to me by a member and costs US $1,050. There are other options which increase the cost.

The version sent to me is an earlier one I am told with dual inputs (labels are wrong by the way):

View attachment 132684

There is a nice textured paint on the front panel which doesn't quite come out correctly on the image above. The two controls are for balance and volume. Strangely the max setting for the volume is where you see.

The back panel as Dave Jones would say is "how you doing:"
View attachment 132685

It is quite low budget for this pricing. Like the fact that AC mains is built-in. Don't like the fact that it has no regulatory certification (kind of the norm in this category of product).

The truth implies transparency. Let's measure it to see if it gets there.

The Truth Pre Amp Measurements
As usual we start with our 1 kHz dashboard using unity gain (2 volts in and 2 volts out). This required max setting on the volume, i.e. this preamp can only attenuate, it cannot amplify:

View attachment 132686

Well, this is not my definition of transparency. We have good bit of distortion which limits performance to about 14 bits in digital audio terms.

SNR is better though although one channel seems to be noisier than the other:

View attachment 132687

The right side is a new test where I adjust the volume to 1/4 output and measure again. This way we can see the effect of residual noise better and are simulating someone listening at less than max volume.

Frequency response is excellent with wide bandwidth:

View attachment 132688

I was surprised that crosstalk was not frequency sensitive and not that good:

View attachment 132689

Seems like there is some coupling on purpose between the channels??? Strange.

IMD test shows that prior to getting to max output performance starts to suffer:
View attachment 132690

This is due to low frequency distortion rising:

View attachment 132691

THD+N versus frequency shows performance that is well below (cheaper) competition:

View attachment 132693

Conclusions
Let's get the obvious out of the way: The Truth Amp does not speaker the truth! :) It adds its own noise and distortion. It is definitely not competitive with squeaky clean design we have access to today that have considerably less noise and distortion while costing less. That would normally lead to a "headless panther" rating but I felt generous and gave it one step higher because it is not broken like some other designs are. That, and the fact that the headless panther was helping with weeding in the garden today and wasn't in a mood to be in the picture. So I left him alone so he could search for his head....

Needless to say, I cannot recommend the The Truth Pre Amp.

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I am even ok for products that measures sub par and cost a fortune if they did the packaging and looks high end.... but this don't even do that! if that it can't even amplify the signal... why one would not opt for a passive preamp like Khozmo at a fraction of cost and provide perfect channel balance?....
 

RobS

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If the member who submitted this for review wants to give it away, I'll gladly take it for free. I'm in need of a pre-amp.
 

GGroch

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That is just idiotic.......

Just Idiotic would have been a far more apt name for the preamp. It is the most ridiculous product I am aware of on multiple levels.

Spacemonkey links to a reviewer who has had one in his system since 2018 and seems unconcerned that the stereo balance shifts depending on temperature but then boldly types that it has "little electronic character of its own".

I have no reason to believe the positive reviews are disingenuous. The builders user forum has all of 16 commenters, so it is not like they are a feared industry powerhouse.

Further proof, if we needed it, that subjective reviews are useless due to expectation bias and that there are fans for everything regardless of how idiotic.

I agree that the panther must reevaluate his headless standards.
 

Helicopter

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Thanks for warning people Amir.

$49 Schiit Sys is way better than this. If you want gain, tube gain on Schiit Saga+ has better performance, as well as better everything for less than half the price. :facepalm:

No wonder Schiit is so successful.

Also, all the Douk stuff is better, and... are those DIY boards from Ali inside it?
 

Francis Vaughan

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Richard Dunn was sure that they were illegal.
Currently available from Digikey, Element-14, RS, DigiKey UK.
I understand CDS cells also have an unfortunate property that the resistance has a small dependency on the voltage across the cell,
They do. It what I was handwaving about when I wrote "and unclear distortion effects in the resistor." It isn't clear that the distortion isn't also dependant on the amount of light. It is a mess.

Cadmium is a disgusting metal, but it isn't as if it will leap out from behind a bush and kill you. There are vastly worse ways to poison oneself. Keeping NiCd batteries out of landfill and avoiding the cadmium leaching into the groundwater is one thing, but imagining that any use of the metal is totally banned is quite another. One of the scariest uses of cadmium is in artists oil paint pigments. Whilst there are lots of modern cadmium free pigments on the market, you can still buy tubes of brilliant coloured premium paints from such UK institutions as Windsor and Newton. If you wander past the cadmium free pigments you will run into the cadmium laden pigments, and then into the chromium colours. Artists get it drummed into them that you don't injest the cadmium. Don't lick your brushes.
 

Thomas savage

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Lordy, this is quite a mess.
A quick Google turns up a few internals pics here: https://www.superbestaudiofriends.o...ve-volume-control-for-dacs-sources.860/page-9

Forum comes compete with a snide remark about Amir. :(

Post above has the other pic I found.

The preamp looks like a total amateur build. There is so much wrong with it I would be utterly ashamed to put my name anywhere near something like this product, and as to charging $1k for it, it is just ridiculous.

The switch on the back is a chassis ground lift. Really. And the switch would never survive a realistic fault current. It might weld itself solid, it might vaporise before a breaker blew leaving you with a lethal live chassis. Some versions don't have the lift switch. It seems then they just don't bother to ground the chassis. The mains wiring inside is not to standard either.

The quality of the soldering is beyond poor. It is what I might expect of a 12 year old doing a circuit build for the first time with poor quality tools. The entire internal layout and construction is quite simply terrible and not of merchantable quality. There is clearly no understanding of ground loops and management of ground return, which will be a contributor to the mains pickup and poor noise figure. Not a cable tie in sight, which along with the terrible soldering will lead to poor reliability.

Now to the circuit. It is an op-amp buffer on the input and output coupled by a light dependant resistor lit by a LED controlled by the volume pot. That is it. There is no light shielding for the LDRs so the chassis had better be light tight to avoid interference from external light sources - especially modern LED lights flickering away. This is a funny idea that keeps raising its head from time to time. The volume control on the front doesn't touch the signal, but just runs the LED. But there are all manner of issues with the idea, poor noise being one of them, and unclear distortion effects in the resistor.

This is a product that needs calling out for what it is. No matter what else, its construction leaves it as an unsafe product that should not be sold.
There needs to be a panther past the headless one. This is deserving of it.
 

GGroch

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My recent $87 eBay passive preamp purchase. Nobsound NS-08P Pro. Also no potentiometers in the signal path. Labels are all correct. Balance does not change depending on temperature. Does not look like it was designed and manufactured by a 12 year old with poor penmanship and soldering skills.

I thought it was a good buy, but did not realize I was saving $950 ;)

N08Pro.jpg
 

bboris77

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Spacemonkey links to a reviewer who has had one in his system since 2018 and seems unconcerned that the stereo balance shifts depending on temperature but then boldly types that it has "little electronic character of its own".

These reviews are far more entertaining than the product. This paragraph is epic:

“When replacing an active line stage with The Truth, you will lose the coloration of that specific component (this can be a good or bad thing), but you will almost certainly gain sharper transients and leading edge; greater intelligibility; vividness; spatial impression; emotional mobility and a sense of appropriateness with regards to the distribution of sound, as it relates to intonation, rhythm, dynamics, etc.”

I have never heard of “emotional mobility” and “sense of appropriateness” being used to describe the sound of a component. This is just on a whole different level of BS.
 

MediumRare

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The Truth is this is broken. If the panthers are to mean anything, this must receive a headless one. It is also dangerous. Does it even have a serial number (legal requirement for sale in some states? It should not be legal to sell; probably isn’t. @amirm over to you.
 
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Bear123

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I don't understand the point of even wasting a review on a product like this, even if it hadn't measured broken. Just doesn't seem relevant now that technology has moved beyond analog 2.0 channel. We don't bother with 8-track reviews……..fidelity is too low, and antiquated. Someone actually spent $1,000 on this, on purpose?
 

Colonel7

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Engineering and safety underwriting by Etsy. Curious as to what the motivation was to get it tested or whether the member who sent it in has some sort of a tie to the builder? I won't dare use the term manufacturer for this box.
 

Helicopter

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Emotional mobility is perhaps the best explanation of how panther kept his head.
Not sure that panther is more forgiving. I am trying to figure out if all he does is send away failed pieces of garbage.
 
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