DIY Purifi Amp builds

[TimoJ]

Right, I don't have such fancy tools, just a regular hand-held drill which will not be as precise. But those holes you drilled, were you using a type of drill bit that inserts a tread so you can just screw it in? Or do you have to use a nut that goes to the outside of the case?

To the bottom? I drilled just regular holes. I used M3 6mm screws thru the bottom plate to fit the amp and psu. i.e. bottom of the EVAL1 and psu have standoff "nuts" that accept those screws. I used button head screws, like the ones in the picture:

 

[starfly]

To the bottom? I drilled just regular holes. I used M3 6mm screws thru the bottom plate to fit the amp and psu. i.e. bottom of the EVAL1 and psu have standoff "nuts" that accept those screws. I used button head screws, like the ones in the picture:
View attachment 64232

Ahh, that makes more sense now. Just screw it in through the bottom, and have the screw head stick out on the bottom of the case. Yeah, I can use a hand-held drill to make those holes. Just have to go slow so the drill bit doesn't drift.

 

[Count Arthur]

Just have to go slow so the drill bit doesn't drift.

Use a centre punch: https://www.amazon.co.uk/Stanley-Ce...d-search-10&pf_rd_t=BROWSE&pf_rd_i=1938989031

 

[iBaloo42]

They're not at the level of someone like Ted Denney, but nonetheless, their site makes a lot of questionable sonic claims. This, for example. At least the pricing isn't stupidly high. But it's "solving" a "problem" which doesn't seem to exist.

As a disclaimer, I’m not in any way associated with VTV. I’m just in search of buying a high-value, non-coloring, and non-distorting power amp, which led me to the VTV Purifi - Hypex factory buffer. However, now, I’m not that sure that I’ll pursue this one anymore, given that this version is built on the NC500 Evaluation board.

I personally believe that an ideal amplifier would have a flat response and no distortions, at least between 20 and 20K Hz.

On the one hand, we could criticize most of the companies out there for selling “colored” audio devices, especially as many of them are simply masking their failures towards obtaining the ideal expected results, reframing the results as purposefully designed sound color. All their marketing material about the sound color of their devices could be considered as “snake oil”.
On the other hand, many people are purposely looking for out-of-the-box “colored” sound (obtained without the use of an EQ). So there is a market for selling “off-ideal curve” speakers, headphones, IEMs, and even amplifiers. It is just natural that there would be companies serving this market segment.

The big question is, are the companies selling audio-colored devices being dishonest in their advertisement?

So, looking at VTV, are they dishonest in their advertisement?
Reading their FAQ material, I cannot find it to be leading in a shameful and dishonest manner. Their FAQ mentions that there are options to color the sound that could be obtained by changing OPAMPs. They are also offering a “color classification” associated with different OPAMPs, but they are mentioning that this classification is based on their subjective observations. Could this "sound coloring" verbiage lead people to buy a more expensive VTV unit and many OPAMPs to experiment with? Definitely, but if I were one of the sound audiophile explorers that are open and have money to pursue OPAMP rolling, by reading this FAQ, I would not consider myself as being misled, but I would see options to be considered.

Personally, from a marketing standpoint, I think that VTV has a valid and diverse offering that is of a higher value on the US market than other vendors that are selling Hypex- and Purifi-based amplifiers, and which is more honest in their advertizement than the vast majority of audio equipment selling companies.

 

[SIY]

If you’re selling a cure to a nonexistent problem and claiming unlikely sonic differences with no evidentiary support, the last word I would use is “honest.”

 

[iBaloo42]

If you’re selling a cure to a nonexistent problem and claiming unlikely sonic differences with no evidentiary support, the last word I would use is “honest.”

Technically, you are right, when you are saying that there is no problem to be resolved by interchanging the OPAMPs; I’ve read about it. I am not debating that.


However, there is a problem that needs a solution. Some people are selecting audio equipment on subjective grounds, and they are very aware of that; many of them are even considering us, people that are paying attention to the concrete measurements, as geeks. I would even say that these subjective-criteria buyers are in the majority, and they are creating this special market demand/segment. One company or another would step to the occasion.

If you would have to sell amps to this market segment, how would you phrase the advertisement material on their behalf, so it would not be distasteful?

 

[JimB]

Use a centre punch: https://www.amazon.co.uk/Stanley-Ce...d-search-10&pf_rd_t=BROWSE&pf_rd_i=1938989031

Or, an automatic one.
https://www.amazon.co.uk/JelBo-Auto...rds=center+punch&qid=1589829030&s=diy&sr=1-10

 

[TimoJ]

Or, an automatic one.
https://www.amazon.co.uk/JelBo-Auto...rds=center+punch&qid=1589829030&s=diy&sr=1-10

I have one of those, but I noticed that I get much better precision with a manual spike like the one in the picture. It has a very sharp tip.

 

[SIY]

Technically, you are right, when you are saying that there is no problem to be resolved by interchanging the OPAMPs; I’ve read about it. I am not debating that.


However, there is a problem that needs a solution. Some people are selecting audio equipment on subjective grounds, and they are very aware of that; many of them are even considering us, people that are paying attention to the concrete measurements, as geeks. I would even say that these subjective-criteria buyers are in the majority, and they are creating this special market demand/segment. One company or another would step to the occasion.

If you would have to sell amps to this market segment, how would you phrase the advertisement material on their behalf, so it would not be distasteful?

You’re making the common error of conflating “subjective” with “totally uncontrolled.” The actual problem is irrationality, and In my mind, exploiting that is not something I could do in good conscience.

 

[JimB]

Or you ask Modushop for drilling the rear panel and just have to drill at 3,5 or 4 for the m3 screw...

Nice. Any reason they couldn't also provide those two holes for the screw points that would make the back-panel electrical connection?

 

[phoenixdogfan]

Try doing it level-matched and without peeking. I'll bet the differences "magically" go away.

Tough to do unless you can get the level matching within .1db.

 

[3ll3d00d]

Any reason they couldn't also provide those two holes for the screw points that would make the back-panel electrical connection?

They just require a DXF file showing what you want. Details in https://modushop.biz/site/index.php?route=product/product&path=263&product_id=490

 

[rebbiputzmaker]

They're not at the level of someone like Ted Denney, but nonetheless, their site makes a lot of questionable sonic claims. This, for example. At least the pricing isn't stupidly high. But it's "solving" a "problem" which doesn't seem to exist.

Smh. There’s nothing wrong with what you linked to. If you don’t think there is a difference in sound between the opamps that’s your opinion, but offering them does not make someone a snake oil salesman. I read what you linked as being honest and straightforward nothing you link to is overhyped, or oversold.

The choices are functional components, as opposed to someone trying to sell the magic wooden block upgrade, todays special only $999.00!!!

 

[PaulD]

Smh. If you don’t think there is a difference in sound between the opamps that’s your opinion

No, it's a fact that opamps do NOT sound different when properly used and implemented. This is not an opinion. Implementations may sound different, but it is the implementation at fault and not the opamp. Every engineer knows this. There is an abundance of evidence to support this, such as:
https://nwavguy.blogspot.com/2011/08/op-amps-myths-facts.html
https://archimago.blogspot.com/2016/01/measurements-asus-xonar-essence-one-dsd.html

Saying that opamps sound different is just another hifi myth. Bet Scott Wurcer or SIY a bottle of Richebourg or La Tache that you can tell the difference in a properly conducted double blind test.

Smh. There’s nothing wrong with what you linked to.

So the linked text is dishonest because the person behind the amplifiers knows that the opamps sound the same when properly implemented! The text is merely playing on the myth and fear of opamp rolling, it is not providing a properly engineered and argued solution to the problem. Worse, it is providing validity for the false idea that opamps sound different, misleading people.

Remember that everything that can be heard can be measured. We can measure well beyond the the limits of human perception. The specifications of the equipment fully characterises how it will sound.

 

[maty]

Purifi 1ET400A / Hypex NC500 Input Buffer

https://neurochrome.com/products/purifi-1et400a-hypex-nc500-input-buffer?

[ This input buffer is intended for use with the Purifi 1ET400A and Hypex NC500 Class D amplifier modules.

Unlike other buffers, including the Purifi EVAL1 and the Hypex NC500 Evaluation Board, this Input Buffer will provide a differential output for the Class D amplifier, even if the input to the Buffer is single-ended. This ensures that even a single-ended source can drive the 1ET400A and NC500 to clipping, something the Purifi EVAL1, Hypex NC500 Evaluation Board, and many other input buffers cannot do. Many also report improvements in sound quality when the Purifi 1ET400A and Hypex NC500 are provided a differential input.

The buffer is a single-channel (mono) buffer, with the following features:

• Differential (balanced, XLR) input, which can easily be configured for single-ended (unbalanced, RCA) operation as well.
• True differential output with common-mode feedback, which ensures a differential output, even when used with a single-ended source.
• Jumper-selectable gain: 0 dB and 13.2 dB for a total amplifier gain of 12.8 dB and 26.0 dB, respectively, when used with the Purifi 1ET400A.
• Gain can be further customized by adding a resistor (1206 size SMD and leaded/PTH supported).
• Plug-and-play connection with Hypex SMPS1200 and future Purifi power supply.
• Opamp power supply: Use the AUX supply provided by the SMPS1200, or add your own regulator. A small daughterboard with support for the Hypex HPR/HNR, LM7812/LM7912, and LM78L12/LM79L12 is available as a product option.
• Status indicator LED output (NC500: CLIP and READY; 1ET400A: READY).
• Speaker output is provided both on 6.3 × 0.81 mm quick-connect spades and a terminal block accepting up to AWG 10 (5.2 mm2) in size.

In addition, the following options are provided for advanced users:

• The buffer can be disabled by removing two resistors. A three-pin connector footprint provides direct access to the Purifi 1ET400A / Hypex NC500 input.
• A two-pin connector footprint provides access to the remote sensing pins of the Purifi 1ET400A / Hypex NC500. ]

 

[Deleted member 65]

« Unlike other buffers, including the Purifi EVAL1 and the Hypex NC500 Evaluation Board, this Input Buffer will provide a differential output for the Class D amplifier »

NOOOO it’s a mistake

With a differential input the EVAL1 provide a differential output to 1ET400
See the diagram below
View attachment 64372

”... even if the input to the Buffer is single-ended.”
Missed that part of the sentence ...

 

[SIY]

Yes it don’t create differential output with a single ended (rca)...

At least at a casual glance (all I've done, admittedly), it does.

 

[starfly]

Had an email exchange with Purifi, and they'll be releasing a mono input buffer next month with XLR/Speakon, XLR/Banana or no pre-installed sockets. No word yet on pricing.

Not sure yet if I should get the Neurochrome or go all Purifi.

 

[boXem | audio]

Had an email exchange with Purifi, and they'll be releasing a mono input buffer next month with XLR/Speakon, XLR/Banana or no pre-installed sockets. No word yet on pricing.

Not sure yet if I should get the Neurochrome or go all Purifi.

Interesting, did they mention anything about the connection system to the power supply?

 

[pos]

I wish they would release a low idle power supply instead...