Review and Measurements of Neurochrome HP-1 High-Performance Amp

[tomchr]

HPA-1 prototype boards are in. Let the assembly begin.

The final revision will be gold plated and the PCB will be made and assembled in Canada (using parts coming from various places).

Tom

 

[Azeia]

HPA-1 prototype boards are in. Let the assembly begin.

The final revision will be gold plated and the PCB will be made and assembled in Canada (using parts coming from various places).

Tom
View attachment 30840View attachment 30841

That looks great. Can't wait to start seeing the boards with all components soldered on and the chassis shots.

 

[tomchr]

I can't either. Especially the chassis! They should be here in 2-3 weeks.

Tom

 

[tomchr]

HPA-1 prototype assembled. I still can't measure its THD. My precision oscillator 'only' gets me to -128 dB or so. The amp's THD is below that (1 V RMS into 300 Ω).

Tom

 

[Azeia]

HPA-1 prototype assembled. I still can't measure its THD. My precision oscillator 'only' gets me to -128 dB or so. The amp's THD is below that (1 V RMS into 300 Ω).
View attachment 30924

Tom

Really cool. Are there other pics? like from above, or rear?

Also, about that vertical dual-RCA connector, I assume a screw holds it up to the back of the chassis to minimize stress? I notice there is what looks like a screw hole on the left, as well as a little notch on the opposing side.

 

[JohnYang1997]

HPA-1 prototype assembled. I still can't measure its THD. My precision oscillator 'only' gets me to -128 dB or so. The amp's THD is below that (1 V RMS into 300 Ω).
View attachment 30924

Tom

Try 2V to 8 ohm load at 1k and 6k. Even 4ohm.

 

[tomchr]

Really cool. Are there other pics? like from above, or rear?

I haven't taken any other pictures. As much as I enjoy playing photographer, my focus right now needs to be on testing the amp, ironing out the last kinks in the design (if there are any), getting a couple of mechanical bits done (support for the pot for example), getting quotes for the assembly so I can determine a final price, getting a website for Tom Christiansen Audio set up, getting a logo designed, getting business cards done, .... oh ... and get ready for RMAF in a month.

I appreciate your enthusiasm, though. Thank you. Next time I have the camera set up, I'll see if I can squeeze in a couple of pictures for you.

Also, about that vertical dual-RCA connector, I assume a screw holds it up to the back of the chassis to minimize stress?

Both the XLRs and the RCAs will be held to the back panel by screws, yes.

Tom

 

[tomchr]

Try 2V to 8 ohm load at 1k and 6k. Even 4ohm.

Why 4 Ω ad 8 Ω? That seems odd for a headphone amp. I'm sure I can get the amp to distort. All I need to do is to drive it to clipping...

Tom

 

[JohnYang1997]

Why 4 Ω ad 8 Ω? That seems odd for a headphone amp. I'm sure I can get the amp to distort. All I need to do is to drive it to clipping...

Tom

You can get 2V 8ohm under -120db. And with 4ohm, you may get 0.00017% or something.

 

[tomchr]

You're making the assumption that I'm using the TPA6120, though.

I agree that I might be able to hit those numbers, but I would have nothing to compare them to as everything else is measured at 32 Ω or above, with some data points available at 20 Ω.

Tom

 

[JohnYang1997]

You're making the assumption that I'm using the TPA6120, though.

I agree that I might be able to hit those numbers, but I would have nothing to compare them to as everything else is measured at 32 Ω or above, with some data points available at 20 Ω.

Tom

With 32ohm it should be still under -130db. As well as 16 or 20ohm.

 

[tomchr]

I am indeed planning to sell this amp on its incredible performance ... assuming I actually get to measure it. I need to get that distortion multiplier circuit done soon! Think equal parts of Baxandall, Cordell, and Christiansen in an updated (and improved) version of Cordell's Distortion Magnifier from Linear Audio Vol. 0.

Tom

 

[tomchr]

What do you fine fellas think of this logo?

I'll probably use a version without the text as well.

Tom

 

[TimW]

 

[amirm]

I like the TCA part. The font below it somehow doesn't go with its style but not bad either.

 

[Azeia]

@TimW Star Wars was my first thought too! =)

 

[tomchr]

Given my target demographic, invoking Star Wars associations is not necessarily a bad thing.

Tom

 

[TimW]

Given my target demographic, invoking Star Wars associations is not necessarily a bad thing.

Tom

I'd like to see a version with closed ends rather than open ones. If that's not too much work.

 

[tomchr]

I'm actually not the one doing the design. A friend of mine is a graphic designer. I'm having him help. I don't want to burn too many CPU cycles with him, so I just hacked a version with closed ends in Photoshop:

Tom

 

[tomchr]

Before going too far down that path, I should probably look at what exactly Lucas Film / Disney are claiming for trademark rights.

Tom