SX-Amp and NX-Amp

[bambadoo]

Beautiful build ! Congrats.

 

[42001]

Thanks bambadoo! I did put a lot of effort in neatness... glad it shows

 

[bambadoo]

Neatness is good. It makes you relax Dont underestimate the good feeling of a 100% finished diy project...
Here is my SX amp. Playing beautifully every day. And yes - 15W and still can rock on fairly sensitive speakers. (96dB)

 

[42001]

Wow Bambadoo, that looks nice and clean. I love the dual toroids

Modu just makes the best chassis around if you ask me.

I have electrostatic panels. My Hiraga of about 45Watt class A sounds really good on them, but it lacks power..... Panels are voltage hungry... that's why I made the NX. More power and good topology.

In about 1 hour I will listen to the NX on the panels I'm driving some Tannoy's now and it sounds really promissing.

 

[Bonsai]

Very nice Sjoerd! hope you enjoy your new amp!

Both you and Bambadoo have done fabulous builds.

(BTW, the sx-amp is about 28W class A peak - i.e. the amp is still in class A. I rated it at 15 W RMS though to be conservative).

 

[42001]

Thank you Bonsai, glad you like it!

Just hooked it up in the livingroom on the panels. Nice sound stage! Needs burning in, that's for sure. But first impressions: close to my Hiraga but a bit harsher on the highs and mids. Bass is just fabulous! Dynamics are really good. Lets give it some time to "age" a bit and see how it develops.

This is a really good amp! Panels are not easy to drive and they are dead honest. Any flaw will present itself without being nice about it so if this was a bad amp, it would have been painfully clear from the start. As said, it is not! Very, very good!

No hum at all! I will update on the highs and mids as soon as this improves. I guess it will take some hours of playing

 

[42001]

Burning in

Sting sounds great! Cat's need to stay out of the room for a while

 

[42001]

Could it be I used the wrong resistors? Highs sound a bit metallic... Know what I mean?

I love the Kiwame resistors but they will not fit in this build.... Hmmmm..... I'm not very happy with the highs and mids..... Any thoughts anyone?

 

[still4given]

My guess is that you got used to the Low-fi of the Hiraga and are not used to hearing the highs and upper mids.I built 5 different Hiragas and all were low-fi sounding compared to all of my other amps.

 

[42001]

True, that could be it. Hiraga's do have a lot of 2nd and 3rd harmonics as in tube amps. Listening to Sara K. On SACD now. Sounds really good!

I will give it time

 

[42001]

Rebecca Pidgeon-Fhear a bhata

Great song for listening to mids and Highs with tonns of dynamics.

Try it!

 

[jwilhelm]

My guess is that you got used to the Low-fi of the Hiraga and are not used to hearing the highs and upper mids.I built 5 different Hiragas and all were low-fi sounding compared to all of my other amps.

They must be very low-fi if you are saying so!

 

[42001]

All a matter of taste but Hiraga low-fi? Don't think so More like a tube sound... And that's a matter of taste i guess.

 

[Bonsai]

Sting sounds great! Cat's need to stay out of the room for a while

Are those Finals [sp] you are driving?

If so, one of the toughest loads in the business at HF - they were referenced in an article by Keith howard in Stereophile.

 

[42001]

Hi Bonsai,

Yes, those are Finals with modified PIO power boxes And yes, very difficult to get good dynamics out of these. They need a lot of voltage and a very fast amp. NX does the job better than Hiraga in dynamics!

 

[still4given]

All a matter of taste but Hiraga low-fi? Don't think so More like a tube sound... And that's a matter of taste i guess.

Hi-fi = accurate
Boosted 2nd and 3rd harmonics = not accurate.

My point is that if you are used to listening to amps that are not reproducing the highs accurately and ampt that does will sound "brighter" and even more harsh on some recordings.

 

[42001]

If you put it that way

I still think I used the wrong resistors. My CD player is modded with pure class A output and does not sound metallic in highs anywhere. Not even on JK class A amps

So I will give it time. But I will probably change some resistors

 

[AndrewT]

Note that there is lots of space in this cabinet. No separate wires even come close to one another.

yes, that is your problem. Big Loop Area.
You appear to have used coaxial for the input. That is a very good alternative to a twisted pair, if you have connected the screen/shield/Return at BOTH ends.

All your single wires should have a return route. The signal flow and the signal return should be run as a twisted pair.
This reduces the loop area and reduces the inteference.

a bit harsher on the highs and mids

Could this be a symptom of excessive interference?

 

[42001]

Hi AndrewT,

Input is shielded Canare starquad, not coaxial. And the screen is only connected to the chassis part. Should be enough for stopping interference shouldn't it? Love to learn!!!

 

[42001]

Ps: not the slightest bit of noise on the speakers when no signal is applied.