advertisement


Hackernap tuning - component choice

chrisn

chrisn

pfm Member
https://www.dropbox.com/s/h6jfc8l08pegnya/P1010231.JPG?dl=0

My newly completed Hacker sounds harsh on vocals, sort of edgy, in particular when compared to my Naim and Avondale amps. Also a bit bass light. It is probably down to poor component choice on my part and I have some ideas about what needs changing from previous advice on here. I just want to check and get it right in one go if possible, dismantling to change components is quite difficult with so many wires.

The input cap is a solid aluminium? BC128 10 uf which I think is ok to keep.
C13 and C14 decouplers are basic Nichcion 470uf 100v which I used as I could not easily get Panasonic fc s. Should I keep these?
The main item is the feedback cap which I used FFB 68uf against advice because I had some I wanted to use. Is this the likely culprit for the sonic signature I am getting? I have x4 47uf bead tants, or should I hold out for a couple of wet tants?
 
Last edited:
The first thing to do is give it some time, very often newly built kit sounds a bit off to start with.
Put one of the speakers out of phase and leave it running playing the radio/something for a day or two at a sensible volume.

Dont rush it changing things on anything newly finished .
 
I'd agree; let it run for a bit, or just leave it on 24hrs; then re-check the output stage bias, and see how you like it over a few days use after that.

(And well done for a tidy build that works out of the box.)
 
Weird, mine, which I finished some weeks ago, sounds exactly the opposite.
Sweet and lots of bass, not as tight as my NCC200 and I attribute that to the wet tantalum I had as feedback cap there (Hackernap has solid one). The film caps I've tried there (feedback) were never harsh but lacked in bass (that was for NCC200, I haven't expirement with HackerNap yet).
That leaves harshness which could be a break-in thing. See how it goes after some time.
 
Thanks for the replies, it is sounding better.
I was initially disappointed as it was not the best thing I ever heard!
Also, I might have had a poor connection using a 4pin - 4pin plus extension/adapter to XLR to the power amp.
Because now on the end of a Nac 52 Spercap fed from a line out off the main system it sounds great, thanks again.
 
Yes, it’s always best to leave it running for a week to let it settle down before passing any judgement. I’m personally not a fan if the BC128 as the input cap, for me things really started to sing when I changed to film. For feedback I’m using a tantalum and have so far not been tempted to try film in this position. As always it down to personal preference in a particular setup

Mark
 
I used the recommended 68uF caps when I first built my hackernaps and it did sound thin, very thin, so after a week or so waiting for it to come on song, I dropped a pair of 47uF Evox in each, and it sounded lovely.

Pete
 
What sort for the input film? And Pete are those the square white boxes that need some flying leads or maybe underneath?
It is sounding good now, but rather dry and grainy for the long term. That is the SL2 signature too I think and the bare dining room set up with no soft furnushings curtains or carpet.
 
Here’s the Farnell code for the input cap that I’m currently using (1413762). For feedback it’s (1187290). These two give a balance that suits me. I don’t recall spending £17 on the feedback cap however so best shop around

Mark
 
I used a Wet Tantalum for both the Input and Feedback cap and my Hackernap sounded good after the intial running in period but was a little bass shy
I experimented with different caps found that everything just snaps into focus with a good quality mil spec wet tantalum the 10UF MMK was pretty good as well
But just the very best input cap is a piece of wire i.e no input cap
Note that I tried some mil spec solid tantalums and the were very explicit but too bright for me
In the output Cap 6 removing the inductors and fitting a 10,000uf Elna cap as the last cap made a significant improvement is bass performance
I still have my hackernap amp and its a Very good amp unfortunately the NCC300 does it better

hackernap 200 by Alan Towell, on Flickr
Alan
 
Great replies, thanks although getting a bit too much for my basic level. I think I need an expensive "wet tant" for the FB
My heatsinks are a bit light for high volume too!
 
chrisn said:
Great replies, thanks although getting a bit too much for my basic level. I think I need an expensive "wet tant" for the FB
My heatsinks are a bit light for high volume too!
Click to expand...
Those heatsinks are worryingly small, especially as they’re enclosed in the case.
 
That looks like a full width dissipante, much better than my effort which used leftover hardware.
Do most builders tap the holes in the heatsinks to mount the output transistors?
I need to learn how to do that. Thanks again.
 
chrisn said:
Do most builders tap the holes in the heatsinks to mount the power transistors?
I need to learn how to do that. Thanks again.
Click to expand...

I work out where they are going to mount, wiggle to avoid a fin and drill all the way through then nylon nut and bolt it.

Non-conductive thermal paste and a isolating pad.
 
https://www.dropbox.com/s/2ncj99jcml4fzvo/P1010232.JPG?dl=0
These heatsinks are bigger and will fit. The Velleman will go vertically between the speaker terminals.
The Pessante case is vented top and bottom. This is a cheaper option than buying a Dissipante, but will it be enough cooling?
While I am doing it I will go for a wet tant FB cap. And some flying leads so I can experiment with the input.
Thanks again.
 
Used a "wet tant" for feedback and a 10uf Wima for the input capacitor, beefed up the heatsinks as in the above picture. I did tap the holes and was surprised by how simple it was. Also upped the Bias and got it steady at 3.4mV (previously I was cautious and it probably ended up about 2.8mV).
Anyway the sound is transformed, full bass, sweet, smooth sound, all the harsh grain gone.
Pleased to say the least. I'd post a picture, but the wiring is too untidy!

Thanks to you all for the help on this forum!
 
https://www.dropbox.com/s/5sdqowxt4o2lzty/P1010234.JPG?dl=0
That's a picture after a tidy up
Replaced the inductors in the output stage capacitor banks with wire links as suggested (seemed to bring a worthwhile improvement in general clarity)
Checked Bias and offset again
Sounds brilliant now. So I'm happy and must resist the temptation to mess with it

Thanks for the help
See post below-
Thanks Alan, and yes about the heatsinks and perforations. I think it's probably ok but I will look out for a taller case with better external sinks.
 
chrisn said:
https://www.dropbox.com/s/5sdqowxt4o2lzty/P1010234.JPG?dl=0
That's a picture after a tidy up
Replaced the inductors in the output stage capacitor banks with wire links as suggested (seemed to bring a worthwhile improvement in general clarity)
Checked Bias and offset again
Sounds brilliant now. So I'm happy and resist the temptation to mess with it

Thanks for the help
Click to expand...
Looking good Chrisn :cool:
Glad you are happy with it, leave it alone now :D
Hope you have perforations in the top plate above the output transistor heat sinks?
Alan
 
Still trying to improve my Hacker so it’s as good as top Naim and ncc220 amps I use. Maybe too much to ask?
Still some harshness on some tracks percussion like cymbals and high hats and some vocals.
Any ideas, my thought was a pair of expensive reservoir caps at the end of the two cap6 banks to the output stage. Replacing a United Chemcon pair.
Can anyone make a definitive suggestion please?
Thanks in advance
 
If you prefer the Naim sound maybe it's a good idea to try the same caps as Naim in the signal path...?
 
You must log in or register to reply here.


advertisement


Back
Top