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Old 28th July 2014, 12:49 PM   #11
simbloke is offline simbloke  United Kingdom
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The amp was never really without a case. The original one was simply what I could find on Farnell at the time. A simple steel case that would have been at home in a rack but not really the living room! I think I posted a picture on the old forum at the time.

The new case is aluminium but I didn't notice a change in the sound. Getting married, moving house and acquiring cushions and curtains did ;-)

Sim

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Old 29th July 2014, 03:23 PM   #12
psp is offline psp  United States
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Default Wood vs. Metal cases

Sjef,
I'm real interested in trying a wood case for an AKSA 55 (Nirvana Plus with Mundorf SIO input caps) that is now in a Par-Metal case. First, I have to admit that this project would get in line behind a long list of audio projects that I've put off (I'm lucky, I have a family that--very happily--keeps me busy and my work is really interesting, at least to me).

It would help a lot though if you can suggest a few case designs that are reasonably easy to build. I do have an old table saw (and still have ten fingers!), can measure accurately, and can cut with reasonable accuracy, but I'm very definitely not an accomplished woodworker.

My wife hates the stark black metal boxes (I don't notice since I listen in low light), but if the amps sound better (I have 8 amp channels driving the Orions), I could be motivated to put them all in wood enclosures.

When you say that wood sounds better, how would you describe the changes you hear? Does choice of wood matter (soft vs. hard), do you (or should one) laminate woods of various mechanical characteristics as an approach to damping vibrations? For example thin layers of balsa between heavy layers of solid birch???

Jens, any thoughts on this?

Many thanks,
Peter
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Old 29th July 2014, 03:47 PM   #13
AndrewT is offline AndrewT  Scotland
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Quote:
My wife hates the stark black metal boxes
If the stark black boxes are hidden behind the speakers she won't see them.
Or attach them behind the speakers to hide them.
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Old 29th July 2014, 06:03 PM   #14
psp is offline psp  United States
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Originally Posted by AndrewT View Post
If the stark black boxes are hidden behind the speakers she won't see them.
Or attach them behind the speakers to hide them.
My amps ARE behind the speakers, but she looks behind them, then complains. Otherwise, she's a most excellent lady.

Nice enclosures WOULD be nicer, though. / Peter
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Old 30th July 2014, 10:21 AM   #15
Jens-AT is offline Jens-AT  Denmark
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Originally Posted by psp View Post
Sjef,
I'm real interested in trying a wood case for an AKSA 55 (Nirvana Plus with Mundorf SIO input caps) that is now in a Par-Metal case. First, I have to admit that this project would get in line behind a long list of audio projects that I've put off (I'm lucky, I have a family that--very happily--keeps me busy and my work is really interesting, at least to me).

It would help a lot though if you can suggest a few case designs that are reasonably easy to build. I do have an old table saw (and still have ten fingers!), can measure accurately, and can cut with reasonable accuracy, but I'm very definitely not an accomplished woodworker.

My wife hates the stark black metal boxes (I don't notice since I listen in low light), but if the amps sound better (I have 8 amp channels driving the Orions), I could be motivated to put them all in wood enclosures.

When you say that wood sounds better, how would you describe the changes you hear? Does choice of wood matter (soft vs. hard), do you (or should one) laminate woods of various mechanical characteristics as an approach to damping vibrations? For example thin layers of balsa between heavy layers of solid birch???

Jens, any thoughts on this?

Many thanks,
Peter
Hi Peter,

As you have probably seen, in my current setup the NAKSAs are without enclosures, since they are directly and firmly attached to the rear of my speakers.

When I first put the rounded metal covers on the rear of the speakers (covering the NAKSAs), they were not connected (electrically) to anything, but I have now grounded them to my mains true earth. I listened before and after I did this, but could hear no real difference.

It should be noted that my entire system is grounded to true earth. This also applies to the heatsinks of the NAKSAs. The ground tags of the amps are then attached to the heatsinks.

Again, before doing the grounding I listened and then re-listened after doing the grounding. There was no real difference in sound quality, but background noise seemed sligthly less.

So, as you can see, I have tried the 'no enclosure' concept, but I haven't really compared without and with enclosure, except as described above.

If you want to go with a wooden enclosure, I would definitely recommend dampening. I would also recommend using a combination of materials - and if you could e.g. bond plywood and MDF with a viscoelastic glue, this would be very beneficial, as such a sandwich will provide extremely good dampening. You could also use the 'constrained layer dampening' method where you screw two layers of material with different mechanical properties together with a layer of bitumenous felt between them. The layers could either be MDF with different thicknesses (i.e. with different resonance frequencies) or MDF and plywood or acrylic or other materials of choice.

If you are going the 'wooden' way, I would still recommend grounding the heatsinks - but I guess this requires a fairly good true earth to be effective.

I hope the above is helpful.

Cheers,

Jens
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Old 31st July 2014, 12:06 AM   #16
Sjef is offline Sjef  Netherlands
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Well not to hijack this thread,

I have not tried all amp in wood and metal enclosure, just a couple. Personally I don't think it because of the wood but because of the absence of a fully enclosed metal box around it with eddy currents all over the place. I have just used wood because it looks nice, is easy to work with and easily available. You can use any other non-metal material you can find. I won't claim wood is the way to go. DNM for instance are using acrylic enclosure for years and even use non metal spacers between power tranistors and heatsink and they are even experimenting with fully heat conductive plastics as heatsinks as well.

I just have build a couple of amps on breadboards and after I thought they sounded good enough I have caged them. For two times in a row the sound became worse in a metal box. One time I just took it out of the box again, back on the table and sound was better again. After I made a wood box for it I heard no difference at all compared to lying on the table. I have reoeated this with three amplifiers, of wich one (my Hiraga) sounded significantly better in wood, another one (My UCD700) made no difference, a third (a gainclone) responded with a bit better sound but not as profound as with the Hiraga. I can not predict how other amps will react but after these experments I came to the conclusion that a wooden enclosure can sound better and at least in any case did not sound worse then a metal enclosure despite the total absence of screening.


I also think damping is of much more concern with metal enclosure the wooden enclosures. My wooden enclosure for my Hiraga amp is acoustily pretty dead and is made of 9 mm multiplex. Any metal enclosure of the same size would ring like a bell like most do.

Again, I don't believe it has much to do with any acoustic properties, but the again I have also never heard any change in sound when using spikes or dampers or special equipment racks with amplifier of any kind.
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Old 31st July 2014, 01:46 AM   #17
AKSA is offline AKSA  Australia
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Sjef,

A really good post, as are all on this thread - thank you.

I can affirm that I too have not perceived sonic effects with spikes, cases, special enclosures. That is not to say it does not exist; but I have not perceived these effects myself. I do believe however that dampers are useful, particularly with mechanical sources like disc players and CD/DVDs, which are very susceptible to sound waves at low frequency and high amplitude.

Aside from the playback chain, I am convinced that the listening environment is very important to a committed listener. Carpets, walls, drapes dimensions - these are critical, but everyone knows this.

Ciao,

Hugh
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Old 31st July 2014, 02:34 AM   #18
Bigun is offline Bigun  Canada
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Aksa 55 still going strong
Thing is, when you put your amplifier pcb flat against the metal heatsink it's not likely the enclosure will have much effect - you need to move the amplifier pcb away from the heatsink and then try to see if there is anything going on. I doubt it myself but you can imagine how a large metal object will capacitively couple to signals nearby - I always make sure my heatsinks are grounded.

I thought the interesting thing about DNM was their fastidious attention to high frequency impedance matching/termination of all interconnects - they use matching terminations all over the place.

My AKSA 55 (clone) has no such funny business and it is in a metal box and.... sounds rather nice
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Old 1st August 2014, 08:38 PM   #19
Sjef is offline Sjef  Netherlands
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Originally Posted by Bigun View Post
I thought the interesting thing about DNM was their fastidious attention to high frequency impedance matching/termination of all interconnects - they use matching terminations all over the place.
Yes that's right. They even use matching termination inside the circuits as well. Part of the reason for doing this is the fact that a perfectly matched transmission-line is much less prone to rf pollution so they do not need any shielding for their circuits and can get away with acrylic enclosures even for something like a MC input amp. No voodoo, Just clever engineering with a slightly different approach, I like that.

I can not predict how a AKSA55 or a NAKSA would respond to metal casing or not. I was just curious when the opening poster said he just caged the AKSA's. Unfortunately they where already in metal cases before. I was just hoping for a second opinion on the subject.
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