• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

AXPONA 2017: REDGUM Audio, Axisvoicebox

Frank Dernie

Major Contributor
Forum Donor
Joined
Mar 24, 2016
Messages
2,520
Likes
4,079
Location
Oxfordshire
#5
Well heat rises so these heatsinks may well work better than fins on the top with air flowing up towards the hottest surface and then out front an back along the grooves rather than very little flow at all. This may even be better than conventional vertical fins on the sides or rear but I can't be bothered to model it since it would be complicated.
Intriguing.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
24,325
Likes
46,721
Location
Seattle Area
#6
Heat does rise and it does so inside the box and thereby puts the electrolytic capacitors at higher temps, potentially causing shorter life. Putting the heatsinks on the sides allows the center of the enclosure to be cooler for other components.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
7,886
Likes
9,524
#7
The designer at Redgum had this to say about the heatsink:

As to the “Where?!!” … well, I could say it is just a reflection of how Aussies are seen by the Rest Of The World. We hang by our feet as we “live in a land Down Under”, so why not have a heat sink Down Under?! ; )

More formally stated, our design always leads to this questioning as to why not have the fins on the sides or the back. Agreed, fins dissipate heat most efficiently when they are vertically orientated. But when you factor in the sheer size (as in surface area) of this heat sink, it then doesn't need such a lot of air flow to keep it cool. And the openness of the "sine" curve allows a generous clearance for air to convect through and up from the heat sink. In fact, with one of those "through" directions always being forward, this creates a real positive for dissipation when units are positioned in cabinets.

So, as the flat "back"/top surface of the heat sink then becomes the base of the amplifier, even driving low impedance loads long and hard means the metal never gets warmer than blood temperature. A case of because the area of the heat sink is "overkill" to the nth degree, the amp doesn't raise a sweat with the more difficult loads. This was the only technical test it needed to deliver on, so we knew after one long, hard session it had passed with flying colours! Along with being rock solid as a heat sink!

As implied, the initial impetus for this design was to meet the changing market urging the use of drivers with ever lower impedances. So that there was plenty of heat sinking to "future proof your system", it seemed only logical to re-design our bigger ENR versions (prior to the Black Series) to use a heat sink as the whole base plate of the amplifier.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
24,325
Likes
46,721
Location
Seattle Area
#8
The real issue with this amp is what is in it:



This is just a bag of parts put together. Now if it were a $500 amp that would be fine. But charging luxury pricing for a DIY amp just makes no sense to me.
 

Sal1950

Major Contributor
The Chicago Crusher
Forum Donor
Joined
Mar 1, 2016
Messages
6,744
Likes
4,773
Location
Central Fl
#9
Heat does rise and it does so inside the box and thereby puts the electrolytic capacitors at higher temps, potentially causing shorter life. Putting the heatsinks on the sides allows the center of the enclosure to be cooler for other components.
The whole idea is just upside down and wrong. LOL.
Yep it's only serving to cook all the components mounted above it and just blocks all the natural vertical air flow for the most part.
But then many amps don't use the best logic for their heatsink arrangement. Why do so many designers put the sinks inside the case with only a bunch of holes in the top and bottom plates to allow of air flow? The most efficient layout is to have the sinks on the left and right side in the open air allowing convection to work in the best possible manner.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
7,886
Likes
9,524
#10
http://www.imaps.org/journal/2001/q1/soodphakdee-1.pdf

These guys say a staggered circular heatsinks cool best.

Slightly different area I worked with UV water disinfection gear at one time. Two things worked hand in hand for the design. A key metric was that each bit of water pass close enough by bulbs to be sure of disinfection. The bulbs ran very hot and would cook themselves into oblivion in minutes without water. Cooling was very important. The same parameters that meant streams of water passed by all bulbs as much as possible also was the best plan for carrying away heat. The pattern best for that with minimal flow restriction was round bulbs in staggered rows perpendicular to the flow of liquid.

So such a staggered arrangement on the sides of amps should do the trick. Or maybe the back. Would be like a porcupine however. So likely people would prefer vertical fins I would think even if less efficient.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
7,886
Likes
9,524
#11
The real issue with this amp is what is in it:



This is just a bag of parts put together. Now if it were a $500 amp that would be fine. But charging luxury pricing for a DIY amp just makes no sense to me.
Yes, I had read about this a few years back. They defended it by saying their version was more reliable than others. Still doesn't justify luxury pricing.
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
8,181
Likes
5,316
Location
Riverview FL
#14

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
8,181
Likes
5,316
Location
Riverview FL
#16
Still the same.

Use your snippy tool instead of a link...
 

Sal1950

Major Contributor
The Chicago Crusher
Forum Donor
Joined
Mar 1, 2016
Messages
6,744
Likes
4,773
Location
Central Fl
#18
It is not my picture so can't do that. What I have provided is just an external link. Just look for redgum internal pictures.
Never worked here either
 
Joined
May 26, 2019
Messages
27
Likes
4
#20
Resurrecting an old thread. New to the forum after reading a whole bunch of measurements / reviews and am finding i like the style of the place!

I might be the only person here in the forums with the same set up to the above. The Axis floorstanders (same as what you see in the image), with the black redgum. Using a hifiberry dac+ pro on volumio as source.

As amir alluded to above, the Redgum definitely does feel very basic compared to all the other amps I've seen around. I detest the remote it comes with as well.

I still went in with this set up as the salesman (and my ears) convinced me the speaker-amp pairing worked, and most importantly it came in a pretty deeply discounted package (maybe not at the $500 level for the Redgum Amir mentioned above, but not too far off). All in for the entire system, I spent less than USD 4k. It was by far the cheapest set of all those that I auditioned during my hunt. My audiophile friends who got me into the hobby scoff at my choice and haven't bothered to come listen since no one seems to have heard of Axisvoicebox before. But I'm happy regardless. :)

And in case anyone's interested in what I think of the sound, my very subjectivist review below:

**Initial Impressions**

At the audition, the one thing that stood out for me was focus. Mind you, I'm not some old audiophile so my terminology is entirely my own. Tack sharp with texture. Imaging is great with decent sound stage. Big bass isn't something I typically look for, so it's not something I paid attention to. I would say it's good enough.

Setting this up in an imperfect environment that is my home, definitely less focused then at the audition room but otherwise exactly as I remembered it from back then as described above.

Not everything is perfect of course. The few things I would point out on the downside: Amp isn't the largest in terms of wattage and is pretty barebones. I went small because I don't need that much volume and I have neighbours nearby. The speakers hiss when I dial the amp up too much. Back to the bass point, I only realised after purchasing these that there's an easy way to change the bass crossover and volume on the floorstanders and I dialled it up a little more for more bass. The bass is much better now, but it ain't exactly a subwoofer-sized driver at the bottom. When the bass extension volume gets dialed up too high, it gets pretty boomy and loses its tautness. Looks-wise, it's understated, but ain't gonna grab attention.

In summary, I would say get these if you love detail, resolution and imaging. Pricing is great. Definitely a buy for someone like me who's new to this!
 

Similar threads

Top Bottom