0 Members and 1 Guest are viewing this topic. Read 28047 times.
Hi Ray,You keep me on my toes, but I love the careful thought behind your curiosity, thanks for the questions..... forces me to order my thinking for my website copy, too, a very good thing! You might appreciate that as the designer, and dominated by the design issues, I'm not so focussed on the issues of installing the completed module into a suitable enclosure, and the minutia of the connections.Hi Hugh,Thanks for the compliments. I had built from a preassembled kit from one of your mates there in Australia and I went through hell getting it finally to work the way it was to be set up. It wasn't his fault though. If I knew what I know now, I would have done things a lot differently. So from what I read, then probably having each heatsink on the left and right side of the case respectively per channel, and then the transformer in the middle? There's no separate PS board? Just trying to imagine how this would all fit together. Will the heatsinks be already mounted on the board? Are the terminals clearly labeled on the board? I presume you are at the input having the amp cap coupled? Ooh that's right, your keeping voltage on the caps minimizes any effects that caps can give. On the output side, what sort of protection is built in there? So if there is a short or current spike at the outputs, I presume like the SkA amp you're using fuses?on the 8 or 4 ohm or lower issue, is 35 V enough for the transformer? What about handling speakers with difficult loads, say Maggies, or if someone still happens to have a pair, Dolquists speakers. Well, probably not, but just trying to think of some speakers with difficult loads.Ok, so on the mounting of the board or heatsinks to the case, I presume there's probably holes in the corresponding sides of the heatsink to mount them on there sides to the bottom plate of the case? The fins would stick out the sides of the case. The fins themselves are probably a couple of inches from tip to base, so just trying to get a handle on the case size. Maybe instead there are holes on the ends of the heatsink to mount the sinks that way. What about fuse sizes at the input say 7A or so for a 500VA trafo?Probably should have PM you about all this, but maybe someone who is buying and building your amp kit for the first time might learn something from my questions here. Thanks for answering my questions. As soon as I can get some cash together, will probably get this amp. I figure I could do a lot worse for the money spent, and it would be a standard for me and others for years. Ray Bronk
So from what I read, then probably having each heatsink on the left and right side of the case respectively per channel, and then the transformer in the middle? There's no separate PS board? Just trying to imagine how this would all fit together.
Will the heatsinks be already mounted on the board? Are the terminals clearly labeled on the board?
I presume you are at the input having the amp cap coupled? Ooh that's right, your keeping voltage on the caps minimizes any effects that caps can give. On the output side, what sort of protection is built in there? So if there is a short or current spike at the outputs, I presume like the SkA amp you're using fuses?
on the 8 or 4 ohm or lower issue, is 35 V enough for the transformer? What about handling speakers with difficult loads, say Maggies, or if someone still happens to have a pair, Dolquists speakers. Well, probably not, but just trying to think of some speakers with difficult loads.
Hi Ray,Nice questions - you clearly have been down this path, and know all the bumps in the road! Hi Hugh,Just one last question I think? Ok, so to mount the heatsinks on the case, would you have holes on the vertical edges of the heatsinks to mount to the open sides of the case, or are there holes on the bottom and tops of the heatsink to mount to the bottom plate of the case?Ray Bronk
Folks,I'm furiously assembling NAKSA 100s now. Here's a piccie of four all complete, awaiting mounting on their heatsinks then testing:These NAKSAs are premium, pricier versions with Nichicon Gold Muse caps; regular NAKSAs have the Nichicon KZ.This batch is ten; all are accounted for, all overseas. (Mind you, from Oz, just about everywhere is overseas!! )I cannot begin to describe how happy I am with the sonics of this amp, might even call it La Stupenda! Cheers,Hugh
Hi Hugh,No worries about speed - just wanted to know so I can start getting the trannies Would you say that 300VA, 35 volts would be fine for monoblocks?Cheers,Jens
Hi Jens (and Ray!!),The two channels of the NAKSA 100 are normally served by one transformer, with rating from 425VA to 500VA (standard ratings, commonly available).If you go for monobloc construction, a choice made quite deliberately so you can place the amps right up close to the speakers, then half these ratings would be fine, and more would be no bad thing.So, you could go as low as 225VA PER CHANNEL, or as high as 300VA PER CHANNEL. Again, these are commonly available ratings. The choice would be entirely arbitrary. Both would give very good results, and in fact would be a bit simpler to wire up because you would not have to splice two additional wires onto each secondary winding of a single transformer to accommodate two modules.Yes, Jens, the 35Vac rating for each secondary is correct!Ray, Jens has thoughtfully specified the more expensive caps... a good choice, they are superb caps, I hope my supply holds out!!Cheers,Hugh
Ray,CAUTION: THERE IS NO CENTER TAP REQUIRED FOR THIS AMP.BOTH SECONDARIES ARE USED INDEPENDENTLY AND ARE NOT INTERCONNECTED TO FORM A CENTER TAP.I do not recommend 40Vac trafos, unfortunately. This is taking the output stage a bridge too far, particularly risky for 4R loads. Only two output pairs are used for this amp; for 56V rails, corresponding to 40Vac trafos, you need THREE output pairs, not TWO.Hope this helps,Hugh
Ray,Thanks for your input! I am indeed going to have the modules mounted on the back of my speakers Here's a photo of one of my speakers:As you can see, the speaker consists of three modules: bass, treble/mid, and bass. A NAKSA 100 will be mounted on the back of each bass module, and a NAKSA 70 (which is a 2-channel module) will be mounted on the back of the treble/mid module. Each NAKSA module will have its own toroid transformer.The entire array will be 'governed' by DSP-controlled electronic x-over/equalizer units that will be housed in the treble/mid enclosure.Bass drivers are 8 ohms, and since each NAKSA 100 module will be powering two drivers, this will be a 4 ohm load. In 4 ohms, the NAKSA 100s deliver close to 200 watts per module, so I'll have around 800 watts of bass power! And that is 'direct-drive', as amplifiers are connected directly to the drivers with no energy-consuming passive x-over inbetween With this setup, speaker cables will be non-existent (apart from the very short lengths running from the amps into the enclosures) and speaker cable influence on sound will be eliminated. Also, with amplifiers mounted on the rear of speakers, it will be easy to hide the rest of the system (GK-1R, heavily modified Oppo BDP-83SE, and an old Denon tuner) and have a very 'clean' looking system Cheers,Jens
Jens, Ray,I'm always amused when people slowly begin to see just how serious Jens is with his system. He has NAKSA 70s already, so knows that the 100 is very similar, and to be selected in this company with some of the finest drivers and baffles on the planet is a great privilege....Jens, one point; you might consider a Zobel correction for all drivers to correct phase shift due to the inductance in each voice coil. I have found this improves depth of image slightly..... but I suggest this only because global feedback amps, even the NAKSA (which has 31dB of global nfb), always benefits with this slight amendment.Thanks for sharing your system, truly impressive!!Hugh
