NAD tweaks

 

Silver Member
Username: Ca_convert

CardiffUK

Post Number: 121
Registered: Jan-05
Does anyone have any recommended tweaks that you can make to NAD C352 (as in taking the lid off and getting a soldering iron out etc - obvioulsy once the warranty has expired). There was a letter in a recent UK magazine from a reader offering such advice, but i didnt manage to obtain a copy and the authors details.

Thanks in advance to anyone who has some tips or links.
 

J. Vigne
Unregistered guest

I can't offer anything specific to the 352, but in general the best place to begin on any product like the NAD is with the passive parts. A new volume and balance control can clear up quite a bit in a budget amp. Replacing connectors is a good idea, though the sonic benefits may not be cost effective. Capacitors are normally the most obvious change in the sound of an amplifier; or even doing small bypass caps on the existing caps can often be a first step. Sorbothane on the chassis will help damp vibration and replacing the feet with cones or ball bearings will do much the same. If the unit has been in use for a few years with no real attention, just a very thorough cleaning and treatment of the connectors and pots will make an audible improvement.


 

Silver Member
Username: Ca_convert

CardiffUK

Post Number: 124
Registered: Jan-05
The amp is about 3 months old. Is replacement of the volume and balance control an upgrade to a better spec'd part, or simply as replacement of worn parts (for the latter case the this clearly would be a waste of time).

I've noted your comments about isolation - I am going to try the very simple and cheap mod of putting some blu tak under the feet before investing in cones (they are not cheap - I really think this kind of accessory is p1ss takin from a cost point of view)

How would I go about changeing the capacitors? What make (I assume I can even determine what the capacitance spec for each is by looking at it?) would I use, and where to get them from??

Questions questions I know, but appreciate your help.
 

J. Vigne
Unregistered guest

The volume control is an upgrade to a better unit.
http://www.partsconnexion.com/catalog/controlsswitches.html
Depending on the space resitriction within the amplifier, you may have some limited choices in the selection of a better part. Most often a volume and balance control have wide open space around them. You should begin by obtaining a schematic of the amplifier. I don't know if NAD will provide this to anyone other than an authorized service center. There are sources on line for some schematics. A shop might let you order through their account. You will be replacing like for like in most every case. If the volume pot is 50k, you replace it with 50k. Most of the capacitors are marked as to their values. There are several online sources; you can begin here:

http://www.partsconnexion.com/

Order their catalog and get some advice on the parts you might want to use. Put something on the order of "diy audio amplifier" in a search engine for more choices.

http://www.audience-av.com/passive.htm

http://www.audioasylum.com/audio/tweaks/default.tcl

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=091-1260

Read about modified equipment and pay attention to the brands chosen. Many diy people will explain why they chose a particular part or brand. Click on the links in these pages; often you'll find a site that will be helpful.

http://www.responseaudio.com/index.html

For the feet on the NAD, if you are not wanting to do cones, there are several alternatives. You must first decide what you want to accomplish with the feet; do you want to isolate from the support system or do you want to drain vibration away from the casework. Using BluTak will make a more solid connection between the shelf and the chassis. Any vibration that arrives at the shelf in the way of acoustic feedback will be more readily transmitted into the NAD with the BluTak. If you want to isolate the amp from the shelf, an inexpensive alternative is to cut tennis balls in half and use them as feet. If you wish to drain energy away from the chassis, the best for that purpose are cones. They act as a mechanical diode. Large ball bearings do much the same at a lower cost.


 

Silver Member
Username: Varney

BirminghamEngland, UK

Post Number: 369
Registered: Sep-04
Ah CA....

Yes - I cannot find the magazine either. Spoke to my local newsagent, who informed me the only way to get hold of the back issues is buy the latest and order the back issues from there. They'll be happy to post 'em to you for a fee....

You have the C352 (I already knew this) but lucky you! Personally, I'm coming to the conclusion that you won't do a lot better than this amp at the price and the C352 has just about been the best amp they do so far in this price range.

Let's face it, NAD offer absolutely THE best budget amps one can buy.... I ought to know, I've heard a few at this price (and higher!) and the C352 would be my immediate choice. I doubt you can make it sound any better without voiding your warranty and going to a lot of risky trouble. I'm begining to think there are three options: Buy the C352, increase my budget range, or forever hold my peace. I think NAD have pretty much done all they can with this amp. I'd say the only significant upgrade would be to invest in their pre/power combination, which is really begining to aproach high end. High end, NAD are not - it's just a budget range with audiophile identity. What it DOES do, for the price, however, is something else.... It just shows that whoever designed the thing (BEE and friends?) is possessed of a peculiar talent for making a cheap amp sound more expensive than it is - and maybe that in itself, is an understatement by me.

I'm wary of taking off the lid of an ancient 3225PE; but I don't know how tempted I might be if I actually got hold of the info - I think you ought to be doubly so with the C352. But if you don't want it, I'll have it :-) Just joking.

V
 

Silver Member
Username: Varney

BirminghamEngland, UK

Post Number: 370
Registered: Sep-04
J, could you please explain to me what 'sorbothane' is?

Thanks,

V
 

Silver Member
Username: Ca_convert

CardiffUK

Post Number: 125
Registered: Jan-05
Varney, I have no intention of fiddling with it for a while, but once the warranty is up, if there is a way of easily improving thisngs then I'll try it. I doubt I will have the courage to take a soldering iron to it in anger.

Jan, I am trying to isolate the amp and the cdp from the shelf support, which is a wooden cabinet (I "have" to use this, I have no choice in this matter) which I think is fairly excitable. How do you use the ball bearings approach - I can't visualise how to use them.
 

J. Vigne
Unregistered guest
Sorbothane; from an online description.

Sorbothane
The elastomeric material Sorbothane is very useful for absorbing vibration. This material has a very high hysteresis, which means it has very low rebound. Panels of adhesive gel can be attached to the top center of the load platform to add damping to the load panel.

http://www.sorbothane.com/

************************************

ca - Scroll down to good pot.

http://www.enjoythemusic.com/doityour.htm



 

J. Vigne
Unregistered guest
http://www.enjoythemusic.com/magazine/equipment/0404/ginkocloud10.htm

More on ball bearings when I have more time. For now draw a cirlcle on a piece of paper then draw two parallel lines; one above and one below that just touch the circle at a tangential point.
That's the idea, it only touches the surface at one small point, much like the tip of a cone.





 

J. Vigne
Unregistered guest

http://www.enjoythemusic.com/magazine/equipment/1203/isolationshootout.htm

 

Silver Member
Username: Ca_convert

CardiffUK

Post Number: 128
Registered: Jan-05
Right, I'm going to try some small foam balls that come with beach tennis sets as a starter. do not have the space nor budget for a specialist support, so this is gong to be a strictly DIY project. I think that tennis balls are too stiff, and again too big.

I like to idea of bubble wrap also, although it will look extremely untidy.

reports on findings to come later
 

Silver Member
Username: Ca_convert

CardiffUK

Post Number: 133
Registered: Jan-05
I made 4 small square "pads" of bubble wrap, folded 6 times and taped to hold in place. each pad was placed underneath the feet on the cdp and the amp.

I used 2 cd's for a very quick comparison: Keb Mo - Slow Down which is a very acoustic recording, and being HDCD encoded makes it even more impressive. Jamelia was used for the second track.

Initial impression are that there is better detail in the midrange. I assumed that the sonci benefits would be greatest at high levels, so I played sveral of the Keb Mo tracks at high volume. I'm sure (though not blindingly certain) that I could more easily follow some of the backing instruments that I couldnt previously. Bass doesn't seem improved, and maybe something is not 100% right in that department (I think the Atacamas are not functioning properly yet). On the whole there appears to be an improvement, whether its real or psychological is irrelevant, subjectively there IS an improvement.

I'm going to also try foam pads (not sure what material but are used in automotive application for ant vibration purposes), some polystyrene pads, and also combinations of all of the above!
 

Silver Member
Username: Varney

BirminghamEngland, UK

Post Number: 385
Registered: Sep-04
I'm trying to think now. Hmmm... give me time on this. My father and I have been constructing working R/C models ever since I was a kid. Consequently, both our workshops collect a lot of junk. If anyone's heard of the 'Dandyfunking' they'll know what I mean.... I tend to collect the feet off old appliances. You wouldn't believe how they come in handy from time to time.

There is a material I and a colleague have been using for 10 years now to contruct swords and shields from for live action role playing. It's called "Plastozote" and is a closed cell foam which has extremely interesting properties where vibration dampening, anti-static needs are concerned. We tend to buy it by the metre these days. It comes in many many grades and I think you would love how neat and tidy it looks. It's used for military, medical, industrial applications and can be bought through mail order, by the metre or block.

One nice little trick you can try is to pose as an industrial consumer who is looking into the product. They will send you a sample booklet. In this swatch of density grades, you may find enough of the blocks to use as dampening feet. The samples in the swatch are roughly the same size as the feet on a typical audio unit. You'll also find this stuff employed in actual use on the bottom of some good equipment - mst often TVs. If the swatch lumps are not a sufficient size, then simply order a small length of the real material in a good solid grade. YOu can cut it with a Stanley Knife and it responds optimally to contact adhesives, such as Evo-Stick.

Best thing of all, is that it is in fact the industry's chosen dampening material for many applications. You'll be making a professional job, by using closed cell foam. It's also usually matt black when I buy it.

Product also known as 'Calogen' foam.

V
 

Larry Hill
Unregistered guest
Capacitor 101

I have not poked around inside newer NAD gear, but the old stuff used electrolytic capacitors in the signal path for dc blocking at several points. The ideal thing to do is replace the electrolytics with polypropyline capacitors, but the same value pprop will be much larger than the electrolytic, and is often not possible, or the part is just not available. The next best thing is to attach a small polyprop cap in parallel with the electrolytic. This is called bypassing, and it helps mitigate the big problem electrolytics have, which is memory (the tendency for a charge to come back after the cap has been dicharged). Any electrolytics in the signal path can be bypassed by a 0.1uf 63V cap (Wima FKP-2), and you can bypass the big electrolytics in the power supply with 1.0uf, any voltage equal or greater than the caps being bypassed. Also, you don't need magic audiophile caps, any good polyprop such as Wima, Sprague Orange Drops, or Panasonic will do nicely.

Bypassing the caps in the signal path should make the sound more open, and details will be less hazed over, and the power supply cap bypass will improve transient response.

Do not use polyester, polycarbonate, or any other poly except styrene, they all have more memory than polypropyline. Polystyrene is slightly better than polyprop, but melts easily, like when you are soldering them.

Sources: I get Wima from Welborne Labs http://www.welbornelabs.com/wima.htm
Both Wima and Vishay/Sprague Orange Drops can be obtained from Mouser Electronics, http://www.mouser.com
Panasonic Capacitors are carried by DigiKey Electronics, http://www.digikey.com

Last but not least, don't over do it. I literaly modded my 3020 to death, the phenolic PC board can only take so much soldering, and cracks easily. Finally after one tweakng session, it developed a hum problem that was terminal.

Best of Luck

Larry
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