NAD 208THX Mods

[pasadena]

Hi,

I am interested in hearing from those who have a NAD 208THX amplifier and what mods they have applied, why they chose the particular mod and what were the results, good or bad?

My impression, as an easy place to start off with would be to replace opamps. What do you think or what path should I take and in what order should I attempt these mods, where are the obvious improvements to be made first?

Any suggestions and details of mods for the 208 would be much appreciated.

I am new here and starting out on my journey into the DIY. Appreciate your patience. Oh and what a great site guys....great wealth of information.....impressive.

Thanks and cheers
Pasadena

 

[gni]

Mods

There are few amps capable of switching to higher power rails
on demand. . .be careful with this unit. . .big supply caps. . . .make
sure they are drained before attempting mods. . . .

The mods that you should perform are to fix any problems "you"
have with the amp. If you like the sound. . .leave it alone. If you
like the functionality then leave it alone.

Do you grind your teeth when you look at it. . .do you feel
abdominal pain when Bon Jovi plays (bad example but it is either
good or bad).

I figure you bought the amp on how it sounds? and had the big buck
to back it up. Over-designed to begin with.

Final thought. . . buy a cheaper amp next time and mod it into the
NAD 208THX. That would be fun!

Let us know how it works.

Chris Browne

 

[pasadena]

Hi Chris,

Thanks for your reply.

I do like the sound of the 208 and looking at didn't scare me....but looking inside it did.

I bought the NAD for about AUD$200...converting to USD...aprox $150.....I reckon I didn't do bad in that department.

n terms of buying a cheaper amp....I think this is cheap and I don't think I could do better.

The sound work's for me, it does a great job and I do agree that if it ain't broken....don't touch it.

I'm having a friend of mine build me a pair of Pass Aleph XA 100 monoblocks so that should be an interesting project....looking forward to it though.

I will however be looking at building something to drive my B&W Nautils HTM1 centre but will see what would be suitable to build as an amp for it.

Thanks for your input.

Cheers
Pasadena.

 

[gni]

Nad amp mods

Nice price. . .it was $$$$ amp when new.

What a nice friend. . . that is a serious amount of time involved.

As for building something for the B&W Nautils HTM1 centre, there
are some great Digital Amp kits out there. . . run very cool and
sound quite good. . . I haven't heard the kits yet though. . . very
energy wise. . . less ozone depletion . . . less cancer, etc. . . .

Chris

 

[cheeky]

Hi Pasadena.

I am not a DIY-er but have played with the 208 for about 10 years and still intend to keep it. However, I have made mostly reversible mods/tweaks which hopefully will help you in your journey:

Adding Ferrite Cores
==============
The internal layout of the 208 is 'messy' by today's amp design standards, ie: multiple circuit boards and lots of wires criss-crossing between the boards. I heard that wires are prone to noise/act as antennae and decided to clamp ferrite cores to 'filter'/screen out the noise.

As the clamps are easily reversible, I played with many different combinations of wires to clamp, to 'tweak' the sound to the direction that I favoured. Of course what I favoured changed over the years - so I had a lot of pleasure 'customising' the sound of the 208 to the source/cable/room/speaker variations I played with over the years, simply by deciding which cables to clamp.

Replace Input Board Signal Cable
=======================
This is the only difficult/non-reversible mods I tried - and it was with much apprehension since I am not a DIY and had to trust a DIY shop manager.

The signal wire from the centre input board to the two power boards on the left & right were cheap, common wires. Decided to change that to a proper audiophile signal wire. The difference was very huge as you now hear more of what was upstream. You also hear more of the input board.

With this change, I could hear very much more of any changes I made in upstream cables/source/equipment supports etc.. ie: the amp becomes more transparent in letting you hear what is happening before it.


Equipment Supports
==============
Unless you like the 208's warmish colouration at the upper bass/lower mid-range, you should replace the rubber feet of the 208 with alternatives.


I was offered to change many other 'inferior parts' by the DIY shop mgr but decide against it since I do not know how the sound would change. I also had no reference, another 208 for example, to compare and decide if the 'changed sonics' is what I wanted.

However, my take on the 208 is that in its original form, it sounds friendly, warmish, powerful with strong bass balance but by today's standard of high-end amplifier design, it is considered not very detailed, thin in the midrange (lack of texture/inner detail resolution), grainy & edgy yet with an overall mushy presentation.

The mods I mention above moved the sound towards higher resolution, greater separation, more liquid and calmer presentation. Tauter & better definition from bass to highs means that music is more tuneful, catchy & involving, ie: you can appreciate how a double bass' walk can drive a music tunefully and how natural, solid highs can create a sound field that offers a glimpse into the soundstage, if there was any in the recording, in the first place.

Cheeky.

 

[pasadena]

Hi Cheeky,

Thanks for the great feedback. I think it's a very good amp and does hold itself against many other good amps.

My Aleph XA100 monoblocks are almost complete, down the the last bits and hoping to get them in about a month.

I haven't as yet tried anything to the 208 except for fix a couple of sold contacts that came apart from the RCA input plug pins. That actually made such a big difference as I was missing a lot of sound. I have been looking at replacing some opamps with AD825's and caps with something from mundorf or the likes but just haven't the time at the moment.

What wire did you use to replace the signal wire? I have the schematics of this amp so I'll have to look into it and from judging from what you're saying, sounds like something I should defintely have done.

Do you have pics you can post of the wire replacements?

I've been looking for a second 208 but that's been a long search with no results but I haven't given up hope.

I will be using the 208 along with the Aleph XA's to horizontally bi-amp my speakers. I am looking for a second 208 so I can hookup my speakers to the preferred vertical bi-amping method as I'm trying to keep my amps close to the speakers.

If you manage to get some pics of your mods, please send them to atheling@hotmail.com.

Thanks again for your input.

Thanks and cheers
Pasadena.