advertisement


Courtiestown - Naim Amplifier (Avondale) Upgrade Project

chiily said:
I have resorted to mounting E-I transformers either on a rubber mat, or on 2mm thick rubber washers between the chassis and the transformer base at each mounting point. That usually quells the hum.
Click to expand...

There's a lot of iron in that pre Garf.

LOL. I used neoprene washers on the 4 mounting points as thats what I had to hand.
 
Wouldn’t have been cheaper to use two off the shelf transformers?. R/S do 500VA EI core transformers.
 
russel said:
Wouldn’t have been cheaper to use two off the shelf transformers?. R/S do 500VA EI core transformers.
Click to expand...

RS and most other mainstream outlets don't really cater for our requirments as they all seem to stock (in most cases) general purpose transformers and most have primary windings of 0-115 0-115 or 230vac. For myself and many who have +240vac mains is what you end up with is secondaries voltages higher than needed or require and quite a bit of hum. They don't do the required secondaries either.
 
Last edited:
Good evening all,

I'm taking time whilst on night shift on this current job to tidy up a few pages on my Excel spreadsheets and horrify myself as to how much I've spent (and I'm also admitting it to Kate.....:()

I updated the spreadsheet I made at the outset for the NCC200v1.5 boards (the link at the start of this thread doesn't work so I've re-posted it here - https://docs.google.com/spreadsheets/d/1_BHcKO3YQ0YIoVhsNTF3El-dtxkRN_Iej0gWs-gId7c/edit?usp=sharing

Believe it or not the cost to buy the parts to make two of these boards is now £245.08 (sourced mainly from Farnell with a couple of items off eBay). The BUV20's I have are actually cheaper than the current cost of the alternate MJ15003's!!!

More overnight......

Regards

Richard
 
The pre-built modules are currently £370, and that's only v1.4. I believe you added a bunch of premium bits, so you're still ahead. ;)
 
Good morning all,

I really do need to get out more. I've completed the costing up for fitting out an SE prototype PCB as per - https://docs.google.com/spreadsheets/d/1h_N2ZvkG-8Hor2sd6OBAYEIu06XXJkRHcki2oTFb55A/edit?usp=sharing

A mere £309.97 for a pair not including the actual PCB cost itself.

While some, few, parts have actually decreased in price and in many cases Farnell have reduced their minimum order quantities the overall trend in prices is up and certainly by more than the headline rate of inflation.

Regards

Richard
 
Good morning Charles,

They may all be capable transformer manufacturers but all are outside the UK, two clearly Chinese based, which makes dealing with problems challenging to say the least, it is easier dealing with a UK based firm. I'm also 'riding' on LesW's back as I imagine he'll have done some legwork to find ETC as I imagine he'll have tried several firms prior to this venture.

Regards

Richard
 
Good morning all,

What do the pfm EE's (others are welcome to contribute of course) reckon to slit foil capacitors in power supplies?? Asking for a friend. :rolleyes: I found a thread on diyaudio which wasn't overly positive but there doesn't seem to be a great deal of information out there that I can see.

Regards

Richard
 
Never heard them, but the theoretical argument in their favor is nonsense. Putting the slits in can only increase the ESR.
 
I think that's how slit-foil caps are supposed to work - a dab of uncontrolled C-R-C.
Much easier/ more economic to do that discreetly & for specified design ends, if that's what you need.
 
Four terminal capacitors are perfectly sensible, although they offer a relatively modest improvement. There are some Jensen parts that don't have the slits; they give about an extra 10 to 20dB of extra rejection in the ultrasonic. As Martin says, you can get a much better effect with CRC, also more cheaply! The 10000uFJensen part is £75. You can buy two nice Kemet 10,000uF 63V parts for less than £20, a wirewound resistor for pennies, get much more rejection, lower output ESR, and save enough money for a decent bottle of whisky.
 
PigletsDad said:
Four terminal capacitors are perfectly sensible, although they offer a relatively modest improvement. There are some Jensen parts that don't have the slits; they give about an extra 10 to 20dB of extra rejection in the ultrasonic. As Martin says, you can get a much better effect with CRC, also more cheaply! The 10000uFJensen part is £75. You can buy two nice Kemet 10,000uF 63V parts for less than £20, a wirewound resistor for pennies, get much more rejection, lower output ESR, and save enough money for a decent bottle of whisky.
Click to expand...

OK so given I'm working within the 'confines' of a CAP6 board to date I've followed the AA route of 6 x 10,000 or 8,200uF @ 80V (original CAP6 bought from AA was fitted with 8,200uF/ 80V) and the 4off SMD inductors what might be 'better'?

Regards

Richard
 
Some people prefer the sound with the inductors shorted/removed… me included.

The ripple on the supply rails looks much worse on a ‘scope, but most amps have PSRR :)
 
S-Man said:
Some people prefer the sound with the inductors shorted/removed… me included.

The ripple on the supply rails looks much worse on a ‘scope, but most amps have PSRR :)
Click to expand...
The last time I experimented with this I was in your camp as well S-Man. Certainly on the output stage PSU I felt the music came to life a bit when the inductors were removed.
 
You must log in or register to reply here.


advertisement


Back
Top