[ChuckT]

Hi, I wonder if there are any here who has modify the inductors in the Nuprime. I own a IDA-8 and has just started to test another inductor inside the IDA-8. The original inductor is a large red inductor, most likely a Micrometal type 2 toroid (iron powder probably T90-2 size) fairly commonly found in class D amps. I measured its value to be around 22uH (also a common class D filter value). Now I have played with several diy class D amps in the past and I know the inductor in the output filter can make a large difference to the sound. So I ordered a Ice component 1D17A and replace the inductor for one channel and I do back and forth comparison by constantly switching speak cable left to right and back. I found the original inductor gives a bit more darker sound and the drums are a tad less impactful. The Ice inductor sound more clearer, the triangle give a touch longer ring and the violin sound a bit more vibrant, even the vocal sound a touch clearer. Whether one likes this sound may depend on taste. Another down side is the Ice inductor gets very hot and this is adding heat to the already fairly hot switching transistors. I used a different value of 15uH for the Ice component. Here is a good link for Class D filter for those whose are interested.

http://www.trevormarshall.com/class-d-tutorial/

[maty]

Other option is add RFI ferrites in the like me with Würth 150 kHz 8 mm ferrites in RCA, USB and woofer cables.

[Spanish] -> http://aficionados.foroactivo.com/t342p25-kef-q100-uni-q-bookshelf-speakers-5-25-coaxial-with-front-bass-reflex#16099

To English -> https://translate.google.com/translate?sl=es&tl=en&js=y&prev=_t&hl=es&ie=UTF-8&u=http%3A%2F%2Faficionados.foroactivo.com%2Ft342p25-kef-q100-uni-q-bookshelf-speakers-5-25-coaxial-with-front-bass-reflex&edit-text=&act=url

And RFI/EMI Schaffner filters FN9244B too.

[Spanish] -> http://aficionados.foroactivo.com/t197p200-usb-isolator-ifi-iusb-vs-teradak-u9va-teralink-adum4160-filtros-schaffner-lampizator-ac-filter-diy-esa-silk-estabilizador-regulador-de-tension-voltaje-isolation-balanced-transformer-dc-blocker-blocking-pc-silencioso-en-aussar-variac#16121

To English -> https://translate.google.com/translate?sl=es&tl=en&js=y&prev=_t&hl=es&ie=UTF-8&u=http%3A%2F%2Faficionados.foroactivo.com%2Ft197p200-usb-isolator-ifi-iusb-vs-teradak-u9va-teralink-adum4160-filtros-schaffner-lampizator-ac-filter-diy-esa-silk-estabilizador-regulador-de-tension-voltaje-isolation-balanced-transformer-dc-blocker-blocking-pc-silencioso-en-aussar-variac%2316121&edit-text=&act=url

My second system.

RFI/EMI Schaffner filters + Würth 150 kHz ferrites (power and RCA cables) and DC & Ripple Blocker to ALL SYSTEM.

I have:

1 Shaffner + 1 Würth ferrite => Power Strip => DC & Ripple Blocker (4 outputs, in star) =>

=> 1 Schaffner -> AV Marantz SR 4500

=> ifi iCAN

=> 1 Schaffner -> PC (with Bequiet! L8 400 PSU: 5mV/10mV ripple in 5V – USB)

1 Schaffner + 1 Würth 150 kHz -> old 17″ Hitachi CRT monitor (1998), with very good image!

PC => 1 Würth 150 kHz (two rounds) in cheap USB cable -> ODAC =>

ODAC -> RCA cable with 2 Würth 150 kHz ferrites -> ifi iCAN

ODAC -> RCA cable with 2 Würth 150 kHz ferrites -> AV Marantz SR4500

And now, in my KEF Q100 speakers, a Würth 150 kHz ferrite ONLY in woofer cable.

[ChuckT]

No, adding external inductor is very different than changing the one inside. You are adding more inductance outside of the amp for additional high frequency roll off, this is different to changing the quality of the inductance inside the amp (by changing to a different inductor) that the output signal pass through.

Note that the IDA-8 already has two inductor for its output filter, one uses a red toroid (around 22uH) and an air core inductor (unknow value but should be fairly low value since its air) that is inside the pack that connects the board to the speaker out connector.

[maty]

We need a big photo.

[maty]

Ice component 1D17A

-> http://www.icecomponents.com/c-115-1d17a.aspx

-> -> http://www.icecomponents.com/images/document/PDF/1D17A.pdf

[ChuckT]

Here you go.
On the amp board (the upper side), two red inductors on each side of the heatsink. There are one more inside the black rubber pack of the speaker output wires, its and air core.
There are two more toroid (cover with copper wire) next to the capacitor bank by the heatsink for power supply filtering.
The two metal case to the left probably houses the secret preamp circuits, that outputs to the green nichicon ES coupling caps and a Muse 8820 opamp (one for each channel, a bit surprise here as this opamp much more expensive than the old NE5532 which were used in RCA input, output, and dac output buffer)
There are more circuit on the underside, the Muse 8820 mentioned above, lots of (what I am guessing) power supply regulations ic with marking "BG S3K" and "DG S4C" for the two opamps and probably part of irs20957 .
The amp board is very well done.

[maty]

Thank you for the photo. Optimized by me:

lots of (what I am guessing) power supply regulations ic

I want more regulators in the modern amps.

Muse 8820

-> http://www.njr.com/MUSES/MUSES8820.html

High quality sound bipolar-input dual OP-Amp MUSES8820

Bipolar input    
Operating Voltage    Vopr=±3.5V to ±16V
Output noise    4.5nV/√Hz
Input Offset Voltage    VIO=0.3mV typ. 3mV max.
Input Bias Current    IB=100nA typ. 500nA max. @Ta=25°C
Voltage Gain    Av=110dB typ.
Slew Rate    SR=5V/µs typ.

Very good info, thank you again.

[rustydoglim]

 
You guys should check out HPA-9, engineer said very high end design for peanuts.

[rustydoglim]

Oh, IDA-8 can be bridged into mono. So is the IDA-16. Both require minor change that some people can DIY. So if we are going to offer it as an upgrade we would need to offer the corresponding stereo amp.
We might consider offering that as a kit for DIY.
99% of people with IDA-8 would not want to upgrade. Otherwise they could have gotten STA-9 and DAC-9.

[Armaegis]

Oh, IDA-8 can be bridged into mono. So is the IDA-16. Both require minor change that some people can DIY. So if we are going to offer it as an upgrade we would need to offer the corresponding stereo amp.
We might consider offering that as a kit for DIY.
99% of people with IDA-8 would not want to upgrade. Otherwise they could have gotten STA-9 and DAC-9.

Bridging an amp with a built-in dac doesn't make much sense... unless there were a way to daisy-chain a pair of them to use both stereo channels... but that's still not a great way to budget your system. *Maybe* it could be useful as a bridged amp for a sub, but you'd still have to downmix into mono.

[rustydoglim]

Agree. People buy IDA-8 for its all-in-one features.  Technically it can be done with the RCA output connecting to another mono amp but not worth the trouble.