DIY DAC Kits and Easy Mods

Chris Adams · « **Reply #180 on:** 26 Dec 2010, 01:53 am »

I just got my AD1865 up and running. There is some noise in the left channel. Best way I can describe it is it sounds like a noisy tube. Goes up and down with the volume. Anyone have this experience? I have an email in to Hui, but no response yet.

wushuliu · « **Reply #181 on:** 30 Dec 2010, 11:12 pm »

Quote from: jema on 14 Dec 2010, 09:56 pm

Will do, but if I don't - what could happen?

/M

What did you end up trying w/ the dac? I see the tube stage is FS on diyaudio...

jema · « **Reply #182 on:** 31 Dec 2010, 09:06 am »

Quote from: wushuliu on 30 Dec 2010, 11:12 pm

What did you end up trying w/ the dac? I see the tube stage is FS on diyaudio...

I soldered 240 ohm resistors temporarily and now I'm finishing the design and I will be trying different resistors for the I/V.

The 240 ohm is more than original in sound volume, but with some google'ing I found that most prefer low ohm's resistors.

What would you say? Since I don't have the sound volume problem, I'm thinking of trying resistors from 240 ohm to 1,5k ohm...

What watt would you say I need on the resistors?

/M

jema · « **Reply #183 on:** 31 Dec 2010, 03:44 pm »

Done!

jema · « **Reply #184 on:** 1 Jan 2011, 09:53 am »

Thoguht you'd be interested in this;

I tried out a different, "supposedly" authentic AD1865-chip. Guess what? It sounds _much_ better now!

Here is the comparison, the "supposedly real deal" closest to the camera;

On the backside of the AD1865-chip that came with the DAC-kit from Raindrop_Hui I read "PHILLIPINES";

Chris Adams · « **Reply #185 on:** 1 Jan 2011, 01:50 pm »

Where did you get the chip?

jema · « **Reply #186 on:** 1 Jan 2011, 02:32 pm »

Quote from: Chris Adams on 1 Jan 2011, 01:50 pm

Where did you get the chip?

eBay.

SET Man · « **Reply #187 on:** 1 Jan 2011, 03:58 pm »

Hey!

jema, that is brilliant using Ikea metal bowl to cover the transfromer!

I will keep that in mind if you don't mind

Take care,
Buddy

jema · « **Reply #188 on:** 1 Jan 2011, 04:02 pm »

Quote from: SET Man on 1 Jan 2011, 03:58 pm

Hey!

jema, that is brilliant using Ikea metal bowl to cover the transfromer! I will keep that in mind if you don't mind

Take care,
Buddy

NP, and due to IKEA's lack of quality, it's really easy to drill holes in also!

wushuliu · « **Reply #189 on:** 1 Jan 2011, 06:07 pm »

Quote from: jema on 1 Jan 2011, 02:32 pm

eBay.

Ah. Thanks for the heads up. Can you post a link for the ebay seller? What does it say on the bottom of the 'fake' chip? Beautiful enclosure!

jema · « **Reply #190 on:** 1 Jan 2011, 07:21 pm »

Quote from: wushuliu on 1 Jan 2011, 06:07 pm

Ah. Thanks for the heads up. Can you post a link for the ebay seller? What does it say on the bottom of the 'fake' chip? Beautiful enclosure!

Nothing, it's clean.

Sure; http://stores.ebay.co.uk/connectors-usa

wushuliu · « **Reply #191 on:** 1 Jan 2011, 07:32 pm »

Quote from: jema on 1 Jan 2011, 07:21 pm

Nothing, it's clean.

Sure; http://stores.ebay.co.uk/connectors-usa

Oops, meant to say the 'real' chip. Good to know. They're located where I live! As for your resistor value question, I didn't hear much difference between 330R and 1.5k except for increase in volume. So if 240ohms is loud enough for you, you're okay. But then maybe with a 'real' chip this may change, so you may want to experiment to be sure.

Chris Adams · « **Reply #192 on:** 1 Jan 2011, 07:58 pm »

Just snagged one of the 'real' chips. I'm curious. I also took a close look at the Sanyo caps on the Mojo dac board. I might get some and see how they work. The voltage values are lower than the ones on the Raindrop board, but still acceptable. I'm going to replace R1 and R14 with TX2575s.

Of course it will be awhile because I just sent my dac back to Hui for replacement. I think there was a bad JFET in the left channel. Didn't want to change them all to find out.

jema · « **Reply #193 on:** 1 Jan 2011, 09:14 pm »

Quote from: wushuliu on 1 Jan 2011, 07:32 pm

As for your resistor value question, I didn't hear much difference between 330R and 1.5k except for increase in volume. So if 240ohms is loud enough for you, you're okay. But then maybe with a 'real' chip this may change, so you may want to experiment to be sure.

I google'd it a bit. Some say DAC zero by Audio Note use 300 ohm, some say 330 ohm, and one page said that DAC one uses 1kohm.
At multiple sites I've read that you need to go beyond 500 ohm to get an acceptable THD level. Whatever that means.

I ordered a set of (very cheap) resistors, just to compare the resistance. When I'll settle for one resistance, I'll try different types of resistors, as carbon composite / wire wounded / tantalum etc...

Do anyone know exactly what capacitors on the Raindraop-board that is used for power supply of the AD1865-chip? I swopped a couple, but I think more is involved and also, it's beginning to cost money. The large 470µF OS-CONS are $20 each.

Have anyone tried adding a C-R-C filter to the PS?

wushuliu · « **Reply #194 on:** 2 Jan 2011, 02:13 am »

Quote from: jema on 1 Jan 2011, 09:14 pm

I google'd it a bit. Some say DAC zero by Audio Note use 300 ohm, some say 330 ohm, and one page said that DAC one uses 1kohm.
At multiple sites I've read that you need to go beyond 500 ohm to get an acceptable THD level. Whatever that means.

I ordered a set of (very cheap) resistors, just to compare the resistance. When I'll settle for one resistance, I'll try different types of resistors, as carbon composite / wire wounded / tantalum etc...

Do anyone know exactly what capacitors on the Raindraop-board that is used for power supply of the AD1865-chip? I swopped a couple, but I think more is involved and also, it's beginning to cost money. The large 470µF OS-CONS are $20 each.

Have anyone tried adding a C-R-C filter to the PS?

Ouch $20? You could have used these (though I guess it's too late now):

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=493-3019-ND

Atlplasma · « **Reply #195 on:** 2 Jan 2011, 02:33 am »

But I am sure those were not made by dwarves in the halls of mordore.

jema · « **Reply #196 on:** 2 Jan 2011, 09:12 am »

Quote from: Atlplasma on 2 Jan 2011, 02:33 am

But I am sure those were not made by dwarves in the halls of mordore.

Me neither, since the dwarfes lives in Moria...

In my research of the AD1865 I found out that several people thinks the AD-chip is more sensitive to ripple than for example the TD1514 chip...

OS-CON'S are world champions in ripple reduction.

jema · « **Reply #197 on:** 3 Jan 2011, 01:54 pm »

With the risk of being anoying, here comes more of what I've found (that you already may know)

This is mostly Ctrl+C/V from datasheet of AD1865;

The AD1865 typically dissipates only 225 mW, with a maximum power dissipation of 260 mW - So why are we adding 10 000µF to them? Higher capacitance, lower ripple reduction?

This figure is confirming what I red in a different forum; You need at least 500 ohm resistance to get acceptable THD-N levels. Though this is written in the datasheet; A load impedance of at least 1.5 kΩ is recommended for best THD+N performance.

THEN! The thing I was looking for, confirmation of AD1865 ripple tolerance; Analog Devices recommends that well regulated power supplies with less than 1% ripple be incorporated into the design of an audio system.
That would mean that the linear regulators is of great importance, as well as the capacitors.

Speedskater · « **Reply #198 on:** 3 Jan 2011, 02:54 pm »

I wonder why they drew "Figure 4" upside down? -100 should be on the bottom and -40 at the top.

Nickel · « **Reply #199 on:** 21 Jan 2011, 08:47 am »

This could be the Philippines 1865 supplier, also on ebay

http://cgi.ebay.com/AD1865N-K-AD1865-18bit-Audio-DAC-upgrade-Audionote-/220541302381?pt=LH_DefaultDomain_0&hash=item335949366d