DIY DAC Kits and Easy Mods

Russellc · « **Reply #160 on:** 14 Nov 2010, 06:44 pm »

Quote from: wushuliu on 14 Nov 2010, 05:47 pm

It will come up under a search for AD1865 on ebay

http://cgi.ebay.com/DAC-AD1865-AD1865N-K-NOS-1-0-NOS-/320616005653?pt=LH_DefaultDomain_0&hash=item4aa6340015#ht_2469wt_1135

OK, found it. Now what other do dads do I need to order to replicate your efforts?

Russellc

wushuliu · « **Reply #161 on:** 15 Nov 2010, 10:33 pm »

Hi Russell. The mods for this board are based on Lukasz' article. If there's a single recommended mod I would say it's replacing the dac bypass caps w/ vishay/oscon. Replacing output caps in the jfet stage w/ film caps is another good start. After that, it's really about how far down the rabbit hole you want to go.

http://www.lampizator.eu/LAMPIZATOR/REFERENCES/NOS-DAC_AD1865/ad1865.html

Russellc · « **Reply #162 on:** 16 Nov 2010, 02:09 pm »

Thanks again for the info...

Russellc

walkern · « **Reply #163 on:** 16 Nov 2010, 05:55 pm »

If you are a little worried about taking on this project because you lack the necessary soldering or technical expertise (as is the case with me) there is a guy named Ted Wilson (met him at DIY Audio) who is doing complete Lampucera DACs (listed on ebay) http://cgi.ebay.com/Lampucera-Mod-Complete-DAC-CS4397-CS4398-24-96-OS-CON-/190450775270?pt=LH_DefaultDomain_0&hash=item2c57c034e6#ht_4068wt_1026

His charge for the whole set up in a cool looking cigar box seems quite reasonable to me... and the one I bought from him sounds terrific. I can't compare it to others here, so I'm not sure where it stands other than to say that it easily bested my previous (but 2X more expensive) NOS DAC.

Neil

jema · « **Reply #164 on:** 22 Nov 2010, 07:44 pm »

Hello again!

I'm struggeling with my I/V tube-stage.

As the pic below describes, there are many different caps and resistors. All of them in this pic is connected to the signal path.

1. What would you recommend to swap them for? The small, brownish electrolytic caps is staggering 280µF, I don't think they are very high quality ie. Could it be OK to put dual K73-16 in serie instead of one of these caps? That means they only be a 44µF instead of 280µF?

2. The big electrolytic caps buffering the voltage regulators, they vary from 2200µF to 4700µF. I don't like them being different, doing the same. What should I change them for? More F?

3. The tube stage has a capacitor of the brand "Mallory", anyone heard of it ever before? Good/Anus?

4. The cheramic caps are different (Some MKP and some MKS), when changing them, should I aim for the same type/F? Which type/brand?

5. The resistors in the tube amp look standard (cheap), in my other tube amp there are wire wounded resistors used, should I aim for the same type here? Some like carbon film resistors - ideas?

Russellc · « **Reply #165 on:** 26 Nov 2010, 11:40 pm »

Quote from: wushuliu on 18 Oct 2010, 11:42 pm

Yes
Are these the OS-cons you speak of? I found some on that auction site, which type are being used here?

russellc

wushuliu · « **Reply #166 on:** 27 Nov 2010, 12:35 am »

47uf vishay organic polymer caps from Digi-Key or mouser 10v or greater.OP equals oscon.

Russellc · « **Reply #167 on:** 27 Nov 2010, 11:11 pm »

Quote from: wushuliu on 27 Nov 2010, 12:35 am

47uf vishay organic polymer caps from Digi-Key or mouser 10v or greater.OP equals oscon.

I see, and thanks again. I ve been looking for a DAC and this certainly seems reasonable for the quality of result. What are you using for a transport?

Russellc

wushuliu · « **Reply #168 on:** 28 Nov 2010, 12:08 am »

For transport I am using my computer with USB to teralink x2 spdif converter and USB isolator.

Russellc · « **Reply #169 on:** 28 Nov 2010, 05:07 am »

Quote from: wushuliu on 28 Nov 2010, 12:08 am

For transport I am using my computer with USB to teralink x2 spdif converter and USB isolator.

I'll have to google that up...I've just getting into this computer source thing and its all greek to me. Any help on setup would be greatly appreciated. That's whats got me looking at DACs in the first place!

Russellc

Chris Adams · « **Reply #170 on:** 14 Dec 2010, 06:22 pm »

Quote from: wushuliu on 9 Aug 2010, 07:31 pm

Well for kicks I swapped out the 4700uf Nichicon Gold Tunes from the AD1865 DAC and replaced them w/ some 15000uf and 18000uf caps. There was a noticeable improvement in sound quality.

Thanks for all the great info! I just ordered one of these and want to start collecting upgrade parts. What is the voltage on those stock Nichicon Gold Tunes?

jema · « **Reply #171 on:** 14 Dec 2010, 06:57 pm »

Quote from: wushuliu on 6 Oct 2010, 09:57 pm

Quick update on the raindrop AD1865 DAC: I was taking a look under the hood earlier this week, thinking I should add some more Oscons to the PS regulator area (which is recommended in Andrea's original design) and thought while I'm poking around, maybe I ought to just bypass the jfet output stage and just use 2 resistors by passed with a small value cap (.0068uf) for a passive I/V.

Would you say that the resistor and bypass-cap enhances the sound? I'm listenig to mine directly from the AD1865 chip with good results...

wushuliu · « **Reply #172 on:** 14 Dec 2010, 08:43 pm »

Quote from: jema on 14 Dec 2010, 06:57 pm

Would you say that the resistor and bypass-cap enhances the sound? I'm listenig to mine directly from the AD1865 chip with good results...

Sorry I havent had a chance to respond to your PM. Did you manage to get things working?

When you say direct, you mean with the resistors as I/V, right? What value resistors are you using? Yes, different types of resistors impart a sound signature.

wushuliu · « **Reply #173 on:** 14 Dec 2010, 08:46 pm »

Quote from: Chris Adams on 14 Dec 2010, 06:22 pm

Thanks for all the great info! I just ordered one of these and want to start collecting upgrade parts. What is the voltage on those stock Nichicon Gold Tunes?

The Gold Tunes were probably 35v. They didn't come with the board though.

jema · « **Reply #174 on:** 14 Dec 2010, 09:05 pm »

Quote from: wushuliu on 14 Dec 2010, 08:46 pm

The Gold Tunes were probably 35v. They didn't come with the board though.

Nope, no resistor at all, connected the RCA's directly from the three (the middle acting as ground for both left and right channel) predrilled soldering points in the marked ring;

The thing is, that it's loud. It is slightly louder than listening to my analog out from my Squeezebox Reciever...

I don't thinkt there would be any problem adding a resistor to this, since it's so loud.
Should I?

Modifry: Yes, it's working now, but when listening thru the Tube I/V-stage, it gets all distorted, maybe because it's too loud signal to amp..?

wushuliu · « **Reply #175 on:** 14 Dec 2010, 09:29 pm »

Quote from: jema on 14 Dec 2010, 09:05 pm

Nope, no resistor at all, connected the RCA's directly from the three (the middle acting as ground for both left and right channel) predrilled soldering points in the marked ring;

The thing is, that it's loud. It is slightly louder than listening to my analog out from my Squeezebox Reciever...

I don't thinkt there would be any problem adding a resistor to this, since it's so loud.
Should I?

Modifry: Yes, it's working now, but when listening thru the Tube I/V-stage, it gets all distorted, maybe because it's too loud signal to amp..?

You need the resistors!!! You can't just listen to it direct. The resistors are needed to convert the current to voltage (I/V). There are inputs for the resistors on either side of those outputs in front of the chip ~220-300 ohms is what most use. On the board it even says 220R.

jema · « **Reply #176 on:** 14 Dec 2010, 09:56 pm »

Quote from: wushuliu on 14 Dec 2010, 09:29 pm

You need the resistors!!! You can't just listen to it direct. The resistors are needed to convert the current to voltage (I/V). There are inputs for the resistors on either side of those outputs in front of the chip ~220-300 ohms is what most use. On the board it even says 220R.

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

/M

wushuliu · « **Reply #177 on:** 14 Dec 2010, 10:12 pm »

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

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

/M

Just saw you mentioned having the tube I/V stage. If you are using that you don't need the resistors then. What do you use after it? preamp? what's the gain of your amp?

EDIT: your tube I/V has a high amplification factor (mu 70) more suited for TDA1541 chips and similar. Way more gain than you need, which would explain the distortion. I am able to get loud enough (for me) volumes with no gain at all.

jema · « **Reply #178 on:** 14 Dec 2010, 10:29 pm »

Quote from: wushuliu on 14 Dec 2010, 10:12 pm

Just saw you mentioned having the tube I/V stage. If you are using that you don't need the resistors then. What do you use after it? preamp? what's the gain of your amp?

EDIT: your tube I/V has a high amplification factor (mu 70) more suited for TDA1541 chips and similar. Way more gain than you need, which would explain the distortion. I am able to get loud enough (for me) volumes with no gain at all.

I'm using a homemade tube amplifier, I use the Squeezebox to set the volume (digital volume control), not optimal but sleak.
That could explain the distortion yes, damn I suck at theese things. Could I lower the amplification factor? Otherwise - who want's to buy a tweaked tube stage?

My set:

wushuliu · « **Reply #179 on:** 14 Dec 2010, 11:08 pm »

Quote from: jema on 14 Dec 2010, 10:29 pm

I'm using a homemade tube amplifier, I use the Squeezebox to set the volume (digital volume control), not optimal but sleak.
That could explain the distortion yes, damn I suck at theese things. Could I lower the amplification factor? Otherwise - who want's to buy a tweaked tube stage?

My set:

I see. You don't need the tube stage then. You can't lower it's gain. Just add the I/V resistors to the board instead.