[NXSTUDIO-DRUMMER]

Had some fun buying the little Douk Audio A5 amp for my bedroom set up.



Danny's GR-Research review: https://www.youtube.com/watch?v=-E8wEJF5jAs&t=1206s

Ron's NRD Review:
https://www.youtube.com/watch?v=7tqudUsJgEY

I'm impressed, for what it cost in stock form. Based on the shoot out Danny, Ron and Hobbs did on the A5. https://www.youtube.com/watch?v=-E8wEJF5jAs
Link for Staccato's op-amps,  https://staccatoaudio.com/

Link for Sparko's op-amps, https://sparkoslabs.com/discrete-op-amps/





However, I really wanted to go with the Staccato op amps, versus the Sparkos op amps in the A5 though. Inspecting the circuit board and corresponding with Jakub Honkisz with Staccato, he advised me, in order to use their op amps, I'll need to use these DIP8pin extenders.












Unfortunately, Danny, Ron and Hobbs didn't get a chance to test the A5 in their shoot out, with the Staccato's installed, because they didn't have the DIP8pin extenders to retrofit into the Douk Audio A5 Class D amp. In their testing, they had a smaller power supply too. They were using a 36V/5amp power supply. I bought the 48V/ 10Amp power supply. The 48V/ 10 Amp makes a big difference, having drive versus a 36V/ 5amp power supply. I've been considering a linear power supply, to see how much it may lower the noise floor. Although, I'll have to say even cranked up, I didn't notice any noise, it was dead silent. Interesting article on GaN technology.
 https://futureaudiophile.com/what-the-hell-is-a-gan-gallium-nitride-amp-and-why-is-it-changing-the-way-audiophiles-now-see-power-amps/

Laughing, I feel like I just bought a grown man's Tonka toy!  This little rascal is going to be a nice addition to my other bedroom stereo system. Needless to say, I'm very pleased!

Thanks for the review of the Douk A5 Class D Digital Amp, Danny, Ron & Hobb's! 
Even Amir with ASR was impressed with the A5 Amp, and we all know Amir, never see's eye to eye with Danny and Ron's audio equipment reviews.
https://www.youtube.com/watch?v=7jyvdgMCOaM&t=2s

Someone who is building some of Danny's kits on a budget, this little amp is a worthy addition too!

[NIGHTFALL1970]

I also purchased a 10 amp power brick and it makes a night and day difference! Symbol crashes sound a lot more life like. I haven’t played around with different opamps yet but,  I bet the power brick has the same difference in quality.

[Jon L]

Who did this and aside from how it looks, did the opamps work kinked like this?  I'd rather use the standard extender and bend the pins than use the super-long wire extenders.

[NXSTUDIO-DRUMMER]

Who did this and aside from how it looks, did the op amps work kinked like this?  I'd rather use the standard extender and bend the pins than use the super-long wire extenders.

Jakub from Staccato sent me that photo, of a another customer attempting to install.

 

[Jon L]

IF I were to get Staccato, I would just use two extenders on one side. 

But I'm trying to refrain from buying any more discrete opamps, including the interesting-looking Virtual Hifi opamps:
https://www.youtube.com/watch?v=Mub-xo619PY&lc=UgxdVC0dgL6KaUa1-qN4AaABAg.AKBzsVzeGuyAKIDM8Gt2Ms

[nlitworld]

Has anyone measured the input impedance of this little guy? Curiosity got the best of me and I just ordered on prime day deal. $95 with the 48v power supply is too tempting. Asking on impedance since I usually run a high pass filter on my preamp output.

[tremrej65]

Has anyone measured the input impedance of this little guy? Curiosity got the best of me and I just ordered on prime day deal. $95 with the 48v power supply is too tempting. Asking on impedance since I usually run a high pass filter on my preamp output.

There's an integrated adjustable high pass filter in that box (the left knob). You most likely don't need an external one.

[nlitworld]

Yeah but typical audiophile neurosis says the capacitors in there to facilitate an adjustable high pass are not very quality compared to the Miflex and Duelund I'm used to hearing. We're guilty of falling down our own rabbit holes in this hobby.  I'll figure out tomorrow when I get it and can report back.

[NXSTUDIO-DRUMMER]

Yeah but typical audiophile neurosis says the capacitors in there to facilitate an adjustable high pass are not very quality compared to the Miflex and Duelund I'm used to hearing. We're guilty of falling down our own rabbit holes in this hobby.  I'll figure out tomorrow when I get it and can report back.

Hey Lloyd, I wondered about it too, however, it has impressed me enough, I don't feel a need to go that route.
Some others have commented on it too. Being we both have the NX-Studio's, that are very revealing monitors.

"The Douk Audio A5 amplifier uses C0G/NP0 ceramic capacitors for high-pass filtering, specifically for their superior performance in audio applications, according to TI.com and In Compliance Magazine. These capacitors are favored for their low distortion, stability over temperature and time, and suitability for high-frequency filtering, according to In Compliance Magazine. Additionally, the amplifier utilizes aluminum electrolytic capacitors for enhanced reliability and longevity."


Here is a nice detailed large photo of the internal components on the circuit board.

[NIGHTFALL1970]

We are all crazy here (so I feel at home) and I thought about adding Danny’s Tube Connectors, but I don’t think there’s room.

[nlitworld]

Yep, I figured at such a cheap entry point, getting wild with a soldering iron on there sounded like fun. RCA jack, speaker post, opamps, etc. Worth it given the cost of the unit, surely not. Fun project for a weekend of tinkering, heck yes. Thanks for the internals photo. Wheels turning for possibilities.

[NXSTUDIO-DRUMMER]

IF I were to get Staccato, I would just use two extenders on one side. 

But I'm trying to refrain from buying any more discrete opamps, including the interesting-looking Virtual Hifi opamps:
https://www.youtube.com/watch?v=Mub-xo619PY&lc=UgxdVC0dgL6KaUa1-qN4AaABAg.AKBzsVzeGuyAKIDM8Gt2Ms

 John, thanks for posting op-amp alternatives for the viewers. Danny, Ron & Hobb's validated there are differences, between different manufactured op-amps and their audio signature.

Here is another manufacture John L shared, Thanks John! 
https://virtualhifi.com/products/supersonic-v1-op-amp

Offering 4 different models

[Jon L]

I really love what Virtual Hifi is doing with Qualio line of speakers, and these opamps do look very interesting.  However!  Make sure your equipment can handle the extra heat and current requirement of Virtual Hifi opamps 

[nlitworld]

First listen in straight stock form, pleasantly surprised, even without subs. Will let it break in then start to mod in a couple weeks. I really don't need another project, but this will be fun.

Also, input impedance is 7,900 if anyone is wondering. That'd make a 0.22uf cap roughly about 90hz xo. Probably have one of those laying around. 

[NXSTUDIO-DRUMMER]

Good information to know Llyod, thanks for advising us all.

Valad point John L

If someone installs the Brute Force One on the A5, and it performs like this, your in for one hell of a ride! 


All kidding aside,
Seriously, if any owners of the Douk Audio A5 have experience with different Op-Amp manufacturers, please take the time out, and share your thoughts with the community. Like tube rolling, these op-amps do have a different sound signature, regardless what the flat earth guys say.
As I'm discovering, there is quite a vast number of variations out in the market, to select from. I'm sure everyone would appreciate feedback on the topic. 

[NXSTUDIO-DRUMMER]

I've heard and read favorable reviews on a SX52B OP-Amp. This YouTube reviewer, is sharing his subjective listening experiences with multiple Op-amp's.
https://www.youtube.com/watch?v=LyV6mZk5GGw&t=1262s

He seems to display integrity with his opinions. I decided to purchase the SX52B on Ali-Express, with free shipping for peanuts. Evidently, based on some peoples assessments. The SX52B performance level, falls somewhere in between, the stock A5's 5552 op-amp, and the Sparkos SS3602 op-amp sound signature on material playback. Exactly what that entails, soundstage, decay wise, etc.?

Another guy comments on this op-amp is below,


I've seen it for sale as low as $10-$12.00 dollars, with free shipping.
 

Here are a few photo's of the SX52B Op-Amp. Yes, it does retrofit into the Douk Audio A5, without modifications or additional parts being required.








I'm sure, some may be shaking their heads, why bother?

[nlitworld]

Sparkos ordered, as well as some Nichicon KZ caps for the coupling caps in the middle there. I already have some extra KLE rca jacks to replace those cheap ones and I'll try to figure out a way to mount some tube connectors off the back. Should be a fun little mod project.

And to think I only investigated these as a summertime hot weather amp alternative to tubes.

[NIGHTFALL1970]

Nlitworld,
Please post pics and step by step instructions if you add tube connectors.

[NXSTUDIO-DRUMMER]

Here is another alternative, where the pricing is similar to the tube connectors. Then drop them in without building or buying another chassis.
https://www.soniccraft.com/product_info.php/cardas-ccgg-binding-post-p-1387









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I did find additional information for Douk A5 owners, that are on the fence, as to what direction they would like to pursue, regarding various Op-Amp manufacturers. The owner of virtual labs, did some comparisons between 10 different Op-Amp Manufacturers. Including taking a few Op-Amps and modifying them, receiving some very promising results. I've included his YT link, as to what he says in the video, on how YT heavily compresses their music, on their channel. Therefore, he attached a link from google drive, that is uncompressed music examples of his testing, between the various Op-Amp manufacturers.



This guy actually put forth a descent presentation. Of course we all know, nothing compares to actually being in a listening environment. Either headphones or your primary stereo set up, should reveal the differences.
 

Here is the Google drive link to the uncompressed comparisons.
https://drive.google.com/file/d/1V66EtN1RVRA5-5qgKT1_Ql8ZB0jDyV_F/view

Here is the link below:
https://www.youtube.com/watch?v=kNDX7SCN6Jc

[nlitworld]

So I did mess around with the high-pass knob this morning. There is a good chop of low frequencies going from off to 50hz area, but the a big stretch of no-man's-land where it will drop a tiny bit but no fine adjustments. Then just on a whim I maxed it to full "200hz" and turned up my Rythmik F8 to 150ish. Oh man that's good. These subs play so well up higher and the little amp sounds much more nimble and open. Not half bad right now, and it's still bone stock. I'll probably investigate higher filter levels since I have some 0.15uf Miflex in the garage which would make for 137hz filter, or even a 0.1uf which would be 200hz.

As to my thought on mounting tube connectors, I was essentially planning to glue a standoff acrylic block in the back that the tube connectors could sit in, Probably add a footer so the balance doesn't cause it to tip over while I'm at it. Should be easy enough and I have 2part adhesives in the garage.