[CADCAM]

Weird, I didn't get anything on my search of Aliexpress...
Your first link is the original P7 with the external PS funny though as it says switching PS in description but you can see the jack for the external PS on the back panel.
I bought the one in the second link with an internal switching PS. Mine did have a fan that ran continuously but was very quiet and really didn't intrude on listening even with open backs. I liked the "newer" front face, the recessed panel with the headphone jacks looks really nice.
It's too bad this amp was such an epic failure because it looks fantastic in person and sounded very good as well.
Maybe my repair guy will be able to repair mine correctly and I'll have it back again but as for purchasing another amp or anything else from Douk for that matter its a hard no.

 

[AudioCats]

the fan probably was quiet enough, but that was within the first month....


If amazon sells the IEC version for $125, I'd get one just for tinkering.
I think we need to look at these amps from a different angle. Looks at them as sub-assemblies. you change / add other components to bring it to completion.

They got the "look" department done, and done pretty well. Which is the harder part. We just need to do the reliability and sound quality, which are the easier things to do.

But I think you might be the guy with the key to really solve the problem. The root of the failures is likely thermal management, which is more of a mechanical thing, and your user name suggests you are the mechanical guy.

here is the challenge: figure out a suitable metal cover that can contain the power supply module linked in post #21. It will be put in the area behind the power tube. Once this is figured out, the little bears are home free: the externally mounted, over-kill-beefy power supply should last forever; the space below the main PCB will now be available to house upgraded output film capacitors. And the evil "fan" can be ditched.
All other required mods are rather minor steps (chassis mounted 2k resistor, etc)

I think the little bear can be made into a kick-ass amp. Free it from the shackle of thermal-related-failures, help it take off into the summer night sky and be the Ursa Minor.....

(cough, cough. cough).




on the other hand, maybe they did figure out a way to deal with the previous issues this time.

 

[CADCAM]

I program in manufacturing using 3D software and everything we make (and sell) goes through rigorous testing in R&D before even getting to QC and ultimately inspection. If Douk wanted to sell a kit it should have. I unfortunately don't have the knowledge to determine what exactly caused the failure(s). I have to agree that it was either thermal or just bad selection of parts in the circuitry. My repair guy has determined it was a power supply failure but what caused it I do not know.
He is supposed to be talented at electronic repair and I hope he can repair this amp. If mounting the PS in a separate enclosure is what's needed I'm OK with that. I like the clean look of an internal PS too but in this case it might just not be possible.
I wonder if the original P7 with the external PS experienced the same failure rate as the new version with the internal supply...

 

[AudioCats]

I suppose manufacturers making generic grade audio gear intended for a very small niche market probably don't have a high profit margin, they are reluctant to do "upgrades" even if it means solving an existing problem. Everything is centered around "cost-down" in that arena. At least they didn't cut major corners in the "looks" department.

There is an internal switching supply in the 24v version, I just saw photos of the internals on DIYaudio. Separate sections for HV and filament supply, good size heatsink in the HV section. This version looks to be a lot easier to make reliable (just beef up the filament supply section and chassis mount the 2k resistors should help a lot.)

 

[AudioCats]

Weird, I didn't get anything on my search of Aliexpress...
....

That site officially scares me. Search results change from time to time; and last night I was gonna order the "250w tube switching supply" module, since it was cheaper on aliexpress than ebay, by the same seller. Started the check-out process, then noticed shipping time was very long. So I closed the aliexpress window and checked ebay....same ship time. went back to aliexpress, and the page showed up was in French.

I just can not trust a site like that.

I did not order that module. No module --> no mods ( I will need the internal space for output caps). Maybe I won't get a P7 after all, even if they do show up on amazon.


Little Bear P8 (transformer version of P7) info thread:
https://www.head-fi.org/threads/little-bear-p8-info-thread.961301/