As the heat sink temperature increases, quiescent current decreases. This prevents thermal runaway. That is the reason why SD669 transistor must be mounted on the heat sink. Therefore, it is necessary to adjust the quiescent current at the desired operating temperature. When you turn on, quiescent current will be higher but will achieve the desired value after the warm-up.
This is clear to me. Why is there such a difference in the channels when a cold amplifier is turned on, all the details are the same.🙄
So you don't recommend using the parts that come with the Ebay kit? The transistors are not trust worthy? And 60 vdc is the target for supply?
Hi @crispycircuit
I have also used preassembled A60+ without the power transistors and power supply capacitors which I have chosen and added. Results were fine. It is the best option if you don't want to solder complete board.
I did so because there is always possibility that the most expensive parts are substituted with fakes or re-branded lower quality components. This is not the case just with Chinese products. Just open any commercial amplifier and find out that there was a great deal of cost-saving solutions. That's economy, not engineering.
Therefore, to find out the truth, I also have used smaller a60 with less output transistor to use exclusively chosen components. The results were similar if not the same.
Note also that there were (are) complete A60+ amplifiers that received excellent review. Look here!
So, all in all, A60 boards aren't so risky investment. Just advice: buy yourself power transistors and power supply capacitors to eliminate the risks.
Good luck! 🙂
I have also used preassembled A60+ without the power transistors and power supply capacitors which I have chosen and added. Results were fine. It is the best option if you don't want to solder complete board.
I did so because there is always possibility that the most expensive parts are substituted with fakes or re-branded lower quality components. This is not the case just with Chinese products. Just open any commercial amplifier and find out that there was a great deal of cost-saving solutions. That's economy, not engineering.
Therefore, to find out the truth, I also have used smaller a60 with less output transistor to use exclusively chosen components. The results were similar if not the same.
Note also that there were (are) complete A60+ amplifiers that received excellent review. Look here!
So, all in all, A60 boards aren't so risky investment. Just advice: buy yourself power transistors and power supply capacitors to eliminate the risks.
Good luck! 🙂
The Ebay "Gold A50" does not supply output transistors or the large supply caps. I'm guessing it's a copy like most are in China. So are the original boards available ? In the advertisement they they talk about different outputs having different sounds. What did you use?
Bare boards can be found on Aliexpress. I got boards from this store.
https://www.aliexpress.com/store/1100808540/search?SearchText=a60
There are posts in this thread about different power transistors used.
https://www.aliexpress.com/store/1100808540/search?SearchText=a60
There are posts in this thread about different power transistors used.
Never heard of "Gold A50"
Here are options at Aliexpress (better than eBay):
Kit A60+
Bare board A60 (EDIT: PS: same as above, my reply was at the same time as @sabertooth)
A60
A60+
PS2: Kit A60+ could be the best option for these who want to have everything under control, but you will have to purchase quite a few of extra components.
Here are options at Aliexpress (better than eBay):
Kit A60+
Bare board A60 (EDIT: PS: same as above, my reply was at the same time as @sabertooth)
A60
A60+
PS2: Kit A60+ could be the best option for these who want to have everything under control, but you will have to purchase quite a few of extra components.
Last edited:
This seller has original transistors from Japan. I have 2 exactly original ones, when compared with them, almost one to one. They are in my A60, and have proven excellent performance. https://aliexpress.ru/item/10050027...l.0.0.7e414aa6qE7JRL&sku_id=12000022178560040
Thank you my friends. As you can see I'm trying to get some solid information. Knowing the amp works and has happy customers makes me more inclined.
Take tested clean boards, or you can even, as they said here, without output transistors and power supply capacitors. Buy separately. My new black version plays perfectly. Radiators, if possible, better more.😉
Paroxod4 .. Great helpful info. I have several large heat sinks. Where do I find these black boards? And is there a parts list or is it printed on the board? What dcv do you use?
Here is today's photo (not the last, there will also be a small power supply with a transformer to illuminate the button and the inscription on the display), this is A60, it has everything on its boards. We have already discussed it in detail here, try to read, and then we will help if there are questions.🙂
Attachments
I think the A60 will be good, since I don't my music loud. My speakers are 4 ohm. I've been looking at what is available. Looks very nice for what I need.
You can have this set, buy the rest https://aliexpress.ru/item/1005004008498262.html?sku_id=12000027723680721;)