You, rightly, report an indisputable experience.
The 250 circuit, already limited by itself, is, in my humble opinion, a poor example of the stabilized power discourse, in my opinion.
With your utmost respect, but I, with a very different scheme from 250, have had opposite results:
greater dynamics,
low, medium-low
scene,
finesse of grain.
Even with the Dartzeel scheme I had identical results, albeit in a different%.
But the Dartzeel is an open link, my scheme is very counter-reacted.
Allow me to add that a stabilizer, not as a scheme, but thought and positioned as in the NAP, well, who explains its sensibility to me?
The 250 circuit, already limited by itself, is, in my humble opinion, a poor example of the stabilized power discourse, in my opinion.
With your utmost respect, but I, with a very different scheme from 250, have had opposite results:
greater dynamics,
low, medium-low
scene,
finesse of grain.
Even with the Dartzeel scheme I had identical results, albeit in a different%.
But the Dartzeel is an open link, my scheme is very counter-reacted.
Allow me to add that a stabilizer, not as a scheme, but thought and positioned as in the NAP, well, who explains its sensibility to me?
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Heatsink size?
The left picture show black metal surfaces at the bottoms of the boxes where the 108 boards are mounted. Are there heat sink "fins" protruding underneath the boxes, or are they just a sheets of aluminium?
I am trying to figure out how large heatsinks I need to buy, one seller on Ali recommends 2 Kg of aluminium per channel! Is that really necessary?
The left picture show black metal surfaces at the bottoms of the boxes where the 108 boards are mounted. Are there heat sink "fins" protruding underneath the boxes, or are they just a sheets of aluminium?
I am trying to figure out how large heatsinks I need to buy, one seller on Ali recommends 2 Kg of aluminium per channel! Is that really necessary?
Weight is hardly a good way to specify heatsinks, but yes, 2kg is around the ballpark. A properly biased amp draws about 350mA per rail, so at 50v rails that's 17.5W of dissipation per rail or 35W per channel. Lots of Chinese clones appear to be underbiased.
And that heatsink facing down... Being huge helps but most of the heat goes into the case.
I see no shielding and the smps is right next to the amp. Is that a ferrite the RCA inputs go through? Another sound killer.
Are you using a readymade amplifier case, such as one of hundreds of designs one can buy on Ali, or do you have some other solution? Picture?
Just trying to get ideas on designs and dimensioning of heatsinks. I found this case on Ali:
https://www.aliexpress.com/wholesal...SB_20200305065435&origin=y&SearchText=BZ3608A
It looks nice, price is good.
Would those heatsinks be big enough for a 108 with two pairs of output transistors and the proper bias current, I wonder?
In this department weight matters. First, all these cases are too little and incapable handling cooling requirements. Just observe transportation costs for larger, adequate units.
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This case is ridiculously small. My pcbs have similar proportions to the originals (single output pair) and are by themselves 80mm wide. Add to this the transistors sticking at opposing sides and you are looking at a heatsink no less than 130mm in height. The sinks i use are 150mm tall and the boards look just comfortable when mounted. For this form factor of the boards slim cases are not an option.
When shipping is taken into account the cases from Audiophonics appear to represent better value. Unfortunately they don't seem to stock the Dartz colour scheme
This case is ridiculously small. My pcbs have similar proportions to the originals (single output pair) and are by themselves 80mm wide. Add to this the transistors sticking at opposing sides and you are looking at a heatsink no less than 130mm in height. The sinks i use are 150mm tall and the boards look just comfortable when mounted. For this form factor of the boards slim cases are not an option.
When shipping is taken into account the cases from Audiophonics appear to represent better value. Unfortunately they don't seem to stock the Dartz colour scheme
The height or fit inside the chassis is not a concern. I am planning to buy this form factor 108:
Buy Products Online from China Wholesalers at Aliexpress.com
I just wonder if a 260*80*40mm can transfer enough heat? I assume the whole aluminium case works, front, rear and top, as an extended heat sink?
Cool.
I guess this 108 board has exactly the same circuit as other 108 boards with 2 pairs of output transistors, aren't they all the same? It also has a C1237HA speaker protection circuit with a 8A relay.
I got a very good deal on three! 500VA Canterbury Windings toroidal transformers from a guy on ebay. They have 2x42V out, I guess 59v DC?
A Russian guy made a very thorough review on them: Клон усилителя DarTZeel, для тех кому хочется тепла. Набор для сборки усилителя. Обзор комплекта для сборки усилителя I use Google translate
I guess this 108 board has exactly the same circuit as other 108 boards with 2 pairs of output transistors, aren't they all the same? It also has a C1237HA speaker protection circuit with a 8A relay.
I got a very good deal on three! 500VA Canterbury Windings toroidal transformers from a guy on ebay. They have 2x42V out, I guess 59v DC?
A Russian guy made a very thorough review on them: Клон усилителя DarTZeel, для тех кому хочется тепла. Набор для сборки усилителя. Обзор комплекта для сборки усилителя I use Google translate
The case is recovered from a 800MHz RF link and is meant to be wall mounted.
I could've flipped the U channel brackets over so that the heatsink fins were vertical but couldn't be bothered in the end due to the size of the heatsink, and also focusing on other tasks.
I had a ferrite clamp on the rca input due to unshielded wires, and I was playing with a SDR (software defined radio) nearby. ferrites that size do nothing for audio.
