Inspired by the famous GoldMund Mimesis 3, I was intrigued with a naughty idea..
I changed the topology final stage from source follower to common source. With this change, there is a slightly more gain going on this stage and give a more punchy bass. This is according to my personal opinion based on my experience in building solid state power amplifier for more than 20 years, Nevertheless, if this opinion is wrong, please feel free to criticize me 🙂
Minor improvement in the input stage also made, I added variable resistor (trimmer) on the CCS circuit which is, at least on my personal seen, never found in any commercial amplifier. However, being a DIY who has a lot of curiosity and naughty ideas 🙂, I let DIY to spoil their ideas with a trial and error in order to obtain a specific or special character of sound which is most appropriate to personal taste.
With adjustable CCS, we can play with various idle current of differential pairs of 2SK170 (LSK170), from 0.8mA - 3 mA. What is the difference? It is difficult to explain in words, but I just give you a clue : different character of vocal, mid and bass.
Well in the mean time, please enjoy the schematic 🙂
Best regards form Jakarta, Indonesia
I changed the topology final stage from source follower to common source. With this change, there is a slightly more gain going on this stage and give a more punchy bass. This is according to my personal opinion based on my experience in building solid state power amplifier for more than 20 years, Nevertheless, if this opinion is wrong, please feel free to criticize me 🙂
Minor improvement in the input stage also made, I added variable resistor (trimmer) on the CCS circuit which is, at least on my personal seen, never found in any commercial amplifier. However, being a DIY who has a lot of curiosity and naughty ideas 🙂, I let DIY to spoil their ideas with a trial and error in order to obtain a specific or special character of sound which is most appropriate to personal taste.
With adjustable CCS, we can play with various idle current of differential pairs of 2SK170 (LSK170), from 0.8mA - 3 mA. What is the difference? It is difficult to explain in words, but I just give you a clue : different character of vocal, mid and bass.
Well in the mean time, please enjoy the schematic 🙂
Best regards form Jakarta, Indonesia
Yes, of course you can 🙂 despite there is Q3 and Q4 which actually already met your idea.
Current mirror present on 2nd VAS, those are Q9, Q10
Bias control, transistor Q8 is actually not a must, it could be removed and substitute it with just VR and silicon diode. This configuration is even more save for the finals mosfet compared to using transistor.
I have designed the pcb, but they are out of stock by friends of mine in "DIY audio community Indonesai" . I think. I should order again the pcb 🙂 🙂
Schematic does not say how high the input supply voltage is.
There are ZENERS that should set the input stage voltage.
The voltage supply says 56V, but regulation output is not defined.
There are ZENERS that should set the input stage voltage.
The voltage supply says 56V, but regulation output is not defined.
yes, the value of the zeners are not given...
i will use the irf640 and the irf9640 instead for the series pass device...
since the output stage is at +-32v. i would say about 39 volt zeners will fit there..
i will use the irf640 and the irf9640 instead for the series pass device...
since the output stage is at +-32v. i would say about 39 volt zeners will fit there..
Didik have you ever think to make the input fully balanced (2sj74) ? Does someone care about this project ?
I would wire the pot that way to Vbe multiplier.
If wiper becomes unattached it will turn on output transistors fully and pop them.
Put pot in lower part of circuit so if wiper becomes unattached the Vbe voltage goes down.
If wiper becomes unattached it will turn on output transistors fully and pop them.
Put pot in lower part of circuit so if wiper becomes unattached the Vbe voltage goes down.
Hi,
Sorry for forgotten to put the ZD value. It is 42 - 45V
Supply for final mosfet, I applied 35V, with bias current 750mA per device (BUZ905/900)
If you use IRP244/9244 as Mr Pass use in all his published schematic, you must put higher bias in order to get same good sound as BUZ905/900 (SK1058/J162//SK1530/J201). The "sweet spot bias" of this circuit when using IRFP is 1.2A - It is according to my experience on this circuit
You are right that input balance or diamond configuration give warmer sounded Use LSK170/LSK74