The drivers are Q3 and Q4. Are those the ones you mean ?
This is not a great design because the bias is fixed and very component dependent.
Assuming a current of around 7ma plus the base bias current of the output stage and you are looking at around 1.5 watts dissipation per driver. So they need heatsinks and will get quite warm/hot.
The only way to make them run cooler (less dissipation) is to lower the supply voltage or lower the current. Increasing R12 and R13 to perhaps 120 ohms might help but be careful. I would suggest you use a bulb tester while experimenting.
This is not a great design because the bias is fixed and very component dependent.
Assuming a current of around 7ma plus the base bias current of the output stage and you are looking at around 1.5 watts dissipation per driver. So they need heatsinks and will get quite warm/hot.
The only way to make them run cooler (less dissipation) is to lower the supply voltage or lower the current. Increasing R12 and R13 to perhaps 120 ohms might help but be careful. I would suggest you use a bulb tester while experimenting.
Multisim 14 simulatoır testing driver transistor Mje15000xx series , bias current 30ma. Dc Offest Ov volt speraker out.
https://www.youtube.com/watch?v=CYTpehIVfRg
I made the 3-way active module, this amplifcator is in the power bass section but it is warming up
I made the 3-way active module, this amplifcator is in the power bass section but it is warming up
The design is usually use for audio pro, when the community want high SPL and do not care (may be do not understand) about sound quality.
I found many people in that community do not notice when clipping happened, until the protection work or burn the speaker.
Ouch!! , it is a very poor design, you should have built one of Apex Audio designs (you can find them here in this Forum in the Solid State section) which are much better, tested and already built by Forum members.
Not too late, you can build them using 90% of what you already have.
In any case, you already built this one, so let´s try to make it work.
Q3 and Q4 transistors are mounted on the big heatsinks so they should warm up but not overheat.
Are both fans connected and running? You NEED them.
Sound quality aside, the big problem with this amplifier is that it does NOT have a speaker out short circuit protection, so when you short cables even for 1/10th of a second, you will blow very expensive transistors.
Then the resulting DC (84V DC will appear at speaker terminals) will blow the speakers.
So be very careful with shorts, only use screw terminals (and check wiring every time) or Speakon connectors, never ever musical instrument type plugs and jacks.
EDIT: are you driving those tiny speakers with a true 600W per channel amplifier?
You will DESTROY them in he first show you use them, sorry.
PS:loved the Music, will soon visit Istanbul again 🙂
Not too late, you can build them using 90% of what you already have.
In any case, you already built this one, so let´s try to make it work.
Q3 and Q4 transistors are mounted on the big heatsinks so they should warm up but not overheat.
Are both fans connected and running? You NEED them.
Sound quality aside, the big problem with this amplifier is that it does NOT have a speaker out short circuit protection, so when you short cables even for 1/10th of a second, you will blow very expensive transistors.
Then the resulting DC (84V DC will appear at speaker terminals) will blow the speakers.
So be very careful with shorts, only use screw terminals (and check wiring every time) or Speakon connectors, never ever musical instrument type plugs and jacks.
EDIT: are you driving those tiny speakers with a true 600W per channel amplifier?
You will DESTROY them in he first show you use them, sorry.
PS:loved the Music, will soon visit Istanbul again 🙂
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Thank you, Istanbul is beautiful, we wait for you to visit your visit. In the meantime, if this scheme is not good, can you share the simple Powerful Power Amplifier document that works on this level?
Check the Apex Audio circuits here in DIY Audio.
You will be able to use the same cabinet/transformer/big filter caps and transistors, which is 90% of the total cost, so you do not waste $$$$$$.
You will have to make new PCBs.
Apex himself does no suppy them, but Forum members have drawn their own and posted them here, also show fully or partly built examples.
He also published add-on speaker protectors which work with many amplifiers, in fact you might add one to your current "video rockola" amplifier ... pity it will not solve its other problems, and mainly lack of stability or thermal problems.
Take care.
You will be able to use the same cabinet/transformer/big filter caps and transistors, which is 90% of the total cost, so you do not waste $$$$$$.
You will have to make new PCBs.
Apex himself does no suppy them, but Forum members have drawn their own and posted them here, also show fully or partly built examples.
He also published add-on speaker protectors which work with many amplifiers, in fact you might add one to your current "video rockola" amplifier ... pity it will not solve its other problems, and mainly lack of stability or thermal problems.
Take care.
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