Hi guys🙂,
last week I started to design an active crossover an I just finished. Now I would like to create two transistor amplifier boards, one with about 100W@8ohms and the other one with 70W@8ohms, both powered with a toroidal transformer. Normally I find the schematics online and I modify them for my purpose, but this time I haven't found anything😱.
Can somebody recommend me something😕?
Best regards
Ben
last week I started to design an active crossover an I just finished. Now I would like to create two transistor amplifier boards, one with about 100W@8ohms and the other one with 70W@8ohms, both powered with a toroidal transformer. Normally I find the schematics online and I modify them for my purpose, but this time I haven't found anything😱.
Can somebody recommend me something😕?
Best regards
Ben
The amp in post 2 appears to be a single output pair amp.
Depends on how long you need 70 W or 100W. I have gotten 25.5 v on 8 ohm speaker for 5 seconds at a time out of my AX6. That is more than 70 W. This violates soa of the white box MJ15003 output transistors, but for that brief period it was fine. That is on 69 v single rail, quite stiff, 6.5 amp capability. It might have gone louder with more input voltage but I was wearing earplugs and didn't want to hear the music any louder.
As I was musing with another on this thread Retro Amp 50W Single Supply
there is plenty of drive current to run two pairs of output transistors with the same 4 transistor configuration. The secret is using capable transistors as MJE15028/29 for VAS and drivers, with plenty of heat sink on them. I use those in my board, with heat sinks on both drivers and the VAS. Perhaps boosting the rail voltage to 75 with two pairs On semi output transistors would allow AX6 to put out 30 vac for 5 seconds at a time on 8 ohm, or 112 W. I'm using MPS8099 for input transistor which is 80 v capable, maybe at 75 v a MPSW06 2 watt capable input transistor might be more appropriate. Newark had some 2n5682 10 W 120 v capable TO18 metal can transitors in 2017, maybe that with a heat sink would be more durable input transistor at the higher rail voltage. The 2 amp rail fuse on AX6 schematic would have to be upgraded, I use 10 A for 2 channels. Also the 2200 uf output capacitor might limit bass, I'd use 4700 uf per channel. I had 3300 uf output cap & rail cap on my test. (1 rail cap both channels, both channels 72 watt simultaneously).
Peavey takes 2 pairs of OT to 130 W/ch rms on 8 ohms in the PV-4c, but that is with +-56 v rails. MJ15024/25 output transistors MJE15032/33 drivers. As that is a direct connect amplifier, with a DC protect crowbar, I won't let the PV-4c touch my $599 list price SP2-XT speakers. I use PV-4c with salvage 6.5" drivers from old projection TV's I found on the curb for the garbage.
Depends on how long you need 70 W or 100W. I have gotten 25.5 v on 8 ohm speaker for 5 seconds at a time out of my AX6. That is more than 70 W. This violates soa of the white box MJ15003 output transistors, but for that brief period it was fine. That is on 69 v single rail, quite stiff, 6.5 amp capability. It might have gone louder with more input voltage but I was wearing earplugs and didn't want to hear the music any louder.
As I was musing with another on this thread Retro Amp 50W Single Supply
there is plenty of drive current to run two pairs of output transistors with the same 4 transistor configuration. The secret is using capable transistors as MJE15028/29 for VAS and drivers, with plenty of heat sink on them. I use those in my board, with heat sinks on both drivers and the VAS. Perhaps boosting the rail voltage to 75 with two pairs On semi output transistors would allow AX6 to put out 30 vac for 5 seconds at a time on 8 ohm, or 112 W. I'm using MPS8099 for input transistor which is 80 v capable, maybe at 75 v a MPSW06 2 watt capable input transistor might be more appropriate. Newark had some 2n5682 10 W 120 v capable TO18 metal can transitors in 2017, maybe that with a heat sink would be more durable input transistor at the higher rail voltage. The 2 amp rail fuse on AX6 schematic would have to be upgraded, I use 10 A for 2 channels. Also the 2200 uf output capacitor might limit bass, I'd use 4700 uf per channel. I had 3300 uf output cap & rail cap on my test. (1 rail cap both channels, both channels 72 watt simultaneously).
Peavey takes 2 pairs of OT to 130 W/ch rms on 8 ohms in the PV-4c, but that is with +-56 v rails. MJ15024/25 output transistors MJE15032/33 drivers. As that is a direct connect amplifier, with a DC protect crowbar, I won't let the PV-4c touch my $599 list price SP2-XT speakers. I use PV-4c with salvage 6.5" drivers from old projection TV's I found on the curb for the garbage.
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There's also the greg ball simple killer amp.
Power Output
150Wrms max into 4/8ohms
Idle Power
11W on +/-50V supplies
Freq. Response
20Hz - 20kHz 0.15dB @ 1W
Sensitivity
1Vrms for 100Wrms/8ohms
Input Impedance
27k // 330pF
Slewing Rate
>15V/uS into 8ohms
THD
<0.025% @ 100W/8ohms
typ
<0.01% 2hD @ 10Wrms
Damping Factor
>500 @ 50Hz for 8ohms
Hum & Noise
< -100dBA w
Power Output
150Wrms max into 4/8ohms
Idle Power
11W on +/-50V supplies
Freq. Response
20Hz - 20kHz 0.15dB @ 1W
Sensitivity
1Vrms for 100Wrms/8ohms
Input Impedance
27k // 330pF
Slewing Rate
>15V/uS into 8ohms
THD
<0.025% @ 100W/8ohms
typ
<0.01% 2hD @ 10Wrms
Damping Factor
>500 @ 50Hz for 8ohms
Hum & Noise
< -100dBA w
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Forgot to mention, the SKA has 4 mosfet irfp24/irfp9240 , but it runs great with just one pair, ideal for mid/high.
4 mosfet for low duty.
4 mosfet for low duty.