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Old 16th June 2009, 10:14 PM   #7941
john65b is offline john65b  United States
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I didn't know the F5 came anywhere near 50wpc...

Ryssen-I have your populated KSA50 krell board still. I have not finished the amp yet. Did you not enjoy the sound?
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Old 17th June 2009, 03:01 PM   #7942
Ryssen is offline Ryssen  Sweden
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Quote:
Ryssen-I have your populated KSA50 krell board still. I have not finished the amp yet. Did you not enjoy the sound?
Yes I did,but then I sold them to another forum member,I havet heard how hes doing,but would be nice to know.

Quote:
I didn't know the F5 came anywhere near 50wpc...
I think the F5 is 25w klass A,and 50w klass AB.
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Old 17th June 2009, 03:17 PM   #7943
john65b is offline john65b  United States
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Yes, you sold it to me. Hopefully back on it shortly.

I did remove the has switch you had, so now it will run full bias all the time.
Are you enjoying the 41hz Amp 5 we traded?
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Old 17th June 2009, 03:34 PM   #7944
Ryssen is offline Ryssen  Sweden
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Quote:
Are you enjoying the 41hz Amp 5 we traded?
Sold it to a guy here in Sweden,built a F5 instead.
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Old 18th June 2009, 09:42 AM   #7945
Adi2009 is offline Adi2009  Poland
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I have new question. Can I use MJ15024/MJ15025. I can't buy original MJ15003/MJ15004 in Poland. Can I use 3 pairs for a channel with bias 0,63A for each transistor?I have one transformer for a channel 450VA with 2x35AC.
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Old 18th June 2009, 10:41 AM   #7946
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by Adi2009
I use MJ15024/MJ15025. ........ Can I use 3 pairs for a channel ?.............I have one transformer for a channel 450VA with 2x35AC.
35Vac will make the amplifier run much hotter.
3pairs with a total bias of 1.9A will be able to dissipate the heat, but the heatsink will require to be much larger than a KSA50.

You will end up with a high bias ClassAB amplifier capable of ~200W into 4r0 and ClassA output for loads >=16r0.
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Old 18th June 2009, 11:09 AM   #7947
Adi2009 is offline Adi2009  Poland
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You will end up with a high bias ClassAB amplifier capable of ~200W into 4r0 and ClassA output for loads >=16r0

What does it mean???
I'll have A Class with 16 Ohm speakers??? I have 8 Ohm speakers and because of this I'll have Class AB? Please explain me.
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Old 18th June 2009, 01:11 PM   #7948
AndrewT is offline AndrewT  Scotland
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I could not edit my last post due to DIYaudio database problems.

The 16r0 should read:
Quote:
You will end up with a high bias ClassAB amplifier capable of ~200W into 4r0 and ClassA output for loads >=11r0.
A ClassA amplifier set to 1.9A bias (KSA50) can send upto 3.8A of ClassA current to the load.
50W into 8r0 ClassA requires that the amplifier should be able to reach 28.3Vpk into an 8r0 load and simultaneously pass 3.5Apk to the same load.

If you connect a 4ohm load to that 50W into 8r0 ClassA amplifier, then you will have a maximum ClassA output of 25W due to reaching the 3.5Apk ClassA current limit into that 4r0 load.

The push-pull amp is capable of delivering even more power if the power supply is able.
The KSA50 will easily deliver 100W into 4r0 as a ClassAB amplifier when the PSU is as standard.


You are proposing a 35Vac transformer and this will give ~+-50vdc from the supply. When biased to 1.9A, the PSU will probably drop to ~+-49Vdc. The amp will easily deliver 100W into 8r0 and very likely be able to deliver 200W into 4r0. All of these maximum powers are in ClassAB mode.

If you want to know the maximum ClassA power available you have to use the ClassA current limit to determine the ClassA power capability.

Check what Vpk and Ipk you will need to get 70W into 11r0.

Try to drive a lower impedance load and the amp will go into ClassAB when driven to maximum output.
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Old 18th June 2009, 01:58 PM   #7949
Adi2009 is offline Adi2009  Poland
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Thanks a lot for help. and what about transistors MJ15024/MJ15025?Are they ok? I have 16pcs - 8pnp & 8npn. How to use it? 2 per channel, 3 or 4pairs?
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Old 18th June 2009, 02:22 PM   #7950
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by AndrewT
35Vac will make the amplifier run much hotter.
3pairs with a total bias of 1.9A will be able to dissipate the heat, but the heatsink will require to be much larger than a KSA50.

Quote:
Originally posted by Adi2009 what about transistors MJ15024/MJ15025?Are they ok? I have 16pcs - 8pnp & 8npn. How to use it? 2 per channel, 3 or 4pairs? [/B]
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