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Old 15th November 2005, 03:04 PM   #21
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Hi, Richie00boy,

The bias is set tobe very little (less than 10mA), so I think (tought , actually) it won't be a problem. That is many years ago. It should work fine with K1058, but this device is much more expensive, not appropriate with the kit's price.

This cct has too many problem. Lack of VBE multiplier. Very dependant on supply rail.

I've removed it.

The main intention of making my website is to share knowledge. I don't think even a glance that it can make people dislikes me. Right, AndrewT?
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Old 15th November 2005, 03:14 PM   #22
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Stability of QC depend also on heat conductivity of heatsink - if conductivity will be large and QC small, probably this amp will be working OK ( little fluctuations of QC exist in every amps ) . But remember, that in this case must be heatsink bigger than " normal " in oposite case is danger of " avalanche " of QC...
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Old 15th November 2005, 04:20 PM   #23
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Hi, Upupa Epops,

You are right. The heatsink plays the whole control in determining "dead or alive" in an amp which do not have thermal tracking. Many "economic" design now (hifi or car amp) do not use thermal tracking at all, just relying on the capability of the heatsink to dissipate heat. Even when they are using bipolars or Vmos output device.

I noticed something (maybe you won't agree with this one ). The more "primitive" the biasing scheme is, the better the sound (and offcourse the worse in danger of heat failure).

Biasing scheme :
-String of diodes sounds better than VBE multiplier.
-Simple R/VR sounds better than string of diodes. (but using only R/VR requires suitable devices, like the mosfet100 schematic in my website which uses K1058/J162). And offcourse, bigger (=more insurance) heatsink.......
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Old 15th November 2005, 04:31 PM   #24
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It's not so simply, Lumanauw, multiplier must be symetric and all is OK...
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Old 15th November 2005, 06:13 PM   #25
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Thanks Lumenauw, that's about what I thought.
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Old 16th November 2005, 07:10 AM   #26
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Hi everyone,

Please be soft on the LumanauW, our David....he is nice..

K a n w a r
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Old 16th November 2005, 07:24 AM   #27
AndrewT is offline AndrewT  Scotland
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Hi,
is that two of you agreeing that a dual complementary Vbe multiplier (as Borbely and others) sounds nicer than a single ended multiplier?
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Old 16th November 2005, 07:54 AM   #28
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Can someone redesign the circuit so it can work and sound like a 50 watt mosfet amplifier ??Come on people im new to this if i could i would have but im a newbie still,Anyways

Looks like im off using P3A from Rod after all
http://sound.westhost.com/project3a.htm
some good feedback from that amp !!

A very big Thank you to everyone would gave there views , feedback and support on this amp that gave me grey hair heheh.
Also Thank you especially to the author LumanauW who at least came out and told everyone about hes amp that dont work .

LumanauW thanks for removing the circuit from ur website respect !

Cheers people !

I`ll be back.
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Old 16th November 2005, 09:57 AM   #29
mcp is offline mcp  United States
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Quote:
Originally posted by Reactance
I used a +/- 15 Supply just to test and I thought maybe the supply is to weak and I applied the full +/- 30Vdc and bang the mosfets fried Instantly
The mosfets could have been wired wrongly.

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Old 16th November 2005, 11:28 AM   #30
AndrewT is offline AndrewT  Scotland
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Hi,
I think the reviews on this forum for ESP amps gives sufficient kudos to consider going down that route.

If you stay with FETs then ESP only use laterals. If you want to save cost and go VFETs then choose from some designs on the forum.
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