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Old 26th June 2005, 10:04 PM   #2841
VT67 is offline VT67  Belgium
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Can't disagree with you Loek. With the 30+ temperatures we have here I'm also spending more time outdoors.
Also have to make the two special heatsinks at work end mill of the main heatsinks before I can continue with the rest.

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Old 27th June 2005, 02:40 PM   #2842
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Hi Guys,

I've got my main boards stuffed and my MJ15003/4's mounted in my heatsinks. I plan to hard wire the resistors to the sockets. Am I correct in assuming that since I am not using the feedback circuit that I don't need RV1,2 & 3?

Also, What would be the bests value for RB 1, 2 & 3 and RE 1, 2 & 3 with these TO-3's?

Does Rail voltage come into play for the values?

I am planning to use a single Power Transformer that is 30-0-30 500vA.

Thanks, Terry
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Old 27th June 2005, 03:14 PM   #2843
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Default Rb s...

...are not necessary and should be 0 ohms, ie use wire shorts.

Rvi are used for the output current limiter, which for 3 pairs of to3's is essentially unneccessary, allowing you to skip all those parts whose numbers are in the 300's

Re should be somewhere between 0.5 and 1 ohm, with 0.68 being the value I and a few others have used. IIRC, one person used much lower values (0.15ohm) successfully, the benefit being slightly greater output. There is a chance of bias instability and high adjustment sensitivity with the lower values. The more output pairs in parallel, the higher the value can be used. For the KSA100, krell had 4 output pairs and 1ohm resistors.

I am considering using 1.36 or 2.04 ohm (ie 2 or 3 x 0.68) ohms for the 16 output pair amp...just a lot of work to solder all those resistors, and I am lazy...time to shop for 2ohm 3w resistors I guess...

Under extreme conditions the output emitter resistors can get hot, they may be slightly warm under normal output conditions.

HTH

Stuart
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Old 27th June 2005, 03:40 PM   #2844
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Hi Stuart,

Can I then just wire the P. output and N. output directly to their respective bases of Q1- Q3 and then 0.68 3W resistors between Q1, Q2 & Q3 emitters and the speaker jacks? I'm not planning on using the output boards at all. Should I use some heatsinks on the emitter resistors?

Thanks, Terry
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Old 27th June 2005, 04:01 PM   #2845
lgreen is offline lgreen  United States
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Quote:
Originally posted by still4given
Hi Guys,

Am I correct in assuming that since I am not using the feedback circuit that I don't need RV1,2 & 3?

Thanks, Terry

WHOA! I see that the feedback circuit connects to a number of circ componets. I think you need to use the feedback circ even with no protection (300 series numbered components) installed.

Have I got this right or is FB not necessary with no protection components installed?
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Old 27th June 2005, 04:11 PM   #2846
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Default output wiring...

Terry,

I hard wired the emitter resisters to the transistor sockets and then collected the output from the junction of all the resistors using a 10 gauge bare copper bus wire. The bases & collectors are hard wired together, with 24 gauge wire for the bases and a 16 gauge wire for each collector, finally using a 10 gauge run from the emitter resistor junction to the output jack, and from the collectors to the power supply caps...

The emitter resistors don't need a heatsink, just room to breath...they are designed to dissipate their rated level of power without additional heatsinking, but they do need 'fresh' air to be able to move around them...

Stuart
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Old 27th June 2005, 04:14 PM   #2847
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Default pay no attention to the...

...components labelled 30x, ie q30x, c30x, r30x, d30x. They have no function in the circuit other than current limiting. The feedback point is from the juntion of the emitter resistors, which is also the output. This is why the components for the current limiter connect there...

None of the 5 channels I've built (or any that krell built) included Rvi or any of the 30x components, they all work perfectly...

Stuart
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Old 27th June 2005, 04:39 PM   #2848
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Default Re: output wiring...

Quote:
Originally posted by Stuart Easson
Terry,

I hard wired the emitter resisters to the transistor sockets and then collected the output from the junction of all the resistors using a 10 gauge bare copper bus wire. The bases & collectors are hard wired together, with 24 gauge wire for the bases and a 16 gauge wire for each collector, finally using a 10 gauge run from the emitter resistor junction to the output jack, and from the collectors to the power supply caps...

The emitter resistors don't need a heatsink, just room to breath...they are designed to dissipate their rated level of power without additional heatsinking, but they do need 'fresh' air to be able to move around them...

Stuart

Very cool! I'm almost done.

I should be testing sometime this week.

Thanks for all the help.

Blessings, Terry
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Old 27th June 2005, 05:36 PM   #2849
neychi is offline neychi  Croatia
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Hi Walter,
No, I'm afraid that's not it.
Cheers
Dean
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Old 27th June 2005, 08:28 PM   #2850
VT67 is offline VT67  Belgium
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When can we expect an update on Brian's KSA50 pages?

Neychi, which boards are they then?

Today I cleaned up my main heatsinks on the milling machine (the sawing got a bit ugly). Tommorow still some small deburring job and washing of the petrolium and I can start moving parts around trying to find a good layout for my amps.
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