JLM 60Watt Power AMP Kit

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greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

top woofer active at 13cm
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top woofer passive at 13cm
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bottom woofer active at 13cm
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bottom woofer passive at 13cm
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greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

looks to me like it could be improved by simply letting more highs thru the woofer, what effect would reducing the 82n and 8.2n caps to 68n and 6.8n have? too much?

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Joe Malone
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Re: JLM 60Watt Power AMP Kit

Post by Joe Malone »

Can you do one woofer and one tweeter (at 10cm for both) with no xover at all so I can see the true driver response.

Use a low level that the tweeter can handle with bottoming it out.
Joe :-)
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greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

OK, but yikes, should i protect the tweeter in some way or is a just low level enough? these tweeters are not replaceable. ceramic dome from early 90s not made anymore etc... is fuse or a big cap better?

while i do that, if i want to try the tweeter at 12dB /8ve what do i do, just remove the inductor?

greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

ok heres the woofer no xover 10cm reasonable level.

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Joe Malone
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Re: JLM 60Watt Power AMP Kit

Post by Joe Malone »

OK just do the woofer without a xover and the tweeter active xover with the cap in series with the 3.3k removed to go back to 12db/oct.

The 3.3k can then be made bigger to help match the tweeter level easier.

You can then try the active speaker with both complete with tweeter in and out of phase to see if it is improving the xover dip
Joe :-)
JLM Audio
Capturing Audio without Injury

greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

and heres the tweeter no xover low level (you can see ambient rumble and room noise)

hope its accurate enough, could maybe try slightly higher level if needed.

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greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

i'll bypass that 33n cap and test at 12dB/8ve

what do you think about the no xover graphs?

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Joe Malone
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Re: JLM 60Watt Power AMP Kit

Post by Joe Malone »

The tweeter and woofers are performing very flat with smooth roll offs in active so once phase and xovers match should be very good flat response.

Just hard to test the response of the total as it will have to be at one metre which is best done outdoors with the speaker about 50cm of the ground facing to the sky.
Joe :-)
JLM Audio
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greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

heres the overall response with tweeter at 12dB/8ve

75cm same setup as before. some improvement, the dip is much worse with the phase reversed.

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greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

BTW changing to 12dB reduced my low level hum quite a bit. still more than the other channel though. is there a right and wrong way around to connect the inductor for shielding? I also replaced the inductor with an identical one so something might have changed there, hmm new inductor is same, but mounted 90deg from where it was, could just be that?

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Joe Malone
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Re: JLM 60Watt Power AMP Kit

Post by Joe Malone »

Can you show me the tweeter response with the new 12dB/oct at 10cm and I will try to rework the woofer xover to match it better.

Is the tweeter running direct from the amp without any series resistance etc? The 2ohm you mentioned a while back?
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greenmanhumming
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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

ok will do - yes i removed the series resistor, i think maybe my perception that the tweeter needed to come down may have been related to the gap in the crossover, and maybe once we get it right it won't need it anyway...

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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

tweeter 12dB active

do you need the graph to show the level at 1k and lower too? (at expense of vertical resolution)

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Re: JLM 60Watt Power AMP Kit

Post by greenmanhumming »

same thing, different scale

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