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Crest CA18 & 9001

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levyte357 View Drop Down
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    Posted: 12 February 2009 at 1:08pm
Originally posted by levyte357 levyte357 wrote:


I was told, CA18 is essentially 9001, with 15kg of power supply/gravity removed.

CA12 is just a smaller amp.

Cheers.


Originally posted by demanddeepbass demanddeepbass wrote:

Looking quickly at the schematics the architecture looks very similar between the CA12 and 18 and they are both class H but the output devices are very different. The CA18 uses FETs as in the high power rail. The output stage of the CA18 does indeed look very similar the 9001. They've got similar amounts of smoothing too, in fact I'm not entirely clear what the main differences are from just a quick glance at the pictures. I expect the mains transformer is a fair bit bigger.


Last time I looked at schematics, I "think" the 9001 also has 12x smoothing caps, but higher values, and "maybe" higher ripple current.

Does the CA18 have same number of O/P transistors as 9001 ?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote demanddeepbass Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 1:34pm
Yep, 18 and 9001 have same number and same type of OP devices.
I did a very quick tot up of farads: 75000uF in the 18 and 76000uF in the 9001: near as makes no difference. Didn't look at ripple figures.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357 Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 2:30pm
Originally posted by demanddeepbass demanddeepbass wrote:

Yep, 18 and 9001 have same number and same type of OP devices.
I did a very quick tot up of farads: 75000uF in the 18 and 76000uF in the 9001: near as makes no difference. Didn't look at ripple figures.


@deepbass:I heard a rumour, that the CA18 current limiting in 2.66 ohm mode is not as restrictive as in 2 ohm mode, hence the amp can actually output over 2.5kw per channel in this mode?

Does that seem possible to you?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 4:42pm
The Crest CA 18 offers a voltage rail of 99 Volts DC +/-

The Crest Professional Series 9001 offers a voltage rail of 114 Volts DC +/-

These amplifiers are not the same.

Best Regards,

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Post Options Post Options   Thanks (0) Thanks(0)   Quote chickenfizz Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 5:03pm
My knowledge of class h and class g designs isn't great but I'm guessing ripple current would not be a factor in these designs? Please someone correct me if I'm wrong.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote demanddeepbass Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 5:22pm
The schematics show them both as having +- 120V are your figures measured voltages Elliot? I'll check the schematics in detail if I get time but the output stages look mighty similar....

It's possible that you might get more power at 2.66 that at 2 if there is indeed a current limiter but id need to sit down and do maths to check - no time right now I'm afraid.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 6:11pm


Originally posted by demanddeepbass demanddeepbass wrote:

The schematics show them both as having +- 120V are your figures measured voltages Elliot? I'll check the schematics in detail if I get time but the output stages look mighty similar....It's possible that you might get more power at 2.66 that at 2 if there is indeed a current limiter but id need to sit down and do maths to check - no time right now I'm afraid.



Both came directly from Crest's spec sheet. It is more than likely taking the load into account. In addition to the power supply sag for, the 9001 offers 65 Amps (120 Volt) while, the CA 18 will deliver 36 Amps (120 Volt) @ 4 ohms maximum. The CA 18's power supply is weaker than the 9001, which affects the overall performance.

Without doing the calculations the CA 18 will meet it's specs while the 9001 will exceed it's published specs.

Best Regards,



Edited by Elliot Thompson - 12 February 2009 at 6:12pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote csg Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 6:39pm
Having owned a few 9001's in the past, and having compared them directly to ca18's i can assure you there is a considerable difference in practice. the 9001 is considerably more powerful.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357 Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 8:02pm
Originally posted by Elliot Thompson Elliot Thompson wrote:



Without doing the calculations the CA 18 will meet it's specs while the 9001 will exceed it's published specs.

Best Regards,




Please correct me where I'm wrong,

Assuming amp is 100% Efficient, which it isn't,

How can 240(V) @ 18(A) * 1 (100% Efficiency) = 5000W ????

EDIT:Suggests values are not measured, but estimated ?



Edited by levyte357 - 12 February 2009 at 8:05pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TRE4U2NV Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 8:15pm
ear 2  ear 9001 all day everydayClap
IM SO SECRETIVE BUT I CANT TELL YOU WHY
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 9:59pm
A 9001 installed with no more than 4m of 10mm square cable back to the main 100A incomer to the building definitely brings a smile to my face every time!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2009 at 10:08pm

Originally posted by levyte357 levyte357 wrote:




Originally posted by Elliot Thompson Elliot Thompson wrote:



Without doing the calculations the CA 18 will meet it's specs while the 9001 will exceed it's published specs.

Best Regards,

Please correct me where I'm wrong, Assuming amp is 100% Efficient, which it isn't,How can 240(V) @ 18(A) * 1 (100% Efficiency) = 5000W ????EDIT:Suggests values are not measured, but estimated ?


Well I did say, I did not do the calculations.

Right!

240 Volts @ 18 Amps = 4320 watts. Bare in mind the amperage stated is under 4 ohms stereo mode not, 2 ohms. Under a 2-ohm configuration the amperage will be greater so, it should achieve 5000 watts.

4320 watts versus 5000 watts yields a 0.6 dB gain. Whether 5000 or 4320 watts you will not hear a difference.

Best Regards,
Elliot Thompson
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