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Old 3rd August 2012, 12:12 AM   #1651
Mr. dB is offline Mr. dB  United States
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Quote:
Originally Posted by coolmaster View Post
Thanks guys. I know its a significant benefit to have a separate PSU since this is a DIY project building from scratch, whereas people have to accept the commercial 1 box version as built. Seeing a picture of the internals of XP15 tells me its alright to copy the same layout, morover the tranny doesn't look shielded. I intend to shield it. Afterall countless pre amps manufactured are 1 box. I've planned to have a pair of Cinemag SUT at the input. Its also intended for MC mode only. Thats why I'm still looking to reduce the gain to 40db maximum.
I'm going to give it a try to mount the PSU the same way as XP15 and see if any issues crop up. If I can get away from 2 box, I'll be a happy camper.

Pic taken from the internet.
Since the Pearl Two is already a MC phono preamp, why would you need additional step-up transformers?
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Old 3rd August 2012, 02:29 AM   #1652
6L6 is offline 6L6  United States
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Transformers load a MC cartridge in a way that can sound very, very good.
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Old 3rd August 2012, 05:54 AM   #1653
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Originally Posted by 6L6 View Post
Transformers load a MC cartridge in a way that can sound very, very good.
That's exactly is to be expected.

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Originally Posted by Mr. dB View Post
Since the Pearl Two is already a MC phono preamp, why would you need additional step-up transformers?
R28 with 100ohm resistor = MC phono preamp
Without R28 = MM phono preamp
Supposed to be like this, no?

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Originally Posted by AVWERK View Post
Or you could try a 3 box solution.
Regards David.

Last edited by coolmaster; 3rd August 2012 at 05:56 AM.
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Old 8th September 2012, 11:38 PM   #1654
Mr. dB is offline Mr. dB  United States
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What are the dimensions of the Pearl II boards?

I'm trying to figure out if the pair will fit a chassis I have. Its internal dimensions are 7 3/4" wide by 11 1/4" deep by 2 1/2" high.

Thanks.
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Old 8th September 2012, 11:45 PM   #1655
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7x5. If you use the intended heat sink for the regulators, it just over 1.5" high.
That doesn't include stand offs.
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Old 9th September 2012, 12:00 AM   #1656
6L6 is offline 6L6  United States
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Yes, that chassis will work, and nicely!

The PSU won't fit, but that can be built in a much smaller (and uglier, as it can be hidden...) case.

As mentioned, do pay attention to the height of your heatsinks and big caps. But it shouldn't present a problem.

It's a fantastic phono stage. Of my DIY phonostages, only the original Pearl is anywhere close to as good.
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Old 9th September 2012, 12:07 AM   #1657
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The PCBs alone are amazing. Now I understand the cost.

Btw- can silver mica caps be used on the output MOSFET? I have 4 in that size and they measure exactly.
10pF fr freq compensation.
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Last edited by vdi_nenna; 9th September 2012 at 12:09 AM.
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Old 9th September 2012, 01:13 AM   #1658
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Yes, silver mica is fine.
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Old 9th September 2012, 04:26 AM   #1659
Mr. dB is offline Mr. dB  United States
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Quote:
Originally Posted by vdi_nenna View Post
7x5. If you use the intended heat sink for the regulators, it just over 1.5" high.
That doesn't include stand offs.
Quote:
Originally Posted by 6L6 View Post
Yes, that chassis will work, and nicely!

The PSU won't fit, but that can be built in a much smaller (and uglier, as it can be hidden...) case.

As mentioned, do pay attention to the height of your heatsinks and big caps. But it shouldn't present a problem.

It's a fantastic phono stage. Of my DIY phonostages, only the original Pearl is anywhere close to as good.
Thanks to both of you!

I've got three of those cases, so I was hoping to fit the phono in one, line stage in another, and the third would house raw DC supplies for both. The cases look exactly like this, except without any knobs (yet):

Click the image to open in full size.
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Old 9th September 2012, 04:34 AM   #1660
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Ooh! Silver bumper Naim gear. Nice!

Are your cases reproductions or just something very similar?

Use 2 for the Pearl, PSU in one, both RIAA in the other.

Save the third for a linestage/selector.

Or, if you want to pursue another direction, sell the cases to me...
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