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PostPosted: 16 Aug 2011, 08:29 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
We have some AFL players you can have for a few bob. :D

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PostPosted: 16 Aug 2011, 09:40 
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Joined: 02 Mar 2009, 12:41
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Location: Vänersborg, Sweden
... and LPs .... :worried:

Glued the small 3 mm green LED in place on the front panel and painted it all pale yellow. When the painmt had dried I simply gave the LED a second in the grindinmg machine :idea: . Still working the layout of the switches. How to hook the switch and DC-inlet and cells together to get the functions: ON (batteries) - ON (external DC) - Charge cells - OFF?? :confused:

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PostPosted: 16 Aug 2011, 13:55 
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Joined: 14 Feb 2010, 13:13
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Location: Lisbon, Portugal
Maybe something like this?


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PostPosted: 16 Aug 2011, 15:55 
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I have only 1pole-2way and 2pole-2way switches ... I will present an idea tomorrow.

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PostPosted: 16 Aug 2011, 16:58 
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Looking good.

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PostPosted: 17 Aug 2011, 11:37 
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I came up with this one. The only problem is that the batteries are always charged when ext DC is connected, which will cause "wear".
As I propably need some 25VDC for the cells the upper diod is there to drop approx 1V, but propably it's not needed.

Image

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PostPosted: 17 Aug 2011, 17:15 
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You need a smart charge cct. which will detect when the batteries are charged then stop the charging. There should be some simple ccts. around for this.

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PostPosted: 31 Aug 2011, 11:34 
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I would like to power this unit from mains.

I´m looking for a 24vdc wall transformer, because I don´t want any PSU inside the cabinet.

But all I find are switching power supplies.

How bad can a SMPS be even being wall type with DC cable out?


Cheers,

Miguel


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PostPosted: 02 Oct 2011, 05:47 
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I finally got a chance to do a comparison between the BHL (Boozhound labs) and Oatley K303 phono preamps. Interesting part is they both use JFETs and (in part) share the 2SK170. And both two stage.

I chose a simple piano and voice (Norah Jones) LP, simple classical, Mahler #1 (side 2) and Mick Jagger "She's the Boss" for test LPs. I went back and forth from one phono preamp to the other a number of times on the first 60 seconds of each track, staying with the one track, before moving along. I only played one track from each LP. I ensured I payed one preamp first on the next track then the other first.

Each time I came back to the BHL. Reason is each instrument sounded fuller, richer and more detailed with the BHL. The sound stage was much more focused and instruments appeared to slow down in their better defined space. Reverb was more extended, you could better feel the air around individual instruments. Attack appeared sharper with the BHL. Over-all there was greater musical flow and a far more complete sound.

BUT we are comparing a $30 kit complete with PS which runs from the mians and is dual power selectable. Not only that you can wire the K303 for MM or MC. The BHL PCB and parts alone are $80! So though I CAN do this comparison it is not quite fair. If you had made the K303 and not heard other kits you would be a very happy vinyl junky. If you want to pay about three times more for something that is porbably three times better go for the BHL. I'll post this on the K303 thread too.

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PostPosted: 03 Oct 2011, 22:37 
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Because I run my BHL pre on batteries there is always the question of how much charge are the batteries holding.This usually meant dropping the lid and test testing the batteries once the preamp has been on for a short time. On other battery devices I have been including external test points. Beause these have been installed on plastic case devices I have been able to use non-insulated small binding posts. Preamp's draw is 15mA so even with cheap batteries you get good life from the batteries (over 100 hours).

The Mongrel Dog Audio/BHL pre is in a metal enclosure so I used cheap RCAs. To stop others from pluging the pickup into these RCAs I included a test switch. The points are not live until the preamp has been turned on and the momentary press button pushed in. I will label this point and add a warning later.

Also I have been using the preamp with a layer of Dacron over the cct. brd. and batteries to muffle any resonance or sound getting into the ventilated case. Onto the Dacron I lay a piece of thick black paper for further dampening and to stop the white Dacron poking through the top vents. After comparison with the Oatley K303 this pre is back as may main phono preamp.
Attachment:
BatteryTestss.jpg
Attachment:
BHLDampeningss.jpg


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