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USSA-5 Build with Review
USSA-5 Build with Review
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Old 23rd May 2020, 10:18 PM   #1321
Vunce is online now Vunce  United States
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Quote:
Originally Posted by Bfpca View Post
...... The fans I have in it sound like a small helicopter is in the amplifier. Not nice in my quiet listening room.
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Old 24th May 2020, 07:54 AM   #1322
Harry3 is offline Harry3  Australia
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Originally Posted by pinnocchio View Post
Thanks all for the comments!

For me it was well worth it just for the extra 2.2V on the PSU. I will give it a listen during the week.

Ciao!
Do
Hi Do
any comments on how the LT4320 sounds in your system?
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Old 24th May 2020, 08:43 AM   #1323
AnthonyA is offline AnthonyA
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Originally Posted by Vunce View Post
Ho... Just install a speed potentio.. It don't really need fast speed something push the air is good enough
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Old 24th May 2020, 09:10 AM   #1324
Harry3 is offline Harry3  Australia
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or a 10Volt 5W zener in series with a 12V fan. However some fans might not start up if they don't get 12V on start up.
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Old 24th May 2020, 09:23 AM   #1325
mbrennwa is offline mbrennwa  Switzerland
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Quote:
Originally Posted by pinnocchio View Post
I have a pair of SLB that I will use in a future amplifier. My USSA 5 is using a CRC PSU and it is totally silent, even with my ear directly on the tweeter, you would believe the amplifier is turned off. I wanted to use the SLB for the USSA 5 but with 4V drop, I would need to change my transformers, which will never happen because I bought those very nice encapsulated Toroidy transfos and I just love them. But I'm planning to replace the diode bridge with the LT4320. They're already assembled and tested, just need time to migrate them over.

Do
I am in the stage of thinking about the PSU of my USSA-5 build. I have already ordered the SLB boards. Now I need to figure out the transformer:
  • Is +/- 24 DC rail voltage okay for the USSA-5? I am thinking of cranking the bias current up to 1.5A to 2A or so, depending on how hot the heatsinks get (I am happily running my Alephs at 1.9 A / 24 V rails in the same chassis).
  • What AC voltage rating for the transformer secondaries would be right for 24 V rails with the SLB? I would guess that a Toroidy with 21 VAC would be about right, but it would be nice if someone could confirm / comment on this.
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Old 24th May 2020, 09:42 AM   #1326
Harry3 is offline Harry3  Australia
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I'm sure Fab will respond about voltage level requirements.
In the mean time look at post 880 page 88.

PS 4 ohm or 8 ohm?
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Old 24th May 2020, 10:38 AM   #1327
meanie is offline meanie  Singapore
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Originally Posted by mbrennwa View Post
I am in the stage of thinking about the PSU of my USSA-5 build. I have already ordered the SLB boards. Now I need to figure out the transformer:
  • What AC voltage rating for the transformer secondaries would be right for 24 V rails with the SLB? I would guess that a Toroidy with 21 VAC would be about right, but it would be nice if someone could confirm / comment on this.
I got +/- 25.9Vdc on my SLB with a 600W, 22+22Vac trafo, drawing about 3.2A resistor load under test. SG main voltage is abit high at 235Vac.

So i think if you can get 21Vac trafo, it may be perfect.
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Old 24th May 2020, 12:25 PM   #1328
manniraj is online now manniraj  India
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19+19Vac and 5A each secondary I get around +/-25vdc without load using the LT4320 of Prasi CRC psu boards.
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Old 25th May 2020, 01:20 AM   #1329
fab is offline fab  Canada
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For the PSU, the LT4320 gives about more than 2 Vdc more than standard diode bridge. I have not used the SLB but I believe that the voltage drop can be adjusted and reduced for less load current. In any case if it is about 2 or 2.5Vdc or so it is mostly compensated by the increase of the LT4320...
So in the end, chose your voltage transfo the same way as if it was a normal PSU. One volt difference is marginal. But as Harry3 indicates read post 880 regarding 4 or 8 speakers.

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Old 25th May 2020, 05:59 AM   #1330
AnthonyA is offline AnthonyA
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If slb is same as cap multiplier..

Slightly higher ac voltage is fine.. Just turn the potentio to drop

More headroom

Also from what I tried... The diode quality becomes not so important.

Don't worry bout it few volts is just few volts
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