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Pass F5 and F5T power supply - CRC or CLC?


tesla13BMW

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You'll see the uneducated / inexperienced DIY approach in play here of "over build it and give yourself some margin".  The F5T is going to be HEAVY!

 

The recommended "standard" PS is a CCRCC and I have the items to build this, but, modeled in Duncan's Amps PSUD2 shows what I thought was high ripple so started reading and looking at CLC.

 

The F5 has bias current of 1.3A at +/- 24VDC and I am building a stereo amp as dual mono (from soft start onward) using the DIYaudio store universal power supply PCB https://diyaudiostore.com/collections/power-supplies-accessories/products/universal-psu for each channel.

 

Each channel will have its own power supply and each rail will have its own rectifiers and transformer secondary winding.  The transformers are Harbuch Electronics T2214 - 400VA with Primary 1 x 240V/50Hz and Secondary 2 x  18V/11.1A.  The diodes are Vishay FEP30DP-E3 and the capacitors Cornell Dubilier 381LL183M035A052 at 18mF and 35V.  R is 4 parallel 0R47 at 3W.

 

Although I can't include the diodes I am to use in the model (I used bridge25) I get ripple voltage with CCRCC of 69mV.  If I use the same model, but, as CCLCC using Hammond 159ZJ at 10mH and 0R160 the ripple voltage comes down to 1.7mV.

 

Q1: Is it worth the cost (4 chokes per amplifier) and real estate (there isn't a lot of room) to get the ripple voltage down or can I rely on the Amplifiers Power Supply Ripple Rejection.

Q2: Can the choke be beneath or above the capacitor bank with say 20mm clearance?

Q3: How far away from other items e.g. main transformer, mains wiring, power supply output wiring etc  could the choke be.

Q4: Should the chokes be put in an enclosure in the main amp enclosure and what material would be used.

 

For interest the F5T has bias current of 2.6A at +/- 32VDC and I am building a stereo amp as dual mono (from soft start onward) using the DIYaudio store universal power supply PCB.

 

Each channel will have its own power supply and each rail will have its own rectifiers and transformer secondary winding.  The transformers are Harbuch Electronics J2221 - 625VA with Primary 1 x 240V/50Hz and Secondary 2 x  24V/13.1A.  The diodes are Vishay FEP30DP-E3 and the capacitors Cornell Dubilier 381LL183M035A062 at 18mF and 50V.  R is 4 parallel 0R47 at 3W.

 

Although I can't include the diodes I am to use in the model (I used bridge25) I get ripple voltage with CCRCC of 139mV.  If I use the same model, but, as CCLCC using Hammond 159ZJ at 10mH and 0R160 the ripple voltage comes down to 3.5mV.

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Hi Chris,

 

You might like to try this PS for your F5:

 

www.diyaudio.com/community/threads/the-slb-smooth-like-butter-active-rect-crc-cap-mx-class-a-power-supply-gb.336479

 

I use this on my 40w Class A 'Alpha Nirvana' amps.  It's very low ripple.

 

Andy

 

 

 

 

 

 

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@andyr that would have been great prior to having bought transformers, diodes and caps🤑.

 

The expense to rebuy to use the SLB power supply isn't the issue, but, I'd then have power supplies waiting to have an amplifier built for them 🤔.

 

I probably shouldn't be thinking that the power supply that Nelson Pass suggests for the amps he designs isn't good enough for me - but, I'm going to trust the model and go with the CLC.  At least others have used it and like it.

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I've tried several times to use chokes in a solid state power amp and you are right to worry about placement.  If you don't have space, don't bother.

The chokes spray EMI all over the inside of the case and my amps where _MUCH_ quieter with a CRC or even a simple Cap input supply.

 

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17 minutes ago, r3x said:

I've tried several times to use chokes in a solid state power amp and you are right to worry about placement.  If you don't have space, don't bother.

The chokes spray EMI all over the inside of the case and my amps where _MUCH_ quieter with a CRC or even a simple Cap input supply.

 

 

That's what I wanted to hear - but, isn't what I wanted to hear.

 

I do have space, but, it is vertical space so the chokes would be above or below the capacitor board.

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I’ve built both and my current f6 amps use CLC crammed into a small chassis and I have zero noise. It’s also true that there was zero noise with CRC

 

Its worth trying an active rectifier which is what I’m using. Look up Prasi’s LT4320 which you can use with the caps and transformers you already have

 

I found an across the board improvement  with my current f6 build however I have no idea what’s doing what as I’m using better caps with the chokes and active rectifiers as well as better transformers 
 

 

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On 2/11/2022 at 11:47 PM, tesla13BMW said:

So, for those who have built an F5 or F5T V2 using the "Pass" CRC power supply found it too noisy and see any reason to try for something better?


My F5 used CRC and was absolutely dead silent. Brilliant amp, just wished the gain was a little higher.

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47 minutes ago, Sub Sonic said:


My F5 used CRC and was absolutely dead silent. Brilliant amp, just wished the gain was a little higher.

That is good to hear. I think I'll be going CRC first. Probably try CLC. But, will read up on the Prasi LT4320 active rectifier though. The SLB means new transformers and the boards etc which doesn't suit.

 

Your comment on not enough gain is that 25W wasn't enough for your speakers or your pre wouldn't drive the F5 to full output? The plan is to put my F5 or F5T on a single pair of ESL57's.

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12 hours ago, tesla13BMW said:

Your comment on not enough gain is that 25W wasn't enough for your speakers or your pre wouldn't drive the F5 to full output? The plan is to put my F5 or F5T on a single pair of ESL57's.


It was my gain structure needing a change as the F5 does not have a great deal of gain in itself. Using inefficient speakers like I was doesn’t help 😄.

 

I didn’t have a problem with the 25 watt output per se.

 

SS

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  • 1 year later...
On 05/11/2022 at 7:35 AM, Sub Sonic said:


It was my gain structure needing a change as the F5 does not have a great deal of gain in itself. Using inefficient speakers like I was doesn’t help 😄.

 

I didn’t have a problem with the 25 watt output per se.

 

SS

 

why not up the F5 rail voltage, remove the protection circuit and increase the gain...... replicate the F5T front end!

With 32v rails bias around 380mV and work up, you should see around 50W @ 8 ohm. Put some balls in the transfo & aim to double down with the protection gone.  I'm doing my F5 next week. PM if you want details

 

I use CRC, noise floor is very quiet even with a Supratek 6SN7  cranked. My PSU's  90,000uF  / R /  60,000uF

 

 

Edited by Allan
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