• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB

Hmmm,
I just looked at the quick reference in the RS specs, which when checked out at the unabridged spec is in fact referenced to 20kHz. The 120Hz for the 22k is 7.89 A and the 15k one is 6.56 A. In future I will only look at the full spec. Once burnt, twice shy.
 
Founder of XSA-Labs
Joined 2012
Paid Member
Hi Folks,
We have a new item under development for a GB: a solid state relay (SSR) DC protection and turn-on delay board. The nice thing about this item is that it will be fully professionally assembled and tested. You just need to solder your own choice of speaker connector (spade, Miolex, or flying lead) and it is read-to-run (RTR). More info here:

Ready-to-Run (RTR) SSR DC Speaker Protection and Delay GB
 
I purchased and have mostly populated an SLB dual rail supply (thanks, board is really nice!) for use in my first big amp build: an F6. I am awaiting the Antek 3222 trafo as well. I'm planning to use a single SLB (at least to start with) and try the grounding scheme described earlier in the thread.

I'm wondering if you have a recommendation for crimp-on spade connectors and a (budget-conscious) crimper tool to use with them.

I'd like to use insulated connectors like these and found an economical crimper from Titan tools.

I'm also curious what the AWG is on the trafo secondaries as it doesn't seem to be listed on Antek's website so I can purchase the correct sized connectors and tool.

Thanks for all the work put into this!
 

Attachments

  • IMG-20190728-WA0001_2.jpg
    IMG-20190728-WA0001_2.jpg
    889.1 KB · Views: 454
Founder of XSA-Labs
Joined 2012
Paid Member
Nice assembly work, Metaphile!

The Antek 3222 secondaries appear to be 14ga. I use many crimpers, and if you get the usual insulated Fastons and loop connectors, these tools work well:
https://www.amazon.com/gp/product/B071D1B7M5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

They squeeze the metal ferule into a square box shape. I also like to crimp with a good bite from a Klein model 1005 prior to use in above crimper for extra security.

https://www.amazon.com/Insulated-No...ein+crimping+plier&qid=1564352691&s=hi&sr=1-4

As far as insulated Faston terminals, these work well:
https://www.amazon.com/gp/product/B010GWZOUW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

and 14-16ga insulated loop terminals:
https://www.amazon.com/gp/product/B01D8BYDAA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Hope that helps. Oh, and you can never have too many crimpers or donut trafos! Those red Kleins on the far right will handle most insulated non-insulated in all sizes and lots of leverage, plus they cut wire too. I have had those for 25 years and still use them almost every day when making amps.

attachment.php
 

Attachments

  • Crimpers.jpg
    Crimpers.jpg
    292.3 KB · Views: 1,931
Last edited:
Appreciate the advice, xrk -- I am indeed planning to use the flying leads and a Molex connector to attach the transistors to the front panel of the 4U chassis -- will be sure I hand trace the wires per the schematic before power up. Will be at least a couple of weeks before I'm ready to power up.
 
Overdue photos and a thank you.

I have two channels of aleph j goodness powered by this very nice power supply. Both boards fired up with no problem. The amps are absolutely silent when no music is playing. The 22000 uf caps don’t heat up at all. Thanks again for this well worked out power supply.

Sorry for the sideways photos.
 

Attachments

  • B4862B8F-166D-4C02-BDAD-EDE7828F620A.jpg
    B4862B8F-166D-4C02-BDAD-EDE7828F620A.jpg
    602.8 KB · Views: 230
  • 6D5DC0BD-0E90-4E6F-AB20-F9678787D038.jpg
    6D5DC0BD-0E90-4E6F-AB20-F9678787D038.jpg
    722.4 KB · Views: 248
  • 6AAACFC9-CEF8-43E6-9A03-3D9B1A679BCA.jpg
    6AAACFC9-CEF8-43E6-9A03-3D9B1A679BCA.jpg
    757.1 KB · Views: 243
Thanks guys.

Putting together the aleph j with your power supply was orders of magnitude easier then getting the glowing bottles to work well. Together they do a wonderful job. The tube amps drive ribbon tweeters and the aleph j amps take care of the mid range. As you have said distortion spectrum seems to matter more then %.
 
Solving hum with F6 and single dual-rail SLB

Hey folks,

I just completed my first big amp build with a single dual-rail SLB supply: an F6 DIY MOSFET version.

First off, thanks to xrk and of course the rest of the folks here in the forum for helping me gain the knowledge necessary to put it together safely and functionally!

I am having a bit of a hum issue. You'll see from the photo below that I haven't yet managed the cables inside the chassis, but I think I have a ground loop rather than inductance issue.

First I tried the grounding scheme described here by xrk with the two RCA grounds landed at the SLB board ground hub and the two black speaker terminals landed at the amplifier channel PCBs. This resulted in a hum on the L channel that was loud when both RCA connectors were plugged in. (I'm using 90dB/8 ohm speakers and my ACA is dead quiet w/ same preamp)

Second I tried moving the speaker grounds to the SLB board ground hub as well, disconnecting them from the amplifier channel PCBs. This resulted in a quieter hum on both speakers, slightly louder on the left channel, that becomes a bit louder still when both RCAs are connected. The hum is audible (if only barely) at the listening position.

Any suggestions for other things I can try? BTW - love the faston connectors, makes it really easy to troubleshoot issues as they are encountered.
 

Attachments

  • IMG_20190808_142910.jpg
    IMG_20190808_142910.jpg
    1 MB · Views: 383
By the way, with an Antek 3222 transformer and each amp channel biased at a little above .5V I've got +/- 26.6 V on each of the two rails of the SLB. During initial testing without a load connected I had about 30V. This is with no adjustments to the trim pots.

Also, I put the LEDs in backwards and somehow broke something while trying to turn them around (I eventually gave up and left them that way). Re-flowing all the solder joints fixed the issue, however. Rejoice!
 
Founder of XSA-Labs
Joined 2012
Paid Member
Hi Metaphile,
Thanks for building and sharing with us. I think we can help when you post a clear photo like this. If I am not mistaken, you have connected your mains earth ground from IEC directly to one of the 0v (clean GND) spade terminals. Move that to the bolt screwed to your chassis ground. That will put the dirty earth ground separated by the NTC from your clean ground. Also make sure you have a good contact from the heatsink to earth or chassis ground. I would add a bonding wire from the same bolt for chassis/earth GND to a bolt on the main heatsink and make sure there is good contact by using sandpaper to scrape away the black anodizing. A poorly grounded heatsink can cause hum.

One more thing, definitely move the purple trafo shield to the earth/chassis ground bolt. That alone will inject 60Hz hum into your circuit.

Also, this is another unshielded signal trafo coupled amp - those trafos pick up hum like crazy. You may need to resort to putting mu-metal shield box around them.

You may need to move the trafo around until noise is less.

Note that hum is worse on left channel where that signal trafo is in close proximity to the AC secondary from the power trafo (blue and green wires). Those need to be twisted pairs to contain their magnetic field.

Like this:
attachment.php
 

Attachments

  • SLB-grounding.jpg
    SLB-grounding.jpg
    148.6 KB · Views: 856
Last edited:
Member
Joined 2014
Paid Member
It’s hard to tell but it looks like the earth ground from the IEC connector is going to the SLB board? The incoming earth gnd needs to connect to the chassis. The SLB gnd tab with the thermistor and capacitor connect to the same spot on the chassis as earth ground.
 
Alright - I quickly tried the suggested changes (added chassis ground to main heatsink after sanding off some anodizing, moved IEC mains ground off SLB to chassis, moved static shield off SLB to chassis, twisted the secondary trafo pairs and zip tied them down away from the Jensen transformer). Pics are attached. I believe this did reduce the volume of the hum, but it hasn't eliminated it completely. It's now audible from 1' or so without RCAs plugged in and barely audible at the listening position with the RCAs connected.

To recap, this is the configuration:

1. Speaker black terminals - to SLB ground hub
2. RCA grounds - to SLB ground hub
3. PCB ground - to SLB ground hub (no other grounds land on PCB except for the leads that I have removed but not yet desoldered)
4. IEC ground, main heatsink, main trafo static shield, SLB "CHASSIS RTN" to chassis bolt.

@xrk - perhaps you're right and the inductance from the noisy Antek is enough to be bothering the Jensen's, I'm not sure. Definitely willing to try some mu metal or moving the Trafo around for best performance. Hum is still louder on the left channel than on the right.

Any other thoughts/suggestions/notes don't hesitate to let me know. I still haven't "finalized" the cable management and I have to run off to an appointment so won't be able to experiment further until later tonight.
 
Oops, forgot the photos!

Alright - I quickly tried the suggested changes (added chassis ground to main heatsink after sanding off some anodizing, moved IEC mains ground off SLB to chassis, moved static shield off SLB to chassis, twisted the secondary trafo pairs and zip tied them down away from the Jensen transformer). Pics are attached. I believe this did reduce the volume of the hum, but it hasn't eliminated it completely. It's now audible from 1' or so without RCAs plugged in and barely audible at the listening position with the RCAs connected.

To recap, this is the configuration:

1. Speaker black terminals - to SLB ground hub
2. RCA grounds - to SLB ground hub
3. PCB ground - to SLB ground hub (no other grounds land on PCB except for the leads that I have removed but not yet desoldered)
4. IEC ground, main heatsink, main trafo static shield, SLB "CHASSIS RTN" to chassis bolt.

@xrk - perhaps you're right and the inductance from the noisy Antek is enough to be bothering the Jensen's, I'm not sure. Definitely willing to try some mu metal or moving the Trafo around for best performance. Hum is still louder on the left channel than on the right.

Any other thoughts/suggestions/notes don't hesitate to let me know. I still haven't "finalized" the cable management and I have to run off to an appointment so won't be able to experiment further until later tonight.
 

Attachments

  • IMG_20190808_154634.jpg
    IMG_20190808_154634.jpg
    1,017.6 KB · Views: 357
  • IMG_20190808_154516.jpg
    IMG_20190808_154516.jpg
    960.2 KB · Views: 352