Salas SSLV1.3 UltraBiB shunt regulator

diyAudio Chief Moderator
Joined 2002
Paid Member
Isn't 3xtotal-current (load+100mA shunt) enough as per guide? E.g. 1A@5V required so 3A*9VAC=27VA then a 9V@30VA?

Yes its enough so the Tx will be cool enough running. In full bridge rectification the Tx's AC current rating should be also derated by 40% or so. That parameter is already considered in our going easy and long life for the parts sizing approach. Constant current draw does not allow them time out in cycles anyway.
 
I plan to build +/- 5V shunts for the Soekris DAM 1121. Will need to find IDSS of <7.5mA for J3.

Will plan to use a 9V battery to connect to the drain and short the source and gate to ground. Do I need to connect a 100R resistor at the drain end?

Is the lower the IDSS value the better?
 
diyAudio Chief Moderator
Joined 2002
Paid Member
The lower IDSS value the less VGS (OFF) voltage which is our concern in this only 5V case for only that particular position. So it doesn't consume the better part of the little available internal voltage meant for other use when at 5V setting. As for how to measure IDSS all the usual techniques for sorting 2SK Toshiba types posted by builders in various threads do apply for any other JFET, also for our PFs. You either put the DMM in series mA mode between the battery and the drain to directly see IDSS or you infer it from voltage drop across the legs of some low value drain resistor. The second method is not prone to blow the DMM's internal fuse due to possible shorting mistakes when handling such tests. DMM grade fuses for properly protected against high energy accidents seriously made meters are expensive and most of the time not readily available in our spares box.
 
Hi Nick, I made some UltraBib at 5V for my Buffalo Dac and Metronome upsampler,and they play outstanding, my previous volt regs was 1.2r.

Now I wish upgrade my FSP with this volt reg.


The R1x (ccs resistor) is 15R for about 40mA, what's the current that sink the circuit, and what the spare current?


I just build a prototype at 35V with Rccs at 15R with a load of 820R and it works . The VGS of M2 is 2.

I wish to low Rccs at 12 or 10R. Can I do it?
My heatsinks are at 10 C°/W.


Thanks for another great design!
 
diyAudio Chief Moderator
Joined 2002
Paid Member
The formula for the UltraBiB CCS current is about 0.6V/R1. The regs in the FSP follow another formula, its (3LedsVF-Q1xVGS)/R1x. Usually 90mA for 15R. You can confirm by the voltage drop between R1x legs divided by 15R. Each FSP channel pulls 35-40mA (MC mode) rest is 50-55mA spare. If to substitute with UltraBiB when wanting to hear a real difference go for 150mA total i.e. R1=3.9R 2W. The sinks may get hot enough especially M2's because of 35V across it. The 110mA spare at 35V gives 3.85W M2 dissipation. Expect 60C+ sink temp in free air or 80C+ enclosed if with just 10C/W sink for M2. Better use a bigger one for long term reliability and a cooler box.
 
I was (and still am actually) one of the lucky few that got to beta test Salas' new baby.

This thing is remarkable.

679548d1525849895-salas-sslv1-3-ultrabib-shunt-regulator-ultrabib_soekris_1-medium-jpg


When we swapped it in place of the BiB 1.1 in my Soekris, the improvement was immediately obvious and not subtle.
Is there a reason you solderd the MUSE elevated from the board?
 
Hi Salas,

I'm currently using a Sigma22 derivative also for Soekris (dual mono 1021). I've heard high praises for the previous iteration many times and seeing this makes me really want to upgrade! Would you have any idea if 1.3 would be noticeably better (or maybe measurably) than Sigma22? Mechanically I should be able to fit the 1.3 (with 2 rails) in my enclosure without a complete overhaul. Thanks so much!

Best,
Michael
 
Can't predict what's to like best. Especially vs configurations I did not evaluate. Up to you checking that. As for group buy it exists and its been open for sign up long time now, I would expect the organizer planning to conclude it rather soon GB UltraBiB

Hi Salas,

That's totally fair. And thanks for pointing me to the link! I just signed up and sent the organizer a PM.

I read the build guide but maybe you could help me double check. If I'm planning on using the +/- rails for two dam1021 with the buffer drawing current, what R1 value should I use? Does it matter that I'm using 12V in and 9V out? Is there something else that I should specify in the group buy sign up...? Really appreciate the help! And very happy to see another great diy product on the forum!

Many thanks,
Michael
 
Can't predict what's to like best. Especially vs configurations I did not evaluate. Up to you checking that. As for group buy it exists and its been open for sign up long time now, I would expect the organizer planning to conclude it rather soon: GB UltraBiB

One more thing, each dam1021 should draw max 5W according to manual. So two boards are 10W max. If I use two sections of Salas 1.3, is a 25W transformer (12V) enough? I currently have a 35W one but it's slightly too large mechanically (I have a very compact layout...probably too compact for many people's tastes), but the 25W should have just the right size. Thanks in advance for your advice!!
 
diyAudio Chief Moderator
Joined 2002
Paid Member
Hi Salas,

That's totally fair. And thanks for pointing me to the link! I just signed up and sent the organizer a PM.

I read the build guide but maybe you could help me double check. If I'm planning on using the +/- rails for two dam1021 with the buffer drawing current, what R1 value should I use? Does it matter that I'm using 12V in and 9V out? Is there something else that I should specify in the group buy sign up...? Really appreciate the help! And very happy to see another great diy product on the forum!

Many thanks,
Michael

R1 2.2R for positive reg 3.3R to 3.9R for negative reg. 12V what? AC?
 
R1 2.2R for positive reg 3.3R to 3.9R for negative reg. 12V what? AC?

12V AC through the UltraBiB then 9V DC into the dam1021 is what I currently do. I'm ordering the mini kits provided in the group buy and have asked the organizer whether I can get anything else through the kit. Otherwise I'll just order on Digikey.

Would you happen to have recommended part numbers for the values you recommended?... Or is the Vishay thin film 0.4w 1% the way to go? Thanks again!
 
diyAudio Chief Moderator
Joined 2002
Paid Member
One more thing, each dam1021 should draw max 5W according to manual. So two boards are 10W max. If I use two sections of Salas 1.3, is a 25W transformer (12V) enough? I currently have a 35W one but it's slightly too large mechanically (I have a very compact layout...probably too compact for many people's tastes), but the 25W should have just the right size. Thanks in advance for your advice!!

I have seen it with 50VA 12-0-12VAC in Dimdim's build that he lent to me for some time, we tested together his 1.3 reg there, his transformer was very cool to the touch. So I think 25VA will not overheat, will just work in normal terms.
 
Yes they will work for your CC settings R1s dissipation, only keep them elevated from the board for air to can go around them.

Of course! I'll elevate the board and fix the mosfet to the bottom chassis (with proper insulation this time...:)). I read the build guide more carefully and do you know if there's a VRR value I can try instead of VR1 for my application? (maybe my setup is close to Dimdim's? dam1021 also accept 8-15v dc so I'm much less worried about absolute precision than burning something in my adjustment process or long-term stability) Also do I need a custom R9 value? I wasn't quite sure what spare current meant in the doc.

Everything else I'll just go with the group buy doc here (if that sounds good): UltraBIB Minikits - Google Sheets

Thank you!
 
Last edited:
diyAudio Chief Moderator
Joined 2002
Paid Member
No, I can't recommend a precisely predicted VRR value instead of trimmer for some target output voltage, that's to be experimentally determined in your own builds because there will be some tolerance in the current running through each VRR resistor due to the involved semis tolerances for creating it.

Get a toroid with a magnetic shield band inside like those from Antek by the way. Its good to have less 60Hz magnetic field around, especially in a compact build.

For R9 use 470R which is a good middle ground for M2's gate damping vs spare current allowed. Wanna order R9 1k also to maybe try at a point? Your choice. Electrically it gives more phase margin as it slows down the reg so its not precarious to try. For creating somewhat heavier tone if you will need it.

Install your R1s in a way to not be touching the board I meant by "elevated". See for chunkier ones like 1 or 2 W also. But 0.6W typically suffices in your case.

Spare current is what's left available from your CC setting mA feed beyond your top load demand. Its the shunt spare current looking for way back mainly through M2 biasing it in the process. Think of it like a Class A amplifier that always burns a good chunk of current to work in spec.
 
diyAudio Chief Moderator
Joined 2002
Paid Member
P.S. The discussed recommendations stand for dual polarity dual mono shunts. In case you want common dual polarity shunts and common transformer between two DAM boards then the R1 values must be cut in half, their power be 2W and the transformer no less than 50VA. Sorry for any confusion as I only thought in terms of some dual mono everything scenario.