Consensus among the builders with the M2x amps: 22v secondaries are good for ~27v +/- out from the SLB. M2x boards handle this well? I love my M2x monoblocks, and plan to upgrade it as possible. I’m in process with Mark Johnson’s 5v switch/soft start boards for my monoblocks. When I take everything out to introduce these, a PC upgrade, and custom fronts could conveniently be included during the disassembly process.
I’m figuring I need to choose between 20 and 22v output transformers.
I have a quad of the big Hammond inductors for a CLC PSU, but very concerned about sticking 2 more large, unshielded, transformers into this box. I would be able to keep my Plitron power transformers.
I’m figuring I need to choose between 20 and 22v output transformers.
I have a quad of the big Hammond inductors for a CLC PSU, but very concerned about sticking 2 more large, unshielded, transformers into this box. I would be able to keep my Plitron power transformers.
It could work, I personally would use 300VA but if you have them already, why not. The way to calculate this is to start with the no load voltage and start subtracting drops and losses.
22v is 31v no load. For a 200va trafo running about 2A I would guess about 5v sag. Another 3v drop across SLb is 8v total. 31v -8v = 23v. Should be ok.
22v is 31v no load. For a 200va trafo running about 2A I would guess about 5v sag. Another 3v drop across SLb is 8v total. 31v -8v = 23v. Should be ok.
How would that calculation work for 300VA 2x22v transformer running just one amp board in a monoblock? Sounding like I should stick with 20v secondaries. Toroidy offers 21v secondary windings, split the difference?
Bones, it's going to be too hot. I think the reason X said it would be okay with 200VA is because of the sag you are going to see with the lower VA tranny. If you are building M2X, I recommend the 300VA 20V with the SLB supply.
It looks something like this: 22V will give you about 31V no-load. You can approx it by taking the voltage of the trans and multiply by approx 1.4, so you have 22V x 1.4 = 30.8 Now with the ripple eater SLB you will see a 2-3V drop hence: 22V x 1.4 = 31 & 31V - 2.5V= 28V rails.
So with some of the daughters not liking much over 24V what do you think?
It looks something like this: 22V will give you about 31V no-load. You can approx it by taking the voltage of the trans and multiply by approx 1.4, so you have 22V x 1.4 = 30.8 Now with the ripple eater SLB you will see a 2-3V drop hence: 22V x 1.4 = 31 & 31V - 2.5V= 28V rails.
So with some of the daughters not liking much over 24V what do you think?
Last edited:
Thanks for all the suggestions! I am going to stick with 20v transformers, as I don't want to limit my input card choices
I put a request into Toroidy to look into shipping prices. That will be the third transformer manufacturer I have emailed looking for some special power transformers. We will see who responds first.
I did order the Hakuin boards, and got some toshibas off Ebay.
XRK971, what brand of resistors are present on your store pictures? They do not appear to be the vishay CMF resistors listed on the schematics.
On another BOM note: On Semiconductor BD139G is EOL, and gone, at Mouser. Any good replacement. The "similar" ones are not exactly the old specs. I think I snagged some from eBay, but you might want to list a suitable replacement in your BOM.
I put a request into Toroidy to look into shipping prices. That will be the third transformer manufacturer I have emailed looking for some special power transformers. We will see who responds first.
I did order the Hakuin boards, and got some toshibas off Ebay.
XRK971, what brand of resistors are present on your store pictures? They do not appear to be the vishay CMF resistors listed on the schematics.
On another BOM note: On Semiconductor BD139G is EOL, and gone, at Mouser. Any good replacement. The "similar" ones are not exactly the old specs. I think I snagged some from eBay, but you might want to list a suitable replacement in your BOM.
They may be no name metal thin films (verification builds often use whatever I have on hand to minimize placing so many order with Mouser). You know how that goes - every order for some reason hits $200. I do have quite an assortment of Vishay and Yageo metal thin films that don’t cost as much as a Dale CMFs but work very well.
I did place an order with Toroidy. Hubert emailed back the next day. Still no word from the other 2 places - their loss. Sent the PP $ today, I'm guessing the order will process for them first of next week. 2 weeks to build, and then whatever the shipping time will be. I'm not in a hurry. I'm betting at least a month to get them here in the US.
Finished the H9KPXG build (x2) today (low voltage switch, and soft start circuit)
Parts in for SMB this week - I will be building those boards next weekend, I'm thinking. Then order parts for the Hakuins, and do those another weekend. Toshibas arrive this week.
I need to get on with making the CAD drawings to order new black fronts, with holes drilled at HiFi2000 for the switches. That way, when I take everything apart next time, I will have all the upgraded parts. Planning to try the grounding scheme you have diagrammed @XRK971.
Finished the H9KPXG build (x2) today (low voltage switch, and soft start circuit)
Parts in for SMB this week - I will be building those boards next weekend, I'm thinking. Then order parts for the Hakuins, and do those another weekend. Toshibas arrive this week.
I need to get on with making the CAD drawings to order new black fronts, with holes drilled at HiFi2000 for the switches. That way, when I take everything apart next time, I will have all the upgraded parts. Planning to try the grounding scheme you have diagrammed @XRK971.
Well, back in early July, I posted that I was reading about -4v on the -ve DC rail of one of my SLBs ... and I was wondering what was causing this problem.
Today I finally solved this problem (I had a delay due to destroying my 'big heat' soldering iron and having to buy a replacement. )! Then other personal things intervened.
The problem was that R18 (2R2 in my case) had a fault - it would seem that I had bent the leads too close to the resistor body ,,, and the lead was fractured. At least, it broke off when I unsoldered that end of the res from the SLB PCB.
I had to order some replacement 2R2 resistors from RS Components and today simply replaced that one resistor. Everything then worked!
Testing with sig-gen & CRO revealed both channels produced 3700mV out from 160mV in. So 23x gain.
Andy
Today I finally solved this problem (I had a delay due to destroying my 'big heat' soldering iron and having to buy a replacement.
)! Then other personal things intervened.The problem was that R18 (2R2 in my case) had a fault - it would seem that I had bent the leads too close to the resistor body ,,, and the lead was fractured. At least, it broke off when I unsoldered that end of the res from the SLB PCB.
I had to order some replacement 2R2 resistors from RS Components and today simply replaced that one resistor. Everything then worked!
Testing with sig-gen & CRO revealed both channels produced 3700mV out from 160mV in. So 23x gain.
Andy
Thanks X. Single rail makes sense. Could be an interesting amplifier. Check it out over in the Solid State forum if you haven't seen it already. Uses UnitedSiC power jfets.
JFET-only Circlotrons without negative feedback.
JFET-only Circlotrons without negative feedback.