Well, I found a shop in France that can make toroïdal trafos on order, here what I'm planning (keeping in mind that I want something not too hungry, but correctly scaled):
Primary: 230Vac
Secondaries:
-60V 0.5A 30va (positive rail)
-19V 1.6A 30.4va (negative rail)
-15V 1.2A 18va (for my selector board)
witch gives me
78.4Vac-->80Va trafo
I'm thinking on adding a electrostatic screen to it, won't hurt I think.
Do you think it's correctly scaled or can I go a little lower? are the voltage correct?
Primary: 230Vac
Secondaries:
-60V 0.5A 30va (positive rail)
-19V 1.6A 30.4va (negative rail)
-15V 1.2A 18va (for my selector board)
witch gives me
78.4Vac-->80Va trafo
I'm thinking on adding a electrostatic screen to it, won't hurt I think.
Do you think it's correctly scaled or can I go a little lower? are the voltage correct?
I'd probably double its VA rating or use one per channel (may be slightly less expensive to do two on a setup.) At least double the 60V winding rating.
According to Design Notes and Efficiencies | Plitron the transformer will see 1.8x IDC, so a minimum rating is about double the DC power draw. I remember it's 20 mA per channel x 60 VAC, that implies 21.6 VA per channel is the MINIMUM rating. Further down the page you see that even slightly over rating dramatically reduces operating temperature.
According to Design Notes and Efficiencies | Plitron the transformer will see 1.8x IDC, so a minimum rating is about double the DC power draw. I remember it's 20 mA per channel x 60 VAC, that implies 21.6 VA per channel is the MINIMUM rating. Further down the page you see that even slightly over rating dramatically reduces operating temperature.
So I got two solutions:
1-One transformer:
60V 1A 60VA (positive)
19V 2.1A 39.9VA (negative)
15V 1A 15VA (selector)
114.9Vac-->200VA transformer
60.50€
2-Two transformers:
Transformer 1
60V 1A 60Vac-->63VA (positive rail)
26€
Transformer 2
19V 2.4A 45.6va
15V 1A 15va
60.6Vac-->63VA (negative rail + selector)
28.6€
total:54.6€
1-One transformer:
60V 1A 60VA (positive)
19V 2.1A 39.9VA (negative)
15V 1A 15VA (selector)
114.9Vac-->200VA transformer
60.50€
2-Two transformers:
Transformer 1
60V 1A 60Vac-->63VA (positive rail)
26€
Transformer 2
19V 2.4A 45.6va
15V 1A 15va
60.6Vac-->63VA (negative rail + selector)
28.6€
total:54.6€
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Either will work, I tend towards spending less money on the easier to mount single transformer.
Or look at 60-80VA 2x30V Trafo and if they are cheap take 2 of them.
One for the +rail and one for the -rail.
I had the luck to find trafos for 10€ per pice unbeatable cheap for new 80VA trafos
One for the +rail and one for the -rail.
I had the luck to find trafos for 10€ per pice unbeatable cheap for new 80VA trafos
There are those who insist things like the switching transformers ought to be on their own transformer as well. Keeps any funky noises out of the preamp supply.
Whoa 😱 wish I could find such bargains, you've made quite a deal here 😉
Although, I don't need 60V on both rails as the Kari boards are CCS, so I need two different voltage (say 60V on + and 19V on -)
I think I'll stick to a total 120VA trafo (60V/19V/15V), I can get it built for 44€ (by Audiophonics), However Daniel, if you know someplaces where trafo are cheap, I'm all ears😛
Here the first version of my BOM for the X CCS Bosoz boards, It misses fancy stuff as IEC, fuse, fuse holder, rca and xlr socket as well as the part to make the regulation for the selector.
I'll probably change some components when I'll receive the board (in regard to parts dimensions mainly)
I'll probably change some components when I'll receive the board (in regard to parts dimensions mainly)
I found a 4ch stepped pot (vishay/Dale) here witch is not to pricey:
Dale 23 Step Serial-Type Balance Potentiometer (Stereo)_Volume Control_Accessories Kit_Analog Metric - DIY Audio Kit
What do you think of it, 10K on the Bosoz output
I also thought about a gear rig to couple two 2ch stepped pots, but it will require quite a lot of work and I'm not really sure this will be as well balanced as with a single pot.
Another solution is using an Alps RK27 4ch pot
Dale 23 Step Serial-Type Balance Potentiometer (Stereo)_Volume Control_Accessories Kit_Analog Metric - DIY Audio Kit
What do you think of it, 10K on the Bosoz output
I also thought about a gear rig to couple two 2ch stepped pots, but it will require quite a lot of work and I'm not really sure this will be as well balanced as with a single pot.
Another solution is using an Alps RK27 4ch pot
I know it's to late,
but i say build the BZLS (BOSOZ) stock schematic.
there's something really sweet in it's simplicity, and resistors doing the work of all those extra CCS parts... 😎
and when you run it balanced to balanced it really shines. even when it's converting unbalanced to balanced.
i really don't think it's an inferior preamp... and i'm looking forward to comparing it to my
incoming Pass Labs X2.5 🙂 🙂 🙂
but i say build the BZLS (BOSOZ) stock schematic.
there's something really sweet in it's simplicity, and resistors doing the work of all those extra CCS parts... 😎
and when you run it balanced to balanced it really shines. even when it's converting unbalanced to balanced.
i really don't think it's an inferior preamp... and i'm looking forward to comparing it to my
incoming Pass Labs X2.5 🙂 🙂 🙂
something like that?
Balance XLR Dact Type 21 Stepped Attenuator Potentiometer 10K | eBay
ook?? good, bad?
Balance XLR Dact Type 21 Stepped Attenuator Potentiometer 10K | eBay
ook?? good, bad?
politely said - worse
regarding ebay - you need to use some shorting link service - ebay links are gibberish on board
regarding ebay - you need to use some shorting link service - ebay links are gibberish on board
Arf😀 at least I learned a new expression 😛
-->so Alps, out!
What about the coupled dact thingy?
-->so Alps, out!
What about the coupled dact thingy?
trying them all , I refuse to put more greenies in resistive attenuator then on what I wrote - cheap ladder with SMD resistors
that cheap thingie is almost good as best pro conductive plastic audio faders , while only thing which will surpass them , Zen Amount wise , is good AVC
ook is politely written word which you can write here , but it ends as row of stars
coupled DACT - need to see exactly on what you meant ; for me - DACT is brand , not type , while ppl are often using the term contrary to that
that cheap thingie is almost good as best pro conductive plastic audio faders , while only thing which will surpass them , Zen Amount wise , is good AVC
ook is politely written word which you can write here , but it ends as row of stars
coupled DACT - need to see exactly on what you meant ; for me - DACT is brand , not type , while ppl are often using the term contrary to that
cowneko, i don't think it will sound better, it was designed by Mr. Pass as a teaching example, thus simplified.
But that doesn't mean it should be written off - it's surprising good, especially if played to it's strengths.
But that doesn't mean it should be written off - it's surprising good, especially if played to it's strengths.
Excuse me if my question seemed offending on stock design, that was absolutely not my intention, I don't imply that simplicity equals simplistic (In fact that's often the contrary) 😉
I'll probably build a stock one later (I'll order more than needed parts for one bosoz) so I'll be enjoying both and can make a gift to my Dad (witch is musicaholic too 😀)
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