Quick question for you guys.
I have made myself a balanced version of the DCB1 and I have 3 Balanced XLR and 2 SE RCA input and on the output I have 1 Balanced XLR and one SE RCA.
I'm using one DCB1 per balanced channel and when using it in SE I do the same thing but connect the signal to +phase and ground to signal ground.
I wanted to know on the RCA input, if I should shunt the antiphase (-phase) to ground or put in a resistor for a fake load since I'm only using one channel per side in SE mode.
Thanks
Do
I have made myself a balanced version of the DCB1 and I have 3 Balanced XLR and 2 SE RCA input and on the output I have 1 Balanced XLR and one SE RCA.
I'm using one DCB1 per balanced channel and when using it in SE I do the same thing but connect the signal to +phase and ground to signal ground.
I wanted to know on the RCA input, if I should shunt the antiphase (-phase) to ground or put in a resistor for a fake load since I'm only using one channel per side in SE mode.
Thanks
Do
All XLR to RCA converter plugs ground it but it can up THD in the balanced source so better terminate it with ~600 Ohm for the redundant phase.
hi,
few quick questions regarding two 35VA pcb 15v transformers I have paralleled. The adjustment R is 2 ohms making it 1.77VDC and 1.92VDC on the rails. Wattage meter shows about 48VA of constant consuming. So as advised by Andrew I'm still in a safe zone 🙂
1. Trafos have 2x110v primaries, is it safe to use them? Checked the mains during the week and it varies from 218 till 228v.
2. I get quite audible hum when I'm close to them (about 10cm). Could that be reduced somehow? Will mu-metal be helpful here?
few quick questions regarding two 35VA pcb 15v transformers I have paralleled. The adjustment R is 2 ohms making it 1.77VDC and 1.92VDC on the rails. Wattage meter shows about 48VA of constant consuming. So as advised by Andrew I'm still in a safe zone 🙂
1. Trafos have 2x110v primaries, is it safe to use them? Checked the mains during the week and it varies from 218 till 228v.
2. I get quite audible hum when I'm close to them (about 10cm). Could that be reduced somehow? Will mu-metal be helpful here?
Attachments
Oh my god
You can not place transformers so near the pot. It will off course result in hum. The 2x 110 is no problem when coupled i series.
You can not place transformers so near the pot. It will off course result in hum. The 2x 110 is no problem when coupled i series.
just to clarify, the pot is just there hanging and the buffer is not connected to any source. By the hum I meant physical hum from transformers.
Try separate them as much as you have space first. See if the mechanical hum softens with distance.
Hi. This have probably been declared many time but the thread is long and I'm about to bench the scrap trannys laying around, so I wonder if someone can be kind to recover what current each card is likely to draw with a 10 ohm resistor, and what AC under load the tranny is recommended to supply on the secondarys?
Best regards
Staffan
Best regards
Staffan
12x12V 30Vac will work well for stock 63 Ohm //
15x15V 50Vac will work well for mid range hot rod 7 - 10 Ohm
15x15V 100Vac will work well for full blown Nitro Drag strip hot rod 3 Ohm = Fire breathing Dragon
Ron
Edit; Look at your own post #1581, your question has already been answered by Salas
15x15V 50Vac will work well for mid range hot rod 7 - 10 Ohm
15x15V 100Vac will work well for full blown Nitro Drag strip hot rod 3 Ohm = Fire breathing Dragon
Ron
Edit; Look at your own post #1581, your question has already been answered by Salas
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Well thank you but actually not. I wondered what current each card acrually draws, not the recommended VA on the tranny. Recommended VA according to manufactuerers spec is usually much more then the actual current draw. I also wondered recommended VAC on the secondarys but since I'm gonna dummyload my trannys they might give 14 or 16 under load and I also wondered what might be decent there. Maybe its 15 minimum?
Thanks anyway.
Staffan
Thanks anyway.
Staffan
Steffan,
I did not mean to be rude, sorry if it came across that way.
I am using a 15V x 15V 50Vac TX, after regulation my V is -9.5 and +9.7, taken at the 3 holes in the middle the board.
Using 7R0 I'm at 197mA and 179mA.
Voltage across R is +1.377 and -1.325. Measurements taken from the 3 pin output show
R= .0002 and L= -.0016 DC offset. Mezmerise board
Hope this helps.
Ron
I did not mean to be rude, sorry if it came across that way.
I am using a 15V x 15V 50Vac TX, after regulation my V is -9.5 and +9.7, taken at the 3 holes in the middle the board.
Using 7R0 I'm at 197mA and 179mA.
Voltage across R is +1.377 and -1.325. Measurements taken from the 3 pin output show
R= .0002 and L= -.0016 DC offset. Mezmerise board
Hope this helps.
Ron
None taken, thanks for the helpful info both of you. I have a closit full of retired trannys, some of them unmarked and unmeasured. So today I made me this dummy doll.
First tranny up was speced 15 VAC*2,6A*2 on secondarys wich makes 78 VA. Loaded on dummydoll it gave 2*17,7 VAC on secondarys and 2*22,5 VDC over R100 resistors. That is about 2*225 mA.
A little biggy for one card, Ill load it more and see what I get.
With 2*33 ohm load it delivers 2*16 VAC wich makes + - 18,6 VDC and it still doesnt hum or get the least warm. Thats 2*560 mA. It will take 2 cards easy, maybe even 4.
Staffan
First tranny up was speced 15 VAC*2,6A*2 on secondarys wich makes 78 VA. Loaded on dummydoll it gave 2*17,7 VAC on secondarys and 2*22,5 VDC over R100 resistors. That is about 2*225 mA.
A little biggy for one card, Ill load it more and see what I get.
With 2*33 ohm load it delivers 2*16 VAC wich makes + - 18,6 VDC and it still doesnt hum or get the least warm. Thats 2*560 mA. It will take 2 cards easy, maybe even 4.
Staffan
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Nice to know I'm not the only dummy. 
Cool bridge you made. Good idea
I've tried 50mA --->300mA, ~200mA is the sweet spot. Sounds great and runs Very cool.
Ron
Cool bridge you made. Good idea
I've tried 50mA --->300mA, ~200mA is the sweet spot. Sounds great and runs Very cool.
Ron
these are fine as no hum exists if only one is used.
thank you! will try later.
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I tormented the 78 VA tranny a bit more today. At 16,2 ohm load I get 16,9 VAC and 20,0 VDC. Thats 2*1,23 A, so about half its spec. It does not get warm (but load resistors do glow). I can now hear a very tiny hum with the ear close the tranny but thats nothing but normal.
I will run 4 cards and the goal is have it configurable for SE stereo, balanced stereo and 8 channel movie. If I go for the 10 ohm resistors it seems like I will end up on say 2*4*170 mA= 1360 mA total, about half the value that for the last half hour has tormented the loadresistors, and a quarter of the tranny-spec.
I'd say a 225 mA tranny that I was thinking to buy would mostly had contributed to more EMC in the case.
Well, testing with the real Mcoy is the final test but this seems like a plan. Now to glowbug/sand-matching.
Have a good day!
Staffan
I will run 4 cards and the goal is have it configurable for SE stereo, balanced stereo and 8 channel movie. If I go for the 10 ohm resistors it seems like I will end up on say 2*4*170 mA= 1360 mA total, about half the value that for the last half hour has tormented the loadresistors, and a quarter of the tranny-spec.
I'd say a 225 mA tranny that I was thinking to buy would mostly had contributed to more EMC in the case.
Well, testing with the real Mcoy is the final test but this seems like a plan. Now to glowbug/sand-matching.
Have a good day!
Staffan