Hi folks.
I will be using Rod Elliott ESP P05C supply for powering 4 opamps. Well actually 2 balanced line transmitters and 2 receivers in a conversion box.
This supply uses a resistor in series with the first and second supply cap on each rail. I will be using a split 12V or 15V supply for powering.
Each opamp can withstand 70mA short circuit current.
Assume I short all 4. **** happens You know.
70mA*4=280mA*12V power=3.36W *2 Rails also 6.72 W ?
Am I correct ?
What will be the max current on each rail ? Half current or the full 70mA ? Does a 3W resistor suffice for each rail ?
And I need a 7W transformer correct ? (theoretical value since there are losses)
Thank You.
I will be using Rod Elliott ESP P05C supply for powering 4 opamps. Well actually 2 balanced line transmitters and 2 receivers in a conversion box.
This supply uses a resistor in series with the first and second supply cap on each rail. I will be using a split 12V or 15V supply for powering.
Each opamp can withstand 70mA short circuit current.
Assume I short all 4. **** happens You know.
70mA*4=280mA*12V power=3.36W *2 Rails also 6.72 W ?
Am I correct ?
What will be the max current on each rail ? Half current or the full 70mA ? Does a 3W resistor suffice for each rail ?
And I need a 7W transformer correct ? (theoretical value since there are losses)
Thank You.
> using Rod Elliott ESP P05C
Please give links. We do not all have all projects memorized. If you make potential helpers search, they may instead move on to another problem.
Power Supply for Preamps
Power Supply for Preamps -B/C version
Do you really need to survive a worst-case shorts party?
I've run a dozen lines to strange users. The usual assumption is that up to 1/3rd of lines may get shorted and the show goes on.
Do you really need 70mA? 15V peak in 600 Ohms (a now unlikely load) is 25mA. Depending on design, a 300r inside the NFB loop will limit max current to 50mA, slightly limit voltage in 600r. I agree that 50mA is near 70mA.
> Half current or the full
It can't ever be both ways. 70mA per output on one side of the supply, but you don't know which. Or if these are balanced drives, then 70mA from + on one side, 70mA from - on the other.
There are _NO_ parts values on P05C? (P05 lacks the resistors you are questioning.) By squinting, I see 10 Ohm resistors. 280mA in 10r is 2.8V, and 2.8V times 0.28A is 0.784 Watts, worst-case. If your shorts are momentary accidents, a 1W will be fine. If you go away for a month and your assistant leaves it shorted day and night, a 2W will survive where a 1W may need replacing.
However 10r is not a lot of added filtering. Since your non-short current is likely under 30mA, and the PT specified (see below) makes a lot more than you need, I'd go 100r for more filtering. Under worst-case, this could be 23V^2/100r or 5.29W. 5W will stand that for a minute, 10W will stand it for a lifetime. Since 10W don't cost much more, and either solution needs off-board mounting, I'd just use 100r 10W.
> I need a 7W transformer
Rod wants you to use 16V AC. So there is possible 23V each side. We have figured the maximum could be 280mA on one side or 140mA on both sides, ad DC. The AC current will be around 1.8 times higher, 0.252A AC. If you use single 16VAC and his doubler connection, the load becomes 0.504A AC. Times 16VAC is indeed 8VA. I would look for a 10VA: 16V >0.6A AC.
Please give links. We do not all have all projects memorized. If you make potential helpers search, they may instead move on to another problem.
Power Supply for Preamps
Power Supply for Preamps -B/C version
Do you really need to survive a worst-case shorts party?
I've run a dozen lines to strange users. The usual assumption is that up to 1/3rd of lines may get shorted and the show goes on.
Do you really need 70mA? 15V peak in 600 Ohms (a now unlikely load) is 25mA. Depending on design, a 300r inside the NFB loop will limit max current to 50mA, slightly limit voltage in 600r. I agree that 50mA is near 70mA.
> Half current or the full
It can't ever be both ways. 70mA per output on one side of the supply, but you don't know which. Or if these are balanced drives, then 70mA from + on one side, 70mA from - on the other.
There are _NO_ parts values on P05C? (P05 lacks the resistors you are questioning.) By squinting, I see 10 Ohm resistors. 280mA in 10r is 2.8V, and 2.8V times 0.28A is 0.784 Watts, worst-case. If your shorts are momentary accidents, a 1W will be fine. If you go away for a month and your assistant leaves it shorted day and night, a 2W will survive where a 1W may need replacing.
However 10r is not a lot of added filtering. Since your non-short current is likely under 30mA, and the PT specified (see below) makes a lot more than you need, I'd go 100r for more filtering. Under worst-case, this could be 23V^2/100r or 5.29W. 5W will stand that for a minute, 10W will stand it for a lifetime. Since 10W don't cost much more, and either solution needs off-board mounting, I'd just use 100r 10W.
> I need a 7W transformer
Rod wants you to use 16V AC. So there is possible 23V each side. We have figured the maximum could be 280mA on one side or 140mA on both sides, ad DC. The AC current will be around 1.8 times higher, 0.252A AC. If you use single 16VAC and his doubler connection, the load becomes 0.504A AC. Times 16VAC is indeed 8VA. I would look for a 10VA: 16V >0.6A AC.
Ok PRR I did try one double 12+12V supply (Muffsy PSU similar to ESP)
Muffsy Hifi Dual Power Supply V2 - PCB from skrodahl on Tindie)
with two modules and it works well with a cannibalized china wall-wart.
My goal would be to use a single AC supply in the voltage doubler configuration. It's simpler to get a single supply wall-wart transformer. I have several 12V ones powering mic receivers. Depends on the hum ripple and of course the final voltage, since it must be halved in order to get the positive and negative voltage for the opamps.
The modules i'll be using are these.
SparkFun THAT 1646 OutSmarts Breakout - BOB-14003 - SparkFun Electronics SparkFun THAT 1206 InGenius Breakout - BOB-14002 - SparkFun Electronics
Unbalanced Receiver and transmitter end will be connected together. 4 for stereo.
The goal is to get RCA in and XLR balanced out, but since the modules have jacks, I will short the rings on the input with a mono jack and when inserting a stereo Jack it also accepts a balanced signal. The same is true for the outputs.
Think of a Direct injection box with lover impedance than those used for guitars.
Usually opamp supplies use 15V, but +4dBu is 1.23V, so perhaps it will work fine with something like 6V+6V (12/2).
On wedding venues I use 50 to 100m of balanced cable between the main dining room and the garden outside were the Cake ceremony takes place.
I know there are ready made boxes for this, but I want to experiment and learn.
Any suggestions ?
Muffsy Hifi Dual Power Supply V2 - PCB from skrodahl on Tindie)
with two modules and it works well with a cannibalized china wall-wart.
My goal would be to use a single AC supply in the voltage doubler configuration. It's simpler to get a single supply wall-wart transformer. I have several 12V ones powering mic receivers. Depends on the hum ripple and of course the final voltage, since it must be halved in order to get the positive and negative voltage for the opamps.
The modules i'll be using are these.
SparkFun THAT 1646 OutSmarts Breakout - BOB-14003 - SparkFun Electronics SparkFun THAT 1206 InGenius Breakout - BOB-14002 - SparkFun Electronics
Unbalanced Receiver and transmitter end will be connected together. 4 for stereo.
The goal is to get RCA in and XLR balanced out, but since the modules have jacks, I will short the rings on the input with a mono jack and when inserting a stereo Jack it also accepts a balanced signal. The same is true for the outputs.
Think of a Direct injection box with lover impedance than those used for guitars.
Usually opamp supplies use 15V, but +4dBu is 1.23V, so perhaps it will work fine with something like 6V+6V (12/2).
On wedding venues I use 50 to 100m of balanced cable between the main dining room and the garden outside were the Cake ceremony takes place.
I know there are ready made boxes for this, but I want to experiment and learn.
Any suggestions ?
> Any suggestions ?
Audio transformers.
There is a stereo audio transformer sold for car-audio, RCA jacks, $10-$25, which works great in these situations. No external power. Bandwidth larger than any wedding guest can appreciate. Total voltaic isolation for when the far end of the line may be plugged to a totally different power phase or a floating generator. Cut the RCA off one side and wire XLR.
Audio transformers.
There is a stereo audio transformer sold for car-audio, RCA jacks, $10-$25, which works great in these situations. No external power. Bandwidth larger than any wedding guest can appreciate. Total voltaic isolation for when the far end of the line may be plugged to a totally different power phase or a floating generator. Cut the RCA off one side and wire XLR.
I've tried those El cheapo transformers.. and I don't like them. Many are made from modem transformers. I could buy some Jensen or the like ones, but they are ridicously expensive.
I carry one but use it only on emergency situations. Usually I try the ground lift first.
Can You provide me a link for it ?
Thank You.
I carry one but use it only on emergency situations. Usually I try the ground lift first.
Can You provide me a link for it ?
Thank You.
+4dbU=1.23 volts rms, yes. But 20 db of headroom is ALSO needed---12.3 volts peak. Thus the need for at least a +/- 14 volt supply.
Consider what level the next stage clips at.
There is no point in providing more headroom than +6dB above the next stages clipping level.
eg.
If you know that the power amp has a sensitivity of 1.5Vac for maximum power, then the preceding stage could have a maximum output of somewhere from 1.55Vac to 3Vac
The 6dB of headroom allows for a ClassA single ended stage to avoid the gross 2nd harmonic building up as maximum output is approached.
Andrew
We are talking about input to amplified speakers here, so they usually have a gain knob that goes from mic to line level or a mic / line switch. It could also go into a small mixer like the Yamaha MG series or the Behringer Xenyx series. I have several PA amps and the sensitivity is something in the 1- 2V range for max power. At this time I've been using the built box with a Pioneer XDJ-R1 console run from the booth outputs with satisfactory results. Please note I'm running the That 1646 boards directly form the RCA outs without any buffer in between. These chips are awesome.
We are talking about input to amplified speakers here, so they usually have a gain knob that goes from mic to line level or a mic / line switch. It could also go into a small mixer like the Yamaha MG series or the Behringer Xenyx series. I have several PA amps and the sensitivity is something in the 1- 2V range for max power. At this time I've been using the built box with a Pioneer XDJ-R1 console run from the booth outputs with satisfactory results. Please note I'm running the That 1646 boards directly form the RCA outs without any buffer in between. These chips are awesome.
PRR those el-cheapo hum transformers don't go well with titanium drivers.
Treble is severely attenuated. We do about 150 to 200 events every summer (APR-SET) and people like to hire us because they like our animations Dj's and our crystal and balanced sound. No Booming or rolling bass, no Harshiness if You understand me. When you do a sunset near the Gin bar on the venues (fashion today during the cocktail and guest-wedding couple photo shooting) You need to place some speakers outside and You need power. We use something in the range from 1 to 4KW power.
A month ago, we were asked to install some sound for a Reggae Band that was playing at that wedding. Nothing fancy, two QSC 2x500W Amps two tops and 2 bass cabs, and an additional 1000W 18 inch bass cab and the band was very pleased with the setup. Well they were using a Presonus 2500€ mixer and Shure mikes and were playing in front of the speakers. I presume the mixing desk did take care of the feedback and limiting and all DSP stuff...
Treble is severely attenuated. We do about 150 to 200 events every summer (APR-SET) and people like to hire us because they like our animations Dj's and our crystal and balanced sound. No Booming or rolling bass, no Harshiness if You understand me. When you do a sunset near the Gin bar on the venues (fashion today during the cocktail and guest-wedding couple photo shooting) You need to place some speakers outside and You need power. We use something in the range from 1 to 4KW power.
A month ago, we were asked to install some sound for a Reggae Band that was playing at that wedding. Nothing fancy, two QSC 2x500W Amps two tops and 2 bass cabs, and an additional 1000W 18 inch bass cab and the band was very pleased with the setup. Well they were using a Presonus 2500€ mixer and Shure mikes and were playing in front of the speakers. I presume the mixing desk did take care of the feedback and limiting and all DSP stuff...
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