Hi everybody,
thank you for showing attention to this thread 🙂
Does such preamplifier exist ?
I`m not guy who know a lot in electronics department and this why asking for help me out.
I would like to have preamp "signal" multiplayer ,if that description makes same seance...🤔
Situation is like this ...mono signal ( separate left and right channels) out of DAC ( Fostex HP-A4 , 2 Vrms) and in to preamp "signal" multiplayer where I can multiplayer to two identical signals out at the same value of 2 Vrms. Off course ,quality is priority. I should look like this:
thank you for showing attention to this thread 🙂
Does such preamplifier exist ?
I`m not guy who know a lot in electronics department and this why asking for help me out.
I would like to have preamp "signal" multiplayer ,if that description makes same seance...🤔
Situation is like this ...mono signal ( separate left and right channels) out of DAC ( Fostex HP-A4 , 2 Vrms) and in to preamp "signal" multiplayer where I can multiplayer to two identical signals out at the same value of 2 Vrms. Off course ,quality is priority. I should look like this:
Attachments
I think that is normally called a distribution amplifier. They were quite common in studios in the good old days when studios were still mainly analogue.
Given that most preamplifiers have a relatively low output impedance and most inputs have a higher impedance - there would be no problem with driving 2 outputs. The RCA outputs on the Fostex HP-A4 have a specification of 'Applicable load impedance: 10 kohms or more'
So if the inputs were over 20k each then they would be able to be driven directly from the DAC out
So if the inputs were over 20k each then they would be able to be driven directly from the DAC out
Do you ever switch off one of them while using the other? I don't know if this applies to miniDSP, but sometimes inputs of equipment become quite nonlinear when the equipment is switched off.
I don't plan to do that and don't see situation where I will do it .
"I don't know if this applies to miniDSP, but sometimes inputs of equipment become quite nonlinear when the equipment is switched off." -about that ,don't have a clue...Bu I can ask mini DSP service guys.
I do the same. My Topping D90 DAC drives a Purifi+Neurochrome Buffer stereo amp for the three upper ways of my loudspeakers and two Hypex Fusion FA501 mono blocks for the sub bass drivers. Impedances are very similar (48Kohm and 50Kohm) giving a combined load of ~24Kohm which the DAC drives without a problem. I just use a splitter cable (well, two, one per channel).
miniDSP 2x4HD
Analog audio input:
Unbalanced stereo (2 channels) analog audio on RCA connectors
- Max input of 4V or 2V RMS, jumper–selectable
- Input impedance: 10kΩ
- THD+N: 0.003% (RCA to USB)
- Dynamic range: 103dB
That would be the easiest way to do it for me...so happy not having to deal with extra boxes... THANK YOU
There is no need to ask, the issue I brought up only applies when one of the two loads is off and the other on.
Then you get a 5 kΩ load when you connect the Fostex HP-A4 to two miniDSP 2x4HD's. 5 kΩ load is less than the 10 kΩ that the Fostex HP-A4 is meant for. The question is then what goes wrong when you load it with 5 kΩ - chances are that you get a very, very minor loss of deep bass and no other issues, but that's just a guess.
Too low of a load can decrease total drive level, increase distortion, and make the drive unit run hotter than it likes to be due to increased current requirement. You can make a small buffer amp to drive whatever you want without issues but more stuff in the path is more places for the sound to get messed up. Try it and see if it is unhappy. If the power supply in the drive unit is heavy enough and it stays cool enough you are good.
Exactly that I was wary about,but it was a gut feeling (no knowledge is present to explain) 😊 But from your explanation,it is not such a bad trade....
Thank you ...I can make nothing what concern electronics..😆 What I can do is to buy same finished PCB made in Europe or China and put all that together in a box.
Yep ,I did that (PSU) solid enough and with 8 mm thick aluminum 300 mm x 280 mm for cooling. That PSU is used to drive miniDSP 2x4HD and Fostex HP-A4.
In theory, you could get gross distortion because of the output going into current limiting, but I don't expect that. Op-amps are usually designed for 2 kohm or even 600 ohm load. If the DAC doesn't use an op-amp but a discrete circuit to drive the output, it will probably be designed such that it has enough current to drive long, cheap cinch cables that are so capacitive that they need more current at high frequencies than that 5 kohm needs.
If there is an AC coupling capacitor at the output, then the cut-off frequency of the AC coupling with the load will increase by almost an octave, from a deep subsonic to a not so deep subsonic frequency. That will give a very minor loss of deep bass.
Anyway, like mdpaudio wrote, just try it.
Thank you MarcelvdG, because your explanation I have much better picture what is going on. Up til now was using TOSLINK conection from DAC to TOSLINK splitter and to two miniDSP 2x4HD. One miniDSP 2x4HD for one channel. Looks like this
