I have a Devinyliser driving the subs in my system.I built this from the Signal Transfer Co kit several years ago.
Now I need to adjust the gain of the output unity summer.
I have lost all the kit paperwork , and need the list of component values referencing the circuit board stuffing numbers.
Anyone got that kit paperwork to hand.
STC arent answering at this time.
Now I need to adjust the gain of the output unity summer.
I have lost all the kit paperwork , and need the list of component values referencing the circuit board stuffing numbers.
Anyone got that kit paperwork to hand.
STC arent answering at this time.
Hans , I have the schematic from Self Vinyl book as well as the Paris .ppt.
This shows only the LH chanel components , and none of the numbers match the STC
board. For example the board has R35 - there is no R35 on the schematic.
Thus I need the board stuffing component values and numbers.
This shows only the LH chanel components , and none of the numbers match the STC
board. For example the board has R35 - there is no R35 on the schematic.
Thus I need the board stuffing component values and numbers.
One last remark:
You cannot simply increase the gain of the output summer.
Say Rf and Rs are on the minus side, then driving Rs gives a gain of Rf/Rs, in this case 1k/2k=0.5
Driving the positive side however gives a gain of (1+Rf/Rs)=1.5
Changing Rf to say 2k to get a different gain, changes the negative gain a factor 2 from 0.5 to 1 but the positive side only from 1.5 to (1+1)=2, so only a factor 1.33, destroying the whole envisaged effect.
To get a gain of 2 from the positive side also, you first will have to amplify this signal before the summer by a factor 1.5 to get 1.5(1+1)= 3, now being also twice as large.
But doing this is just as much trouble as placing a simple opamp behind the summer.
Hans
You cannot simply increase the gain of the output summer.
Say Rf and Rs are on the minus side, then driving Rs gives a gain of Rf/Rs, in this case 1k/2k=0.5
Driving the positive side however gives a gain of (1+Rf/Rs)=1.5
Changing Rf to say 2k to get a different gain, changes the negative gain a factor 2 from 0.5 to 1 but the positive side only from 1.5 to (1+1)=2, so only a factor 1.33, destroying the whole envisaged effect.
To get a gain of 2 from the positive side also, you first will have to amplify this signal before the summer by a factor 1.5 to get 1.5(1+1)= 3, now being also twice as large.
But doing this is just as much trouble as placing a simple opamp behind the summer.
Hans
Thank you for the heads up.Currently the single ended Devinyliser is simply driven off the hot side of the preamps second pair of XLR out sockets.
So it would appear that the best approch is to insert a Balanced to Unbalanced buffer, with 2X gain into this circuit to drive the Devinyliser , then subs.
Very easy to add a small board into the same box as it has already has a suitable power supply.
So it would appear that the best approch is to insert a Balanced to Unbalanced buffer, with 2X gain into this circuit to drive the Devinyliser , then subs.
Very easy to add a small board into the same box as it has already has a suitable power supply.