Question about minimum input voltage using Voltage Regulator L7809?

[antonis]

You have 5 HPFs of very different individual cut-off frequencies..
Shouldn't you settle down them a bit..?? 



P.S.
IMHO, you could omit J201 stage, make TL072 first stage feedback resistor 150k, make second TL072 stage of a gain of 2 (just like first stage) and let it rest in peace..

[duck_arse]

you are 100% correct - about your breadboarding. here's something - see those long red and blue lines along the long strips? they indicate that that stip/busbar is continuous for the length of the line. it is common to see busbars with a break [a single break] in the line at the midpoint of the board. so, pull all those little staples out of your busses, that'll be a few less points you might short to.

are you going to do a lot of breadboarding from here on in? if yes, dedicate some parts to it. straighten ALL those resistor legs. then hairpin a whole load, and cut their leads even and "short", so's they are good to stretch only across 2 or 3 strips. for 5 and 6 stretch, bend some neatly and square and then trim them down so they only stand say 5mm higher than the board. for a 4 stretch? just avoid them, practise moving parts closer/further.

capacitors - don't splay the legs, use them straight up and down. use wire to link things, that's what it's for.

build/rebuild your input stage near the input cable. keep your sections together and sane, not spread from end to end.

ALL parts go straight/square, NEVER EVER slanty. this rule must never be broken!


your input cap is not in the right place in that breadboard shot. rebuild the input section in a section, then see what is. I hope some of this guff proves helpful.

[Jasonmatthew911]

You have 5 HPFs of very different individual cut-off frequencies..
Shouldn't you settle down them a bit..?? 



P.S.
IMHO, you could omit J201 stage, make TL072 first stage feedback resistor 150k, make second TL072 stage of a gain of 2 (just like first stage) and let it rest in peace..

Ok, so I'll try omitting the J201, and try what you say to see if it gives me enough Clean Gain at the output and Headphone amp...For the first stage, you're saying I should take the (2) 10K's and .1uf out completely and put them on the 2nd stage, and just add a 150K from Pin2 to Pin1 of 1st stage, correct?...Would 100K or 220K do the trick, at the moment I don't have 150K?

Also, you mentioned that I have 5 HPF's of very different cut-off frequencies...Please let me know what you would recommend trying?...Keeping in mind that these PreAmps would be for Guitar, Bass and Synth...That's why I'm not sure what would be good in between values to work for a full range of frequencies...I started learning electronics 15 years ago, I know I should be more advanced, but it's been off and on, I haven't had much time to experiment in the past, so I tend to forget a lot that I've learned, and there's a lot I never learned...Now with the plandemic I have more time for this, so thanks for all the help guys...I'm just aiming for all to sound good without getting too complicated and to be theoretically correct...Cheers!

[antonis]

You can play with caps values values for HPFs & LPFs cut-off frequencies of your taste..




P.S.
Saved you some items for breadbording easiness..

[Jasonmatthew911]

You can play with caps values values for HPFs & LPFs cut-off frequencies of your taste..




P.S.
Saved you some items for breadbording easiness..

Thanks for this, I actually tried it, but it wasn't really enough Gain, even changing 2nd stage to Gain of 3 and 5 didn't really feel as loud or as much mojo as I get with the J201 in the circuit...So far going into the J201 then TL072 sounds best to me, a little more mojo, unless it's mental haha, but seriously the J201 seems to add a slight tube dynamic to the signal...I did however take out the Cap and 1M resistor going from pin1 to pin5...I'm confused though, at the beginning I think most were telling me that I should have that 1M going to the (2) 10K voltage divider resistors off of Pin5??...So should I omit the Cap and 1M resistor going to Voltage divider between Pin 1 & 5 or keep it?...Not sure what's best now, it seems to work the same either way.

[antonis]

If you like it with the JFET, let it be..
(although, modified circuit exhibits a slightly higher total gain - 32 instead of 30..)

>I did however take out the Cap and 1M resistor going from pin1 to pin5...I'm confused though, at the beginning I think most were telling me that I should have that 1M going to the (2) 10K voltage divider resistors off of Pin5??...So should I omit the Cap and 1M resistor going to Voltage divider between Pin 1 & 5 or keep it?...Not sure what's best now, it seems to work the same either way.<

Capacitor & 1M bias resistor should be helpful in case of you wish another HPF between stages..
Pin 5 DOES need +4.5V bias and it can get it via 2 ways..
1. Directly from pin 1 output (DC gain is rolled-off to unity due to 100nF DC blocking capacitor in series with 10k resistor - stage 1 acts as a DC unity buffer..)
2. Via 1M bias resistor (the one connectet to voltage divider) ONLY when there is a DC blocking capacitor between pins 1 & 5..

[PRR]

OK.

[Jasonmatthew911]

If you like it with the JFET, let it be..
(although, modified circuit exhibits a slightly higher total gain - 32 instead of 30..)

>I did however take out the Cap and 1M resistor going from pin1 to pin5...I'm confused though, at the beginning I think most were telling me that I should have that 1M going to the (2) 10K voltage divider resistors off of Pin5??...So should I omit the Cap and 1M resistor going to Voltage divider between Pin 1 & 5 or keep it?...Not sure what's best now, it seems to work the same either way.<

Capacitor & 1M bias resistor should be helpful in case of you wish another HPF between stages..
Pin 5 DOES need +4.5V bias and it can get it via 2 ways..
1. Directly from pin 1 output (DC gain is rolled-off to unity due to 100nF DC blocking capacitor in series with 10k resistor - stage 1 acts as a DC unity buffer..)
2. Via 1M bias resistor (the one connectet to voltage divider) ONLY when there is a DC blocking capacitor between pins 1 & 5..

Ok, so after trying many different things, like the TL072 on its own playing with the Gain stages, I also tried (2) J201's into each other and no TL072, it was alright, but noisier, so not that great for a clean pre amp..I tried the J201 before and after the TL072, and after combining different recomendations that you guys have given me, I think this has been the sound and volume loudness that I've liked the most...With the J201 at input, it seems I only have to put the 1st Gain stage at a Gain of 2, and I didn't need the 2nd Gain stage due to the J201, so it's connected like Buffer instead of the 2nd Gain stage...I get a good clean boost sound up until about 3 o'clock, when Volume is full there is only slight saturation, but it sounds pretty usable/decent I think...Please give this last schematic a final look and let me know if it's good to go or if you'd still recommend changing a value or part placement?...Thanks!...

[antonis]

Can't figure out the reason for having a 1.6Hz HPF (100nF/1M bias reistor for pin 3) AFTER the 7.3Hz LPF (22nF/1M Gate bias resistor..)
Try to make 100nF coupling cap 10nF..

Also, second 470μF reservoir cap is only necessary in case of 9-18V board input is faaaaar away from pin 8..

[duck_arse]

I was going to say "that's it!", but I'll defer to antonis.

[antonis]

Plz Stephen, be my guest.. 

@Jasonmatthew: Ignore my last post and proceed according to your last diagram..

[Jasonmatthew911]

Finally!!!...Thanks a lot for all the help guys, I'm very thankful that this Forum exists...I will proceed to Breadboard the CabSim section of my project now, if I have any issue with that, I'll just start another Post  Cheers!

[Jasonmatthew911]

Quick question...Since I'm sending 2 separate PreAmp signals to the same outputs and same input of the DI Transformer, is it enough just to use a mixing resistor for each signal at all the points where the 2 signals come together, and/or should I add a 1uf-10uf Cap in series with a mixing resistor to further prevent signals from feeding back into each other, or is the extra Cap not necessary in this case?...Also should the mixing resistors be around 10K or should they be smaller?...I know for my Headphone amp the mono to fake stereo mixing resistors I'm using are 100 Ohm resistors after the big 470uf Cap, but after my PreAmps I'm using 10K mixing resistors to send the signal to the different outputs where the 2 separate PreAmps will meet...Is this good, or should I be using different values?

[antonis]

In general, 10k resistors are considered OK for mixing low output impedance signals..
(which impedance is dependent upon Volume/Level pot setting..)

Series capacitors do nothing on signals feeding back prevention..
(actually, they form HPF & LPF with mixing resistors of the very same cut-off frequency.. - I guess you don't wish it, do you..??)

[duck_arse]

as requested - "that's it!"