Build Thread:PQD2

[Gustav]

Ok thank you ! I failed calculating the correct drop voltage resistor I have 6.3V to the lamp but don't have enough Ampers... But I know why.... And I don't understand how the drop resistor is related to the 6.3V  that seems to be the output of the LM317 ? But I don't know if you have the time to explain me that.

I am sorry, but I am not sure what youre asking here, so Ill freestyle it.

IF you are drawing the connection from the 6.3V, you dont need a drop resistor to power a 6.3V LED package (You mentioned the desire to use such an LED in your previous post).  You only need the drop resistor if you are drawing from the 9V secondary, which I would recommend.

You dont have enough amps, and you know why!? Could you rephrase this problem? I doubt you have a lack of available current, which is what it reads like..

If you answer the question "How are you trying to connect the LED?", it may clear it up

PS : last question... In the case that I bought there was already a switch with the IE Socket and I have wired it, is it a problem if wire a second switch  at the primary thoroidal transformer ?

I dont see why, other than having two switches doing the same thing. 

Gustav

 

[Eddy.L]

Sorry my post was very confused... So I'll start again.

I follow your advice for the lamp. I wired it to the 9V secondary this is why I was talking about a drop resistor (and my problem of current might because I calculated the value of the resistor in order to have 0,015A instead of 0,15A).

And the thing that I don't understand is how the 2W drop resistor which is named R120 on the scheme have an effect on the 6.3V which goes to the tubes ? But if you don't have the time to explain it's okay !

Thank you again for your help !

PS : the lamp is this kind of lamp it's not a led https://www.banzaimusic.com/47-Light-Bulb.html

 

[Gustav]

Sorry my post was very confused... So I'll start again.

I follow your advice for the lamp. I wired it to the 9V secondary this is why I was talking about a drop resistor (and my problem of current might because I calculated the value of the resistor in order to have 0,015A instead of 0,15A).

Amount of voltage you need to drop = 9-6,3 = 2,7V (Measure real life voltage output from the secondary)

V = R x I

2,7 = 0,15 x R

Isolate R to get the value of the resistor you need in ohms.

And the thing that I don't understand is how the 2W drop resistor which is named R120 on the scheme have an effect on the 6.3V which goes to the tubes ?

It shouldn't. Not unless theres something wrong. 

Gustav

 

[Eddy.L]

And the thing that I don't understand is how the 2W drop resistor which is named R120 on the scheme have an effect on the 6.3V which goes to the tubes ?

It shouldn't. Not unless theres something wrong. 

So I think I didn't understand how to choose the good resistor value for R120 ? Which voltage should I check ?

 

[p0ulp]

Hello, I m currently making my order for this project but can't find inductance that looks like the one on the pcb (they look like resistor at leat in format) but there is no spec or type of package specified.
I someone could post picture of his unit where the inductance are shown that would maybe help me or any mouser/rs/digikey reference ?

I ve only found smaller value that could fit the PCB

thank you

 

[Gustav]

Hello, I m currently making my order for this project but can't find inductance that looks like the one on the pcb (they look like resistor at leat in format) but there is no spec or type of package specified.
I someone could post picture of his unit where the inductance are shown that would maybe help me or any mouser/rs/digikey reference ?

I ve only found smaller value that could fit the PCB

thank you

If you haven't bought the boards yet, I have a package of suitable inductors in the hard candy section of the store..

The shape of the silk screen is not the determining factor here...sorry if thats confusing.

Gustav

 

[Gustav]

So I think I didn't understand how to choose the good resistor value for R120 ? Which voltage should I check ?

Are you saying you dont know which voltage the resistor R120 is supposed to drop?  (Im afraid you might even be thinking its related to the hook-up of your light at this point!?).

1. If that is the case, I think you should get help from someone who knows what they are doing to stay safe.

2. See attached picture.


Gustav

 

[Eddy.L]

I found it by myself yesterday afternoon looking checking the scheme in fact, I don't know why I understood it was linked to the 6.3V.... Thank you again for your help ! And sorry for my dumb questions...

 

[Gustav]

I found it by myself yesterday afternoon looking checking the scheme in fact, I don't know why I understood it was linked to the 6.3V.... Thank you again for your help ! And sorry for my dumb questions...

I dont believe theres such a thing as dumb questions, but...

When I see someone who doesn't know how to follow a trace building a GssL or similar, I see it as a goal to bring him a few steps forward. When I see someone who doesn't know how to follow a clear supply line building a high voltage project, I get the instinct to take him a few steps back.

Its simply a matter of keeping safe while making mistakes

Gustav

 

[Patch]

Hey Gustav, nice looking project man, I have always gotten my boards from you (apart from my neve) and they've always been top class.

I've actually been looking to build another Dual G Pultec but this time I wanted to make it stereo 1U with ganged pots and ganged (double deck)  switches. But it seems according to Jakob that with ganged pots can you'll be lucky to get the tracking within 10%, which doesn't sound good at all for stereo tracking.

As this version of the G Pultec only uses switches I was thinking it may be better to use for ganged controls. What do you think to that?

I was also wondering how this circuit differs (apart from PCB layout and switches) to Jakob's G Pultec?

Last question sorry... The optional 'Variable level control', does this boost gain post eq? (i presume it must), is there potential to get a bit of saturation from the valve gain stage into the TRX? Don;t want to get off into the subjective too much (as I know the heavy weights on this forum don;t tend to get into that) but a bit of saturation control for some added colour would be interesting, but perhaps not ideal for this unit. 

 

[Gustav]

Ill answer what I feel I can...

I was also wondering how this circuit differs (apart from PCB layout and switches) to Jakob's G Pultec?

It doesnt...

The optional 'Variable level control',

...is on the MS PQ76 I did with no tubes, not this project.

Gustav

 

[Patch]

Thanks for the ultra quick response.

I think you may need to update your info on PCB grinder then as it states for this project:

Features

-All controls detented for level matching and recall
-Regulated heater supply for stable operation
-Variable level control available at builders own preference.


You didn;t answer the bit on dual gang, although thinking about it I'm guessing of course switches are going to get good tracking right, Pots are more the issue with dual gang tracking....

 

[Gustav]

-Variable level control available at builders own preference.

What I mean is the option of varying the level of the EQ boost/cut controls with resistor selection. Ill put it on my to-do list to reword it, as I can see how it can be misread.

For switches, tracking will depend on the resistors you solder into the switch.

Gustav

 

[Patch]

Ahhh ok, that makes sense now. Thanks you 

 

[Patch]

For switches, tracking will depend on the resistors you solder into the switch.

Gustav

Yes of course, but sourcing matching resistors and also having the option to chop and change them to find the 'perfect two' seems a lot safer than these dual gang pots which Jakob says are rarely used in EQs as the tracking is rarely better than 10% (that's a scary number to me).....

Just gotta decide if the steps are going to be to my satisfaction... I guess as you said about the 'variable level' you can tailor the step changes as you wish, so I'm thinking I will go for this PQD2

 

[p0ulp]

Hello, I m currently making my order for this project but can't find inductance that looks like the one on the pcb (they look like resistor at leat in format) but there is no spec or type of package specified.
I someone could post picture of his unit where the inductance are shown that would maybe help me or any mouser/rs/digikey reference ?

I ve only found smaller value that could fit the PCB

thank you

If you haven't bought the boards yet, I have a package of suitable inductors in the hard candy section of the store..

The shape of the silk screen is not the determining factor here...sorry if thats confusing.

Gustav

That's ok I ve seen the inductor on your store that's still good visual information

 

[p0ulp]

populating this one ... also , and looking for the calculation tools, it only concern the low boost/low cut so I guess its the same calculation for the high boost/cut since it's supposed to act as a 10k log/100k log also ? am I right ? it's indicated A/F for the 100k and B/G for the 10k , so that one is ok I suppose.

My question is about frequency and Q ... is there a tools that we can use to calculate those value without having to compute all the filter information (which I am sure would lead me to error as I m not yet comfortable with it) , a tool like harpo did for the neteq maybe ?

Also may I suggest an "offboard" overlay for the cap value just as a pdf to document the build, the overlay can be a little tricky to read

 

[Gustav]

populating this one ... also , and looking for the calculation tools, it only concern the low boost/low cut so I guess its the same calculation for the high boost/cut since it's supposed to act as a 10k log/100k log also ? am I right ? it's indicated A/F for the 100k and B/G for the 10k , so that one is ok I suppose.

My question is about frequency and Q ... is there a tools that we can use to calculate those value without having to compute all the filter information (which I am sure would lead me to error as I m not yet comfortable with it) , a tool like harpo did for the neteq maybe ?

Also may I suggest an "offboard" overlay for the cap value just as a pdf to document the build, the overlay can be a little tricky to read

The only thing the calculator does is make sure the total sum is correct and round the resistor values to the E96 ladder (I have to figure out how to make this into E24 some day). I put in the graphs so you can see the log curves, which I know now was a mistake (and really doesn't make much sense). A lot of people think the goal is to get a linear curve going by changing values around. The high cut and high boost are linear, which is why the table simply states the value to put into each, identical step.

When I do another run, I will change the nominators on the board and put in the "default" values from the sheet. They work out very well, and with pre-fixed values. Tinkering with the values for the sake of tinkering with no real idea what the prefix would've done is not really productive imo.

For the high Q/(bandwidth), it might make sense to experiment if you want to measure exact Q values. Personally, I am not someone who is very discerning when it comes to specific Q values, as long as the switch has a throw to it where I can hear the steps working.

Gustav

 

[Vac11]

Hi Gustav!

1) In BOM are these resistors:

3x470R
2x470K
2x75R
2x1M
2x1K
4x10K
1x1K8

Are these standard 1/4W, 1% tol.? How critical are these parts?

2) What exactly is an inscription ""high voltage" on the capacitor specified in BOM? It is sufficient 250V , rather than  400V and higher?

Thanks

MV

 

[Gustav]

Hi Gustav!

1) In BOM are these resistors:

3x470R
2x470K
2x75R
2x1M
2x1K
4x10K
1x1K8

Are these standard 1/4W, 1% tol.? How critical are these parts?

2) What exactly is an inscription ""high voltage" on the capacitor specified in BOM? It is sufficient 250V , rather than  400V and higher?

Thanks

MV

1/4Watt is fine. I think the 470R could benefit from being 1/2 or 1 watt in tight situations. (I think its 470R, check with the schematic yourself)

HV is just an indicator it should be sufficient for the high voltage rail, wether you're running it at 180 or 250V.

Gustav