Jump to content


Photo

Numark PT-01 modding thread


  • Please log in to reply
731 replies to this topic

#1 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 06 July 2015 - 09:02 AM

Thought I'd start a new thread for this.

 

First step is to jot down a rough schematic for my PT01 so planning mods will be easier. Note that not all the components have the correct names yet.

XdvNlEa.png
 

Some things to note :

  • This is for the PT01USB version, which has an extra connector (TE13) on the main board that sends the signal to the USB board, and the motor control circuit uses a different IC. The circuit looks broadly similar to the regular PT-01 however and the components have the same names.
  • The top section of the schematic is the main audio/motor board, the bottom section is the power supply/IO board.
  • Connector TE11 connects to TE12 via the black ribbon cable.
  • The phono preamps are a common-emitter class A transistor design with no proper RIAA equalisation. This might actually be a good thing as most of us turn the bass down when cutting anyway.
  • The L/R connectors on the black ribbon cable are actually AFTER the power amp. Wiring a fader in at this point probably isn't a great idea as they aren't really meant to handle that kind of power, but I guess if it works it works.
  • A better place to put faders would probably be after the DC-blocking caps C8/C18, or perhaps after connector TE8 (the tone/volume knobs).
  • For an AUX IN port, putting a couple of resistors in series with the AUX and connecting it to TE8 pins 1 and 3 (or 4 and 6 if you don't want it to be affected by the volume/tone knobs) would probably work.

Next step is to reverse-engineer the motor control section, hopefully ultrapitch will be doable.


  • honna, djdiggla, petesasqwax and 5 others like this

#2 petesasqwax

petesasqwax

    1/3 of Phonobrow

  • Elite Member
  • 4,531 posts

Posted 06 July 2015 - 10:40 AM

I neither have nor plan to get a portable scratch setup but I still absolutely love that this thread exists


  • honna, djnumnuts, rasteri and 4 others like this

Look, we should all know by now Pete doesn't get into that shiny G-Funk sound. If it doesn't sound like a discarded flip-flop hitting an old bin lid, recorded onto a dictaphone, then pressed to shellac and buried in a pile of gravel for thirty years, dug up and sampled on an S950 with a broken dial, he ain't fucking with it.


#3 Acts_One

Acts_One
  • Elite Member
  • 241 posts

Posted 06 July 2015 - 12:45 PM

I don't mod stuff myself and I'm glad you guys are embarking on this.

 

There are only two things I really want on this thing.....

 

Ultrapitch

Proper adapter for Carts (M447)

 

If there is anyway you guys figure this out.... I'm going to do it!



#4 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 06 July 2015 - 03:27 PM

Are M447s really necessary? I figure most people are using skipless vinyl anyway, and I'm getting pretty good tracking from the stock needle just by putting a couple of 5ps on it.



#5 Acts_One

Acts_One
  • Elite Member
  • 241 posts

Posted 06 July 2015 - 03:35 PM

Are M447s really necessary? I figure most people are using skipless vinyl anyway, and I'm getting pretty good tracking from the stock needle just by putting a couple of 5ps on it.

lol... I have a coin on my stylus as well.  Its decent.... just not optimal for stabs imo.  but its probably my heavy ass hand.  



#6 Symatic

Symatic
  • Elite Member
  • 5,445 posts

Posted 06 July 2015 - 03:53 PM

HashtagRasteriIsABadman

 

the different carts thing is valid i tihnk - because the red sylus totally mashes up your vinyl.

i suspect in 6 months there are gonna be a lot of ruined 7" scratch recs.....

 

ultrapitch would be the golden grail though......



#7 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 06 July 2015 - 06:38 PM

Figured out ultrapitch. Replace VR1 with a 2K resistor and that lowers the 33RPM speed to about 20RPM.

 

Bigger resistor values will make it even slower if you want.


  • Creature13 likes this

#8 Symatic

Symatic
  • Elite Member
  • 5,445 posts

Posted 06 July 2015 - 08:17 PM

ninja



#9 Backtrack

Backtrack
  • Elite Member
  • 218 posts

Posted 06 July 2015 - 08:23 PM

Awesome Rasteri! I did a VCA fader mod for friend in the PT. I would have had great help if you reversed it in april :)

I took the phono signal (after RIIA) and hijacked the line in and made a new preamp more or less. Used a VCA because I was suposed to have a Mini-Innofader. But in the end didn't have any at the moment so ended up with a old vestax 05 fader. Used a ADC on micro from the fader to control the cutin and just outputted 1 or 0 to the VCA. It worked just fine. It could have been done so much better but it worked. Fun project and got to try the PCB machine at work.
Im making one for my self in the future and Im gonna study your schematic to make a better circuit. Thanks man!
2_zpsoadla4at.jpeg4_zpsgonrvqmp.jpeg

sctrax_zps8xw0wr1d.png
 


  • djnumnuts, djdiggla, rasteri and 2 others like this

#10 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 07 July 2015 - 12:07 PM

That's sick! Does it work good without popping noises etc? VCA cut circuits are hard to get right without pops and clicks.

 

I'm prob gonna use a vestax fader too (I have like 15 of them lying around, mostly thanks to rockwell/dubbadutch), but I'm hoping I can get away with using an analog switch IC (like a 4066) triggered by an opamp comparator to cut the signal. Perhaps with a D-type flipflop to delay the cut until the next zero crossing.

 

Although I reckon if you used an innofader pro you wouldn't need any extra circuitry, just wire it up like this : http://www.innofader....php?id=5&pid=2- and set the cut to sharp.


  • DJ Rock Well likes this

#11 Backtrack

Backtrack
  • Elite Member
  • 218 posts

Posted 07 July 2015 - 12:46 PM

You can hear a slight pop if you have nothing on. But nothing that is bothering when cutting.
I did try different op amp solutions as input to the VCA.

 

Here is one before I used a microcontroller.
the graph is over the fader movement from one side to the next
http://i1292.photobu...zpsllmxvkql.png


 


  • rasteri likes this

#12 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 07 July 2015 - 01:43 PM

Amazing.

 

I was just going to use a comparator (or maybe schmitt trigger) to set a threshold close to the edge of the fader and use that as the input for the analog switch. Hopefully it works.



#13 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 08 July 2015 - 10:18 AM

Tested the 4013/4066 cut circuitry with a Vestax PCV fader, it works like a charm. Razor sharp with no pops/clicks and cuts on both sides of the fader (U-shaped curve).

 

Also got AUX IN working. It just involves putting 1K resistors after C8/C18 and the AUX signal, then connecting them together. I'll post a guide when I get a chance.

 

Now to figure out the best place to attach the fader...


  • djdiggla and DJ Rock Well like this

#14 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 08 July 2015 - 04:44 PM

In the spirit of open source, here's the schematic for the fader and AUX IN circuit I'm using :

94eOAlH.png

Unfortunately this won't work with an Innofader mini or PNP without disabling the 2-sided-cut functionality :(
  • Focus and indigno80 like this

#15 Focus

Focus
  • Member
  • 55 posts

Posted 09 July 2015 - 06:02 AM

You guys are on fire with this...

Do any of you have experience using a Photomos? I was looking for a way to keep the parts count to as minimal as posible and they seem promising...

I just ordered a few but if any of you have an old pc soundcard of fax card they usually have a photmos chip in there somewhere...It be ideal if we could add a few parts, add power, audio input and connect fader...As usual the Clicks/Popping is the issue...

 

These Raiden/Frisk Faders are coo to keep the momentum going for Scratching but they bring it back to the old days of not having high end faders in mixers since they are entry level alpha/nobel faders imo...

 

Focus Fader V1.0 was just a IR Transmitter/Receiver since the 05 already had the VCA Circuitry everything fell into place and the timing was right...This could be the same thing with these Portable Cut Machines, a Photmos plus battery, modified Vestax or other fader Mechanism with IR Pair and done...

 

Adding a Variable Potetiometer would be cool for the Ultra Pitch Adjustment...This gives room to make some Ultra Pitched 7" Records...


  • Dubba Dutchdj likes this

#16 Symatic

Symatic
  • Elite Member
  • 5,445 posts

Posted 09 July 2015 - 08:14 AM



Adding a Variable Potetiometer would be cool for the Ultra Pitch Adjustment...This gives room to make some Ultra Pitched 7" Records...

 

hmmmmm, funny you should say that.....


  • Focus likes this

#17 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 09 July 2015 - 11:30 AM

Yeah I did consider using a photoMOS before I settled on the analog switch. There are a lot of advantages to the photoMOS - total isolation between the control circuit and the audio, the ability to pass an AC signal so you don't need to use a negative voltage rail or bias the signal - but as you say it'll click and pop since there's no real way to do zero-crossing detection.

 


hmmmmm, funny you should say that.....

 

You filthy little tease



#18 DJ Rock Well

DJ Rock Well
  • Team DV
  • 6,958 posts

Posted 09 July 2015 - 01:36 PM

Are we suggesting that Si's made a record for a turntable that hasn't even been invented yet? ;)

Like DJ Shadow before him, he's "too future"

#19 Symatic

Symatic
  • Elite Member
  • 5,445 posts

Posted 09 July 2015 - 02:48 PM

i didn't invent sheeit, the scratch science 7" is ultrapitch.....  :)

 

but ultrapitch on a 7" deck would be effin sweeeeeet



#20 rasteri

rasteri
  • Elite Member
  • 2,008 posts

Posted 09 July 2015 - 03:15 PM

Yeah like I said for now a crude ultrapitch can be got by replacing VR1 with a 2K resistor and that gives you about 20RPM. I'll try and figure out a better/more flexible way of doing ultrapitch.

I wonder if it would just be worth making a whole new mainboard that had all the features we need - decent phono preamp (the stock one sucks), decent speed/torque control (the stock one sucks), decent speaker amp (the stock one sucks), decent EQ (the stock one sucks), fader cut circuit (the stock one doesn't even exist).
  • Focus and indigno80 like this


1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users