Numark PT-01 modding thread

[rasputin]

I'd like to share my very own idea of "the perfect portable":



http://www.bilder-upload.eu/upload/641447-1506969503.jpg

http://www.bilder-upload.eu/upload/bcc1ee-1506969607.jpg

http://www.bilder-upload.eu/upload/74cf16-1506970125.jpg

 

- Custom-made 3D-printed platter
- Custom-made tonearm, adjustable counterweight
- Modified Shure M44-7 cartridge
- Phono-preamp (Av:Link STP-2)
- Phono buttons (red, from top to bottom): Gain, Speed (relocated stock knob), Pitch, Start/Stop (modified Sanwa)
- Custom made fader box (can house JDDX2RS or Innofader)
- Raspberry Pi, AudioInjector soundcard, 5" touch display, plus PiDeck software => DVS inside
- Button to switch between "phono" and "DVS" mode
- USB port for MP3 files on a USB stick
- Line-Out (Cinch & 3.5mm)
- Relocated speaker position, high-quality 2" fullrange driver (Monacor SPX-21M)
- Dedicated vented cabinet (~0.4 litres, tuned to 110 Hz), vent exits at the turntable's bottom to boost bass
- 6W aplifier (Kemo M033N), power/volume knob
- Headphone amplifier (M-Audio Bass Traveller)
- Line-In
- 5V 10Ah powerbank (Fontastic "Eta"), powers the DVS system and headphones amp, plus
- 9V Step-Up power regulator to power the PT01 circuit boards

 

It was all wired up and working before disassembling and preparing the parts for the "final build". So it's not 100% finished yet, i.e. cover plate, front/rear panels and faderbox cover plates are still missing,..

 

r

 

[Mutis Mayfield]

http://atelier.tkrworks.net/

https://github.com/tkrworks/SigmaMIX_Hardware

[Mutis Mayfield]

[kleerkoat]

is there anything comparable to the power boards JDD and OpenFormat have in their kits?

[PortableModManiac]

I just upgraded my tonearm to a bihari + shure m447.

 

I'm curious though, the tone arm on my pt01 always felt loose. And now even with the new tonearm, it feels loose.

 

Is there a way to tighten this up?

 

Here is a video for reference:

https://youtu.be/1B4s_Z24U7Q

I have been obsessing over the Bihari Tonearm for far too long and worked out a few things that I am glad I fixed before I damaged my timecode vinyl. The first thing is that the height is only reasonably aligned with the weight on the headshell. The only thing wrong with that was the weight was doing damage to the Serato vinyl. I was a total turntable, DJ and vinyl novice before getting a PT01. I had to learn and guess what the tutorials were talking about as I went.

 

I hadn't aligned a cartridge before so trying to get info on how to get a good alignment with a custom tonearm and a portable turntable online was not happening. I realised that Serato DJ has a DVS calibration tool and I used that to get a reading on the Shure cartridge. I noticed the weight was carving up the grooves after using the same spot then recalibrating. I then removed the weight. The problem then was the arm angled down and skipped more.

 

Long story short I readded the weight and made a counter weight using a pack of round coloured magnets. Same colour and different sizes so that the weight could be adjusted. This fixed the alignment and skips but I also noticed the weight of the arm is probably too much for the original thin metal base that the Bihari connects to. This also gives the false impression of balance initially as the thing is stiff and won't lean towards the heavy side.

 

Moving this eventually loosens the hold and the metal bands. Anyway I have posted this on Instagram and will try link it here.

 

https://instagram.com/p/BaJRD1fASXz/

 

Some people found the weight was doing damage and others think I am going too far for a PT01 lol.

[Mutis Mayfield]

 

If you remove the last / of instagram links forum usually embeds them.

[PortableModManiac]

https://instagram.com/p/BaJRD1fASXz

If you remove the last / of instagram links forum usually embeds them.

Ha thanks I have been lurking here but not posting as I find it hard enough to follow the info I have a question about the tonearm wiring that is something I want to try but I can't explain it properly.

 

I am thinking of doing the Bihari mod on a PT01 USB that is used for DVS with Serato. I have been able to get a vintage deck and wire the tonearm wiring to an RCA jack and the output is fine using the Akai AMX phono input. The only thing that is different is the vintage has no internal circuits I stripped it out.

 

Would it be possible to wire up the Bihari and cartridge to the RCA directly? Or is it just the same signal if I left the stock preamp inside?

 

Link To Clip of The RCA AMX Test

 

I hope that link is embedded (probably isn't) but it shows the deck which I have been able to get the tonearm wiring to an RCA output and then sent to the AMX. I am trying to find a way to go directly from the Pt01 USB tonearm wiring to the PCB with the RCA output on without damaging the setup so possibly a switch that activates the built-in preamp and then turns it off for phono input to a DJ mixer.

 

Or is leaving the stock preamp inside and using a Shure cartridge basically the same as no preamp?

Edited November 8, 2017 by PortableModManiac

[VST]

For a momentary switch start/stop you can use one of these Polulu boards (low voltage model).

https://www.pololu.com/product/2808

 

Silent and solid state. Works really well, the only downside is if you are also running an ultrapitch board this will make a speaker pop when you start the motor. Haven't bothered to find a fix for that. I just run it without the PWM ultrapitch.

Hey, thanks for this tip! I bought that switch because I think it's a great way to go but I'm having trouble wiring it up. I snipped the old switch wires and ran them into the V- and V+ of the switch and grounded it to the chassis but it only moves the platter for a half second whenever I hit the arcade button which I have wired to the switches button inputs. What am I doing wrong? Thanks for any help.

[Mutis Mayfield]

SigmaMix

https://github.com/tkrworks/SigmaMIX_Hardware

[Jam Burglar]

Anybody have the pre-modded tables Jessie Dean is doing? If so how are they? The prices are good enough that it makes me consider just buying one where he's done the work. I figure after modding a ton of them he's probably got a pretty good process as well. I'm not opposed to digging in myself but if his pre-modded decks are good I can save myself the time and potential error rate.

[mgroovey]

Hi new here, and this might be a stupid question and someone might have answered it earlier in the thread, but here we go:

 

Have anyone done a DIY phono preamp to the PT01 for a M44-7, like the Bihari Design's preamps?

[Rudys]

Can anyone help me with tips to upgrade my PT01s built in speaker. Thanks

[dootejun]

Hi everybody

this is my mod touch button start/stop and fix tonearm rest has been broken

 

 

[Jam Burglar]

Can anyone help me with tips to upgrade my PT01s built in speaker. Thanks

 

Bahari recommends some replacement speakers. Check his site.

[Jam Burglar]

Anybody have the pre-modded tables Jessie Dean is doing? If so how are they? The prices are good enough that it makes me consider just buying one where he's done the work. I figure after modding a ton of them he's probably got a pretty good process as well. I'm not opposed to digging in myself but if his pre-modded decks are good I can save myself the time and potential error rate.

 

FYI, I scooped one of these. It's great out of the box. My only complaint is the ultrapitch. It just doesn't have the torque at lower speeds and results in some warbling when you release the record. Without knowing where true 0% is on the dial, it's hard to tell but it feels like anything below 0% leads to warbling. If you up the speed, it goes away. His pitch mod also bypasses the factory switches so 33/45/78 switch and the factory pitch dial do nothing. I put a band on the platter to try to increase the torque and that helped a little but not enough to fully resolve the issue.

 

Looking at this thread and on the net, it seems like the ultra-pitch is the biggest obstacle with the PT-01. I've seen about a half-dozen people comment on the warbling and nobody chiming in saying "this specific ultra-pitch mod doesn't do that" etc. The only place that I can find the mod on the net is the Open Format site. Dean's is not on his site. I might be able to get some improvement by adjusting my style but it would be cool if there was a way to maintain torque and reduce speed as well.

[Guest rasteri]

Looking at this thread and on the net, it seems like the ultra-pitch is the biggest obstacle with the PT-01. I've seen about a half-dozen people comment on the warbling and nobody chiming in saying "this specific ultra-pitch mod doesn't do that" etc. The only place that I can find the mod on the net is the Open Format site. Dean's is not on his site. I might be able to get some improvement by adjusting my style but it would be cool if there was a way to maintain torque and reduce speed as well.

The pt-01 uses a motor driver that compensates (to some extent) for the friction of the record by measuring the back-emf of the motor. All of the ultrapitch mods I've seen use a very simple 555/mosfet PWM circuit that do no compensation whatsoever.

 

I've been experimenting with a PWM circuit that does the neccesary EMF-measurement + compensation but fuck knows if I'll ever have time to release it.

[Jam Burglar]

You might do well with it if you care about monetizing it. Seems like people are going nuts on these portables right now.

[rasputin]

I have built two quite different PT01 in the past few months...

 

PT01 "Righthand":

 

(tonearm swapped with fader (Innofader Mini), the large white knob above the fader is the start/stop button, honeycomb platter)

 

...and the "LoFa Late Night":

(all rotary knobs replaced with linear pots, honeycomb platter)

For the "LoFa", I used a PWM module that has proven to work well, and added a pot/resistor circuit to it that enables to set 33 or 45, and a ± pitch. As a spin-off, I designed some "addon" solutions for the PT01 (or others). The linear version can be installed without soldering or drilling (cable is fed into the module through the old "pitch" opening):

 

 

 

 

The pt-01 uses a motor driver that compensates (to some extent) for the friction of the record by measuring the back-emf of the motor.

Is that the reason for that "seesaw"-style circuit? It appears that the "33" circuit is always connected, serving as a reference or feedback circuit? I tried to explore the secrets of the PT01 motor controller with an "experimental" board I made. But I totally suck at electronics...

 

 

 

Seems like people are going nuts on these portables right now.

To me it appears that the craze is already over...

 

r

Edited March 21, 2018 by rasputin

[Guest rasteri]

Is that the reason for that "seesaw"-style circuit? It appears that the "33" circuit is always connected, serving as a reference or feedback circuit? I tried to explore the secrets of the PT01 motor controller with an "experimental" board I made. But I totally suck at electronics..

Cool! The "magic" happens in the UPC1470 chip on the main board however. Essentially it boils down to this circuit :

 

 

 

The 33/45/78 swich and pitch pots essentially just alter the values of R_T and R_S, like this :

 

[rasputin]

I spent hours and hours looking at Your circuit diagramm in the past year, until my eyes were bleeding. I cannot tell how much I appreciate that You had posted it. I had also collected the data sheets to all major components, therefor I recognize the first picture that You now posted.

 

What I was referring to with my "seesaw" comment is the 33 section in the top-left corner of Your circuit picture. If I set the switch to 45 or 78, that 33 circuit is still connected. Could You explain the reason or intention behind that?

 

r

[Guest rasteri]

I imagine the maths just worked out that way - perhaps having the 33RPM in circuit meant that they could use a particularly convenient set of resistor values in the 45 and 78RPM ranges.

[Jam Burglar]

I guess that would explain why my pitch mod, which seems to bypass the factory switches all together (they're completely non-functional on my PT-01) worbles and the factory settings don't. So integration of UPC1470, or something like it, into the pitch expansion mod could restore the EMF measurement/compensation and give worble free performance?

[Guest rasteri]

I guess that would explain why my pitch mod, which seems to bypass the factory switches all together (they're completely non-functional on my PT-01) worbles and the factory settings don't. So integration of UPC1470, or something like it, into the pitch expansion mod could restore the EMF measurement/compensation and give worble free performance?

Yeah exactly. Try desoldering the UPC1470 and using a separate pot for both the torque and speed resistors. The UPC1470 in the pt-01 is unstable at low RPM but fiddling with the torque control might fix that.

[Jam Burglar]

Is the torque resistor R11 or is that resistor located on the right side of the diagram? And I'm assuming VR4 is the speed control pot?

[Guest rasteri]

Correct and correct.