About

The Sequentix P3 is a step sequencer with analog pots for entering notes and other data. It was originally sold both as a kit and assembled, but recently (most likely due to RoHS legislation) it is now only available wholly assembled.

The About P3 section of the Sequentix site states begins:

The P3 Sequencer is an 8 track, hardware MIDI sequencer, with a user interface comprised of knobs, keys and LEDs. A sixteen character by two line PLED display provides confirmation of pattern data and access to advanced features and configuration options.

P3 allows real-time control of track mutes and simple pattern or pattern chain selection across multiple tracks, plus analogue-style editing of patterns. Each of its 384 patterns has independent values for note, velocity, tie, gate, length, gate delay, and a combination of up to four MIDI controllers, extra notes, or 'auxiliary events', per step.

I've never really cared for sequencing music by clicking around in a computer so I figured that a hardware sequencer would be especially useful for me. With my recent building of (all too) many MIDI-controlled synthesizers I was also needing something other than a keyboard for triggering them, so when I had the unexpected chance to purchase the parts for a P3 and built it myself, I jumped at the chance. In the end it cost a bit more than I'd originally planned, but it seems worthwhile thus far.

P3 End of Life

On September 5th, 2006 Colin Fraser posted a message on the Sequentix Music Systems News Release page stating that the P3 will soon be out of production. The release states:

It's been just over a year since the P3 Sequencer was launched as a production unit.

We have sold well over 100 units in that time, and the response from users has been excellent.

However, due to a number of factors, we have decided to cease production of P3 after the current run is sold out.

The main reason for this is that a thorough review of the numbers shows P3 is simply too expensive to produce.

All units built so far have been assembled in-house.

The amount of effort this requires has meant we have been unable concentrate on developing future products.

Fully out-sourcing production of P3 in its current form would mean a significant increase in the final price - it just wasn't designed to be cheap to manufacture, with a large number of separate circuit boards, internal wiring, and a complex case design.

Ceasing production will give us the opportunity to take the lessons learned from P3 and develop a replacement product that can be made and sold at a viable price.

In the meantime, we expect the remaining stocks of P3 to move quickly.

They will be available until stocks are exhausted, direct from Sequentix, from our US dealer Analogue Haven, and our German dealer Schneiders Buero.

Later, on September 7th a new post was made stating:

All remaining units are now spoken for.

There is a reserve list in case anyone decides not to follow through on an order, so there is a small chance if you are quick...

So, it sounds as if they are all gone.

According to a recent posting by Colin Fraser on the analogue-sequencer Yahoo! Group, after the final Sequentix P3 is shipped there will have been 137 production units made. An additional 24 pre-production P3s were made and there were a total of 86 kits sold. Assuming that all kits were assembled, there are only 247 (at most) P3s in the world. So not only is this an interesting, fairly unique sequencer, it's somewhat rare, too.

Rackmount Sequentix P3

Kit

Around April 2006 a few remaining sets of P3 PCBs surfaced and were made available for purchase through analoguehanven for US$249. I purchased one of these and let it sit in my basement for a few months.

After directly contacting Colin Fraser, the creator of the P3, I was able to purchase one of the pre-made enclosures for the P3 from him. This enclosure kit also included Cherry keyswitches and keycaps which were custom-labeled for the P3. While the price of US$339.55 plus $77.62 postage (after exchange from GBP) seemed a bit high at first, when I took into account the time it would take to design my own enclosure, locating the switches, and the cost of having a custom front panel made, and the price seemed pretty reasonable.

With another US$200 or so in parts from Mouser, Digi-Key, and Jameco I had everything needed to assemble the P3.

Assembly went very smoothly, and except for an issue with the clearance of the top pot board (which turned out to be a known assembly issue) there weren't any problems. The PCBs are fairly simple and assembly was easy with the most difficult part being the making of jigs for the keyswitches on the step board and keypad board. This is definitely one of the easier kits I've assembled.

There are various photos of the construction of my P3 available, all of which can be seen in the Gallery album entitled Sequentix P3. Specifically, there are separate albums showing some of the parts used, various photos of the assembly in progress, and a few of the completed Sequentix P3.

On November 15th, 2006 the wooden end cheeks for the Sequentix P3 arrived. These took a few minutes to install and have really polished off the look of the P3. Images of the completed Sequentix P3 have been added to the latter half of the completed Sequentix P3 photos. While the rackmount version is nice, I greatly prefer the smooth, finished look when the wooden end cheeks are fitted.

Bill of Materials

This bill of materials details all parts which I purchased from US suppliers and used for the assembly of my P3 with the v1.6 PCB set. As of the time when I started this project there was no coheasive BOM for the v1.6 of the P3 PCB set, so hopefully others will find this useful. This was initially based on the v1.52 BOM posted to the Sequentix P3 Yahoo! Group by Colin, but since many of the parts are no longer available I'd made some changes.

Most parts are from Mouser. Digi-Key was used for a few harder to find ICs and the switching slim wall wart-type power supply was purchased from Jameco. The PLED display is from Crystalfontz. Listed part numbers link to the product pages at the various vendor's sites.

Note that not all parts are RoHS compliant, so anyone ordering components from the EU may want to pay attention to what is being ordered.

In my assembly I did not have the proper length LED standoffs available to me when assembling the Function Switch Board, so I stacked two shorter standoffs. The specified .32" standoffs should be the appropriate length, but it is suggested that you order a few similar sizes and see what fits best.

When doing the final assembly on my P3, I found that the case wouldn't close. It turned out that the top Main Pot Board hit the back of the case, keeping it from closing. I found that if one bends the top board back against the housings and makes the connecting cable a slight bit longer (maybe another 5mm) everything fits great. In some email sent with a great degree of synchronicity, Colin confirmed that this needs to be done on some P3s, depending on which pots are used. Keep this in mind when building a P3. In order to make connecting cables easier, you may also wish to mount the 16 Pin header on the opposite side of the PCB.

Main Board

Main Board

Part Name on PCB	Value	Part Number	Quantity
C1, C2	33pF	81-RPE5C1H330J2P1Z03	2
C4	150pF	81-RPE5C1H151J2P1A03	1
C6, C8-C12, C14	100nF	80-C322C104K5R	7
C5	10nF	140-PF2A103G	1
C3, C7, C15	10uF	140-L16V10-RC	3
C13	1000uF	140-XRL25V1000-RC	1
VR1	10KΩ	531-PT10V-10K	1
R10-R13	100Ω	271-100-RC	4
R18, R21, R25, R26	10KΩ	271-10K-RC	4
R19, R27	10Ω	271-10-RC	2
R-9	150Ω	271-150-RC	4
R1, R32-R36	220Ω	271-220-RC	6
R23,R24	22Ω	271-22-RC	2
R14-R17	4.7KΩ	271-4.7K-RC	4
R2	510Ω	271-510-RC	1
D1	5.6V Zener	512-1N5232B	1
D2	1N4148	512-1N4148	1
D6	1N4001	512-1N4001	1
U1	AT89C51ED2	Ships w/ PCBs	1
U2, U3	62256	428-1782-ND	2
U4	74HC573	512-MM74HC573N_Q	1
U5,U8	74HC138	512-MM74HC138N	2
U6	DS1210+	DS1210+-ND	1
U7, U10, U11, U15	74HC574	595-SN74HC574N	4
U9	74HC245	595-SN74HC245N	1
U12,U13	74HC241	296-8271-5-ND	2
U14	ADC0804	ADC0804LCN-ND	1
U16	4051B	595-CD4051BE	1
U17	6N139	512-6N139	1
U18	7805	511-L7805ACV	1
U19	PIC 12F629	Ships w/ PCBs	1
U20	74HC04	511-M74HC04	1
Q2	BC547B	512-BC547BTAR	1
F1	500ma FUSE	652-MFR050-LF	1
J1	3 Pin Vertical Header	538-70543-0002	1
J6	4 Pin Vertical Header	538-70543-0003	2
J2-J5	16 Pin Box Header	517-30316-6002	4
XTAL1	24 MHZ	520-HCU2400-S	1
VB	CR2032	525-E-CR2032BP	1
VB	PCB Cell Holder	534-103	1
L1, L2	Ferrite	81-BL01RN1A1D2B	2
U6, U17, U19	8 Pin DIP Socket	575-193308	3
U20	14 Pin DIP Socket	575-193314	1
U5, U8, U16	16 Pin DIP Socket	575-193316	3
U4, U7, U9-U15	20 Pin DIP Socket	575-193320	9
U2, U3	28 Pin DIP Socket	575-193628	2
U1	40 Pin DIP Socket	575-193640	1
U18	TO220 Heatsink	532-504102B00	1
U18	TO220 Mounting Kit	532-4880	1

Step Board

Step Board

Part Name on PCB	Value	Part Number	Quantity
D1-D16	1N4148	512-1N4148	16
D17-D32	Dual-Color LED	604-WP59EGW	16
D17-D32	LED Standoff	593-STD250B	16
J1	16 Pin Box Header	517-30316-6002	1
S1-S9	Keyswitch	Ships w/ Enclosure	9
S1-S9	Keycap	Ships w/ Enclosure	9

Keypad Board

Keypad Board

Part Name on PCB	Value	Part Number	Quantity
D1-D9	1N4148	512-1N4148	9
J1	16 Pin Box Header	517-30316-6002	1
S1-S9	Keyswitch	Ships w/ Enclosure	9
S1-S9	Keycap	Ships w/ Enclosure	9

Function Switch Board

Function Switch Board

NOTE: Square pad on LED pads is anode. This is commonly the longer lead on the non-flat side of an LED.

Part Name on PCB	Value	Part Number	Quantity
D1-D4	Green LED	604-WP7104PGD	4
D5-D8	Red LED	604-WP7104ID	4
D9,D10	1N4148	512-1N4148	2
S1, S2	Keyswitch	Ships w/ Enclosure	2
S1, S2	Keycap	Ships w/ Enclosure	2
J1	16 Pin Box Header	517-30316-6002	1
J2	2 Vertical Header	538-70543-0001	1
D1-D8	LED Standoff	593-ST320B	8

Main Pot Board

Main Pot Board

NOTE: There are two Pot Boards, Upper and Lower. Part names are duplicated on each.

Part Name on PCB	Value	Part Number	Quantity
VR1-VR16	10K Linear	31CA401F	32
C1, C2	100nF	80-C322C104K5R	4
U1, U2	4051B	595-CD4051BE	4
U1, U2	16 Pin DIP Socket	575-193316	4
J1	16 Pin Box Header	517-30316-6002	2
VR1-VR4, VR9-VR12	White Knob	550-67005	16
VR5-VR8, VR13-VR16	Gray Knob	550-67003	16

I/O Board

I/O Board

Part Name on PCB	Value	Part Number	Quantity
MIDI IN, OUT 1-4, SYNC	5 PIN DIN Socket	161-0504	6
J1	16 Pin Box Header	517-30316-6002	1
R1-R5	220R	271-220-RC	5
F1-F10	RFI Filter	81-DSS306Y5S102M100	10

Data / Tempo Pot Board

External Links

• Sequentix Music Systems - Maker of the P3 Sequencer.
• analogue-sequencer Yahoo! Group - Yahoo! Group for the Sequentix P3, containing lots of related files including firmware, BOMs, pictures of users' P3s, etc.