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DIY True Analog Minipops7 Clone *Samba & Rhumba 1/1 comp
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3, 4, 5, 6, 7  Next [all]
Author DIY True Analog Minipops7 Clone *Samba & Rhumba 1/1 comp
2018-02-20 Samba and Rhumba one on one audio compare
2018-02-19 Live Compare
2018-02-18 Oxygene ?
2018-02-18 Bongos updated by request
2018-02-17 Claves updated by request
2018-02-14 Original vs MiniP7 video
2018-02-11 Quijada updated
2018-02-11 Teaser Movie Rumba rhythm
2018-02-11 PCB fully populated
2018-02-10 PCB SMD populated, most sounds already OK
2018-02-08 Updated with BassDrum
2018-02-09 Option requests for MP7 closes tonight at 23.59 CET
2018-02-08 Updated with Rimshot

Dear all,

being an analog synth enthousiast for a long time, and being prety much active in electronics, I decided a couple years ago to start building analog synths (modules) and drum machines mainly for own use.

All analog stuff I built was own design, based of course on existing stuff, but never an exact copy.

As I do want to offer the remake of the Minipops 7 as a ready to use module as well as a kit with pre-assembled SMD, I didn't want to make use of the physical inductors (as too much winding work) but decided to use negative impedances instead.

After analysing the schematics that are on the internet, I started simulating the circuits and then comparing with original music on youtube, etc...
Both the original and simulated sounds did sound very much alike, but sometimes different. I later discovered the main differences between the Minipops7 as used in JMJ's Equinox and the Univox 95.

As to make sure I was simulating the right circuits and comparing to the right sound, I decided to buy a Minipops7 which arrived a couple months ago. It now was possible to do a 1 on 1 comparisson not only by listening, but also by measuring and analysing.

Since the simulations made sense, I decided to start designing the stuff.

Below you will find a screen dump of a Minipops7 clone PCB, called MINI P7, I've been working on lately. (noise and preamp still to be implemented)
This is a complete analog machine for all of the audio. The processor on the right only contains the sequencer. It's format is choosen to be a look-alike of the original. Since this MINI P7 will come as a 3U 48HP module, there are no rear connections available, so the audio output and the pedal switch input will be placed on the module at the right side (will be updated shortly).

For this first version, I want to stick to the original as much as possible, thus without midi interface. I hope you understand.

Looking foreward for your reactions !

Looks sweet, definitely want to hear it!

...but if you are doing this eurorack you need clock and trigger inputs. Internal sequencer is nice but not necessary and neither is midi. As a standalone unit though, it looks great!
Dear ablearcher,

thanks for the feedback and thanks for valuing the work done.

For the first version I like to stick as much as possible to the original, but version two will come anyhow.
I'll take your advise for the triggers etc. with me when designing the update.

Some simulated sounds:
This is nostalgia !
Great project, keep going.

I had once the opportunity to play a Minipops in real. Amazing what they did with the in those days available components.
Do you mind to share some pictures?

Nice to see that you are using SMT to resurrect this almost forgotten darling.
cv and trigger ins please w00t

this is a great machine, looking forward to see your take on it SlayerBadger!
Very interested in a PCB. And yes, please provide a trigger input for each voice.
The original minipops contains 13 instruments with a total of 15 triggers.
That is 14 triggers and 1 on-off (CV) for the Guiro.

Instruments in the Minipops7.
Quijada, BassDrum, RimShot, Claves, Large Bongo, Small Bongo, Conga
CowBell, Cymbals 1, Cymbals 2, HiHat, Snare Drum 1, Snare Drum 2, Tambourine

If anyone else has the same kind of request as for the triggers and CV / clock etc...,
pls let me know, version 2 may arrive faster then expected if sufficient interest in the modif/expantion.

@ Fitchie: I will add a picture of the baught unit later today.
Would be in for a PCB or Kit. Love the Mini Pops sound!
This looks great! I'm in.
Picture of my recently acquired minipops7.
Arrived in mint condition.
This unit is not for sale.
the bad producer
I'd love a triggerable PCB version!
Fantastic work!

I’m interested in the possibility of a PCB with trigger inputs.
Can’t decide if I’d be more interested in a version with or without the built-in sequencer, though I’d hope the latter would be smaller, and the former might include a Clock In/Out and maybe a Start/Stop gate input.
The mounting holes are perfect for those of us who don’t build in the Eurorack format.
Any idea of how much a PCB might cost?
To be completed:
White Noise
Audio out connector
Start-Stop foot switch connector

All the rest is 100% routed and DfM-checked (0 violations)

Some Data:
smalest isolation 0.15 mm
smalest trace 0.2 mm
number of components so far 573
two layer PCB

Costs will depend on batch size as about 550 componets are SMD and will be placed by assembly robot (out-house subcontractor)

Initial debugging will be hand soldered
All standard R's and C's are 0603 (imperial)

Initial SCH and PCB design should be finished tomorrow Sunday evening.

Interested. Feel free to message me when ready. In case I miss the post
Cool project! But why are all the components so close to eachother? There is loads of space left on the board..!

Components are not so very close as it may look.
Still well solderable by hand (one does need experience), but this is designed for machine assembly.

The previous picture shows the component's Courtyard in green.
For DfM the courtyard should not overlap. The Courtyard is for these realtive small components rather big.

The picture below shows the real component sizes in orange.

Some technical background why I prefer to group stuff and keep everything as small (short) as possible.

Yes, there's lots of space on the board, though spreading the components would have a negative influence in HF coupling. Read µ-controller and other immunity problem causing sources. The smaller the structures, the higher the frequencies have to be to couple with. Now this is all HF, but HF does get demodulated in semiconductors causing unwanted audible disturbances.

I prefer this topic not to become a technical discussion in depth, but feel free to PM me if you want to talk more about technical stuff.

It sounds cool, but if it is in eurorack it needs at least trigger ins, individual audio outputs for each voice would be cool too.

Individual voices or a few of the voices on a smaller module would be interesting as well.
About the reference to Sequencer / Sync / Clock

I may have expressed myself wrong using the word Sequencer in my first post.
I ment, original Minipops7 Rhytms, selectable by means of the 10 buttons on the front and bank selectable between Red and Black rhythms.

For those requesting Sync and Clock,
Would you be able to provide a 1/16 or a 1/32 clock ?
So 16 clocks in a 4/4 measure using 16ths and 32 clock in a 4/4 measure using 32th.

The Minipops7 uses 16th notes and has some rhytms spread over two measures.
definitely interested!

I would also like to see trigger input. Yet best, in a modular system, to have the "sequencer" as a separate module that connects to the soundboard via r ribbon cable on the back -- such that you can use the rhythms of the sequencer also with other sounds (always fun) ... and you have the sounds with trigger inputs.

With a connection on the back, it can still be used as a stand-alone unit. Imho biggest mistake of the DrumDokta mk2 (DR-110) is to tie the sounds to the internal sequencer. This was a really poor decision and should not be repeated.

Actually, falafular once made a similar "sequencer" (no sounds) inspired by the CR8000:

Boogie wrote:

For those requesting Sync and Clock,
Would you be able to provide a 1/16 or a 1/32 clock ?
So 16 clocks in a 4/4 measure using 16ths and 32 clock in a 4/4 measure using 32th.

The Minipops7 uses 16th notes and has some rhytms spread over two measures.

I would give the option to either use 16th clock (which is more common), but then some of the 32th steps might be lost. Or a 24ppqn clock (DinSync) then all subdivisions can be done. Mutable Grids does it the same way: you can use a 16th clock, but then some substeps in the preset patterns are ignored. Or you use a 24ppqn clock, then all steps have correct timing. A 32th clock is very unusual.
SMD is not a problem for me. (as well as many others)

I'd be very interested in a PCB.
Interested here too.

More or less replicating the original in function with added clock in, individual voice input triggers and audio outs would seal it for me.
Hello all,

as mentioned in my first post, I wantefd to build a Minipops7 replica.
So without all the nice things which have been mentioned.

No worries for all wigglers looking for extra features,
while waiting to receive the boards for this first version, which I still want to order tonight, I'll start implementing most of your requests like sync, clock, midi and seperate trigger for each instrument.

I've done a TR808 clone for myself (900+ components) and added the analog outputs per instrument. It was quite a dissapointment when feeding most instruments via an effect board (with a VF-1). The only ones sounding good, adding 'volume' to the sound were BD and SD. So, I'm not yet convinced to add the analog outputs. Up to you guys to convince me.

Today I finished the first version which is the replica / clone of the Minipops7. Below are some more screen dumps of the design. (now V0.2)

During the next days I will work on the frontpanel, as for this replica, it will be made with 'gold' anodized aluminium using 'Front Panel Designer'.

For the 'expanded' version I will use black (dark gray) anodized aluminium with gray scale printing as I did for my TR808 clone.

@Boogie Nice work!

Out of curiosity - it seems there are almost 20 traces going from the mcu to read out the 10 white buttons... rather a lot of. More than this there seems to be 2 muxes. Are the buttons illuminated or of special function?

Any thoughts about open source this?
Hello Picard,


10 for the switches and 10 for the leds.

The original unit uses mechanical latched switches, so one sees wich one is selected.
Due to construction and financial reasons (switches turn out to be very expensive), I've choosen for Illuminated Tactile switches. The two chips you see are not multiplexers but led drivers.
The processor can only source/sink 8 mA.

The switch selected will light up.
As with the original, multiple rhythms selected at the same time can also be selected by holding down all rhythms one wants to select, and then release them. (as done in JMJ's equinoxe)

Altough the traces are pretty long, they will not have a negative influence on performance as they are static and only toggle when a switch gets pressed.

For the follow-up, with most of the requested features, the chips will be replaced by a transistor for each led, as I need the space to place the 3.5mm trigger, etc... jacks.

Sorry, but no open source for now.
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