Drum Pad Medeli DD315 Bug 2021, Alesis CompactKit 7, Ashton EPD 450, Pyle PTED01 - Page 1
Forum section: electronics / repair

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 04, 2020, 04:29:11 pm
content: Hi Guys,Question, if you own any of the models listed in the topic this bug may interest you.For those that don't, nothing to see here move on.Question. Would you expect, given you have two hands, holding two drums sticks, that every combination of the 7 pads + 2 foot pedals should make a sound if struck together?(Of course, mis-triggering is a problem but, what if it's not your accuracy but a design flaw, a very deceptive one)For those that are interested and care about the gear they use and love read on.Let me start by saying there has been some debate on an electronics repair forum about whether anyone cares, in other words these drum pads are cheep.You get what you pay for they do the job. But do they do the job and would you care if there was an issue? Especially if it effects playing ability and MIDI triggering.Some care. I care because I wan't to know if my electronic drum pad, I paid good money for has a design flaw and this limitation should be documented in the user manual. Not hidden from the user.You might also be especially interested, if you paid for theAlesis CompactKit 7. (The most expensive "premium" model) @ $325AUSWhy it matters is because you have been sold a product with, what I would call more than a serious design flaw, more like a blunder.It matters because Alesis has lowered it's once great standard in pro-audio gear.All these units have a serious bug. (Glitch, major trigger problem) Again, if you care read on.Another Question. but before I do, the reason I'm being somewhat cryptic about the problem is that I'm trying to gauge if this is worth my time pursuing with a Youtube video detailing the problem. I don't want to waste days of shooting and editing to explain the problem and find out no one gives a crap.Question. Would you expect, given you have two hands, holding two drums sticks, that every combination of the 7 pads + 2 foot pedals should make a sound if struck together?For me that is a resounding yes. Just like if you had an electronic piano, you would never have two keys that if played together not sound. You would say that's ridiculous.Well it would seem that Medeli thinks playing two pads at the same time is a revolutionary concept, one that is just unreasonably.It matters to me because of the following reasons.1. Does not affect Medeli DD 305. (This unit plays perfect.)2. Left handed drummers will have problems?3. Open Handed drumming technique is a problem.4. You cannot play simple Cha Cha, Latin patterns which is heavy on Toms and HH.5. You cannot use the unit as a reliable MIDI trigger because of unpredictable mis-triggering.6. That mis-triggering pad that didn't sound was not a mis-triggering pad it was the drum pad limitation.If you owned an oscilloscope the best you could afford, would you want to know if someone found a wandering bug?==================================================================Medeli Award DD 315 Bug 2021 (Video soon)Affects: Alesis CompactKit 7, Ashton EPD 450, Pyle PTED01, Medeli DD 315, Fame DD 350==================================================================Medeli DD 315 Bug 2021 Drum padI found this bug while playing tom side Latin drumming. HH (LH) + Toms (RH)Fault presents as follows. (How to test)@ approximately 120 Bpm or less it doesn't matter, faster, slower.Simultaneous strike the follow two drum pads.Open HH + R/Low Tom repeatedly on 8th notes. Tom LED does not light and crazy random mis-triggering.Still with 8th notes on Open HH move to Mid Tom, (always simultaneously) then back to the low Tom.You will see mis-triggering on the Toms to the point where they stop sounding at times.Suspect problematic when used as a MIDI controller. This unit is not for the left handed player. Even though you can program the snare (infact the whole kit) for left hand playing, the mis-triggering is chaotic, random, irregular. Might be cool if you want something random to come out but fails as a simple kit for studying Latin rhythm and open handed technique, without reprogramming the HH. The HH just mutes the toms when played simultaneously. The two sounds at random times can not sound together with regularity.The reliability is horrid in my opinion something you would never find in Yamaha nor Roland gear. Alesis?Medeli Award DD 315 Bug 2021 (Video soon)Affects: Alesis CompactKit 7, Ashton EPD 450, Pyle PTED01, Medeli DD 315, Fame DD 350

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 04, 2020, 07:18:20 pm
content: As I understand it, the problem is the unit will not produce Hi hats and Toms at the same time.You have made this very clear.It surely wouldn't take that much effort to record a few seconds of video on a phone to demonstrate this and post it on Youtube with the minimum of editing required, especially as there doesn't appear to be any other evidence to support your accusation.If the design mutually excludes Toms and Hi-Hats at the same time, then I would definitely say this is NOT fit for purpose, and you have every right to be angry about it.Maybe you should make that video.Edit: I'd like to see it - if this is true then this is indeed a monumental cock-up in the design department.Video here, starts at 38 seconds, where he demonstrates Hi Hat and Tom together.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 04, 2020, 07:42:31 pm
content: "Edit: I'd like to see it - if this is true then this is indeed a monumental cock-up in the design department."Thanks for the feedback.That is so encouragingI will make the video.This is not about complaining. It's about dicey practice! No mention in the manual.

author: KevinA
author_rank: Regular Contributor
timestamp: December 04, 2020, 08:52:12 pm
content: Quite a few years ago, my company had a sample Medeli drum module for evaluation. The big problem was that when you changed patch, you were treated to a mass of noise as the parameters reset.Despite quite a few E-mails to them, they could not understand the problem. It was only resolved when I sent them their schematic with a mute circuit added to it.So yes, it is quite possible a design error, a requirement they never considered.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 04, 2020, 10:18:11 pm
content: I was really surprised getting the schematics, although incomplete. I found that fact alone spoke volumes. I've never succeeded in getting schematics from China.I would love to know what's causing such a limitation. What's the big problem when you can make a piano with 88 keys no problem but Medeli struggle with 7?Interesting that they make keyboards.Again this is not complaining. Just sharing with the community.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 07, 2020, 01:31:53 am
content: Thanks AudioRepair,Can I quote you in video."...if this is true then this is indeed a monumental cock-up in the design department."Most are not seeing the gravity of this. I was playing my brand new out of the box unit yesterday and I'm thinking God this is the biggest turd. It even mis-triggers when you play the Snare and HH together.Medeli need a medal for their master piece.It should be called the Medeli award. "Medeli Award 2021"I wonder what Alesis think about this horrid drum pad? Did they know. I will ask for an official statement, I suspect they didn't even know.This really is the worst drum pad every designed. I would not even called it designed, more like rushed out the door.I am not complaining about this thing. I can get my money back, well on one of them.This thing is all shine but under the hood wow a mess. I found some rogue code by holding a button down on while powering up, trying to find the Firmware details.It read PoF. At first I thought, "same to you." what does that stand for PoF?I look at the previous model manual and find a reference. Shows they have no idea what they are doing over there in Medeli land.They are electronic hacks IHMO and coupled with KevinA dealings with the company, this seems to confirm that statement.I'm throwing this one back in China's face, they have no problem calling Australians chewing gum on a boot and more. . .They want the medal for being a super power, my video will make them look like buffoons.If anyone can add to this topic from a design perspective, I would be most grateful. Dave and I had an email conversation. He gets it but doesn't have the time. I get that. I have the schematic. (Part of?)Medeli Award 2021 video coming soon.Steve

author: Renate
author_rank: Super Contributor
timestamp: December 07, 2020, 01:13:17 pm
content: I'm no drummer and certainly couldn't hit two of anything simultaneously.You may have hit (so to speak) on something.I think you need to reduce this to a simple case (something that I could understand).I'm thinking, a pair of round car speakers lying on the pads to trigger them with a "whump".That way, you could cycle one pad, cycle the other pad, cycle both and adjust the timing, all the while looking at the MIDI output.(It would be easier to inject a signal into the piezos, but I think the manufacturer would be more easily convinced by something external.)OTOH, you could also jumper two piezos together or just switch one piezo to two detectors.It's hard to tell from a video you using two sticks what the time relationship is.This could easily be a software bug or just failing to understand that people want to hit two things at a time.I wouldn't put up with this (and I don't even know what cha-cha is).

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 08, 2020, 04:07:18 am
content: Hi Renate,You have posted some interesting thoughts."This could easily be a software bug" Do they look like this? >< the guys that have nothing better to do, then yes. (In my mind that's what software bugs look like)".....and I don't even know what cha-cha is"That's not a bad thing. Playing difficult rhythms, challenges you as a player. I pushes you to greater playing levels.You can still go legally busk totally Cha Cha alone. You might get arrested but hey a great story to tell your grandchildren.Thanks for the great comments.Steve H

author: Renate
author_rank: Super Contributor
timestamp: December 08, 2020, 01:33:16 pm
content: Ah, I finally Googled all these models and realized that they are all the same thing.I got involved in a discussion on MIDI keyboard latencies.I taped a piezo sensor to the top of a key, scoped that against a detector output on a USB analyzer.It was pretty consistently 5 mS, probably most of that the key debouncing.So this is happening consistently the same on both the built-in speakers and the USB MIDI output?I presume that there is only one processor and not [drum pad -> MIDI] [MIDI synth]?It can be tricky in software to figure out every possible combination of timing events.It might even be that your left hand is 1.5 mS slower than your right hand and nobody has ever properly seen/tested this.Is there even the possibility for a software update?How about some schematics or board photos?I'm not sure there is a good resolution to this.Edit: If someone wants to mail me a damaged/unused one of these units I'd look at it.I'm not sure about a good unit because a) You'd have to trust me, b) I'd have to send it back.Moreover, even if I discovered something, I wouldn't reverse-engineer the whole thing and write new software (presuming that's even possible).Edit^2: You know what? I think that this is intentional.With a single physical unit (vs physically separate pads) the mechanical crosstalk between the different piezo sensors is so bad that they just mask for some amount of time whenever a pad is hit.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 09, 2020, 05:17:13 am
content: Hi Renate,Again your input is invaluable. Thank you.I really want to answer some of your questions in more detail and I will later.You really sound like the person I need to have a look at this unit. (It's highly suspect!) So I will try to get a unit shipped to your work bench. Do you have a youtube channel please?Do I have the schematics?Yes, I got them in a 3 part instalment plan, the first of which I suspect is fake. To get the Service Manual was like going to the dentist to get a tooth pulled. You would think this is top secret"Classified Information"over inMedeli land.Roland respect their customers, those with a curious mind and a love for electronics. I don't have to beg Roland for Service Manuals. I have a relationship with them as I did once with Medeli until this dodgy thing showed up.You mentioned crosstalk problem because its all in the same case. This has been mentioned on one of the many drumming forums I have been posting on about this turd of a drum pad. However, I'm not buying the crosstalk sales BS. (I might be wrong, but something is seriously wrong with this unit)I will test the "Crosstalk" theory on my Yamaha DD-6.Again thanks, I will hunt around the internet and get a unit shipped to you.The problem here is this company has that many models on the market, no one can keep up. Medeli has saturated the market beyond belief with confusing names off shoot brands and more. They are good at pumping their rubbish out on a global scale. Too big to fail? Medeli are insulting the drumming community and ripping off hard working parents that pay for this rubbish.Thanks again.Zero_EgoUpdate effected models in the description.Seems Germany is being sold this turd on Amazon (Germany).Medeli Award Bug 2021 --------------->Fame DD 350Quote from user from Amazon Germany. . ."Good stuff for beginners and to get a feel of what it could be.After practising (not much to be honest)with a midi software,I started noticing theSnare drum misses beats(that I definitely hit, and it doesn't register)."Guten Tag Germany.Medeli Award 2021 documentary coming soon.SteveHow.Zero_Ego

author: Renate
author_rank: Super Contributor
timestamp: December 09, 2020, 01:19:37 pm
content: A demonstration of my drumming skills.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 10, 2020, 05:01:29 am
content: The sound of one stick drumming.You have me curious. That circuit looked interesting but it was so short.Nice one.Edit: I just remembered I can slow it down - youtube settings. We shall see.ThanksSome time later.I have never seen that material you are striking.I had to slow down the footage right down, haha, then I spotted the small white wires.What is that you are hitting? Cool!Update.Models affected. Amazon Australia, Amazon USAMedeli Award Bug 2021goes to. . . (drum roll). . . thePyle PTED01

author: Renate
author_rank: Super Contributor
timestamp: December 10, 2020, 12:33:55 pm
content: That's a piezo crystal. It came out of one of those little round black plastic beepersI needed a sensor for a sneaker project that I was working on.You know that it's a beeper because it has that third contact in the middle for feedback to the driving circuit.It's cheaper, easier, more efficient to make the disc oscillate at the mechanical resonance frequency than to feed it with something fixed.That's the one with the white wires, 22 mm.The other one with the red/black is 20 mm that I bought in a batch of three after that project and haven't used yet.They are inexpensive and available in 12 to 50 mm diameter.The most accurate way to handle piezos is with acharge amplifierI've no idea if drum makers do that or just a regular resistive feedback.The circuit in the demo was the simplest, both wires fed into two µC inputs with internal pullups.We're relying on the pullups and the input diodes to work.I'm not using it as velocity sensitive, only basic detection.There was somewhat of a point to the demo. I'm sending two drum hits in a single USB packet of 8 bytes.I was just checking to make sure that worked ok.I'll probably build my own "Flintstones" drum pad with two pads out of plywood/rubber.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 10, 2020, 03:52:26 pm
content: Quote from: Renate on December 10, 2020, 12:33:55 pmThis is Rolands circuit from the SPD-SX machine.Its a very good machine, many times more expensive then the Medeli and it works very well.

author: Renate
author_rank: Super Contributor
timestamp: December 10, 2020, 04:33:46 pm
content: Quote from: Audiorepair on December 10, 2020, 03:52:26 pmWow, that's very interesting and clever.It's not a charge amplifier because it has mostly resistive feedback.Looking at IC4, the top amplifier:D6, the output dual diode is interesting. It does two things.The first thing that it does is provide two separate outputs from the first stage, one with the positive half of the cycles, one with the negative half of the cycles.This is the first step to making a full wave bridge.The other thing it does is take the logarithm of the input.This converts the (presumably large) dynamic range of the input to something more linear.Nope, dunno what I was thinking.The 22 pFs do a bit of high frequency filtering.The D5, the input dual diodes are there to do a bit of clipping on the really big inputs.We then go to the right half of IC4 which is a normal peak detector using D7, another dual diode.But! It gets the two different outputs from the first stage into two different polarity inputs, so it's a full wave peak detector.I had presumed that everybody just standardized on a hit being positive polarity and you'd never have to deal with this.I guess that if you're a big company you have to deal with things being wired wrong.One of the things I wanted to check with my piezo is how different a tap from a slam is, what the dynamic range is.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 10, 2020, 07:37:50 pm
content: The predecessor to the SPD-SX, the SPD-S, had a simpler circuit.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 11, 2020, 06:06:26 am
content: Hi Renate and Audiorepair,I am really enjoying reading all your comments.Great reading professionals talk in their native tongue.It's a language all of its own, one that only you guys know how to speak. Anyone who over hears your conversation thinks "What you talkin' about Willis?". Esoteric tech talk, I have much to learn. A lot of it is way too advanced but I still love reading and studying the topics. Plus, it reignites my passion for electronics, double bonus!I especially love reading how you guys can analysis circuits just be reading schematics. Brilliant!Renate:I went back and had a look at your video. I eventually spotted the small round piezo under the material you were striking with the drum stick. {Didn’t spot it until you mentioned it above)Quote from: Renate on December 10, 2020, 12:33:55 pmIs that sneaker as in shoe? If so (haha) what are you doing? I love the idea piezo pickups in sneakers. Drum while you walk.“Want a drum roll, run fast.’ Sneakers that trigger drum beats in your earbuds as you exersize. . . where can I invest? $$$Quote from: Renate on December 10, 2020, 12:33:55 pmWow you don’t mess around.It would take me all day to comment on just one of your posts. Great stuff.Audiorepair:Quote from: Audiorepair on December 10, 2020, 03:52:26 pmIt’s interesting you mentioned the Roland SPD. I own one that has a minor fault in one of the stereo output audio channels. Either the left or the right channel (can’t remember off hand) has a definite lower signal level than the other.I would love to post the schematics and troubleshoot if you have the time.Can I PM you guys this manual. I would love to know your thoughts. (If you have time)Many thanks for the interesting read.Edit:I can substantiate my claim about theMedeli Award Bug DD 315 2021.Medeli Award 2021. Movie Coming soonIn Widescreen, 8K Dolby, Surround Sound.A story about a lonely drummer boy, obsessed with the Cha Cha.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 11, 2020, 08:23:11 am
content: Quote from: Zero_Ego on December 11, 2020, 06:06:26 amIf the headphone output is ok, this is most likely the electrolytic capacitors close to the output sockets.Sometimes it is the mute transistors also close to the outputs, particulalry if they are JFets.You can just remove these transitors for testing purposes, they are there to stop thumps etc at power up and down.(or maybe cut the leg connected to signal, so you can later resolder it back if it makes no difference)Yes, you can pm me the dodgy manual, never used the pm service here before.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 11, 2020, 09:46:27 am
content: Quote from: Audiorepair on December 11, 2020, 08:23:11 amThanks so much.You have motivated me to dust it off my Roland SPX 11. (I might have to get some help please troubleshooting)I formally studied electronics yet moved over to professional musician. Thanks to Covid, I don't have two cents but I have a mountain of gear to remind me of days before the big pandemic.I shall dust off my Roland SPX 11 and find the schematics.We all need hobbies.

author: Renate
author_rank: Super Contributor
timestamp: December 11, 2020, 01:11:48 pm
content: Quote from: Audiorepair on December 10, 2020, 07:37:50 pmIt's interesting that they hedged their bets by putting so many optional components on the board.The clipping circuit on this is more sophisticated with two separate clipping curve segments (from DA8, topmost dual diode).I was doing some more experimenting with piezos.I had one taped to my desk.A smart tap with the fingernail of a finger would actually cause a detectable "echo" to the original pulse as the shock pulse travelled down the desk, hit an open edge and reflected.Hmm, I think that I have to recheck that. I looked at the figures for speed of sound in plywood and something is fishy.I also could get a LED to light up (dimly) just by connecting the piezo directly to the LED.Yeah, the sneaker project. A friend was talking about a research project in the abstract.I'd rather build than talk, so I threw something together on the spot.A drum pad you only care about hits, but a sneaker you want to have good low frequency response, below 1 Hz.You certainly could make MIDI sneakers.That would work pretty cool if you were Fred Astaire.I'll just stick to foot pedals, of which I'm a big fan: triple transcription USB pedals, iRig Blueboards, single Bluetooth page turners.Part of the fun here is mixing it up with people with different experience.OTOH, you always live in fear of spouting out nonsense only to be challenged by the world's greatest authority on the subject!

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 11, 2020, 03:48:04 pm
content: Zero_Ego's SPD11, quite old now, is different again.Clearly they have evolved!

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 11, 2020, 03:55:33 pm
content: Zero_Ego, here's your output section.If the headphones are fine, there's not a lot it can be, really.

author: Renate
author_rank: Super Contributor
timestamp: December 11, 2020, 05:55:45 pm
content: I like your idea about the mute transistor, Audiorepair, especially if the audio is normal but low (instead of missing bass, like a bad cap).A good static zap on the output cable could take it out.It's interesting that the even older input circuit uses two transistors to do the same two stage soft clip as the newer one.(But it doesn't do the feedback AFTER the peak detector diode.)So how important is velocity sensitivity on a drum set?Not really, it won't kill me if all hits are the same volume.I really have to have at least two different levels, soft & loudIt isn't a real drum set unless I can control the volume over a range.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 11, 2020, 06:43:28 pm
content: Velocity sensitivity on a drum kit is aboslutely essential.I don't think you would actually find any without velocity sensitivity, other than embedded in a soft toy or a pair of shoes.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: December 11, 2020, 06:49:08 pm
content: Some professional pads have a centre sensor, and an edge sensor, so you can alter the blend of two different drum sounds depending on where on the pad you make your hit.

author: Renate
author_rank: Super Contributor
timestamp: December 11, 2020, 08:06:33 pm
content: I was trying some experiments and it seems a bit tricky to come up with a pad that has consistent response over a reasonable fraction of the area of a 6 inch or larger pad.

author: Zero_Ego
author_rank: Regular Contributor
timestamp: December 13, 2020, 03:54:19 am
content: I clearly cannot read a schematic.

author: Renate
author_rank: Super Contributor
timestamp: December 13, 2020, 12:01:30 pm
content: Aw, you'll get there.Like anything else it just takes a bit of practice.Just ask questions.

author: Renate
author_rank: Super Contributor
timestamp: December 19, 2020, 12:48:20 am
content: I've been trying to get sufficient area coverage for a drum pad. It's not easy.I saw an acoustic video of the Alesis setup and I was amazed how loud it is (without electricity).Looking around, I see that you can buy piezo film in large sizes (like 8.5" x 11") but it's expensive! ($150)With a top layer of rubber it would be a good way to come up with a drum pad that's as quiet as a practice pad.

author: jhong9287
author_rank: Newbie
timestamp: March 23, 2021, 02:49:48 am
content: need help.. my medeli drum has no power someone help me to figure out what is the problem.? someone give me schematics or circuit diagram.?