Vintage hardware emulation legality - Page 1
Forum section: electronics / general

author: gordano
author_rank: Newbie
timestamp: January 27, 2019, 07:02:21 pm
content: Hi,I had the idea for a while that cool long term project would be to try and emulate "80's vintage" synthesizers with an fpga, hopefully reverse engineering them to the point where they could be faithful clones. Examples of these early digital synthesizers would be the Roland D-50 or Yamaha tx81z. The idea would be the same as fpga clones of vintage gaming hardware, but in this case for old digital synthesizers.Would this go against some kind of licence or other legal protection for intellectual property? I'm sure it's not a simple thing to answer, but I was wondering if anyone knows of what or any restrictions there are on a project like this.Thanks

author: tsman
author_rank: Frequent Contributor
timestamp: January 27, 2019, 07:17:42 pm
content: You shouldn't have any problems with the actual hardware but you'll have issues distributing the necessary ROMs. Replacing them with a clean reimplementation is going to be a lot of work and you'll have to be careful as it'll change the sound output as well. It'll probably need to be something like MAME where the end user has to provide the missing ROMs.

author: gordano
author_rank: Newbie
timestamp: January 31, 2019, 10:29:51 pm
content: I see, it makes sense that the most faithful reverse engineering would be a ROM dump, in which case I guess you would be in the shady territory of having users "find" roms.

author: james_s
author_rank: Super Contributor
timestamp: February 01, 2019, 06:58:04 am
content: With anything that has a ROM, there's no way around dumping that ROM and using it if you want 100% faithful reproduction.Fortunately most people don't care about the legality aspect, IMHO if nobody is selling it anymore then it's fair game to get it through other methods and I don't feel even a little bit bad about doing so.

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: February 01, 2019, 04:33:59 pm
content: Quote from: gordano on January 27, 2019, 07:02:21 pmBehringer keep releasing clones without problem. Model D (Minimoog), MS-101 (Roland SH-101 clone), VC-340 (Roland Vp-330 clone), RD-808 (Roland TR-808 clone), Pro-One (Sequential Circuits Pro-One clone), and a ARP Odyssey clone.

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 01, 2019, 04:41:00 pm
content: Quote from: BloodyCactus on February 01, 2019, 04:33:59 pmIs is known whether or not they worked with the original manufacturers of those devices?

author: tsman
author_rank: Frequent Contributor
timestamp: February 01, 2019, 05:12:59 pm
content: Quote from: BloodyCactus on February 01, 2019, 04:33:59 pmThey're all analog synths so no ROMs unlike the Roland D-50 or Yamaha TX81Z that gordano mentions.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: February 01, 2019, 05:14:25 pm
content: They are going to build a TR909 also, they have rom for the metal section.The legal way would be : sample the outputs of the synth, make your own ROM with that.I would throw in the original ROM data, sue me.

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: February 01, 2019, 05:21:10 pm
content: well Roland never cared about MUNT, the MT32 emulator (you have to bring your own roms tho). The MT32 LA engine was a subset I think of the D-50 engine. MUNT might be a good place to start with the LA synthesis if your going D50.

author: tsman
author_rank: Frequent Contributor
timestamp: February 01, 2019, 05:39:12 pm
content: Quote from: BloodyCactus on February 01, 2019, 05:21:10 pmNo. They definitely did care about that. Roland sent out a C&D for Munt years ago. AFAIK it was resolved in the end because Roland didn't register copyright of the ROMs correctly which was a requirement back then.

author: nctnico
author_rank: Super Contributor
timestamp: February 01, 2019, 05:41:45 pm
content: Quote from: gordano on January 27, 2019, 07:02:21 pmWhy would you want to use FPGA hardware if a PC has enough grunt to do the well. AFAIK the formulas used for the sound generation of the TX81z (IIRC 4 DX7s in one box) are well described.

author: helius
author_rank: Super Contributor
timestamp: February 01, 2019, 05:52:54 pm
content: The TX81Z is a OPZ based synthesizer, related to the OPL chips used in soundcards. It is nothing like a DX7.The TX816 was the unit with up to 8 DX7-like units in a box.

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 01, 2019, 07:29:33 pm
content: Quote from: nctnico on February 01, 2019, 05:41:45 pmTrue. It may even be possible to do this on a simple MCU. A Cortex-M4 @200Mhz will allow you to implement a lot of those old synthesizers IMO.Of course a PC is more than able to do this, it can probably emulate a few tens of D-50 at once if well written. The harder part is always to do that glitch-free and with minimal latency (if you intend on making it playable in real-time) on non-real-time OS's. Definitely possible but not trivial.

author: gordano
author_rank: Newbie
timestamp: February 01, 2019, 09:15:54 pm
content: It's definitely true that an fpga isn't really necessary to emulate the device, but in my mind attempting to clone the circuit, especially the actual converters, seemed like it would capture more of the genuine sound with crosstalk in the case of the tx81z etc. I had the impression that software emulation often does a bad job at this, recreating the algorithms faithfully but missing some of the incidental sound that come from the actual hardware. I suppose you could emulate those things closely so it could be some bias towards the appeal of emulating hardware devices with an fpga.

author: gordano
author_rank: Newbie
timestamp: February 01, 2019, 09:18:04 pm
content: Quote from: tsman on February 01, 2019, 05:39:12 pmThat's very interesing, I hadn't heard of MUNT. There is an fpga emulation of an OPL chip here:https://github.com/gtaylormb/opl3_fpga

author: donotdespisethesnake
author_rank: Super Contributor
timestamp: February 02, 2019, 08:52:18 am
content: Quote from: Jan Audio on February 01, 2019, 05:14:25 pmNo, if the original sounds constitute a copyrighted work, then copying them wholesale is an infringement, regardless of whether you do it at the bit level or resampling.

author: Rerouter
author_rank: Super Contributor
timestamp: February 02, 2019, 09:24:02 am
content: Emulation with a rom would be a problem if it still has an active copyright (was hit by a cease and desist by a test gear manufacturer for uploading a rom, never mind the product stopped being sold in 1987, and the company moved to another field a year later)recreating the filters / effects in your own hardware without using recordings the original product should be fine,Reusing the company and product names may cause strife with trademarks

author: helius
author_rank: Super Contributor
timestamp: February 02, 2019, 09:31:07 am
content: IANAL, but for strictly FM machines like the DX7 or TX81Z, there are no samples, only pure waveforms like sine and sawtooth, which are not copyrightable. It is possible to exactly reproduce their behavior without any of the copyrighted ROM code, if a sufficiently precise specification is made. This is the textbook case for cleanroom engineering.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: February 02, 2019, 02:39:47 pm
content: Quote from: donotdespisethesnake on February 02, 2019, 08:52:18 amIts an instrument you payd for to sample the outputs, all sounds at the output is your property.

author: tsman
author_rank: Frequent Contributor
timestamp: February 02, 2019, 03:05:21 pm
content: Quote from: Jan Audio on February 02, 2019, 02:39:47 pmNo. You can't just rerecord the samples to make your own synth.Roland sued because DREAM recorded the output of a SoundCanvas to make their own ROM.QuoteThere was anundisclosed settlement. DREAM ended up recreating it all from scratch with their own samples instead of presumably paying royalties to Roland.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: February 02, 2019, 03:38:03 pm
content: Just give empty ROM, let the end user be able to fill it with the original sounds.

author: beyon
author_rank: Newbie
timestamp: February 03, 2019, 09:44:28 am
content: QuoteIf you want to be anal they are not pure waveforms, the FM ICs are digital and uses lookup tables for waveform generation. So for true emulation you need to replicate the actual lookup-tables and digital logic but I guess you are right in that they wouldn't be copyrightable.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: February 03, 2019, 01:31:26 pm
content: Maybe you can clone Korg without getting sued.Roland sure is a company that does everything for money.

author: gordano
author_rank: Newbie
timestamp: February 03, 2019, 10:48:38 pm
content: Quote from: beyon on February 03, 2019, 09:44:28 amRoland recently released a clone of their own D-50, so they probably would want to protect it. Likely true for the Korg M1 as well, but there are less popular digital synths from that era as well like ones from Kawai, but I am most interested in the Tx81z, and it's particular implementation quirks. I read some of the details about it's hardware and tricks it uses with it's lookup table in this quote:"TECH CPU HD63803XP Hitachi manages 8 voices polyphony- DAC is based on a IC YM3012. Main IC chip YM2414B features 4 OP + 8 combinations - unlike DX7 synthesis based on a 6 operators system with just pure sinewave and 32 combinations algorithms.Internal ROM contains a stored digital half sinewave on a lookup table that can be read in different way and speed, creating 7 harmonics sinewaves variations with partials overtones and fundamentals fixed settings"It would be a pretty interesting target for reverse engineering.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: February 04, 2019, 04:47:46 pm
content: You can buy these Yamaha operator chips in china on ebay.btw : i made a Yamaha DX in MCU, simplest synth ever.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: February 08, 2019, 03:36:57 pm
content: Looks like they sueing behringer for the 808 now.

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: February 11, 2019, 03:35:45 pm
content: well roland have just registered design trademarks for 808/303 etc. just means behringer cant make it look like a copy of the roland gear. not that they are being sued for copying the 808 (which preproduction models look exactly like the roland, so they just have to make tweaks)