TG Diagrams

[chrisregent]

I have started to draw TG12345 Mk2 circuit diagrams for public consumption, these are for repair or DIY use.

There are PDF's but also the actual DipTrace files.

Start with the Master Data document for all the information as it comes.

https://drive.google.com/drive/folders/12HOTedl4DBSBVCiZ04xIjiNPonGZNHBz?usp=sharing

I cannot share any of the original drawings or text so don't ask for them.

So we have diagrams for:
Type A
Type B
Type C
Type D (Mic Pre)
Type E
Type F - Filter
Type G
Type K
Type P
Type R - Output amp
Type X - Presence EQ
Type Z - Bass EQ
Zener Limiter

 

[gyraf]

A major task, documenting these - but makes service and repair a lot simpler for many users now and in the future..

Thank you, appreciated.

/Jakob E.

 

[chrisregent]

You are welcome Jakob!
I wish I could just scan the service manual as a pdf and go "here's the service manual for the TG12345 Mk2" sadly its not possible.

The other thing that is very important to me is serviceability and transparency of manufacturers.

I am doing something similar for the AMS DMX and RMX units, There is a lot of mystery surrounding them that there doesn't need to be. As I now service and repair many of them including making new PCB's I do think the more people that have the data they need the more these things can be made to last without high costs.

 

[wlinart]

Thank you for drawing it! Real nice work.
The manual without schematics was already online since a long time, together with your schematics it's a lot easier to understand.
https://archive.org/details/heamtg12345mk2/mode/2up

 

[madswitcher]

I have started to draw TG12345 Mk2 circuit diagrams for public consumption, these are for repair or DIY use.
Please be aware that some of the data in the manual is left open to the interpretation of text so some of this may have to be altered.
There are PDF's but also the actual DipTrace files.

Start with the Master Data document for all the information as it comes.

https://drive.google.com/drive/folders/12HOTedl4DBSBVCiZ04xIjiNPonGZNHBz?usp=sharing

I cannot share any of the original drawings or text so don't ask for them.

I would ask you to kindly reconsider publishing these, even if you reverse engineer them for your own use.  Because:

(a) they relate to rare and expensive items with unique history and provenance and intellectual property

(b) you may be compromising the income and livelihood of small businesses that have legitimately obtained the originals and who run a business servicing such equipment,  allowing any Tom, Dick or Harry to set themselves up as a 'TG repairman'.  From what you say, this may also include yourself

(c) Despite your stated intent, you may find yourself at the end of a 'Cease and desist' letter as at least one of the members here has been.

(d) I think that it will not help your own reputation as one who helps preserve intellectual property.

Kind regards

Mike

 

[abbey road d enfer]

(a) they relate to rare and expensive items with unique history and provenance and intellectual property

The intellectual property should be covered by patents, that would prevent using the principles that are patented. I doubt the patents are still running.
The schematics may be copyrighted, but nothing prevents anyone redrawing them and offering them for free.

(b) you may be compromising the income and livelihood of small businesses that have legitimately obtained the originals and who run a business servicing such equipment,

Nothing can prevent anyone figuring out the operation of a product he owns (or is commissioned by the owner to) in order to repair it. Neithet for building a clone, as long as it's not commercialised. Actually, manufacturers that don't divulge their schemos are at fault in many countries.

(c) Despite your stated intent, you may find yourself at the end of a 'Cease and desist' letter as at least one of the members here has been.

That's what companies do, threaten but seldom have a legal basis to do so. Considering these products are out of production for about 50 years, I don't think they have a leg to stand on. What prejudice could they prove?

(d) I think that it will not help your own reputation as one who helps preserve intellectual property.

To me, it seems the OP is not trying to gain from this IP, he allegedly offers these schemo for helping ohers to understand and fix relevant equipment.

DISCLAIMER: I'm not a lawier, but when I see how Behringer got off the hook after having blatantly copied the patented designs and copyrighted documentations of dbx and Aphex...

 

[chrisregent]

I did seek legal advice before going ahead with this.

Everything that has been said on this matter has been said quite eloquently in the above post.

The circuits are not held under patent to my knowledge, especially, as attempting to patent a transistor as an amplifier might be a little difficult... And there really isn't anything unique about the diagrams in question.

I will also point out that these drawings are my copyright and property.

The publication of circuit diagrams is highly unlikely to impact the sales of manufacturers (or manufacturer) especially as the console in question hasn't been manufactured for the last 50 years. It has been well discussed here before that most people that DIY projects wouldn't be customers anyway. I would also add that making it difficult to repair things is starting to become highly frowned upon.

My work and my products will always have circuit diagrams published with no attempt to hide what I have designed not only because I'm quite aware that if someone wants to work out a circuit, they will, but also because as someone that spends their time repairing things I appreciate a circuit diagram.

I also don't appreciate the threat, and it wont go down well as I believe my reputation for public transparency will be quite persistent.

 

[madswitcher]

Hi again Chrisregent,

The fact that you ought legal advice may be good – I don’t know as I am not a copyright lawyer either – I am just passing on what has happened in the past when other members have published similar material.

The fact that EMI limit the distribution of such material implies that they hold them to be proprietary information despite what other people think.  I think you also have a sensitivity in that you say that you will not publish the original manuals

If you publish circuit diagrams of all your products that is your decision, but the point made by the Moderator of manufacturers not publishing their schematic does not apply to this situation as we talking about a very small number of recording and mastering consoles that were manufactured purely for in-house use and not as commercial products.

Also, the Moderator was a bit too quick in their response: I did not state that your publication would impact the likes of EMI.  However, it may, impact the likes of TGMixers amongst other, who are ex-EMI engineers with legitimate copies of EMI documentation, and who have small businesses in servicing the TG line as well as the REDD series.  If you re-read my comment, I also included yourself as being someone who may be impacted and not as ‘Being a Tom, Dick or Harry’.

There is a mismatch in opinions.  I have asked you to kindly reconsider for what I considered to be valid reasons and because I have a sensitivity in that area - you have declined – not a problem – the world goes on.  Incidentally I did not mean any threat to your reputation by what I stated.

Kind regards

Mike

 

[abbey road d enfer]

The fact that EMI limit the distribution of such material implies that they hold them to be proprietary information despite what other people think.

They may well, but there's no legal foundation in them feeling cheated.
Just a fact of life. A man can feel cheated if someone runs away with his wife, but he cannot claim damages.

I did not state that your publication would impact the likes of EMI.  However, it may, impact the likes of TGMixers amongst other, who are ex-EMI engineers with legitimate copies of EMI documentation, and who have small businesses in servicing the TG line as well as the REDD series.

So you would consider normal these people take advantage of insider knowledge and deny others valuable information? Seems a little shabby to me...
I'd be curious to know how many people make a living servicing TG mixers...

 

[chrisregent]

Hi Mike,
If the manual was out of the 70 year copyright time, I would have it scanned and on the web, that is the only reason it is not. Law regarding electronics design is well understood and apart from bullying behaviour they are no legal grounds to prevent the availability of any circuit diagrams. That includes diagrams of patented circuits as long as you own the drawing. I could even manufacture copies, however I couldn't give them the same name (not that I would do either).

Just because people have access to circuit diagrams, does not mean that they can or will fix something, it also doesn't mean they will get the job to fix something. Look at all the "expert" tech's that are out there they all still have their jobs despite this and are very well paid for their knowledge, not for holding a diagram. Neve, API, SSL to name but a fraction of the circuits all being in the public forum and being more valuable that the TG circuits in reality.
I highly doubt that Mark is going to go, "oh look I've got the circuit diagrams I might try and fix that faulty mic pre in my TG12345" put down his guitar and pick up a soldering iron... No, a known expert will such as Brian who can go straight to the board with the fault and fix it in 10 minutes which was needed in working studios. (not that there ever would be a fault on mark's equipment, that place is immaculate) In fact I would surmise that their jobs are more secure than that of Mr Neve repair man or Mr SSL repair man because of the privileged ownership of the equipment in question and the protective environment around it. You wouldn't take a pedigree racehorse to the local vet or a DB5 to the local garage for a rebuild.

I also take issue because if I didn't have circuit diagrams available I wouldn't (or at least it would be far slower and more costly for my clients) be repairing equipment today and at the level that I do. So in the same breath you are stating that all the people that were around at the beginning should keep a monopoly on their jobs and that I and other people should go and sweep the roads.

I got a service manual out of a manufacturer after them saying they wouldn't release it because of "protecting their design" I dew out the electronics and sent them their diagram saying if "i wanted to copy it i would, without your manual"

Maybe people are worried that everyone will realise that the mixer isn't really anything special underneath the knobs and its just that it happened to be in a very famous and popular studio for the top bands that happened to record hit records.

Anyway, this thread is about engineering and the circuit diagrams that are being presented.

Uploaded now are the output stage, Bass control and the bandpass filter too that is integral to the sound of the console. I will put up some of the buffers and the mix amp and call it a day for now because other amplifiers are all essentially variations on a theme.

I'm intrigued by the Sowter listings of TG transformers that you can buy, I wonder if they were specified by Brian or Mike for a repair or custom job and how correct they are...

 

[Bo Deadly]

(b) you may be compromising the income and livelihood of small businesses that have legitimately obtained the originals and who run a business servicing such equipment,  allowing any Tom, Dick or Harry to set themselves up as a 'TG repairman'.  From what you say, this may also include yourself

I have to doubt that anyone is making much money as a 'TG repairman'. Not with everything being 98% digital and certainly not by hoarding 50 year old product manuals and schems.

If the circuits are of any real interest to anyone, then I think more business would be generated by releasing the full schematics and manuals and promoting "EMI" as a legendary brand and actually encouraging companies to create channel strips and compressors and such. There's a LOT more value in that to more people than what little there is in fixing the few remaining consoles that even fewer people actually use.

 

[Squeaky]

I'm not trying to provide any legal advice here but I thought I would point a couple of things out that might be of use.

Patent IP. The patent system is (supposed to be) set up as a quid pro quo between disclosing your idea and obtaining a monopoly. The notion of the monopoly is actually cast in a negative sense, that is, you don't have a right to exploit, you have the right to prohibit other from exploiting. The disclosure of your invention is meant to allow for others to innovate. That is why there are such things as "best method" provisions and concepts like "sufficiency". The main point being that the invention enters into the public domain. There are even provisions (to be consider on a jurisdiction by jurisdiction basis) for experimental use. Patents have a maximum 20 yr life span. The patent system is highly unlikely to be relevant here (at least as far as historical drawings go).

Patent IP is different to a trade secret type IP for which there are no "registered rights". However, if you are bound by a confidentiality agreement, and you disclose something that you should have reasonably understood to be confidential under that agreement, then you may be in breach of that agreement. Similarly, if you received information from someone who was bound by a confidentiality agreement, then there may be repercussions for that person based on their disclosure to you. Depends on the wording of the agreement. Confidentiality agreements should be taken very seriously and I believe it is unethical to mistreat confidence.

Finally I make mention of Trade marks. Trade marks may be (but not always) in the form of a registered right. If you were to build a TG-type amplifier, put an EMI logo on the front (without approval), and offer it for sale, then that might not be considered very ethical at all. I would argue that you should avoid using brand names like Neve, Helios, API, or the like, on your own DIY builds, even if these builds are never intended to be used commercially, but that is just a personal opinion.

I agree with the OP about serviceability and transparency of manufacturers. I have had problems in this regard (transistors being (intentionally) unidentifiable so replacement very difficult after failure).

 

[leadbreath]

Hi Chris Regent,

Salute to you sir for posting this , think in the long term it will be invaluable to have these saved on the web for future reference...

As for the Sowter transformers, these were built on request for me (Checkout Hayes Middlesex pre/channel)  using the original schematics which I supplied to Brian Sowter. Strangely enough he included the schematic diagram on his website but its no longer on there, wonder if he got a "Cease and desist" letter from these assholes... ;D

Much appreciated.
Mick

 

[gyraf]

As these designs are not current-production by the original manufacturer, I see no real reason to keep the information and technology under a smokescreen

The only benefit there could be from keeping this information secret would be to install those designs with the "angel-dust of the unknown" - and even though this dust is applied heavily in marketing of recent-made clones, I really don't think it morally deserves protection by obscurity

/Jakob E.

 

[chrisregent]

As for the Sowter transformers, these were built on request for me (Checkout Hayes Middlesex pre/channel)  using the original schematics which I supplied to Brian Sowter. Strangely enough he included the schematic diagram on his website but its no longer on there, wonder if he got a "Cease and desist" letter from these assholes... ;D

Much appreciated.
Mick

That's really interesting, does the mic input have the three additional taps on the secondary?

As these designs are not current-production by the original manufacturer, I see no real reason to keep the information and technology under a smokescreen
/Jakob E.

Well there is no smoke screen for the console anymore!

 

[leadbreath]

Hi,

From the Sowter website:
[quote Recording quality microphone transformer designed for this excellent amplifier originally used by the Beatles at Abbey Road. Ratio 1:3.16 with -5 dB, -10 dB and -15 dB secondary taps/quote]

 

[warpie]

Good luck ordering from Sowter though... Unless they have it in stock, it'll take ages.

 

[chrisregent]

Good luck ordering from Sowter though... Unless they have it in stock, it'll take ages.

They are speeding up, my last order took 25 weeks but the latest batch has come through much faster.
The handover to Carnhill wasn't luckily timed with the virus.

Hi,

From the Sowter website:
[quote Recording quality microphone transformer designed for this excellent amplifier originally used by the Beatles at Abbey Road. Ratio 1:3.16 with -5 dB, -10 dB and -15 dB secondary taps/quote]

I completely missed that because it wasn't on the page i was looking at.

 

[rp]

Thanks chrisregent for posting these! I'm looking forward to learning from reading them.

Regarding the conflict of interest in posting the schemos, I'm having a hard time imagining this hurting the "TG repairman" industry. I'd guess that those who own a TG can probably also afford to pay someone else to maintain it, and will continue to do so. And those who are experts at repairing them will continue to be sought out.

 

[Winston OBoogie]

Hi,

From the Sowter website:
[quote Recording quality microphone transformer designed for this excellent amplifier originally used by the Beatles at Abbey Road. Ratio 1:3.16 with -5 dB, -10 dB and -15 dB secondary taps/quote]

Those attenuating taps were a very good design choice by Mike Bachelor too, makes for a consistently quiet mic amp at all settings. 
It's interesting that, to the best of my knowledge, none of the iterations of the official TG 'clones' do it that way.  Unless it's recently changed, they utilize a Carnhill 10468 and the Neve attenuator on the secondary.

I'd go for the Sowter.