Later Drake 784-139 OT and 1202-164 PT quality? Very conflicting infos. Can some veterans chime in?

[LPman]

I find myself digging deeper and deeper into different Marshall rabbit holes. Conflicting infos galore. Most guys with expertise have been saying for years that good irons are the heart and soul of Marshall amps - you can replace caps for NOS Mustards, mod '68 plexi / '72 metal panel specs back and forth in RI amps with minimal solder work but starting with a set of quality irons is absolutely essential. That's why folks have been replacing even stock 2000s Dagnalls and Drakes in their RI Marshalls for Merrens, Marstrans, Heyboers and so on, right? At least this is what I've figured so far.

What about the late '80s - early '90s Drakes (784-139 OTs and 1202-164 PTs) like the one on the photo below? I was in the belief that these were still primo stuff, more or less in the ballpark of the real deal golden era material. To my surprise while digging for infos I've found a quote from some guy on gearpage who repairs amps that these are "absolutely the worst trannies ever made" because Drake "switched from traditional 'synthetic' enamel or Epoxy, which are excellent, to atoms thin 'self stripping enamel'."

This question is relevant to me - and for many others I suppose who are lifelong tone chasers in similar shoes - because I chose to buy an earliest edition 1987 RI for the very reason of having these original older Drake irons. So can you veteran members with plenty of experience and knowledge chime in to clarify the truth about these irons and the overall quality of UK Drakes throughout the years from the late 60s until the late 90s?

This is the Drake OT in question. This one is a '83 OT, mine is a '90 with the exact same sticker and exact same look. So what category these later UK Drakes fall in: trash / mediocre / acceptable / fine / superb (in comparison with both earlier UK Drakes and the later 2000s ones)? Appreciate for all who take their time to do a little deep diving.

 

[neikeel]

A lot said about OTs (transformers generally!) quite a bit of it is incorrect. We like the sound of saturated and stressed transformers for our distorted sounds and the late 60s/70s versions are made with relatively cheap steel for the laminations and do the job well. This steel has particular characteristics of inductance and losses
You will notice the bright steel on the laminations on the newer trasnformers. The typical material for most transformers is M6 grain oriented this differs in the quality/silicon content which affects the efficiency of the transformer, assuming winding geometry and overall construction is the same as well as plastic vs paper vs pressphan former for said windings.
I cannot comment on the quality of insulation on the windings of the new Drakes (you need an expert like Brian Wallace or Chris Merren or maybe self-winders like @william vogel to chip in. The really well made chunky iron made by people like Partridge have wider band width need much more push to get that saturated sound and are less favoured.
I guess the question for you is - do you like the sound?
I do try to collect old transformers for builds (maybe because I am cheap) as my impression is that the nearly always sound good but have also had very good results with Marstran and Merren (although my 65 JTM45 has an RI Dagnall in it that sounds better than any of my previous 45s it is staying in and I have been really tardy in getting the original rewound I am not selling the amp so no rush!).
I have had one truly duff experience with a no-name -139 clone that had bright lams, plastic bobbin (can't recall or comment on wire) but it sounded crap, both back to back with the original 89 Drake 389 and the Merc mag reissue which in turn was too clean and spiky vs a Metro clone.
Afraid you are going to have to go with your ears and feel on this one!

 

[Marcomel79]

I guess the question for you is - do you like the sound?

This. The rest is irrelevant

 

[william vogel]

I can’t tell you if yours is better/worse than the old ones. The picture you provided is a /3. That is apparently a version 3. I haven’t had the opportunity to dissect one of those. It probably uses a more modern steel but I have no idea.

 

[Pete Farrington]

I wonder when the /3 version was introduced?
I suspect that the version number will go up with each amendment to the spec.
And that the lower rated, solder through insulation winding wire J M Fahey discovered may have been specific to JCM900 range.
So if the /3 version appearsd some time prior to the 90s, it may still use the highest rated, motor grade wire.
Whereas if its introduction coincides with that of the JCM900 range, then it seems more likely that /3 spec may may include the lower rated wire.

 

[dman8372]

@LPman - don't worry, I am right down in that rabbit hole with you! After picking up a perfectly sized but shorted vintage choke for a 50W build I've been investigating rewinding, which rather rapidly ended up with me considering winding an OT and maybe even a PT (although the insulation testing is a bit of a concern with PTs). Then the study begins - I've read the RDH4, Wolperts, Babani and countless online info and videos and I reckon I have way more than enough info to design and build a decent working trafo (at least after a few prototypes!!). BUT the secret sauce is in the core material and the fact as @neikeel mentions above, a saturated core is actually part of the desired sound. The hi-fi crowd are after THD as low as possible, so they are chasing a different animal to most of us here so most of what they are up to is not relevant. And these days the base silicon steel that we can get our hands on is probably much better than the best steels used in the 50/60's. I've also seen so much conflicting information on what spec the material was in early Drakes/Dagnalls/RS that I would not know what to believe. And as many people point out, even if we did know would we be able to source that material now?

 

[79 2203]

There’s a 68 50 watt Plexi for sale locally that the seller says is all original and is asking huge money for(AU$14000)
But the OT has the Drake sticker with 784-139/7. What year did the version 7 come out ??

 

[playloud]

There’s a 68 50 watt Plexi for sale locally that the seller says is all original and is asking huge money for(AU$14000)
But the OT has the Drake sticker with 784-139/7. What year did the version 7 come out ??

Late 80s? You see that version in the Silver Jubilees (1987):

(Edit: added OT pic)

That seller sounds like a real dreamer!

BUT the secret sauce is in the core material and the fact as @neikeel mentions above, a saturated core is actually part of the desired sound. The hi-fi crowd are after THD as low as possible, so they are chasing a different animal to most of us here so most of what they are up to is not relevant. And these days the base silicon steel that we can get our hands on is probably much better than the best steels used in the 50/60's. I've also seen so much conflicting information on what spec the material was in early Drakes/Dagnalls/RS that I would not know what to believe. And as many people point out, even if we did know would we be able to source that material now?

As you say, there is conflicting info about which grade of steel was used by which manufacturer. Dagnall certainly used M6 and I'm not convinced that was different to the M6 you can buy today (I know some on the internet have claimed the modern stuff is "better" but it doesn't really make sense). Drake may well have used unoriented steel.

I know one transformer winder who says that the UK was much faster to adopt cost-cutting measures (plastic bobbins, poly tape etc.), so you see a consistent deterioration in quality in the 70s. Certainly you can see that between the Dagnall C1998 and C2668 (introduced in '71). I don't know about the 784-139s - you'd have to tear them down to tell.

 

[dman8372]

There’s a 68 50 watt Plexi for sale locally that the seller says is all original and is asking huge money for(AU$14000)
But the OT has the Drake sticker with 784-139/7. What year did the version 7 come out ??

I think the code on the side looks like Aug 87 to my eyes - and yes for $14k I would want the original OT to be included!

 

[79 2203]

I think the code on the side looks like Aug 87 to my eyes - and yes for $14k I would want the original OT to be included!

View attachment 154191

Yeah it’s a ridiculous and apparently he’s been told it’s a replacement but insists on the price. Personally, I think it’s too much even if it was a fully original amp. I think AU$11k is realistic these days. Can’t see one with a replaced OT going for much over AU$6k

 

[playloud]

Yeah it’s a ridiculous and apparently he’s been told it’s a replacement but insists on the price. Personally, I think it’s too much even if it was a fully original amp. I think AU$11k is realistic these days. Can’t see one with a replaced OT going for much over AU$6k

I'm assuming it's this one? Definitely a bit of a joker! https://reverb.com/item/81934227-marshall-jmp50-plexi-collector-grade-1968

$11k would be high, even with original iron. There was a 1987T from this era that sold on Reverb a couple of days ago. It was listed just under US$5k and the buyer accepted an offer (so presumably closer to 4k). Probably a more realistic idea of price.

 

[79 2203]

I'm assuming it's this one? Definitely a bit of a joker! https://reverb.com/item/81934227-marshall-jmp50-plexi-collector-grade-1968

$11k would be high, even with original iron. There was a 1987T from this era that sold on Reverb a couple of days ago. It was listed just under US$5k and the buyer accepted an offer (so presumably closer to 4k). Probably a more realistic idea of price.

Yeah that’s the one. Only about 20 minutes from my place too. He’s got a lot of other gear listed and most of it sky high like an 82 SG for AU$10k.
US$5k is a great price for a Plexi 1987.

 

[dman8372]

@playloud I'm actually researching the 784-103 which is even more punishing. If anyone has any info it would be much appreciated!

 

[neikeel]

@playloud I'm actually researching the 784-103 which is even more punishing. If anyone has any info it would be much appreciated!

Don’t forget the 784-74 which was the first JTM45 OT from Drake (4,8 and 16ohm with selector on end bell). Introduced in mid 65 and used in the first dual OT 45/100s.
The 784-103 was plain end bells and 8, 16 and 100v taps. So typically selector on chassis.

 

[dman8372]

Thanks Neikeel, yes I was aiming for '66 spec with my build and whilst I'm not looking to build a 'heritage replica' clone, I want to stay as true to spec on the main components such as the OT and will be using KT66's. Plain end bells is much easier to replicate. I've now found a bit more on the specs on the RS OT so I may head more in that direction now (or give up chasing unicorns entirely and just build the damn thing!).

 

[Pete Farrington]

I was aiming for '66 spec with my build

Were RS DeLuxe OTs still being used in '66?

I've now found a bit more on the specs on the RS OT

The RS DeLuxe OT is something of a singularity in valve guitar amps, with its lowish power rating, multi tapped primary and 3 section secondary, I'm not aware that any exact replics are available off the shelf.
Michael at Modulus has good stuff, so this may be a good option, especially for a 6k6 primary https://modulusamplification.com/jtm45-output-transformer---based-on-rs-deluxe-3137-p.asp

 

[neikeel]

Last Marshall I’m aware of with RS deluxe would be the gold block logo amps mid 65

 

[LoudStroud]

Adding my opinion of old vs new... I lean towards old. But even my friend's '69 Small box lead 50 with a replacement '86 Canadian export Drake OT (only has 8 &16 taps) sounds really damn good.