Choosing transformers: is mercury magnetics a snake oil scheme?

[pdf64]

I was surprised by the tonal difference too; for the MM just pipped the Weber, it seemed to have pleasing mid range resonance, whereas yes, the Triode was noticeably less appealing than either.
I wish he'd checked / reported on the winding ratios.

[Helmholtz]

Interesting test!

I definitely liked the neck PU sound best with #2 (Triode).

[Chuck H]

So!!! That's three votes so far and three different choices See? Subjective. But we all know the drill when choosing a speaker for a given amp. Four hundred dollars later you might have the best one. You have certainly chosen your favorite of the three you purchased I guess now we need to do this with output transformers too

[pdf64]

I absolutely DO But it isn't just for hum. Most of the (production) cascade preamps that employ a partial bypass first gain stage are also employing DC filaments now. I recently did some ear testing before changing one of my long standing designs. This amp does NOT suffer from any filament related hum. I arranged a 4pdt switch with a 3.3uf bypass cap, a 22uf bypass cap and associated circuitry to "correct" the frequency content after decoupling. I tried several different 12ax7's in the first position just to rule out the probability of a noisy tube influencing the test. The results were consistent and the fully bypassed cathode was always quieter, but it wasn't hum that was eliminated because, as I mentioned, this amp doesn't hum. Further, the noise wasn't 60Hz and it wasn't a sine wave. More like a low frequency hash. Since I have limited bench gear for testing such things I can only guess that it's some sort of emission noise inherent to elevated tube cathode circuits. It's therefor my experienced opinion that the trend toward partially bypassed cathode circuits in modern amps began with the genre of amp modification and hasn't been adequately examined with respect to this noise consequence...

Good test, I don't remember noticing that you reported on this previously?

I seem to remember a thread about noise and grid stoppers, where Merlin advised that with a regular input stage, the 68k or 33k grid stopper value was usually the most significant noise source in the amp, but if the cathode was unbypassed, then noise from the cathode resistor became significant too, as the cathode is then in the signal path, and although the cathode resistor value was much lower than grid circuit resistance, the cathode current was massively higher.
Hope I paraphrased / remembered things correctly, it seems to make sense to me at the moment

Of course with a partial bypass, the bypass cap would get rid of the higher frequency part of the noise, whilst the lower freq would remain, which may help to explain your finding.

Maybe someone else may have more luck searching for that thread than me.

[mikepukmel]

Then I shoulda got heyboers and had some end bells made up painted with the big M.

[Leo_Gnardo]

Then I shoulda got heyboers and had some end bells made up painted with the big M.

Have some decals made up. These days you can do it on your computer.

[catalin gramada]

Then I shoulda got heyboers and had some end bells made up painted with the big M.

Or do something like that. You can add a copper flux band with a big M logo anytime.

[nickb]

I was surprised by the tonal difference too; for the MM just pipped the Weber, it seemed to have pleasing mid range resonance, whereas yes, the Triode was noticeably less appealing than either.
I wish he'd checked / reported on the winding ratios.

I see the Weber and Triode are both 6.6K whereas the MM is 8k. Worthy of note is that both the Weber and Triode are fully steel enclosed (less radiation) whereas the MM is not.

[nsubulysses]

if the transformers don't have the same primary impedance how is it fair to evaluate them? It seems that of course they would sound different

That's like saying an orange drop capacitor sounds better than a panasonic but thte panasonic is .1uF and the orange drop was .022

Also, and I know I'm nitpicking, but the audio example of the person playing the riff should be recorded and played back for all the different sound tests so it's actually played the same, same inflection, same volume of notes due to how hard the pick attack is, etc.

It seems like it would be easy to play the riff slightly softer and then one OT is "warmer" sounding.

[mikepukmel]

They said in the ad that sometimes you should replace a "tired" old choke. This company should be sued and put out of business. They still don't publish any specs on their site because it's not aimed at tech people which would see through their idiotic marketing bluster in an instant. They are trying to attract the "cool, rock guitar guy," or the endlessly searching tone hound-type. So basically people that don't know how to change a plate or cathode resistor and actually adjust the sound of their amp


Edit: two seconds on their site and I come across this. I remember I saw this a couple years ago and also got mad:



I am no doctor but I thought ear fatigue had to do with high SPL for extended periods of time. Not if the amp had a MM transformer or not

Edit again: I am laughing thinking of EVERY classic amp that everyone loves the sound of that doesnt' come with a MM transformer. Do any famous, legendary, desirable, etc amps actually come with MM transformers?

Re: "It's the output transformer's job to emphasize the even-order harmonics and make tones more musical, appealing, and less fatiguing." Oh man. Heh. What was that joke post "My amp has bloom and sunshine". I wonder if ear fatigue is related to over bloom or under sunshine or both?

[Chuck H]

I wonder if ear fatigue is related to over bloom or under sunshine or both?

My first laugh of the day Thank you!

[Mike K]

I know this is an old thread but I came upon it looking for something else and couldn't resist putting in my 0.02 (joined this forum just to do so).

First comment: This entire thread reeks of inexperience. Don't take that personal, but with all these threads I see nobody comment that has any actual experience in testing A/B in real life. In some threads I've seen this reported, but honestly can't figure out how they came to the conclusions they did. But hey, we all have different ears.

Years ago I first started trying MM - and yeah I was skeptical of hype and secrecy, but I was also curious AF, so I wanted to try. I paid full price for my first one, and TBH, I wasn't in love with it. My observations at the time compared to Hammond and Heyboers I was using: It WAS LOUD - on the same amp way more efficient. It WAS bright - like almost too bright to the point it would sound washed out when cranked. It was built perfectly and much better than a Hammond, and far better than Heyboer (who use wood shims in their transformers - still can't wrap my head around that - think I'm lying, I have some I can take pics of now).

So for a while I really likedHeyboer, and they were doing it for me. Until I made some clips one day and someone pointed something out to me that I had never noticed. A terrible low frequency resonance - a BRRRRR sound, that followed the transformer on whatever circuit I would put it on. That was an "AHA" moment for me, and when I really started to understand what made transformers "sound" different. I knew they did, but I couldn't always explain what it was. I can say with a great deal of certainty that EVERY Mercury has a resonance tone that sounds more like a hard K sound - like KAHHH or KRRR (vs say lower modes like BRRRR or GRRRRR). That may not be for everything, but once you get that, you can really work with it. And you may prefer that kind of resonance over another. I can't say you're wrong if you like the lower modes of Heyboers, but for me, they aren't it. They sound flubby and muddy, and this is somewhat irrespective of circuit. You can tune some of it out, but it will always be there to some degree - just like a speaker has a characteristic voice that will follow with it no matter the amp, so will an OT.

As far the secrecy, I can totally understand that. Put it bluntly, guitar players are idiots. And a lot of times amp builders know even less (trust me, I've been there). MM doesn't want to dink around arguing with you about specs that they worked hard to develop that create some subjective experience and then for you to take those specs to another supplier so they can try to copy at a lower price. Try it. If you don't like it, return it. If you are designing amps and have a repertoire with them, they will give you the relevant info. For PTs they are a little more difficult to work with, but I have to say, the published specs on other PTs are just as bad in determining the actual voltages you'll get. The best are actually Hammond, who give you the necessary info to properly calculate loaded voltages. But they have the biggest tolerance too... As far as MM PTs that were designed for a specific amp - they were damn near perfect. Perfect loaded voltages. As far as price, with the "good guy pricing" i.e. once you've bought a couple, the PTs cost about the same when you factor in shipping (if you're buying a Merc OT, it's cheaper to get their PT than to pay shipping from another supplier). Their OTs are more expensive, but to me, they sound better than anything else. They have far more clarity and punch and no weird harmonics i.e. low modes or FIZZ (I found every Classic Tone I used had horrible fizz driven).

As far as my preconceived and incorrect notions, mostly coming from the internet, I can say MM has proved me wrong in a few instances. One was PT loading, the other was OT loading. In both cases they were correct and I was not, so I can see why they don't want to argue with internet know-it-alls about transformer designs. I will say also that a Mercury OT sounds like a Mercury OT at 5k with a giant core or 12k with a medium core. There are some minor differences, but they sound more like each other than they do other brands. That was always a big surprise to me and I've tested multiple MM against other OTs both at the same and different impedances and core sizes. Honestly a tiny MM always kicked the $hit out even a big fat cheap OT.

Back in the day when I was learning all this I did some blind tests too - I put them on a popular amp building forum and even had a couple Mercury's in there to throw things off. I did not post the results, but only emailed them back to people once they had emailed me their guess, so as to keep forum chatter from biasing things. A Mercury (Axiom) won, hands down, but a Mercury Tone Clone (which was the proper OT for that amp design lost). The tone clone sounded great IMO, but was a vastly smaller core than any of the competitors (as is sometimes the case in stock OTs) and people definitely prefer the sound of larger cores, IME.

Right now I'm playing a little VOX AC15 type amp that I built with a Gibson MM OT - it's tiny, only 10W running 10k with two EL84s to about 10W in true Class A PP. I compared it to an off-the-shelf Vox AC15 and it doesn't sound as good clean (it doesn't have the volume or headroom) but driven it kicks the snot out of the Vox. If I were going for headroom AND sweet driven tone I would have used higher voltages, biased up toward 15-18W and used a large Radiospares MM OT. But I was going for a less headroom and a bit less volume. Not sure it's something that would be commercially successful, but I like it. There's lots of different ways to build amps and lots of different ways they are going to sound good or poor. Generally though, you do get what you pay for.

PS I have MM Radiospares 18W clone and Heyboer 18W OT from Mojo that I want to compare. I'll tell you right now, they are totally different other than physical size. The laminations are much different on the Heyboer and the bobbins are different (although, in theory, that in no way should affect tone, but I can tell you which one is cheaply made). I've worked with the MM Radiospares clones before and they were phenomenal, so this Heyboer really has to knock it out of the park to have a chance. It might, I have no bias, and it might just sound better with certain speakers and preamps. The price was quite different, even with my healthy discount from buying lots of Mercs, I think the MM was still 50% more in cost. But if I'm going to skimp somewhere in an amp, it's not going to be the iron... just my philosophy.

[Chuck H]

Welcome to the forum Mike K. You're free to leave any time if you don't like us. "Don't take this personal" but I only say this because I don't like you.

[Mike K]

I don't plan to stay long, I just thought I'd give some actual experience instead of "someone who knows someone" or whatever it is you guys go by. Listen, maybe things are different now with Patrick gone and dealing with post-Covid nonsense, but I think most builders who actual used Mercs weren't going to waste their time arguing about it on a forum. They probably saw it as an advantage and were perfectly happy with you or anyone else using something they felt was inferior. The fact that no one on this thread could find one OEM that used Mercs is pretty sad. In terms of boutique amps, there were a ton. And there were a lot more that started off using Mercs until they got big, and then switched to high volume, lower cost suppliers. I don't think MM could ever keep the volume of some of the larger amp builders if they could meet the cost requirements. They do still, to my knowledge, supply Fender with transformers for their 57 custom shop tweed amps, both the Deluxe and the Twin. I've used the Deluxe OT a few times and I can say it's certainly my favorite of the number of them out there.

As far as negative comments I've read from people who actually tested they were on Marshall forums where guys claimed the MM OTs were dark and muddy. Maybe they are, can't say. I've never built or had the need for an amp over 20 watts. But that seems very contrary to my experience with them i.e. they've always been on the other end of the spectrum compared to everything else.

As far as the power cord thing... that I don't know? Maybe for a 100W head you might be better off with a thicker cord. It's probably BS though. All I know is in my dealings with the company it was never once mentioned but I was always inquiring about low wattage stuff and was always directed where I needed to be.

My belief based on dealings with this company for over 15 years is they give you what you give them. If you want something stupid, they'll give it to you and smile taking your money. If you want something serious, they have the expertise to do that, and they'll do everything they can to make sure it's exactly what you want, within reason. Obviously if you've bought more stuff from them, they'll invest more time in you. If you come in wanting something for nothing, my bet is they'll just blow you off.

Also I think the pricing has something to do with trying to discourage small amp builders from buying a single unit and sending it to a competitor to be cloned. It also seems to be to help their installer network actually make some kind of money on upgrades. IME they seem very willing to support shops and small builders, provided you aren't asking beyond your reach.

[nosaj]

I'll have to say this when I was interested in them I called and I got Patrick on the phone and he was gracious enough to spend time on the phone answering all my questions even wanting to send promotional items to drum up interest locally. But i was honest with him about what I do in that it is a hobby for me and not a full time shop. It was a neat experience from my position in being able to speak to someone who didn't blow me off because I wasn't a volume customer.

In the end I did not buy from them though. Classictone got the job

nosaj