Audio Technology Magazine
The following is an interview with EveAnna Manley given to Greg Simmons of Audio Technology magazine which took place at Manly Beach, NSW, Australia in March 1999.
Reprinted with kind permission.
EveAnna Manley, owner and president of Manley Laboratories, reveals a little ‘Manley Magic’ to Greg Simmons…
EveAnna Manley is quick-witted, technically savvy and a great conversationalist. The following interview took place at an outdoor café on Manly Beach (of course!), just hours before she boarded a plane back to the USA.
Greg Simmons: Let’s start with the history behind the Massive Passive…
EveAnna Manley: The Massive Passive! [strings it out in her Californian accent] The history of the Massive Passive goes back to the Pultec EQs we’d been building, the mid band and the hi/low one. When we decided to make those old Pultecs, back in ‘89, we actually sought out the old guy behind Pulse Technologies [the original manufacturers of Pultec equipment], Eugene Shenk, to get his permission and offer royalties. We could’ve just reverse engineered them out, but we wanted to do the right thing. Eugene gave us permission, but he also told us that he only designed the tube stuff – the passive equaliser designs actually belonged to Western Electric and were originally designed for telephone circuits! So we asked Western Electric for permission, and they said, “Oh yeah, sure. Just mention our place in the history.” So we do…
We’ve been building those mono passive EQs with our own tube make-up gain circuits for a long time. But everyone was asking us to build a stereo version. So as a quicky kind of thing, we doubled up two Pultecs, one over the other, into a 2U chassis, it’s like two mono units with a single face plate. It was simple to do. We brought it out at a nice price, and we’ve had that out for a year or so as a stereo Pultec. But everyone was still saying, “No, we need all those other frequencies too”.
GS: How many bands did the stereo Pultec have?
EM: Just high and low, really. The bass section has the separate boost and cut controls… um, you’ve used Pultecs before?
GS: Sure have. I always thought it was strange to have separate boost and cut knobs, ‘cause it tends to defy any logic. Perhaps you can explain?
EM: Well, if you boost and cut at the same time you can bring the Q of that filter in a little bit, and when you do that it actually creates a little notch at the bottom of the filter. Say your main goal is to boost your bass. You can whack up the boost, or you can whack it up a little more than you want and then add a little cut. That’s a shelf circuit we’re talking about, so when you add the little cut to the boost, you’re pulling in the Q of the shelf – tightening the slope of it. So instead of extending out to, say, 1kHz, it’s now only extending out to 700Hz. And when you add that cut, it puts the little notch at the bottom of the shelf.
GS: Is that the notch shown in the shelving pics on the Massive Passive’s front panel?
EM: That’s the one. There’s been a lot of EQs where they’ll engineer that notch out because it’s not ‘proper’, it looks ‘wrong’ on the measurements. But guess what? That’s why a Pultec sounds so freakin’ good! That ‘imperfection’ is the magic!
GS: As is often the case with classic gear…
EM: Right. So we built that behaviour into the Massive Passive – that’s one of its little secrets.
GS: But the Massive Passive doesn’t have separate boost and cut controls. It’s got a single ‘0 to 20dB’ knob with a switch to select boost or cut, so how can I do both at the same time?
EM: Well, for that little trick, Hutch [Craig Hutchison, Manley’s Chief Designer] deserves all the credit. He’s the one who cottoned upon this little dip at the bottom of the Pultecs and why it made them sound so marvellous, and he’s the one who figured out how to do it on the Massive Passive. The effect is created with the Q control when you’re in shelf mode. When you’re on the lower Q settings, it’s pretty much a straight shelf, like if you’re only boosting on a Pultec without cutting. But as you increase the Q, the slope of the shelf tightens up and it puts that little dip in there, just like if you’re boosting and cutting at the same time on a Pultec.
There are some really funky tricks you can do with that, with things like the 12kHz position, where you’re actually boosting it but, because you’ve got that little dip in there, the damn thing sounds like you’re cutting it! (laughs)
GS: So how much does the Massive Passive owe to the original Pultec designs?
EM: Truth be told, the Massive Passive, and the whole way that the passive EQ works, draws upon ideas from the Pultec, such as the shapes of the curves that we’ve been talking about. But from a circuit design point of view, the way the whole thing works together, being a parallel circuit design – with four bands per channel, overlapping and interleaving, plus the high and low filters banged on on top of that, all in stereo – is really pretty much a new thing.
GS: One of the important points for our readers to realise is that those EQ and filter stages are all passive, using capacitors and real inductors, not integrated circuits…
EM: That’s right, totally passive.
GS: With all that passive boosting and cutting going on, it must need a fair amount of make-up gain…
EM: There’s 40dB of active make-up gain, and it is all tube. We worked out a new circuit for that, it’s a single-ended circuit. Even though we’ve got balanced and unbalanced inputs and outputs, the topology inside is all single-ended.
GS: ‘Single-ended’ is a term often used in conjunction with high quality audio products. But some manufacturers seem confused between single-ended and Class A circuitry. What’s your definition?
EM: Well, a lot of amplifier designs, whether they’re low level signal amplifers or power amplifiers, split the signal into two opposing waveforms – the positive and negative half cycles – and then each half cycle has its own amplifier circuitry. They’re usually called ‘push-pull’ amplifiers. Now, when the two amplified half cycles are added back together, unless the amplifier is extremely well designed, you get crossover distortion at all the points where they join.
But ‘single-ended’ means you’re not splitting the signal into two halves, you’re amplifying it as a complete signal. It’s the purest form of amplification. I like single-ended circuits quite a lot.
GS: …and Class A?
EM: Class A really refers to how an amplifier circuit is biased. If it’s Class A, it means it is biased on all the time, so it’s always drawing current and is less efficient. A Class A circuit could be single-ended, or it could be push-pull. Biasing a push-pull circuit into Class A usually helps reduce crossover distortion. So being Class A doesn’t necessarily mean a circuit is single-ended! People get this stuff confused all the time. All our pro gear is Class A, and for the critical low level stuff, it’s also single-ended. Our Variable Mu limiter employs a push-pull design.
GS: Thank you for that clarification! Now let’s talk about the Manley ‘Philosophy Of Design’…
EM: Before he left the company, David [Manley] started us on a track of some good ideas, from which I’ve evolved our Philosophy Of Design. Ways we will place a wire, ways we will keep a signal off the PC board as much as we can, keep the tunes really just jumping from component to component as if it were hard-wired. Those kind of things…
All the little bits add up, so you take one thing that’s pretty good to do, and you don’t skimp on that. Like, take the output capacitor in the Massive Passive and the VoxBox: it’s a big bomb Multicap, 30uF 200V rating, costs a freakin’ fortune! But you know, all your tunes are going through that one component, so what are you going to do? Put a cheapo 30 cent electrolytic cap there? The whole unit will end up sounding like a 30 cent cap! You have to say, “balls to the walls, this is the ‘moment critique’, let’s put the best we’ve got right here”. For all those critical parts, where the tunes are really gonna count, you have to put your best foot forward. That’s good philosophy of design. Not designing to a price point, that’s also good philosophy of design…
GS: Does this philosophy extend to the look of your products?
EM: We’re expanding upon a philosophy of visual design that David got us started on, with the black inlayed and engraved into the blue-grey mother panel. I took it another step and incorporated ergonomics into that. Like, the shapes of the V and B on the front of the VoxBox – your brain will lead your hand to a knob a lot faster if there’s a shape to associate with it…
GS: …that makes sense.
EM: If you’ve got a plain black face plate with a whole heap of identical knobs on it, when you first see that piece of gear you gotta read through every knob, and maybe there’s nothing delineating where each section is, so it’s a much longer mental process when you need to hit that button. Whereas, the different panel shapes and the different sized knobs on our products clearly define the sections – the shapes work in your brain so much faster like that. It’s much better than having a mass of knobs on a faceplate…
GS: But I could argue that the Massive Passive is just a “mass of knobs on a faceplate”!
EM: Well, you could, but the thing with the Massive Passive is that, on that front panel, you’ve got eight sets of identical knobs. So the thing there was to make each of the knobs in each set easy to find, which we did with different sizes, and then make each set easy to distinguish from the rest, which we did by putting the black oval shapes behind them.
GS: Yes, it’s a self-explanatory layout, really…
EM: Right. Good philosophy of design also extends to where you place components inside the box, like paying attention to where sensitive high impedance circuitry is located relative to power transformers and other noise sources. And those decisions ultimately affect where you can place knobs and switches on the front and rear panels.
GS: Sounds like one helluva juggling game!
EM: Always, always… And you always have to work your way around conflicts and make compromises as you go. Or figure out a new way to do it. Balta [Baltazar Hernandez, Manley’s Chief Draftsman] is particularly good at solving these sorts of problems. I mean, he’ll run up against a wall on something and say, “Ah, you told me to do this, but I can’t really get there from here”, and then he’ll come up with a new solution. We all get involved and, after a long time, it all works out…
GS: EveAnna, it’s been a real pleasure talking with you but I’m afraid we’re about to drop off the bottom of the page. Thank you very much for your time, I’m sure our readers will appreciate it.
EM: Sure! Let’s do it again some time, huh?