John Hardy replacement card for the Sony MXP-3000 Console

Hi! that's my first post here, so hello.
I decided that I want to build a good preamp, that way I can practice some of my knowledge in electronics, and have a good preamp.
I've found the John Hardy replacement card for the Sony MXP-3000 console. It has quality components inside(990 opamp and jensen transformer) and it seems like it has the same design as the m-1/m-2 preamps(am I right?).

It seems that all I should do is build a power supply, input and output jacks, phase reverse switch, output transformer and supply a chasis(it comes with a faceplate). It looks to me like a nice project to begin with(i've built some pedals before, but nothing i'd call a project). But what is the potential of this unit? does it have the potential to sound like an API for example?

Any response will be appreciated,
Eliya Gwetta.

[quote author="eliya"]does it have the potential to sound like an API for example?[/quote]
No

...unless you want to completey repopulate it with a capacitor coupled 2520 and add an all steel output transformer. Then it might sound like an AP*I.

I'm not being sarcastic.

AP*I and a John H*ardy are two entirely different beasts. They both sound pretty awesome in the right context, but nothing alike.

Anyway, welcome to the lab! Best forum ever! Most folks are very forgiving and helpful, and understand that there's no such thing as a stupid question. Good luck on racking/building a killer pre! That's what we all do 'round here. :thumb:

Thank you for your reply!
It is one of the best forums ever, tons of information!
Maybe the question should be "Does it have the potential to be in the same league as the API?"

Absolutely.

Samuel

it'll probably wind up sounding bigger and well more open than anything api. Im a big api fan and so are lots of people here, but the stuff is hardly the holy grail. It sounds cool, but specs for shit on paper, doesnt have the greatest headroom in the world, inst the queitest stuff in the world and the old consoles were built like absolute garbage. API gear sounds cool, but so does a lot of other stuff. being "in the same league" as api really isnt saying too much, IMO. Im the first person around here to set a spec sheet on fire and while the api stuff does sound cool and while I do use it on every project I do consistently, there is stuff that is just way cooler and much more robust. If people are actually listening to this stuff and not judging by some idealized reputation, there is no reason IMO why api shit is fiended over and transistor RCA stuff is not. That is a total mystery to me, if you are listening to the sound the things actually make.

If you want the sound of the hardy with more flexability, you might consider also looking at the boards JLM audio has for sale, you can order two 990 opamps from john hardy and use those with the JLM board which is wildly flexable for DIY, you can set it up transformerless, with transformers, with or without a servo, and would actually be easier to rack than the sony plug in as yuo would only need to drill holes (could even use a hand drill) to mount pots and switches instead of having to cut out the block for the hardy frontpanel. Of course the hardy thing might look cooler when you are done. All things you need to weigh.

dave

Im sorry to bring this up again, but when you said not the greatest headroom in the world etc', you talked about the api or hardy? just out of curiosity..

btw, I know that the hardy 990 opamps can work with 24 v and not only 18 v, so is it pssible to power this unit with 24v? It would give more headroom and possibly better signal to noise ratio, wouldn't it?

Welcome to the DIY. I loive API stuff except their MIc pre's which tend to not have a lot of headroom. There Eq's and comps are great but not a big fan of their mic pre' s.

So IMO I believe he is talking about the 2520 which you can now get a schematic for off the internet or search here for one. Thenm build your own. No secret now. As for the 990's, they do work well with 24V and sound great. Yes to your question. As for the MXP 3000 retrofits I have never heard the John Hardy retrofit but if it's anything like his other stuff it should be good.
Welcome

The 990C can work at +/-24VDC, but the little DC servo op-amp is limited to somewhat lower voltages. The MPC-1 mic preamp card of the M-1 mic preamp includes voltage regulators to bring the +/-24VDC supplies down to +/-15V. The 990C runs at +/-24VDC and the DC-servo op-amp runs at +/-15VDC.

The MPC-3000 mic preamp card was designed to operate in a Sony MXP-3000 console that has +/-18VDC supplies, so I did not include voltage regulators for the DC-servo op-amp . The DC-servo op-amp and the 990C use whatever supply voltage is delivered to the card.

If someone wanted to used the MPC-3000 card in its own box with its own supplies, it could probably work with supplies as low as +/-12VDC, and as high as about +/-20VDC, depending on the limitations of the DC-servo op-amp. Same story if you wanted to build the circuit yourself.

John Hardy
The John Hardy Co.
www.johnhardyco.com

Hi John,

What are you using for servo IC's? AD706? BurrBrown OPA177? BB604's would take the +/-24V rails, but have higher offset than either of those two, so wouldn't be as precise.

Cheers,

Kris

I?ve used FF?s OPA604 servo circuit show here http://www.forsselltech.com/schematics/JE16%20Mike%20Preamp.PDF and it works great ? all the way up to +/-24V.

As for 2520?s not having headroom, seems like for DIY, one can be built using higher voltage transistors for more +/-V then the original API version? Does anyone else remember this?

While we?re on the subject, how about a JH990 using the JT-16 input transformer and API type output transformer? Looks like you?d have a super low noise, dynamic pre with that cool API sound? Anyone made one of these?

I have used several op-amps for the DC-servo circuit. Some have been discontinued. Currently I am using the OP97FP. Prior to that, the AD705J. In the early days, the Linear Technology LT1012, then the National Semiconductor and Motorola LM11CN. All of these have extremely low DC offset and very low offset drift vs. time and temperature, important for use in a DC-servo circuit. They are also very slow op-amps (trade-offs), but they don't need speed because they are dealing with extremely low frequency signals only.

All of these op-amps have the ability to be further trimmed for the lowest DC offset by adding a trim pot between pins 8 and 1 with the wiper going to the positive supply. On their own, the op-amps get the 990 offset down to less that 200uV or better, but the added trim pot can get it down to <10uV, basically to the point where you can't be sure of what the heck you are measuring. I have a couple of meters that can measure to TENTHS of a microvolt, and that is what I use when doing the final DC offset trim with the added trim pot. But much care must be taken when making such measurements.

BTW, I redesigned the MPC-600 and MPC-3000 cards a couple of years ago. One thing I did was to add that extra trim pot for the DC-servo op-amp.

John Hardy
The John Hardy Co.
www.johnhardyco.com

Hello John!

Thanks for chiming in with that info. We appreciate you sharing with us very much.

Flatpicker,

I like your idea!

Peace!
Charlie

I would agree a 100% with "soundguy" that the API products are over rated in terms of specs and sound. I'm not saying the stuff is junk but just over rated and there's other stuff out in audio land that's just as good or better.
I have called John Hardy in past many times with MXP3000 questions and also design concepts with the 990 and other which he was very helpful. :grin: In comparison, API is a very snobbish and unhelpful company who have bought and sold to many times and I wouldn?t purchase a screw from them presently. :shock:

...

[quote author="eliya"]Im sorry to bring this up again, but when you said not the greatest headroom in the world etc', you talked about the api or hardy?[/quote]

I was referring to the api stuff. The hardy pre's are the polar opposite in all respects.

[quote author="pucho812"]you can now get a schematic for off the internet or search here for one. Thenm build your own. No secret now.[/quote]

you can belileve that if you want, I guess. Have you built one? There are several different schematics I have seen over the years online, api over the years also built several different sounding opamps however they all have the same name... I built up two different opamps from schematics I found, one I couldnt get to work at all and the other was just sort of ok. Neither sounded remotely close to a 2520 with the huntington sticker on it. If you've built one that sounds like one of those, let us know which schematic matches. I suspect the magic is still plenty secret locked away in some obsolete semiconductor since the new 2520s from api dont even sound anything like those old opamps.

dave

I don't think the amp I've seen in those schematics would have the same high frequency response and distortion characteristics were it not laid out with the PCB and epoxy potted. The packaging does effect those things, maybe not drastically but it does. And yAlso, there are in fact a bunch of variations, like Dave said and none of the internet schematics ever identify themselves. For example, the 2520 went surface mount after P. Wolff took over. I imagine that alone could change the sound quite a bit.