PM1000 Rack FINISHED +Pics & info

[khstudio]

It's been a few day & I've had time to compare my new PM1000 Rack to other pre's & these things kick ass :green:

I love em... Lots of up front punch & balls, if you want it. Not sure if it's the 44v rails or what. Also, LOTs of headroom! Just when I push my other pre's to that sweet spot they seem to poop out & get dirty but the PM1000 keeps going past that point... no problem. Smooth rolled off high's & unlike others I like the EQ - it doesn't give full control but is very musical (Passive with inductors like Pultec's) not irritating if not overused. I think I'm going to move the 10k band up to 12k though :idea: Phantom power scares me because it's not a slow ramp but I'm not sure it's a problem - but I DO NOT want to blow up my U87's, etc... It kills for ROCK vocals with an sm58 + Distressor. I grounded pin 1 to the chassis & connected the circuit ground from the sheild of the output wire (Green in pic) + output tranny GND + output XLR. Seems to work well - NO hum or noise.
6 Diodes for dropping the voltage to 44v for the circuit B+.
Original tranny's in/out from PM1000.
All Panasonic FC + left the Tantalums alone, just tested for correct values to keep units matched... although the units ARE NOT exactly the same. One definitly beats the other but not bad. Basically the EQ seems to react more on one than the other & I don't know where to start if anyone can help?The one in question is an older model, inductors seem to be different style or vender, resistors look a little bigger than the better unit (I'm not sure but they might be Alen Bradley's :? ???) Anyhoo, the older one is just a little darker, besides that they're the same component wise. Any ideas?

Input gain selector is my favorite feature... it actually changes the input circuitry to several configurations - check out the schematic, it's cool.
It gives a different character & placement with each click. It seems for any one instrument or mic there's a 3 tick range... by using it along with the output control the sound can be backed off, normal, or in your face.

More to come...

Kevin - KHStudio

 

[cuelist]

[quote author="khstudio"]Lots of up front punch & balls, if you want it. Not sure if it's the 44v rails or what. Also, LOTs of headroom! Just when I push my other pre's to that sweet spot they seem to poop out & get dirty but the PM1000 keeps going past that point... no problem. [/quote]

Single ended (not differential) stages on single rail. Does not clip so "hard" like opamp (IC or discrete) style units do. Also, the 2nd order distorsion dominates.

Who's box are you using - looks nice.

 

[khstudio]

Par Metal, they're located in New Jersey, USA.

I saw another guy here in the LAB with this design & not only did it look great but it is less work & keeps the original channel face/controls.

I'd say this is my favorite DIY besides my LA-2A of course.
Cheap = $300, easy & extremely usable.


NEXT UP = PM2000 rack... but I need help with that one if anyone is up for it :wink:

 

[Scodiddly]

Looks great in that natural aluminum finish. I like the mounting bracket on the module backs a lot.

How did you cut the big hole in front?

 

[khstudio]

[quote author="Scodiddly"]Looks great in that natural aluminum finish. I like the mounting bracket on the module backs a lot.

How did you cut the big hole in front?[/quote]

Bracket is just a shaped piece of scrap aluminum.

1st thing I do is tape one side with shipping tape for protection.
Then I carfully layed it out, drill as close to the corners as possible, then cut with a hand JIGSAW. After that about 10 minuts of metal filing.

Those damn Par-Metal enclosures have a top & bottom lip that has to be cut dow too What a PITA.

Scodiddly,

I'd like to add LED's to the phantom switches... will it be OK to run them off the same line as the main LED - which is pulled off the 44v thru a 3.9k resistor. I don't care if they dim down a little. OR, should they each have their own 3.9k or whatever?

Got any idea's on how to match the 2 units up a little better... I talked about it in the first post?

BTW, thanks for your help :thumb:

Kevin

 

[tubejay]

Wow man, looks great! Nice job.

I highly recommend trying to throw some poly's in the eq section and trying different values. If you don't like it, you can take them out. I think at least changing the caps to poly's is a wise thing. I a/b tested the eq's and I think they sound significantly better (less harsh). Though, I changed the eq points, AND put in poly's.

Welcome to the world of PM1000's! These things are great, period.

 

[cuelist]

[quote author="khstudio"]I'd like to add LED's to the phantom switches[/b]... will it be OK to run them off the same line as the main LED - which is pulled off the 44v thru a 3.9k resistor. I don't care if they dim down a little. OR, should they each have their own 3.9k or whatever?[/quote]

Do NOT paralell two LEDs...

Put the two LEDs in series with the 3k9 resistor and use a section of the phantom power switch to simply short (bypass) the LED for that channel.

 

[digitaldrummer]

Kevin,

looks great! I may have to try this method for my next pair.

Mike



http://www.digitaldrummer.net/pm1000.htm

 

[khstudio]

Thank's man,
Your PM1000 info page was very helpful... especially the cap layout, good work :thumb: .

I can't say enough about these pre's but I've found they are lacking in the subs/low end a little. Good headroom & very punchy. Also, my 2 channels don't match, the top one sound great, EQ very responsive & more high end detail - this one seems newer & has different inductor, transistors & resistors than the bottom one. The top ones EQ is LESS responsive & seems darker but the gains are close.

Top unit (newer):
inductor - Have silver sticker w/number
transistors - C1681
resistors - smaller, light brown


Bottom unit (older):
inductor - No sticker & rounded over top
transistors - C1000
resistors - Larger, light brown

I'm not sure where to start to get them to match
I have 1 more strip that has the newer inductor's & transistors but has the OLD resistor types... should I swap the inductor's & transistors :?:

I was thinking about overhauling the extra one I have with METAL Films to see what happens. Then after that test, swap out the Tantalums for films.
BTW, All electro's are Panasonic FC's with the final output cap being 100uf.

I could REALLY use some help matching these things up. :green:

Kevin

 

[tommypiper]

I personally would swap the tants for FCs or similar, not films. Dunno about the different EQs. You could put in some new MPSA18 transistors, remember the legs are different. And try new EQ caps. Those are the first tings I would try and are likely to be improvements... and easily reversed. (But I haven't worked any PM1000s yet so I'm not experienced with that circuit.)

What was wrong with the Par Metal tops? I was thinking of getting those.

Looks great!

 

[Scodiddly]

The deal with the Par-Metal chassis is that the top and bottom pieces have a little folded-down bit in front to stiffen them up. They only connect (with screws) to the sides & back, so have that folded bit. As mentioned in another thread somewhere, a pair of PM-1000 modules in a 2-space rack chassis is kind of a tight fit. So you have to cut away a bit of that folded top/bottom sheet metal to get it to fit together.

 

[khstudio]

This is correct.

I find myself having to cut some of the lip away for all the projects I've done with these... I don't understand why it's SO big, it really gets in the way... especially when installing VU meters.

Has anyone done a direct comparison of caps - Tant to Poly... I know you guys upgrade them but how much, or at all, did you listen or track with the Tants before the change?

tommypiper

I personally would swap the tants for FCs or similar, not films. Dunno about the different EQs. You could put in some new MPSA18 transistors, remember the legs are different. And try new EQ caps. Those are the first tings I would try and are likely to be improvements... and easily reversed. (But I haven't worked any PM1000s yet so I'm not experienced with that circuit.)

What was wrong with the Par Metal tops? I was thinking of getting those.

Looks great!

Thanks for compliment ...BUT why not Films :?:

Also, does anyone know of the difference of the Transistors from C1000 to C1681's? Obviously Yamaha switched to the newer C1681's for some reason. They're ALSO in my PM2000 ch strip - that I'm currently getting ready to rack up :green: I started another thread on this if anyone is interested... Power supply completed & should be hooked up tonite.
http://www.groupdiy.com/index.php?topic=171616#171616

Any help or info is welcome :thumb:

Thanks,
Kevin

 

[soundguy]

the aluminum series chasis from par metal do not have that lip on the front, they mount flush.

IMO, the whole changing of the caps thing is such a personal issue I dont understand why anyone would take anyone elses word for such a subjective thing that is so easy to do for yourself. Reading the internet I thought that panasonic FC's would be the best electrolytic ever and then I listened to them in a few circuits and really really really dislike them as a general rule, but find their character a perfect fit for one circuit in particular. So yeah, Id say that I loathe them, except love them to death in this one circuit I use alot. See where Im going? People that say tants are shitty, like, what, in every circuit under the sun? Tantalum caps may have gotten a bad name because of their presence in neve circuits, some of which have the cloudiest sounding output transformer I may have ever heard. Add that to dark, slow souding caps and its not the best combination.

I think the only true statements you can make are that caps all have a unique sound and its up to you to figure out where that unique sound works best in the circuits you use based upon the sound you want to come out of them. There are probably some generalities you can make about how caps sound as their series resistance increases as well, but saying stuff like panasonic FC's are good or tants are bad or whatever is taking a really simple minded approach to this. Auditioning caps is easy. Shit, there are guys that will tell you those blue xicon caps are good or bad, go measure some, about the only thing you can say about them is that they are inconsistent... Years ago I didnt find those caps good enough for a fuzz box, I gotta laugh at people using them in pro audio.

dave

 

[khstudio]

I WILL be trying other caps but a little feedback can help give an idea of what to expect :wink: . Like right now... I love the top unit in my rack but it could use just a touch of air &/or bass, so if that's what these guys get, cool. BTW, I'm diggin them as is... Tants & ALL.

I must say my main concern is to get the bottom unit up to speed with the top first :!: Then make changes.

I'm getting a good feel for them every day I track:
So Far:
Acc Guitar - NO
Vocals - YES
Kick & Snare - Punchy & nice (Even touch the Q a little) Needs a hair of SUBs
Bass (Dir inputs) - Same as above
Waiting to track Guitars but there's so many styles & amps I have, it will take a while... I'm sure it'll shine on something.

I guess I'm on my own with matching them up.

Kevin

 

[khstudio]

soundguy,
You seem like a smart guy & I respect your opinions but some of you come down on guys like me when we ask these subjective questions... I have my own take on this - I've learned a lot from topics that ask them but will ALWAYS come to my own conclusion. I do share you view. Some of the cheepest & worst equipment or instruments in my studio beat the most expensive (or "industry standard) in any given situation... you're preaching to the choir :wink:

Kevin

 

[soundguy]

kevin-

as you screw with this stuff more you'll understand where Im coming from. Im not "coming down on you" Im trying to save you some time. If you learn what different caps do, you'll be able to strategically use them. If you dont bother to take that step you'll be asking the same questions every time you have a new project.
dave

 

[tommypiper]

It is personal. And it's also circuit specific. We've gone over these many times before, there are some general characters that everyone seems to agree with on most of the capicitors discussed. FCs tend to be hi-fi, even scooped in the mids. They sound clearer, brighter, maybe in your face more than others... Nichicons are less harsh compared to FCs. Look up the previous discussions, there have been several, for more details and opinions. There are different Nichicons, etc.

I personally have had good luck replacing tants with polypropelenes. I replaced all the tants in my 1272s with FC and with Nichicons. Both sounded good to me. John Klett also replaces all the tants in his Neves. Since the PM1000 may be using tants similarly, I personally would try an FC or Nichicon or similar there as a starting point. Never tried films for a tant, so I was just going with what has worked for me previously as a starting point.

Dave is right, it's all about your taste and experimenting on the particular circuit. Other guys have posted what they have used for the EQ caps, like Tubejay, so I would try those recommendations there for starters. Since you have a different EQ sound between your two modules, the EQ caps would be particularly interesting/important to swap and experiment with.

Often after one or two cap replacement experiments I have already improved the sound to my liking and usually don't go further. But in the case of 1272s I tried a lot of caps, including Black Gates. I find most of them sound good, just a bit different from each other.

Hope it helps. Let us know what happens.

 

[khstudio]

Points taken. I just want them to match a little better so I can mod 1 at a time for a better comparison... that's all, I'm not afraid to try :green:

BTW, I just roughly finished connecting the PM2000 & it's got MAJOR POOP/VOLUME coming out & sound pretty good. I'll give more details tomorrow:

I'm getting some high freq hiss... it's pretty much wide open laying on a table - could the hiss be from that :?:

Thanks
kevin

 

[khstudio]

I finally got my pictures back up... :green:

BTW, This has been my main vocal pre since I racked it up... it's been several weeks.

Kevin

 

[The Odd Coil]

This is George

Look at this link to see samples of some of my work

http://photobucket.com/albums/b121/SalesBoy/

I was sent a link to your post.

I worked with Ken who was selling modules on Ebay.

I racked up some modules but not as easy as the way you (Kevin - KHStudio) did it. I actually replaced the pots with new ones as the originals are not re-moveable because of the glue.

Look at ?Two Yamaha Transistor Mic Preamp Cards in a Rack? picture.

These are two cards from either the Cue or Talkback modules.
The ?Four PM1000 Preamp? pic shows four of these cards in one rack.

When Ken scrapped out some consoles he gave me the Cue and Talkback modules and I took the cards out. These cards have the same four-transistor circuit that the channels have. I tried making a Mic pre just by bare bones wiring up a module to in/out trans, gain and power pots, and in/out connectors.

The signal path is, in trans, 1st. stage that has gain control, level control, then line stage, then out trans. The level control allows you to ?overdrive? the gain stage. The out trans smooths out the sound. Going straight from out to Pin2+ gives a harder more solid bass.

Ken and I were surprised at how nice and clear and tight the preamp sounded. I ended up racking up and selling about twenty cards.

The EQ circuit really takes a lot of clarity out of the sound. The one transistor can not take a lot of level, so the gain switch keeps the level to the EQ phase splitter at about ?10. Then the line stage takes it up to +4
out so if you put a out trans on then you can use the module as a separate.

If you put a EQ bypass switch in the channel, then you can improve the clarity of the channel by taking the whole circuit out.

A. What I would like to do is to make a PC board that is the same as the Yam board, but would have all new parts. The only glitch is the transistors. Yamaha and Sony made their own parts. We are doing a search for transistors that would have the same sound and same or better noise figures as original.

Then we could sell a PC board that would make a nice preamp and DI, drive a 600 ohm out trans, and sound pretty good. Another option I was going to try was to use a single card and one 12ax7 tube as the 1st gain stage for each channel. Then one card and one 12ax7 would make a stereo pair of preamps.

B. Another option is to take one 12ax7 and one card, (two 4-trans amps per card with gain control on the first amp, gain trim on the second) and drive a transformer that has two primary windings and one 600 ohm out winding. Then you would have a transformerless Mic preamp that is balanced in so no in trans, just a out trans. This would be a killer preamp as without the input trans, a lot more clarity is there.

C. Two cars and one 12au7 tube as a buffer between the two Yam amp stages, and then you would have one tube stage for warmth. This would make a stereo preamp.

I am making different samples for production. I am interested in tube/trans combos as they cost is low and you get a low impedance out and can drive a 600 ohm out trans.

Here are some notes on transistor/Yam stuff

A. Tantalum caps are bad. I have a collection of ?Audio Ameteur? magazine from the first issue to the late 1970?s. When op-amps came out, there was not much happening in coupling caps. Tantalum caps came out and they were going to be the new big thing in audio. Then someone did frequency response tests on them and found they become resistive at high frequencies. They need to go. Metal Polyester caps are vastly better.

Aluminum electrolytics are the best for the larger caps. A tech that works on a lot of transistor gear told me that XICON red are the best. You have to check all the caps by scope as the Panasonic caps are made in big quantities and they sit and degrade.

A simple 4.7K resistor in series with a DC power source, hook the cap up and the resistor will allow the cap to charge up. Unhook the + wire while hot and let the caps sit. I will charge up ten caps at the same time with the one resistor by hooking all up and then turning on the power.

Caps that are good will sit for a ½ hour and still hold a charge. Then they are formed back up and will now work the best.

B. The Mylar green caps in the EQ are not good. They cause the EQ bands to be mushy and ?loose?. Replace with metal-poly and the EQ bands will be tight and on frequency.

I have info on cap values for Neve frequencys. I can post Mouser part# for good EQ caps. The resistors are different for each freq as they are trying to make the boost/cut levels of the diff freqs equal. You can change these values to adjust boost/cut.

Make C15 .039 film cap for 12Khz.

You can change the Freqs to Neve values. I have the info...

C. There is a gain trim pot on the line amp and the gains can be off. The transistors were changed a few times and you might have diff transistors on the channels. You have to use a scope and a stable oscillator to go though the channels and match up gains and check freq response.

Also any original coupling caps could be bad and you have to scope or pull caps to check??

D. The extra 4V from phantom supply will not harm the transistors as they can take more voltage. The two output trans split the voltage in half. You should measure close to ½ the supply at the 22 ohm resistors.

I use a resistor of about 30 ohms and a 1000Mfd cap to filter the 48+ down to channel level.

E. Put a 100 ohm resistor in series with the phantom feed to the channel and a 100Mfd cap across the input to the channel and ground. When the switch is closed, the resistor is in series with the cap. The cap has to charge up and this gives a slow up slope so you do not cream a mike. Also the 100Mfd cap puts the 3.3K resistor to ground audio wise so noise does not come in through the phantom feed.

Let me know if I can help. I also do all sorts of custom work.

You can make a seven-band EQ out of one of these modules. I can post some info on that later..

gEO?
:wink: