RE: SCA preamps + access..

  • Thread starter Thread starter TragikRemix
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TragikRemix

TragikRemix

I am NOT a Gear Whore. ;)
RE: SCA preamps + access..

i want to get some nice pre's in my studio, but i dont want to kill the checking account, so i decided to build some SCA's.

here's my question; can i just buy a kit and get my own PSU (and chassis) for it, just for now? i know the deal with the psu, chassis and one kit package deal, but i don't want to spend the $650+ right this minute. i would like to just get one kit for now and see if i even like it.

what would i use for PSU? anyone make something up for themselves, or use a PSU from something else?

lemme hear what others have done.
 
No offense... but stupid idea. You can easily sell it if you dont like it, minus your time.
Did you add it all up? You end up getting the PS and chassis for almost free once you put it into the order form. Its a no brainer. You'd spend more trying it any other way, and this way wont blow your preamp up.
 
TragikRemix said:
what would i use for PSU? anyone make something up for themselves, or use a PSU from something else?
Click to expand...

This tells me that you have no experience in DIY power supplies and really shouldn't try now. The chasis is one thing, however unless you have some nice toys and the know-how, yours will never be as nice as the 7th circle stuff. My recommendation would be to get one of the 84 preamps, the chasis, and the power supply. They throw the power supply in for free. Its not too difficult of a project and it will be much better than trying to do that stuff on your own.

Rory
 
I agree with the others, not a great idea, getting a PSU together will be a headache.

I'd recommend the baby animal kits by JLM audio, they're in Australia but the shipping (to the UK) was very quick in my experience (ordered on a Wednesaday evening, arrived the follwing Monday morning).

http://www.jlmaudio.com/Baby_Animal_Mic_Pre.htm

The cheapest kit for one channel (with an OPA2604 Opamp and JLM14 input transformer) will set you back $75. The PSU which can power 4 to 8 channels (depending on what opamp and xformer you use) will set you back $29. Or if you need more power they sell a more capapble supply which can power up to 24 channels for $72.

They're not clones like the SCA kits but they apparently sound fantastic and you can get quite a variation in sound depending on the opamp/xformer combo you use. I've built two channels but have to wait until the end of the month when I get paid before I can afford to buy the input iron (I'm using Lundahls together with JLM's 'hybrid' opamp).

There's a thread at group DIY with lots of discussion about the BA, it's also a support thread and Joe and Matt check in most days.

They know their gear at group DIY and the BAs have gone down a storm.

http://www.prodigy-pro.com/forum/viewtopic.php?t=15245&start=0&postdays=0&postorder=asc&highlight=
 
i do have experiance in DIY stuff, just not with PSU's.

i figure i would get one channel for now, and then get the psu chassis and another channel later.

why is that a supid idea? sure, they give you the psu (almost) but that initial order is still over $600. what if it's not what im looking for? now i spent $600 on something i dont like and have to take a significant loss, whereas if i only have to lose on a single channel, it's no big deal.

i'm not looking to build a PSU, because if i messed that up, everything would be crap. i was looking to see if anyone had done somthing that was simple.
 
What if its not what you are looking for? Dude, an API or Neve is EXACTLY what you are looking for if you do anything even remotely rockish. Unless you are doing classical, you want as many API's as you can get. You wont be sorry and the price is great. For only $375 you add another preamp. You know if you actually fill out the order form with 3 pieces the price drops, right? Plus you can have 4 different flavors and up to 8 pres in the same box. No brainer dude. If you can build it (its not easy) then get to it.
 
TragikRemix said:
i want to get some nice pre's in my studio, but i dont want to kill the checking account, so i decided to build some SCA's.

here's my question; can i just buy a kit and get my own PSU (and chassis) for it, just for now? i know the deal with the psu, chassis and one kit package deal, but i don't want to spend the $650+ right this minute. i would like to just get one kit for now and see if i even like it.

what would i use for PSU? anyone make something up for themselves, or use a PSU from something else?

lemme hear what others have done.
Click to expand...

Drop and email directly to those guys at SCA. They are super up front guys. I had a long email exchange with them where they suggested that due to my lack of experience with PCB's that I should not buy their stuff now.

They also pointed me to some kits to buy to build some skills.

I think they are great stand up guys who would give you a very quick and direct answer.

Jim
 
thanks guys,

thanks for the links too. i'm a member on prodigy pro but they are too smart for me over there ;) i know some stuff but they just run circles around ya..

ahh decisions now.. which pre's are for me.. i'm just gonna get the chassis and psu from them, when i have the extra $650, then i can add a pre every once in a while.
 
I personally do not consider Kits DIY, Just like "Paint By Numbers" isn"t art and a Lego isn"t Construction....
Kits are closer to "Paint my Numbers" than they are to DIY and many Times after finnishing a Kit you haven"t learned a single thing about electronics just like after finnishing a "Paint By Numbers" kit you aren"t any more of an artist, You are just following instructions which anyone who can read can do....

If you really want to do a real DIY project go find a Good preamp schematic and then design and Etch your own PCB and then source your own Parts and troubleshoot any problems yourself....

You should find that after doing this that you will feel much more proud of what you have accomplished and you will have learned a great deal more than any "Kit" could teach you and you will have saved a Lot more money than Buying a Kit, Sure it might take quite a Bit longer to build but most real DIY will take longer and take a Bit of brain Power......

I have a Pretty big Mic preamp schematic collection with power supplies ,some designed by me and some by other poeple, they are all Proven designs and you are wellcome to them.....

Cheers
 
thanks minion.

i have thought about it alot. i printed like 30 pages on a neve 1272 preamp, with part sources and all that jazz. the problem always fell back to PSU's. maybe i should learn to build a PSU or something.

i'm pretty proficient with electronics, enough so that i could properly build them and troubleshoot. i'm not someone who can sit down and build something from their head though. i can't tell you that you need an XYZ diode for this, and a XX uf Capacitor for something else, but i can read my way through a schemo well.

hey, if the offer is there, could you post something you think might be a good starter project? i'm gonna read up on PSU's in my electronics textbook (from school last year) and see what i can learn.

yeah, i dont consider kits to be DIY really either, but it's more than ordering it from a catalog and plugging it in.

so if it's not too much trouble, i'd love your recommendation on a schemo for a pre that i could build. maybe if you got a schemo for a PSU for it too, that would be killer. or even a good link for me to read up on stuff.

thanks alot everyone, again. i love this forum!
 
Well I do have quite a few different PSU Designs but the one I use most often for Mic preamps is the one that is used for the Green Preamp....

The psu can be adapted for pretty much any Voltage and also supplies 48v Phantom power and a single PSU can Power Many Channels of Preamp (probably at least 16 channels with the proper Transformer)....

Actually the "Green Pre" Might be a Good project for you to do....

It is extremely Quiet and Crystal clear and transparent and there are Many different versions you can do that have Varying Features....I did the first version which is the most Basic version and it is the Go to Preamp in My Home studio.....

I see you have Posted a question on the Prodigy pro forum, That Place is a Goldmine of Info and help but they can get a Bit snotty if you have problems understanding there concepts......

If you search the Prodigy pro forum for the Green Pre PSU you will find the PCB design and schematic....It can be used to Power Pretty much any Solid State Mic pre for several channels....

And if you Look at this thread there are many Great Pre amp designs that are really top notch...

http://www.prodigy-pro.com/forum/viewtopic.php?t=20038



:)


PS: Most Solid state preamps will Need a +/-15v to +/-24v and also +48v phantom power and the green pre PSU can supply those Voltages with enough Current for several Channels (with the right Transformer).....
 
Go for the JLM Audio 99v dual opamp job its amazing.....biggest job is getting all the parts together. That JLM PSU is dead easy to make, run em off plus minus 34v with a Llundhal? 1538 input transformer for real clean sound.
Vikki(uk)
 
i've been posting in prodigy pro, they are extremely helpful. they managed to clarify alot, and they inspired me to do my own thing and try to really DIY and build from nothing.

hey minion, do you have a recommendation of a good pre to start with, something relatively simple, where i build the PSU and all? i'm not worried about it being a good pre or anything, i just want something to play with and learn on.
 
I personally do not consider Kits DIY, Just like "Paint By Numbers" isn"t art and a Lego isn"t Construction....
Kits are closer to "Paint my Numbers" than they are to DIY and many Times after finnishing a Kit you haven"t learned a single thing about electronics just like after finnishing a "Paint By Numbers" kit you aren"t any more of an artist, You are just following instructions which anyone who can read can do....

If you really want to do a real DIY project go find a Good preamp schematic and then design and Etch your own PCB and then source your own Parts and troubleshoot any problems yourself....

You should find that after doing this that you will feel much more proud of what you have accomplished and you will have learned a great deal more than any "Kit" could teach you and you will have saved a Lot more money than Buying a Kit, Sure it might take quite a Bit longer to build but most real DIY will take longer and take a Bit of brain Power......

I have a Pretty big Mic preamp schematic collection with power supplies ,some designed by me and some by other poeple, they are all Proven designs and you are wellcome to them.....

Cheers
Click to expand...

you're totally forgetting that most people don't order the kit because they want a DIY project...they do it because the kits are hundreds less than a pre-built preamp
 
What about the Green Pre that the guys on the Prodigy Forums have designed its quite straight forward and produces good results, there's a guy on there selling the pcb's. Looks like someones already mentioned the green so pass on my post.
Vikki(uk)
 
TragikRemix said:
i've been posting in prodigy pro, they are extremely helpful. they managed to clarify alot, and they inspired me to do my own thing and try to really DIY and build from nothing.

hey minion, do you have a recommendation of a good pre to start with, something relatively simple, where i build the PSU and all? i'm not worried about it being a good pre or anything, i just want something to play with and learn on.
Click to expand...


Well Like I mentioned before Maybe try a "Green pre" as they are quite easy to build (Not the easiest pre but still very easy) and all the info and PCB designs can be found at the Prodigy pro forum.....

You can even try something easier like one based on the INA217 Mic preamp IC....The INA217 Datasheet has a schematic for a High quality Mic preamp useing the INA217 that uses very few external components...The preamp has Ballanced inputs but unballanced outputs but you can add an Output transformer or a Ballanced line driver at the end to create a Ballanced output or even use Impedance Ballanceing which is also very easy and can be implemented by useing a simple resistor to ground at Pin 3 of the XLR of the same value of the Output impedance.....

I built a 2 channel Green pre with PSU for under $50 but I did etch my own PCB"s and sourced my own Parts and scavanged a Chassis which saved me a Lot of Cash...also the Green pre is based arround a couple NE5532 Opamps which are only like 0.25c each.....

The INA217 Chip is only about $5 with about another $5 in Parts per channel Pluss maybe another $20 to build the Power supply for several channels Pluss a Chassis and XLR Connectors and a Transformer so Say maybe $20 per channel if you do it yourself and carefully source your parts and etch your own PCB"s or use a piece of Verto/Perf board.....

If you PM me with your e-mail address I can send you some schematics and PCB designs that should get you started.....


Cheers
 
hey,

thats funny, i've been research the green pre all evening now ;)

the website
http://1176neve.tripod.com/id11.html

seems pretty straightfoward.

i was also going to etch the PCB's. since it gives me all the info for the PSU and everything, it will not be a big problem for me.

one question i have, on the website, he says that you can switch it either from 15V or 18V, which does the pre call for, or does it not make a difference? can i push the 18v even if the pre is only going to be using, say 12v, and have the circuitry block that out?

where does it mention the power requirements of the circuit? it doesnt mention it anywhere on the schemo itself to my knowledge, it just has (+) and (-), and 48v..
 
and also, another thought; the gain rotary switch..

couldnt i just substitute a pot for that? what value would i use for that?
 
Tragic,

The Green is a great starting point and a great pre..........it's origins go back to the Amek Mozart consoles. That said, if you have questions about it you would be far better off to ask at "The Lab" or contact PeterC direct, he's a nice guy and the Green was his baby.

:cool:
 
The "Green Pre" Can be run from +/-15 to +/-18...with +/-18 you have a slight bit more headroom but the chips will run a bit hotter as they are only rated at a Max of +/-18v so I personally didn"t want to risk Frying the Chips so I went with +/-15v...

Also there are several different PSU"s that can be built for this Preamp , Some use the 7815/7915 Regulators and some use the LM317/337 regulators , the LM317/337 are adjustable with a Resistor so you can change the Voltages in the Future if you want to and the LM317/337 are much Quiter with Much less ripple than the 7815/7915 regulators so If I were you I would find a PSU design that uses the Lm317/337 regulators, but they are more expensive....

As for the Rotary Gain Switch it is very difficult to find a pot that you can use as a replacement for the Rotary Gain switch as you would need a 120k Reverse Log Taper Pot which are extremely rare and hard to find.....I suppose you could use a 100k reverse log taper pot but the Minimum gain would be something like 20db (just a Guess) as opposed to being 0db as minimum gain but it shouldn"t affect the Maximum Gain.....

You could also try building several channels of different preamp circuits in the Same Chassis so you get different Flavors in the Same Box....I know of one very good mostly descrete design that is very simple and has near theoretical minimum noise and 30db (for fully discrete design) or up to 60db (with discrete and IC hybrid design) that can use as little space as 2in x 2in of PCB space per channel.....

Like I said before if you would like to see some of these designs then PM me with your e-mail and I"ll send them to you....

Cheers
 
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