PGA2500
- Thread starter Rochey
- Start date
Help Support GroupDIY Audio Forum:
About a month ago, I had a call from my friend from Russia,
his work is FOH for filarmony (big orchestra).
He asked me for 48 digitally controlled pre-amps, with output
splited to 2 consoles.
At his home studio, he using my Studio Box which includes
controll room module, 2 discrete transistor class A
transformer-based preamps, 24-input summing and phone amps.
It using >100 relays to implement digital controll over everything
even switching pre's to mix mode...
so the mind was to build same pre's with other interface.
Then, came up idea about RF or infrared controll, then, like normal
freaks, we calculated whole project's cost and said:
"Heheheh....Beavis....NO WAY!!!!!!!!!"
I heard PGA2500 evaluation board, can't say it is best sounding pre'
for my bad taste..
A way OT, but I like 5-80k bandwidth high-level trunny's,
cascode single-ended fet-bipolar topology which gives
at least 22 dB relation beetween 2nd and 3rd harmonic,
when loaded heavy with high level, and allmost
distortionless at low signals, +/-24v power supply's...etc...
Anyway, PGA2500 is clean pre-amp and worth each penny soundwise.
Last week, I stared on this tread, then called guy who programmed
chips for my projects.
Everything seems possible, and came up an architecture
of 16-channel system, which can control 1-16 of PGA's, with
single or splitted control, TX/RX interface, etc.
I going to use poly's on input of PGA, but place for 'lythic's
will be reserved on PCB as well.
To achieve good headroom, PGA will be followed by fast 10dB amp,
running on +/-18V, and 20 dB PAD will be automatically
inserted on input when running at gain range 0-20dB.
This way, we have 0-75 dB gain range, phantom/phase/insert
(for HPF or EQ), "smart gain" button which puts down gain when
-3 or -1 dB reached, gain encoder...2x7-digit display...etc.
Don't think I will ever do more than these 48 digitally controlled pre's...
(the reason to run your own business is to do things you like)
(but who knows?)
Anyway, it can come up as great DIY project.
Have some days to think on this, to take this project or no.
Is there some interest for making this as DIY project?
Thoughts? Ideas?
Huh. Too much english typing for today. Lafroaig.
his work is FOH for filarmony (big orchestra).
He asked me for 48 digitally controlled pre-amps, with output
splited to 2 consoles.
At his home studio, he using my Studio Box which includes
controll room module, 2 discrete transistor class A
transformer-based preamps, 24-input summing and phone amps.
It using >100 relays to implement digital controll over everything
even switching pre's to mix mode...
so the mind was to build same pre's with other interface.
Then, came up idea about RF or infrared controll, then, like normal
freaks, we calculated whole project's cost and said:
"Heheheh....Beavis....NO WAY!!!!!!!!!"
I heard PGA2500 evaluation board, can't say it is best sounding pre'
for my bad taste..
A way OT, but I like 5-80k bandwidth high-level trunny's,
cascode single-ended fet-bipolar topology which gives
at least 22 dB relation beetween 2nd and 3rd harmonic,
when loaded heavy with high level, and allmost
distortionless at low signals, +/-24v power supply's...etc...
Anyway, PGA2500 is clean pre-amp and worth each penny soundwise.
Last week, I stared on this tread, then called guy who programmed
chips for my projects.
Everything seems possible, and came up an architecture
of 16-channel system, which can control 1-16 of PGA's, with
single or splitted control, TX/RX interface, etc.
I going to use poly's on input of PGA, but place for 'lythic's
will be reserved on PCB as well.
To achieve good headroom, PGA will be followed by fast 10dB amp,
running on +/-18V, and 20 dB PAD will be automatically
inserted on input when running at gain range 0-20dB.
This way, we have 0-75 dB gain range, phantom/phase/insert
(for HPF or EQ), "smart gain" button which puts down gain when
-3 or -1 dB reached, gain encoder...2x7-digit display...etc.
Don't think I will ever do more than these 48 digitally controlled pre's...
(the reason to run your own business is to do things you like)
(but who knows?)
Anyway, it can come up as great DIY project.
Have some days to think on this, to take this project or no.
Is there some interest for making this as DIY project?
Thoughts? Ideas?
Huh. Too much english typing for today. Lafroaig.
jensenmann
Well-known member
[quote author="Igor"]
Huh. Too much english typing for today. Lafroaig.[/quote]
Ramazotti and espresso here :green:
Huh. Too much english typing for today. Lafroaig.[/quote]
Ramazotti and espresso here :green:
> can a Microchip PIC Microcontroller be used for the SPI communication ?
You can do it with a Basic Stamp II and a couple buttons, LEDs or LCDs if you want it.
http://geocities.com/SiliconValley/Orchard/6633/EEPROM.html
http://geocities.com/SiliconValley/Orchard/6633/max187.html
http://www.parallax.com/Portals/0/Downloads/appnt/sx/An20Spi.pdf
http://www.parallax.com/Portals/0/Downloads/docs/prod/sx/SpiDemom.zip
http://www.seetron.com/
You can do it with a Basic Stamp II and a couple buttons, LEDs or LCDs if you want it.
http://geocities.com/SiliconValley/Orchard/6633/EEPROM.html
http://geocities.com/SiliconValley/Orchard/6633/max187.html
http://www.parallax.com/Portals/0/Downloads/appnt/sx/An20Spi.pdf
http://www.parallax.com/Portals/0/Downloads/docs/prod/sx/SpiDemom.zip
http://www.seetron.com/
Dunno... just hooked up PGA to uP and checked we can change gain
and light up 1's at GPO's....still far to be a project
Yes, Basic Stamp simplifyes the things, but Assembler+PIC
rules. You know exactly what happens, without surprises.
Parts cost isn't so high, programming/R&D...yes.
The plans are gorgeous.
Dunno...let's see...
wtmnmf
Well-known member
Igor - You are encouraged to proceed at top speed!!! I've just picked up 25 of these :green:
Can you recommend a good distributer fot PGA's?
Ordered some pcb's for tests...there's some points
on interface to be solved...
BTW.
Idea about output buffer is to take something like
DRV134's output circuit...with gain of3,OPA2604 or worst case 5532
will do perfect job. Even possible to go without output coupling
caps and additional DC servo's, OPA2604 has an excellent DC char's.
Or....
Very like opa1632's.
Sound-wise, cleanest thing and excellent chip.
Tried them in volume controller...nice. No color at all.
But.
Nothing about driving cap/ind loads in datasheet.
Loong cables????Real world......
And, this little chip doesn't like when it's output see ground.
(common situation if connected to unbalanced input...)
Hmmm....
In my pre's, will need to have a split option on PCB.
Output current!!!!!!! And, loong cables......
THEN....something discrete???????
Why not?
Will drive long lines like a big boy...+/-24V...Huge current....Fast....
PGA have CM pin...excellent to bias transistors....
People?
Ordered some pcb's for tests...there's some points
on interface to be solved...
BTW.
Idea about output buffer is to take something like
DRV134's output circuit...with gain of3,OPA2604 or worst case 5532
will do perfect job. Even possible to go without output coupling
caps and additional DC servo's, OPA2604 has an excellent DC char's.
Or....
Very like opa1632's.
Sound-wise, cleanest thing and excellent chip.
Tried them in volume controller...nice. No color at all.
But.
Nothing about driving cap/ind loads in datasheet.
Loong cables????Real world......
And, this little chip doesn't like when it's output see ground.
(common situation if connected to unbalanced input...)
Hmmm....
In my pre's, will need to have a split option on PCB.
Output current!!!!!!! And, loong cables......
THEN....something discrete???????
Why not?
Will drive long lines like a big boy...+/-24V...Huge current....Fast....
PGA have CM pin...excellent to bias transistors....
People?
Svart
Well-known member
FPGA? The smallest FPGAs are cheaper than stamps and pics.
Xilinx has free SPI IP that you can use..
You can also use a CPLD for SPI control, cheaper than PIC and STAMP too..
CPLDs can be flashed one time whereas the FPGA needs a PROM for bootup.
Xilinx has free SPI IP that you can use..
You can also use a CPLD for SPI control, cheaper than PIC and STAMP too..
CPLDs can be flashed one time whereas the FPGA needs a PROM for bootup.
[quote author="PRR"]> can a Microchip PIC Microcontroller be used for the SPI communication ?
You can do it with a Basic Stamp II and a couple buttons, LEDs or LCDs if you want it.
http://geocities.com/SiliconValley/Orchard/6633/EEPROM.html
http://geocities.com/SiliconValley/Orchard/6633/max187.html
http://www.parallax.com/Portals/0/Downloads/appnt/sx/An20Spi.pdf
http://www.parallax.com/Portals/0/Downloads/docs/prod/sx/SpiDemom.zip
http://www.seetron.com/[/quote]
thx prr
will take a look on to that
You can do it with a Basic Stamp II and a couple buttons, LEDs or LCDs if you want it.
http://geocities.com/SiliconValley/Orchard/6633/EEPROM.html
http://geocities.com/SiliconValley/Orchard/6633/max187.html
http://www.parallax.com/Portals/0/Downloads/appnt/sx/An20Spi.pdf
http://www.parallax.com/Portals/0/Downloads/docs/prod/sx/SpiDemom.zip
http://www.seetron.com/[/quote]
thx prr
will take a look on to that
yes?
watching to see what happens
watching to see what happens
Andy Peters
Well-known member
[quote author="Svart"]I'm working on building up protocol state machines in VHDL..
[/quote]
I've written both a "simple" SPI master and a fully-configurable SPI master that emulates the Silicon Labs 8051's peripheral.
The former is about a dozen lines of VHDL. Essentially it is two shift registers (transmit and receive) and a shift enable.
The latter is rather more complicated, although it's a lot smaller than the Xilinx IP core that it replaced. It started out being simple, but then I added generics to control the length of the shift registers (at compile time), and whether a receiver should actually be built, and whether the slave-select output is automatically asserted by the state machine or whether it has to be driven by a separate control. This last option was added when I needed to access the Xilinx Spartan 3AN internal EEPROM, where some functions have longer commands than others.
-a
[/quote]
I've written both a "simple" SPI master and a fully-configurable SPI master that emulates the Silicon Labs 8051's peripheral.
The former is about a dozen lines of VHDL. Essentially it is two shift registers (transmit and receive) and a shift enable.
The latter is rather more complicated, although it's a lot smaller than the Xilinx IP core that it replaced. It started out being simple, but then I added generics to control the length of the shift registers (at compile time), and whether a receiver should actually be built, and whether the slave-select output is automatically asserted by the state machine or whether it has to be driven by a separate control. This last option was added when I needed to access the Xilinx Spartan 3AN internal EEPROM, where some functions have longer commands than others.
-a
Andy Peters
Well-known member
[quote author="Svart"]CPLDs can be flashed one time whereas the FPGA needs a PROM for bootup.[/quote]
Xilinx Spartan 3AN has internal config memory, which is cool, and you can use it to store general-purpose stuff (like gain settings) in addition to the configuration.
And Digikey tells me that the XC3S50AN in TQFP-144 is nine dollars. Wow.
Lattice also have FPGAs with internal config EEPROM.
-a
Xilinx Spartan 3AN has internal config memory, which is cool, and you can use it to store general-purpose stuff (like gain settings) in addition to the configuration.
And Digikey tells me that the XC3S50AN in TQFP-144 is nine dollars. Wow.
Lattice also have FPGAs with internal config EEPROM.
-a
Like this:
(one pre's pcb layout):
PIC's are still breadboarded....
A lot of work on programming.
We doing 16x pre's interface with smart gain, memory banks, etc. features.
And a lot of work outside this project.
So, it goes slowly...but SURE
(one pre's pcb layout):
PIC's are still breadboarded....
A lot of work on programming.
We doing 16x pre's interface with smart gain, memory banks, etc. features.
And a lot of work outside this project.
So, it goes slowly...but SURE
Rolo - chill man
I'm sure Igor will have it in good time!
I'm sure Igor will have it in good time!
Hmmm...Yap....
We can controll gain and general purpose outs of PGA2500...
The thing left is interface between master whish controls 16xpre's
(it can be any qty in range 1-16 btw) and controll boards itselves
(small pcb with pic, bcd to 7seg, rotary, indicators,
4 buttons and address switch)....
Two lines for tx/rx where you can parallel up to 16 controll boards.
And...some misc stuff like avoid clicks when phantom on/off,
real-time update in case tx/rx wireless and dead (real world)...
Well, it should be option for wiress controll, if we go digital!
:razz:
The interface is rs-232 compatible.
There's a lot of chinese 232-compatible RF interfaces....
ok...slow...but sure....
:roll:
:shock:
We can controll gain and general purpose outs of PGA2500...
The thing left is interface between master whish controls 16xpre's
(it can be any qty in range 1-16 btw) and controll boards itselves
(small pcb with pic, bcd to 7seg, rotary, indicators,
4 buttons and address switch)....
Two lines for tx/rx where you can parallel up to 16 controll boards.
And...some misc stuff like avoid clicks when phantom on/off,
real-time update in case tx/rx wireless and dead (real world)...
Well, it should be option for wiress controll, if we go digital!
:razz:
The interface is rs-232 compatible.
There's a lot of chinese 232-compatible RF interfaces....
ok...slow...but sure....
:roll:
:shock:
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