This is my last preamplifier project. I simply started an experiment with the PGA2310 that finally led me in a complete project - as usually .
A summary of its properties:
1) It can be managed either locally thru 2 push switches and a rotary encoder, or remotely from a RC5 compatible universal remote control handset. Includes 5 Inputs, 1 Main Output and 1 Record Output. Control functions are the 7 basic: a)Power On/Stand By b) Mute c)Volume increment d)Volume decrement e)Balance f)Input selection in forward sequence and g)Input selection in backward sequence. All these functions are also supported by the remote control except the Balance.
2) The analog signal process is obtained thru a PGA2310 programmable volume control IC. Voltage gain can be adjusted from -95 up to +6dB in steps of 1dB. Volume control IC is buffered from input and output devices like CD players and Power amplifiers from four LME49710 operational amplifiers configured as voltage followers.
3) Separate power supplies are used for Analog and Digital section..
4) Input selection and Output Mute functions are obtained with the use of high quality Latching relays. The Stand By function (i.e. enable – disable the analog power supply transformer) is also obtained with a powerful SPNO/10A Latching relay. Latching type relays ensure both power saving and noise immunity on audio signal as their coils are inactive for most time. A momentary voltage pulse of 15ms is enough to change the location of their contacts.
5) The whole device is managed by a PIC16F887 microcontroller. The appropriate program code has obtained with the use of the powerful Visual Programming Software FlowCode v5 of Matrix Multimedia.
For a more detailed description, schematics and an offer to you my good friends a free copy of code in hex format so you can program your PIC16F887 with any type programming device you own please here:
Matrix Multimedia user forums • View topic - Hi-Fi audio preamplifier using Burr-Brown PGA2310
Here some pictures showing its functionality
A summary of its properties:
1) It can be managed either locally thru 2 push switches and a rotary encoder, or remotely from a RC5 compatible universal remote control handset. Includes 5 Inputs, 1 Main Output and 1 Record Output. Control functions are the 7 basic: a)Power On/Stand By b) Mute c)Volume increment d)Volume decrement e)Balance f)Input selection in forward sequence and g)Input selection in backward sequence. All these functions are also supported by the remote control except the Balance.
2) The analog signal process is obtained thru a PGA2310 programmable volume control IC. Voltage gain can be adjusted from -95 up to +6dB in steps of 1dB. Volume control IC is buffered from input and output devices like CD players and Power amplifiers from four LME49710 operational amplifiers configured as voltage followers.
3) Separate power supplies are used for Analog and Digital section..
4) Input selection and Output Mute functions are obtained with the use of high quality Latching relays. The Stand By function (i.e. enable – disable the analog power supply transformer) is also obtained with a powerful SPNO/10A Latching relay. Latching type relays ensure both power saving and noise immunity on audio signal as their coils are inactive for most time. A momentary voltage pulse of 15ms is enough to change the location of their contacts.
5) The whole device is managed by a PIC16F887 microcontroller. The appropriate program code has obtained with the use of the powerful Visual Programming Software FlowCode v5 of Matrix Multimedia.
For a more detailed description, schematics and an offer to you my good friends a free copy of code in hex format so you can program your PIC16F887 with any type programming device you own please here:
Matrix Multimedia user forums • View topic - Hi-Fi audio preamplifier using Burr-Brown PGA2310
Here some pictures showing its functionality
Attachments
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PGA2310 Line Preamplifier - Part 2
Here is a general view of project, and a very - very interesting second picture. In the last you can see the performance of preamplifier. In this DSO screen shot it is obvious the rise time of signal at the output of preamplifier. After a pass thru 3 ICs: LME49710-->PGA2310-->LME49710 the square wave rise time has increased just to 200nsec! That means bandwidth: BW = 0.34 / 200nsec = 1.7MHz with negligible overshoot. Voltage gain was "1" (or 0dB) in this measurement.
Here is a general view of project, and a very - very interesting second picture. In the last you can see the performance of preamplifier. In this DSO screen shot it is obvious the rise time of signal at the output of preamplifier. After a pass thru 3 ICs: LME49710-->PGA2310-->LME49710 the square wave rise time has increased just to 200nsec! That means bandwidth: BW = 0.34 / 200nsec = 1.7MHz with negligible overshoot. Voltage gain was "1" (or 0dB) in this measurement.
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I think the PGA23xx chips are very good. I have used them on my new preamp (still have to box it up) and I am very impressed with the sound and performance.
I remember your debate with other people: discretes vs ICs. You were right my friend. In the meantime i tried some of those new tremendous ICs of National (LME4xxxx). This PGA2310 was also a big surprise to me! I also have some samples of TI OPAxxxx with jfet inputs. I will try these soon.
The only issue - though not so serious - is that LME can work with supply rails up to +/-22V while PGA2310 up to +/-16V as much. In other project with just 2 LME49720 or 2 LME4520 trying different supply levels, in audition tests i had the impression that at +/-18V these operational amplifiers perform some better.
Very good Fotios - let us know your results with the other op-amps. I will try some ADI JFET input devices in the next few months on my 'X-Altra Mini'. I will also report back on my findings.
🙂
🙂
Andrew you should know that I follow closely the development of your project on your website. I snoop you.
Haha 🙂
I am holding thumbs for Greece my friend and hope the sun shines in your country again. Paxos, Santorini, Skopolos, Thasos. Favorite places for me!
FlowCode is one of the highest-level programming languages in the world. Matrix Multimedia offers ready "e-blocks" which can be compined to achive this project. MM has recently added to its e-blocks range, a new module with two rotary encoders. The RC-5 Infrared Tx/Rx e-block already exists 6 months ago. For real time simulation, i use two LED e-blocks in the place of relays. The same for the SDO-CLK-CS lines of PGA2310. BTW, i don't finaly used the SPI of P16F887 for the last. I just assembled a macro to do so, it was easier and resolved stack overflow issues.
Now of course what I am telling you all this at the moment that you can try them yourself?
Thank you so much for the support my good friend. Indeed at this moment, half Greeks - including me - who are not civil servants go through difficult days. But there is no need to worry, the sun still shines over Greece. Greece just needs cleaning up of the state apparatus, that is the problem. If it happens, then the growth will be back swiftly to positive rate.
BTW my place is very close to Thassos island, just 30 kilometers by road and another 10 miles by sea. The Summer we used to go there many weekends, the time required is just 2 hours.
The next time you will be able to come in Greece, will go together in Thassos. In a very beautiful place called Potos.
Yes, i did upgrade to FlowCode v5 (for PIC) from the first day that launched. Some useful new features are:
PortB IOC (Interrupt On Change) is now simulated on all 8 pins of PortB. In previous v4, just from RB.4 - RB.7.
During simulation, if you forgot to initialise some variables an error window appears on the bottom of screen. Thru it, you can directly modify variables.
C-code table of a project, is splitted in two halves. The upper half presents the code in traditional way, while the lower presents the code with icons exactly as in Flow Chart.
And many others that i don't remember this moment.
My project is offered in both v4 and v5. So if you have v4, you can download the corresponding fcf file to play it in simulator.
Are you using the MM EB006 programmer?
VERSION 2
Because enough people asked me for a version with common type relays instead Latching ones, i decided to design this time a multipurpose preamplifier - control unit with any possible facility.
To the present, i can show you only the block diagram to get an idea of what i have in my mind. Enough from the things included on block diagram are requests and advices of a friend from Wales who is working in recording studios and live stages. I have finished the program code today and i am in the process of drawing schematics and PCBs. I also wait to receive parts that i ordered to complette the unit.
I haven't yet decided what OPAs i will use. My main choice are the dual LME49720 or LME4562. But i have still in my mind the LME49710 which offer 125dB PSRR, instead the 120dB of 49720 - 4562.
Tell me please your opinion on this.
Thank you for your attention.
Because enough people asked me for a version with common type relays instead Latching ones, i decided to design this time a multipurpose preamplifier - control unit with any possible facility.
To the present, i can show you only the block diagram to get an idea of what i have in my mind. Enough from the things included on block diagram are requests and advices of a friend from Wales who is working in recording studios and live stages. I have finished the program code today and i am in the process of drawing schematics and PCBs. I also wait to receive parts that i ordered to complette the unit.
I haven't yet decided what OPAs i will use. My main choice are the dual LME49720 or LME4562. But i have still in my mind the LME49710 which offer 125dB PSRR, instead the 120dB of 49720 - 4562.
Tell me please your opinion on this.
Thank you for your attention.
Attachments
This reply simply serves to pull the thread on the first page. I know very well that there are enough people who will be interested in this very useful control unit offered for free.
Fotios, I would put 47 or 50 ohm resistors in series with all your op amp outputs just to make sure if you do end up driving a capacitive load, you won't have an oscillation problem. Nice to see that you have buffered your rec loop by the way!
Opamp choices are ok in my view. Look at the PSRR at HF as well btw -so 50 or 100KHz.
Nice overall design and very flexible in my view. Look forward to seeing the finished result!
Opamp choices are ok in my view. Look at the PSRR at HF as well btw -so 50 or 100KHz.
Nice overall design and very flexible in my view. Look forward to seeing the finished result!
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Thanks Andrew for information, i will put these resistors. I have in my stock 2 - 3 hundreds of 49.9Ω / 0.6W Vishay SFERNICE. Looking at your X-Ultra, i saw that you use DALE resistors. I don't know if these make some difference in sound. To be sincere, i didn't any audition test! Just only measurements with DSO. Fortunately there is a guy who made this project and informed me that, in audition test, -95dB attenuation is quite extreme for PGA2310. He told me that -60dB max attenuation is more than enough.
Well, i already had in my plans to make more flexible the control unit taking into account demands of some members. To obtain it, I have to upgrade the mcu from P16Fxxxx to P18Fxxxx. The current mcu that i use is a PIC16F887 and i spent a 90% of its small program memory (8192 words capacity) so far. Its software stack level has also just 8 level depth.
10 days ago, i received some samples of new PICs from "mom" Microchip in which were included two tremendous new micros. The P16F1827 and the P18F45K22. With the second i can do everything i want (big program memory of 16384 words and 31-level stack) and much more. It offers possibility of capacitive touch on many inputs, so no need for traditional push-button switches.
Currently i am working with P16F1827 to build my own remote control handset compatible with the last upgrade that i have in my plans. I will show the block diagram in the next post.
Happy Easter
Last upgrade
In this upgrade I will include:
1) New powerfull PIC18F45K22 MCU.
2) Replacement of 2 X 16 characters display with a 2 X 20. This will give possibility of printing fractional numbers, e.g. -37.5dB, -22.0dB etc.
3) Additional menu functions for the user:
3.a) Selection between 1dB and 0.5dB step for PGA2310
3.b) Selection of max / min attenuation-amplification level of PGA2310
3.c) Naming of inputs
3.d) Naming of recording devices
4) All main functions will be remotely controlled with the new (12 to 16 buttons) remote control handset.
And much more
Here the new block diagram
In this upgrade I will include:
1) New powerfull PIC18F45K22 MCU.
2) Replacement of 2 X 16 characters display with a 2 X 20. This will give possibility of printing fractional numbers, e.g. -37.5dB, -22.0dB etc.
3) Additional menu functions for the user:
3.a) Selection between 1dB and 0.5dB step for PGA2310
3.b) Selection of max / min attenuation-amplification level of PGA2310
3.c) Naming of inputs
3.d) Naming of recording devices
4) All main functions will be remotely controlled with the new (12 to 16 buttons) remote control handset.
And much more
Here the new block diagram
Attachments
This is overkill.For what you need such a preamp? Will be to expensive also.If you have nothing else to do then you can build it, but nobody else needs it.
Well, dear Leon i have to agree with Bonsai.
In the beginning I had same impression like you. For that reason the prototype that I built, offers just 5 inputs managed by latching relays. Later on, some members at Matrix Multimedia forum asked me if i could make a unit that will include all above. Then I thought like you if the cost will be worthy. Well, the most expensive part is the PGA2310 (Mouser sells it for 15 Euro) but you can find it for 5 Euro in e-bay stores.
You should know that most people make purchases from e-bay, no one is willing to pay "an arm and a leg" shipping cost that charges Farnell, Mouser, Digi-Key, RS etc. I bought 20 pieces Omron G6A234P-BS (one rail) for just 5 Euro, a 2X20 LCD black on yellow for... 1 Euro, very nice SWICHCRAFT gold plated RCA sockets PCB mounting (set of 4 pairs = 5 Euro), what else!
I have collected all parts needed and the cost is roughly 120 Euro. If we add 40 Euro for PCBs and a 1U metal case, total cost will be not more than 150 to 160 Euro.
The concept behind this project, is that with those new super ICs of NS, BB-Texas, ADI etc. discrete implemented preamplifiers does not make sense anymore.
If you want something that sounds really different, make a jump to tubes. For example, Single Ended class-A tube preamplifiers - power amplifiers (offering tons of 2nd harmonic) are the ultimate Hi-End approach.
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