If you want them to be solderable by many then SOT223 regulators should be fine. Cursing in the church: almost any set of local regulators like even 78xx/79xx or better LM317/LM337 is already better than no set of local regulators at all.
That having said I would pick an LDO regulator of today. The TPS7A4901/3001 were not difficult to solder. Fine performance too.
It is 2024 after all, SMD is standard for decades. Insisting on TH is like wanting to drive a steam powered car. Admitting to TH means DIP opamps in 1-2-3.
That having said I would pick an LDO regulator of today. The TPS7A4901/3001 were not difficult to solder. Fine performance too.
It is 2024 after all, SMD is standard for decades. Insisting on TH is like wanting to drive a steam powered car. Admitting to TH means DIP opamps in 1-2-3.
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Hi Geoff. Just got up and thought of PCB mount XLR connectors. There is much space on the board. Saves a lot of ugly wiring too and although I have the Molex KK crimping stuff not everyone has. Why add wiring when it is not necessary? One will have to obtain XLR connectors anyway be it chassis mount or PCB mount.
The original design had a lot of well thought out features like onboard XLR, 2 inputs switched by relay (everyone thinks 1 source is enough until a friend comes buy to demonstrate his DAC), CRC in the PSU, muting and practically no wiring except the AC wires. Encasing it was therefor easier and the first view was tidy. Its only real drawback was the linear potentiometer and a possibly bad wiper.
BTW ADP7118/7182 are available in TSOT which is definitely solderable by hand. Never used them so input by others would be welcome as always.
The original design had a lot of well thought out features like onboard XLR, 2 inputs switched by relay (everyone thinks 1 source is enough until a friend comes buy to demonstrate his DAC), CRC in the PSU, muting and practically no wiring except the AC wires. Encasing it was therefor easier and the first view was tidy. Its only real drawback was the linear potentiometer and a possibly bad wiper.
BTW ADP7118/7182 are available in TSOT which is definitely solderable by hand. Never used them so input by others would be welcome as always.
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I'd planned to have an input selector before the muses so it would be a bit redundant for me. That said as long as the mounting holes for the molex are kept I'm not bothered.
It is a Putzeys balanced preamp with Muses volume control to cure the Achilles' heel of the original. The Putzeys design has relay controlled inputs which is about the best one can have with shortest possible PCB tracks/wiring. No wiring, no antennas, no crimping, no chain of various contacts, no crosstalk, no source switch, no possible bad contacts of badly crimped Molex KK, no reseating of Molex KK necessary after time ......In short it is about the best one can choose seen from various angles. Someone was doing the most to obtain best results. Good old fashioned engineering. This was the reason of its success and performance. I do wonder what the guy himself would say today about the choice for that potentiometer.
One could argue to have the PCB exactly compatible with the original to give existing users of the original one a drop in replacement. The PCB was done very convenient even with onboard source switch. Those that like excess wiring generally also like modular approach and Bruno Putzeys apparently is not one of them 🙂
One could argue to have the PCB exactly compatible with the original to give existing users of the original one a drop in replacement. The PCB was done very convenient even with onboard source switch. Those that like excess wiring generally also like modular approach and Bruno Putzeys apparently is not one of them 🙂
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Strictly, it isn't. I'm going by all that's been published to date, single input, single output. I can see why you'd want to avoid wiring, but by adding input selection to the boards you're actually making it more specialised and reducing it's utility.
Big IMO/YMMV there of course and an advance apology if I've misunderstood the direction of the thread...
Thread title is:"Putzeys Balanced Preamplifier with MUSES72323 Volume" 🙂
You are a nice guy but you state that having 2 inputs instead of 1 is reducing its utility?!?! What is the agenda? A preamp without source selection is no usable preamp in many many cases 😀 Anyway it is Geoffs thread, time and energy, best is he decides. My experience with group projects is broad and also that always some totally irrealistic demands come up. One has to make decisions based on input of members if one is willing to do so. But ... before you know it someone asks for adaptation to an existing input board that no one else has.
I am pretty sure the board can have all the stuff and the ESP32 on just 1 board with the encoder where the potentiometer originally was. Certainly when the average DIY person has to solder a project like this wiring and crimping are about the least he/she needs.
You are a nice guy but you state that having 2 inputs instead of 1 is reducing its utility?!?! What is the agenda? A preamp without source selection is no usable preamp in many many cases 😀 Anyway it is Geoffs thread, time and energy, best is he decides. My experience with group projects is broad and also that always some totally irrealistic demands come up. One has to make decisions based on input of members if one is willing to do so. But ... before you know it someone asks for adaptation to an existing input board that no one else has.
I am pretty sure the board can have all the stuff and the ESP32 on just 1 board with the encoder where the potentiometer originally was. Certainly when the average DIY person has to solder a project like this wiring and crimping are about the least he/she needs.
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Nope. Not what I'm saying and I don't have an agenda. Ultimately if that's the way things go I can always use Geoff's original as in post #1 and be happy.
Two inputs might be enough for you. But what if I want more? Or attaching them to the board makes me compromise on overall preamp layout. I'm saying that adding inputs and input selection to the board makes it harder to incorporate into something else. That's all.
How would you activate input selection change? Switch or through remote & spi with display of selected input on a screen?
The software side of stuff does not interest me a jota. It all starts with sound electric/electronic designing as sound quality is the main goal of audio equipment. Only when that is optimized the software can be done and programmers can go wild on features. If one wants multicolor displays (telling you what you just commanded), features, Bluetooth, remote control, apps, bright blue LEDs and hours of fiddling with programming/changing there are many devices around that focus on exactly these important items. One is kept busy then and does not need to listen to music 🙂
Sometimes it seems that today the main purpose of audio gear so highest possible measured/sonical sound quality (just like Mr. Putzeys clearly intended) is of secondary interest.
What about deprogramming the extra input? Deleting the extra XLR connectors to dev/null if you don't need these? Impossible? Uncomfortable? HàRdWäre?
Sometimes it seems that today the main purpose of audio gear so highest possible measured/sonical sound quality (just like Mr. Putzeys clearly intended) is of secondary interest.
What about deprogramming the extra input? Deleting the extra XLR connectors to dev/null if you don't need these? Impossible? Uncomfortable? HàRdWäre?
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And yet, here we are discussing a board with a muses chip that can only be controlled with a software interface where displaying volume level on an LCD is a natural thing to do. Odd then to have a pre where where the current input is manually selected and not on the display...
I develop software and I spent decades thinking modular/reuse and it's uncomfortable mentally to go back to thinking monolith/AIO 🙂
That's my last word on this, I'll leave it to Geoff to take it where he will, at the end of it, it'll be his name on the board.
Looking through the last few posts, there's a few items to talk about:
- On-board XLR input and output connectors
The original Putzeys board had two selectable XLR inputs and one mutable XLR output. If you go through the original article by Bruno, the use of the selectable inputs was as much as to enable A/B comparisons with other pre-amps. Looking at various posts relating to Bruno's original design and layout, a common query related to adding addition input selections to allow for selection of more than two sources. For my part, and I suspect this is a common configuration for many HiFi users, I wish to be able to select from Phono, Media player / DAC, CD player (hardly used these days) and a Tuner. Others also want provision for tape in/out. My choice of solution to this is a separate input/output board, hence the external source select function you may see in the controller I use. This also happened to be the solution my original 2012 Douglas Self designed pre-amp used. I'm sticking with this as it provides the easiest and most adaptable option. - On-board ultra-low noise LDO regulation
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Whoops, seem to have hit the wrong button mid-typing 🙄
Looking through the last few posts, there's a few items to talk about:
Looking through the last few posts, there's a few items to talk about:
- On-board XLR input and output connectors
The original Putzeys board had two selectable XLR inputs and one mutable XLR output. If you go through the original article by Bruno, the use of the selectable inputs was as much as to enable A/B comparisons with other pre-amps. Looking at various posts relating to Bruno's original design and layout, a common query related to adding addition input selections to allow for selection of more than two sources. For my part, and I suspect this is a common configuration for many HiFi users, I wish to be able to select from Phono, Media player / DAC, CD player (hardly used these days) and a Tuner. Others also want provision for tape in/out. My choice of solution to this is a separate input/output board, hence the external source select function you may see in the controller I use. This also happened to be the solution my original 2012 Douglas Self designed pre-amp used. I'm sticking with this as it provides the easiest and most adaptable option. - On-board ultra-low noise LDO regulation
Having looked at the suggested ultra-low noise LDOs, my feeling are they aren't reasonably easily assembled onto a board by many even moderately skilled DIYers. Also, the potential benefits from them aren't necessarily needed for this already low noise circuit. - On-board Input/Output XLR connectors
The original Putzeys circuit included these and within the original article these were primarily in place to enable easy A/B comparison to other pre-amp solutions. Looking at queries brought up in an earlier (and still active) discussion on the pre-amp, there was a need for more than two input sources, which was typically solved by means of separate input/output selector bords. That's the solution I have on my current setup, this I inherited from my earlier Douglas Self 2012 Pre-amplifier design. As a solution, it has stood the test of time. - Output Muting
My current setup has output muting but it's on the separate input/output board I use. Provided I don't need to move too much around to do it, I'll add it onto the current board. If like me you don't need it, it can easily be linked out. - Controller / Programming
Inherent in having a digital volume controller is having something to actually control it. How you do it and what bells and whistles you include in that is entirely up to each one of you. There are a number of different microcontrollers that can be used to facilitate the control for the Volume chip. In the past, I've chosen to use an Arduino Nano for this and coupled it up with rotary encoder, infra-red receiver and LCD display. For my current implementation, I went over to using an ESP32 dev board couped with the same rotary encoder, IR receiver but a bigger, brighter, easier to read TFT display. Like Steven mentioned, programming methodology invites the modular approach - namely using libraries of code to do common tasks you may want to use again in other functions. If you have a look at the coding I've linked to, you'll see lots of commonality to the code used for the Arduino version and for the ESP32 version. I happened to have remote handsets around for my Arcam CD player and Tuner. These are also intended to communicate to an associated Amplifier. These handsets use RC5 protocol for doing the remote comms and that's what I did for my implementation. It would also be quite easy ( the libraries are freely available) to cater for an Apple, NEC or whatever controller.
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I don't. I can crimp them quite easily with a £25 repair mans crimping tool. Also, there's no reason not to hardwire them if you really want to or use your own favourite 0.1inch pitch connector
It's the original input relay board I had in my system for input selection.
My original preamplifier consisted of a set of boards (PSU, Phono, input select, main preamp/tone control and a couple of others) which were designed by Douglas Self and published in the Elector on-line magazine as Preamplifier 2012. It was an excellent preamplifier but as I got older and lazier, the lack of remote control for volume and source selection started me on my DiyAudio travels and I began one by one to replace each of the modules with something of my own design.
Board revised to include output muting relay circuitry (as per original Putzeys design).
There's still shed loads of space on the board so I'll look at adding the go-faster regulator parts for those that may want to use them. For those that may find assembling the ultra low noise LDO packages onto the board, it is quite easy to not fit them and just fit links in their place. More later...
How would the mute relay be switched? I can see the muses offers 120db mute, I'd be more inclined to use that tbh unless the relay is offering something more that just absolute black...
Not asking for the relay to go, just curious...
Not asking for the relay to go, just curious...
If you have a look at the original "The G word" article that forms the basis of this current one, there is a relay and relay activation circuit that ensures the pre-amp output is shorted out in the absence of dc power. The relay doesn't do anything except when power is applied or removed, i.e. switch on or off of the pre-amp. It's there purely to prevent speaker thump in the event of turning your pre-amp off before the power amp.
Ahhh, ok. Thanks, then it's not the mute I was looking for (if you know what I mean) and I'd be using the muses mute regardless...
Looking at my setup in use at present, there isn't an output muting relay in place . Today, turning off the pre-amp while the power amp is still active induces speaker thump. I'd tried it a couple of days ago and no thump.
Guess what? I'll be adding the output relay into my setup - I can't rely on the wife remembering to switch stuff off in the correct order!
Guess what? I'll be adding the output relay into my setup - I can't rely on the wife remembering to switch stuff off in the correct order!