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DIY audio: what are you building?


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On 06/06/2020 at 9:47 PM, DQ828 said:

Slowly getting there, I'll dunk it in some resin next.

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Hi Simon

Regarding your image with a shield around the toroidal, there is a general rule I always follow, that is never to circumnavigate earthing wiring around any transformer. The shield is quite OK, and a good idea,  on its own, which can be viewed as a  Faraday shield  https://en.wikipedia.org/wiki/Faraday_cage

 

The green earth wire therefore is not needed to touch other earthing, or indeed the shield you have made, should also insulate from earth chassis metal. 

 

The reasons for this are that the fields you are trying to cancel from the transformer, are then given possible path to couple, see "What causes Earth Ground loops"   https://sound-au.com/earthing.htm

 

I hope that is helpful

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4 hours ago, RankStranger said:

Be careful because there’s not much between making a round hole big enough to take the square nub and being visible outside the circumference of the washer

 

Thanks for the warning, Simon - I shall investigate closely, in due course.

 

Andy

 

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On 08/06/2020 at 1:20 PM, stereo coffee said:

Hi Simon

Regarding your image with a shield around the toroidal, there is a general rule I always follow, that is never to circumnavigate earthing wiring around any transformer. The shield is quite OK, and a good idea,  on its own, which can be viewed as a  Faraday shield  https://en.wikipedia.org/wiki/Faraday_cage

 

The green earth wire therefore is not needed to touch other earthing, or indeed the shield you have made, should also insulate from earth chassis metal. 

 

The reasons for this are that the fields you are trying to cancel from the transformer, are then given possible path to couple, see "What causes Earth Ground loops"   https://sound-au.com/earthing.htm

 

I hope that is helpful

 

The names David :)

 

Hmmm interesting, the last 2 transformers I had custom built by Harbuch Transformers came with Flux Bands and earthing leads coming off them so I just followed thier lead. The EI transformer I pulled out of of a Mazantz amp had a flux band but I cant say whether it was earthed.

 

My lasted Preamp has one of the Harbuch transformers in to so I might try and sidconnect the flux band earth lead from the Star Ground and seee if anything changes.

 

Well it finished, but it will be sitting on the shelf for a while as I ned to get on and make a stereo cabinet to put all this gear in, and it will take a while!

 

 

 

Tran 10.jpg

Tran 11.jpg

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3 hours ago, DQ828 said:

 

The names David :)

 

Hmmm interesting, the last 2 transformers I had custom built by Harbuch Transformers came with Flux Bands and earthing leads coming off them so I just followed thier lead. The EI transformer I pulled out of of a Mazantz amp had a flux band but I cant say whether it was earthed.

 

My lasted Preamp has one of the Harbuch transformers in to so I might try and sidconnect the flux band earth lead from the Star Ground and seee if anything changes.

 

Well it finished, but it will be sitting on the shelf for a while as I ned to get on and make a stereo cabinet to put all this gear in, and it will take a while!

 

 

 

Tran 10.jpg

Tran 11.jpg

Sorry I had your name wrong David. Yes its the concept of creating a earth in itself around the outer flux of the toroidal, but not inviting what is then nicely contained, to go elsewhere. 

 

Some fascinating points about toroidals is flux is highest at the inner core, and when not subject to loading, from circuitry drawing current, flux is awkwardly at its highest. This then goes on with very low current draw circuits to play havoc where smaller than 10va  toroidals are used.  The circuits I build are 20ma or less, and I always use a 20VA or higher for that reason.

 

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I don't know how much interest there is in this, but I have turned a raspberry Pi into a poor mans Audio Puffin.

 

I implemented this 2 ways - a command line version using Ecasound, and a graphical version using Puredata which is way cool (picture below).  Puredata is a graphical design language for working with multimedia.  So easy, just draw lines to connect function blocks.

 

I have all the basic phono stuff working - Rumble Filter, Gain, Phono Equaliser, Scratch Filter, Bass Boost and "Air". Slider controls for the parameters are coloured.   I have made extensive use of the same LADSPA audio plugins in both versions.

 

In the picture below it is set up for playing old jazz 78s that I have (turnover 250 Hz, flat (no rolloff), scratch filter 5500 Hz.

 

image.png.fe7e461f5364e078e18012db59212d2d.png

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Lots of improvements.  Presets on eq settings,  stereo/mono switching and mixing, loudness switch, lots of presets on everything, COMMENTS in the code/drawing :) 

 

image.png.c2b9dace4943f8bb5bf9e6872f967253.png

Edited by aussievintage
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46 minutes ago, aussievintage said:

Lots of improvements.  Presets on eq settings,  stereo/mono switching and mixing, loudness switch, lots of presets on everything, COMMENTS in the code/drawing :) 

 

image.png.c2b9dace4943f8bb5bf9e6872f967253.png

This one is way beyond my pay level in this hobby...

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1 hour ago, Red MacKay said:

This one is way beyond my pay level in this hobby...

 

Nah, it looks more complicated than it is.   

 

You could grab a raspberry Pi, and a hifiberry DAC ADC hat (or other audio interfaces), install Raspbian, Puredata, etc and run my program, and have a poor man's Audio Puffin (that's over $700 on Amazon Australia).

 

Note, I haven't tried a hifiberry hat yet.  I have prototyped this on USB interfaces I already had (at 16 bit/48kHz), but I think I'll buy a hat, 'cos it will give me 24bit/192kHz I believe (depending on CPU load etc).  The DAC ADC hat has up to 32 dB gain, so, pending loading requirements etc, it may work as is.   

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9 hours ago, aussievintage said:

 

I don't know how much interest there is in this, but I have turned a raspberry Pi into a poor mans Audio Puffin.

 

I implemented this 2 ways - a command line version using Ecasound, and a graphical version using Puredata which is way cool (picture below).  Puredata is a graphical design language for working with multimedia.  So easy, just draw lines to connect function blocks.

 

I have all the basic phono stuff working - Rumble Filter, Gain, Phono Equaliser, Scratch Filter, Bass Boost and "Air". Slider controls for the parameters are coloured.   I have made extensive use of the same LADSPA audio plugins in both versions.

 

In the picture below it is set up for playing old jazz 78s that I have (turnover 250 Hz, flat (no rolloff), scratch filter 5500 Hz.

 

image.png.fe7e461f5364e078e18012db59212d2d.png

Looks like fun :) Well done

 

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3 minutes ago, oohms said:

What sort of DSP horsepower does a raspberry pi have?

Ah, that was the thought that started my experiment.  On a raspberry Pi 3B it all runs with about 20% cpu - see the monitoring program below and command line tools.   I thought I might need a Pi 4 for more memory and grunt, but not at 48kHz anyway, it is running smoothly.

 

 

image.png.340277c90d9688ed4d422b71dd46fdaa.png

 

                    total             used        free          shared  buff/cache   available
Mem:         948280      196428      326716       18012      425136      675984
Swap:        102396        1280          101116

 

 

  PID USER      PR  NI    VIRT    RES        SHR S  %CPU  %MEM     TIME+ COMMAND    
 8535 pi            -7      0    25764  10260   7624 S  18.2           1.1            61:05.63 pd         
 

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2 minutes ago, aussievintage said:

PID USER      PR  NI    VIRT    RES        SHR S  %CPU  %MEM     TIME+ COMMAND    
 8535 pi            -7      0    25764  10260   7624 S  18.2           1.1            61:05.63 pd      

 

Actually that's just Puredata.  Total load seems to stay under 50% easily - that's with Raspbian desktop and VNC running.  Puredata and Wish (Tcl) seem to be under 30% of the total.

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Thought it worth a photo of the test rig. As I said, it's only 48kHz capable, but the sound is still quite good.   

 

All this stuff is USB powered from the tiny rPi as well.

 

 

 

IMG_20200611_083524.jpg.0d94e8afccf6d33c16412dcb591194ca.jpg

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I have more pairs of Gold Lion E88CC for yet another SRPP preamp. Bruce of American oddwatt fame has given me a new SRPP design for these tubes. Got all the parts from de lab only had to buy the chassis. Biggest decision is What colour?

4C05F4AC-FCF9-4849-94DA-5BC8FC69D1DE.jpeg

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In the past i have had PCBs made at Seeed Studio but they also have an array of assembled boards for Raspberry Pi.

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On 10/06/2020 at 9:20 AM, aussievintage said:

...I have turned a raspberry Pi into a poor mans Audio Puffin.

Now that I've googled Audio Puffin and know what you done, I'm impressed.

Ingenious and inexpensive.

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36 minutes ago, pwstereo said:

Now that I've googled Audio Puffin and know what you done, I'm impressed.

Ingenious and inexpensive.

 

I'm a bit chuffed with myself too :)   So much functionality on the cheap.    I just plugged my D10 DAC into the output of the rPi.  I must say, the Fiio is pretty good anyway, but the D10 at least shows the sample rate.

 

I am just going to have to shell out for a Hifiberry DAC+ ADC hat.  That will put everything in one small box.

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6 hours ago, mwhouston said:

I have more pairs of Gold Lion E88CC for yet another SRPP preamp. Bruce of American oddwatt fame has given me a new SRPP design for these tubes. Got all the parts from de lab only had to buy the chassis. Biggest decision is What colour?

4C05F4AC-FCF9-4849-94DA-5BC8FC69D1DE.jpeg

What is the pot Mark?

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17 hours ago, Red MacKay said:

What is the pot Mark?

The pot is an $80 stepper. Gold contact etc. but I’m going back to a Alps Blue velvet. 

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17 minutes ago, mwhouston said:

The pot is an $80 stepper. Gold contact etc. but I’m going back to a Alps Blue velvet. 

 

Ah, pots.  Another interesting subject.  Don't know if you recall, but I put an ALPs pot into my main preamp a little while back.  Well, I just noticed it is getting noisy already  !!!    Disappointing

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3 hours ago, aussievintage said:

 

Ah, pots.  Another interesting subject.  Don't know if you recall, but I put an ALPs pot into my main preamp a little while back.  Well, I just noticed it is getting noisy already  !!!    Disappointing

Never had it happen and I’ve used about 30. 

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On 10/06/2020 at 9:42 PM, oohms said:

What sort of DSP horsepower does a raspberry pi have?

 

Got a further feel for how well it is coping today.  For starters, I have the scratch and rumble filters set stupidly high while testing (8 poles), so I wound them back to 4 pole, same as the Puffin uses.    Also, it now appears that the cpu load showing, was just from one of the four cpus.  nmon is reporting an average much less than that - about 6%.

 

Next experiment, I turned the processing up 192k sample rate.  This gives about 50% instead of about 15% at48k (again on one cpu).  Not really a fair test, because I was not actually processing audio -I had to use a different input (the internal Pi HDMI interface) as the one I am using for audio stops at 48k

 

IN the end, I don't think the Pi is struggling at all.  

 

 

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OK, not audio, but a DIY kit, Ducati Panigale V4 R by LEGO.

 

Work In Progress.

 

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IMG_0134.thumb.JPG.c881ed00dfcaf8a02098121523f34d44.JPG

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12 minutes ago, mwhouston said:

Partially assembled but not wired - “Rosso” - E88CC/6922 SRPP preamp is starting to come together. .   

CB71CC97-3FB0-4414-B40A-48513BDA55A6.jpeg

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Is it difficult to add a remote with on/off and volume control to an preamp like that? Thanks 

Edited by Bunno77
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1 hour ago, Bunno77 said:

Is it difficult to add a remote with on/off and volume control to an preamp like that? Thanks 

Not usually , the main issue tends to internal space depending of the design of the pre.

Hificollective in the UK sells a kit based on the Alps blue pot and a control board , you just need to power it from around 12v's and make the remote reciver eye visible from the outside. You cam also buy TKD motorised pots to use with the above board ,more expensive but better sounding apparently. The there are the resistor ladder remote boards which I have found to be good.

https://www.hificollective.co.uk/potentiometers/alps-blue-beauty-motorised.html

https://www.hificollective.co.uk/potentiometers/tkd-2cp-2511-mc-motorised-potentiometer.html

https://www.hificollective.co.uk/potentiometers/glasshouse-remote-control-kit-motorised-alps.html

https://www.aliexpress.com/item/33017583213.html?spm=a2g0o.productlist.0.0.5c2339074fZnS7&algo_pvid=cd9822bd-0e39-4367-b94e-d8c7bf508f5d&algo_expid=cd9822bd-0e39-4367-b94e-d8c7bf508f5d-4&btsid=0ab6f83a15921136791847132e5bac&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

None of the above switch the mains but a bit or further research should find something.

https://hfc-fs.s3-eu-west-1.amazonaws.com/s3fs-public/gh_remote_instuctions_0.pdf

Edited by Ozcall
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16 hours ago, Ozcall said:

I'd be interested on any up-to-date feedback on such implementations.

 

Resistor attenuators - FWIW some years ago, experimenting with vol controls, I built a 'ladder' attenuator using a silver-contact switch & experimented with various Rs, eg Holco, Dale, Roederstein Rs.  I found that all the Rs had an obvious 'sound, esp wrt HF tone.

 

And none sounded as good (to me) as a DACT CT-1  switched attenuator (series type).

I never did figure out whether it was the lead-less SMDs that were magic, or something else.

 

I found also that relays in the signal path (eg switching line level signals), flatten 'dynamics  (YMMV of course).

 

Cheers, Owen

Dark Lantern blog - http://darklanternforowen.wordpress.com/

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2 hours ago, Owen Y said:

Resistor attenuators - FWIW some years ago, experimenting with vol controls, I built a 'ladder' attenuator using a silver-contact switch & experimented with various Rs, eg Holco, Dale, Roederstein Rs.  I found that all the Rs had an obvious 'sound, esp wrt HF tone.

Interesting observation.  I had a Khosmo Passive - Shunt style stepped attentuator a couple of years back that I was using purely as a switch - so set to full volume.  I sensed a similar impact on sound quality so did some basic measurement.  I found a noticeable roll off in top end appearing as the volume got close to 100% - from memory it was noticeable in measurement from 80% or so up.  Didn't pursue it further as I switched to a DAC/Pre-amp.

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On 14/06/2020 at 2:49 PM, Bunno77 said:

Is it difficult to add a remote with on/off and volume control to an preamp like that? Thanks 

Difficult to add but easier to construct from scratch. 

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7 hours ago, gibbo9000 said:

Interesting observation.  I had a Khosmo Passive - Shunt style stepped attentuator a couple of years back that I was using purely as a switch - so set to full volume.  I sensed a similar impact on sound quality so did some basic measurement.  I found a noticeable roll off in top end appearing as the volume got close to 100% - from memory it was noticeable in measurement from 80% or so up.  Didn't pursue it further as I switched to a DAC/Pre-amp.

Have read others say this about the shunt type only.

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You have to include the source and load in the evaluation of each type of attenuator - and it makes a considerable difference.  The old "rule of thumb" ratios are just a starting point.

 

Some types of attenuators will suit a load but not a source and the reverse - some types will not suit either but occasionally, a really good match will result in a huge change that'll suit the overall sound to the listener better - many of us settle for a reasonable or convenient compromise but it's never an easy or simple choice - sometimes, we just get lucky.

 

Some systems will benefit with a TVR, some an active stage, some a buffer, etc, etc and as nearly all our hearing preferences are different,  the variations of attenuators have a wide & varied market.

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It lives. Got all done in 5.5 hours - all wiring and filament and HT balance.  Played first on.

 

ive been pleased with the Gold Lion E88CC tubes in a previous build. This one has been re-design and tweaked by Bruce of American oddwatt fame. All different passive values. Beautiful crisp treble and solid bass. The treble is the standout. 
 

Called it “Rosso”. 

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E113AEC7-DE62-46CC-AE80-7FC5368E3230.jpeg

Edited by mwhouston
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My first attempt at DIY, sealed 12 inch Dayton Ultramax, 0retty basic but learnt a lot in terms of wood work atleast... 

 

Finally got the router I had dirty. 

 

Built entirely to their advertised specs, braced sealed box, 2cft, 1lb poly fill. 

 

Sitting on heavy rubber feet

received_2422462908052127.jpeg

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