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DIY audio: what are you building?


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15 minutes ago, mwhouston said:

A kit like this is good if you are getting into tube audio. But with just four 5 tag tag strips you can make a point to point preamp and save money for possibly a better result. I know easy for me to say I’ve been doing it for 50 years but once you do one you’ll realise how easy and cost effective it is. I’m happy to guide others if they want to have a go. But not as neat and compact as a PCB based one. 

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I just bought the PCB's because they were cheap and was wanting a nice tube pre-amp, i used to have one before but it was stolen out of my house with amungst other audio related devices i had :( 

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10 minutes ago, aussievintage said:

In these days of earth leakage protection and double insulation,  have you ever wondered about just using a 6 or 12V transformer, and just rectifying the mains for the HT? 

 

Electrically I can't see the problem, and it's not as if Australia never allowed appliances without power transformers.   I remember a portable valve TV that didn't for example.   Not as dangerous as, for example,  240V fluoro tubes sitting in a metal case above open water of an aquarium!!

You HAVE TO HAVE an isolation transformer. I tried it once, using raw 240V, with a tube power amp and nearly wiped out all my gear in one go. Not only that the safety switch with fire if you RCA negatives are earthed. Also I could have killed myself if no safety switch. Don’t try it. 

 

Ill never, ever, ever going to try it again. Just use two 300VAC step down trannies (cheap from Altronics or RS) one backwards. So 240 to 12 - 12 to (near) 240V. I run three tube power amps this way with no problems and you get good mains filtering. Dead safe too. 

4 minutes ago, itsparks said:

 

I just bought the PCB's because they were cheap and was wanting a nice tube pre-amp, i used to have one before but it was stolen out of my house with amungst other audio related devices i had :( 

The beauty of theses compact PCB based kits is you can assemble the PCB in about two stubbies or so. My way is a lot slower and involves more cursing. 

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4 minutes ago, mwhouston said:

 

 

Ill never, ever, ever going to try it again. Just use two 300VAC step down trannies (cheap from Altronics or RS) one backwards. So 240 to 12 - 12 to (near) 240V. I run three tube power amps this way with no problems and you get good mains filtering. Dead safe too. 

The beauty of theses compact PCB based kits is you can assemble the PCB in about two stubbies or so. My way is a lot slower and involves more cursing. 

You're way sure looks good too tho ! Love some P2P action !! Now to find all the pieces for the kit and the hardest part, the transformer.. 

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23 minutes ago, itsparks said:

 

I just bought the PCB's because they were cheap and was wanting a nice tube pre-amp, i used to have one before but it was stolen out of my house with amungst other audio related devices i had :( 

I remember hearing about you having all your gear stolen. That was awful. Hope you are slowly getting back a decent system. My general setup is tube preamp and phono stage with SS power amp. I have four low power tube amps I swap in for the 500W SS amp for a few weeks at a time. Love my little 2W tubers which play loud with my speakers.
 

Tube power amps just seem to do “music” better. Of course I’m 100% DIY here over three seperate systems. Keep us informed of your upcoming build.

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2 minutes ago, mwhouston said:

I remember hearing about you having all your gear stolen. That was awful. Hope you are slowly getting back a decent system. My general setup is tube preamp and phono stage with SS power amp. I have four low power tube amps I swap in for the 500W SS amp for a few weeks at a time. Love my little 2W tubers which play loud with my speakers.
 

Tube power amps just seem to do “music” better. Of course I’m 100% DIY here over three seperate systems. Keep us informed of your upcoming build.

ALL my amplifiers are DIY & pre-amps & speakers :P Only thing Store bought would be the CD player, and at one time that was all DIY.  Hpe one day to finish my Anthony Holton AV800 amplifier mono blocks :) 

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48 minutes ago, mwhouston said:

You HAVE TO HAVE an isolation transformer. I tried it once, using raw 240V, with a tube power amp and nearly wiped out all my gear in one go. Not only that the safety switch with fire if you RCA negatives are earthed. Also I could have killed myself if no safety switch. Don’t try it. 

 

 

Electrically all you need to do is connect the safety earth to signal ground and the case.  It's only if you float them there's any danger.  Think about your toaster - no isolation there, and you WILL get a shock if you touch the element, but also you will trip the earth leakage with even wet toast :) .   As I said,  there were portable TVs and radios on sale in Australia years ago, that had no transformer.  I know I had to fix one that burnt out the big power dropping resistors.  I am sure the regs might prevent it these days.  In America they did it all the time, and even had live chassis.

 

  Note for any beginners, I am not suggesting this in anyway get's around legalities and legislative requirements.  Just musing on what you COULD do.

 

51 minutes ago, mwhouston said:

Just use two 300VAC step down trannies (cheap from Altronics or RS) one backwards. So 240 to 12 - 12 to (near) 240V. I run three tube power amps this way with no problems and you get good mains filtering. Dead safe too. 

 

This is what I do as well.   Although sometimes the first transformer is an external 12V AC plugpack.

 

 

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42 minutes ago, aussievintage said:

 

Electrically all you need to do is connect the safety earth to signal ground and the case.  It's only if you float them there's any danger.  Think about your toaster - no isolation there, and you WILL get a shock if you touch the element, but also you will trip the earth leakage with even wet toast :) .   As I said,  there were portable TVs and radios on sale in Australia years ago, that had no transformer.  I know I had to fix one that burnt out the big power dropping resistors.  I am sure the regs might prevent it these days.  In America they did it all the time, and even had live chassis.

 

  Note for any beginners, I am not suggesting this in anyway get's around legalities and legislative requirements.  Just musing on what you COULD do.

 

 

This is what I do as well.   Although sometimes the first transformer is an external 12V AC plugpack.

 

 

Same here, 24V AC 1A Jaycar special into 24V 130mA Tranni. Works a treat for preamps. 

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A new preamp all completed in record time. Should be Ive probably made eight like this. Gooda lub the obby 

 

Apart from having to replace a faulty RCA (Jaycar’s new RCAs - from last year - don’t solder. I think the center pin is steel and solder just balls up and won’t get a grip).  I have put in a complaint but I didn’t think anyone looks at them. My last complaint never got answered. 
 

Back to the preamp. Sounds detailed, laid back and smooth with the Psvane 12AU7 TIIs. Worked at first on.
 

Voltages are;

HT = 247V

bias = 2.44V

current = 5mA.

 

Im using a Radi0kit external PS kit. Regulated 12V and electronically smoothed HT. Turn it up and it’s dead quiet no hum, buzz, crackle, snap or pop. Looks and sound extremely good. Called it “Noir”. 
 

Alps pot on the output, Russian PIO output caps and SRPP topology. Metal film resistors. Wood cheeks have been finished with a finishing oil. They really have lifted.  Epoxy enamel paint on top of etching primer. Enjoying it now with my 2W 6L6 SE UL wine box amp. 

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I’m not going to post every little nuances of the preamp but must mention this - the sound stage is bloody HUGE!  Stretches way beyond my speakers. My expensive Psvane 6SN7 spheres don’t do this near as well.

 

I thought at first the preamp has some sort of phase issues but under a test CD phasing is perfect. I’m a happy man. I made this for some one else. Hope he changing his mind. 

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Tube buffer with LDR volume control build in progress.

If I ever get my LDR board back from NZ I can finish the build.

But it looks like my customer will have to wait another few month.

I will be ordering from the US next time......

 

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Edited by Ihearmusic
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7 hours ago, Ihearmusic said:

Tube buffer with LDR volume control build in progress.

If I ever get my LDR board back from NZ I can finish the build.

But it looks like my customer will have to wait another few month.

I will be ordering from the US next time......

 

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Looks pro. Schematic? 

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22 minutes ago, Ihearmusic said:

John Broskie designed Octal Aikido Cathode Follower.

A simple but effective affair. 

 

 

 

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An interesting circuit.  I was wondering what all the jumpers etc are about.  I see now, it can be converted to a White cathode follower as well.  Hmmm, something I might have a play with myself sometime.  I have a nice little chassis where I can do a point to point version.

 

 

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This came up on my retro-thermionic FB page. Too bad we don’t have the equivalent here. I suppose it just takes a few people to organise it and a lot to support it. 
 

“The NY Noise show brought together DIY hi-fi artisans who enjoy the glories of lower-powered vacuum tube gear. Their creativity shined through with incredible works of vacuum tube art! Blackie Pagano and JC Morrison organized this New York City extravaganza. This event was strictly by invitation only, and was so popular that it was standing room only!“

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I have no idea how this would sound.
 

Just made my 8,000th post. Do I win a frozen chicken or a hat?  

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12 minutes ago, mwhouston said:

I have no idea how this would sound.
 

Just made my 8,000th post. Do I win a frozen chicken or a hat?  

2C4A2B3B-0DC8-46FC-BE44-ADFFE2E5C747.jpeg

 

Internet cookie ? 

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On 08/02/2021 at 1:05 PM, aussievintage said:

 

 

An interesting circuit.  I was wondering what all the jumpers etc are about.  I see now, it can be converted to a White cathode follower as well.  Hmmm, something I might have a play with myself sometime.  I have a nice little chassis where I can do a point to point version.

 

 

I did get a couple of the boards of the Glassware web shop and I am very impressed with the quality of the PCB.

Some people could take a leave out of his book.

I normally like to do point to point wiring but there is nothing wrong with supporting people that support the DIY community with so much free information. 

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My second attempt at the Radi0kit tube PS. Better this time. Slightly bigger enclosure and both 240V and preamp umbilical cord out the rear. Listening with it now. These PSs are excellent. Dead quiet, regged 12V and electronically smoothed 250V. Come with Tranni and all parts. You can have the brd assembled in an hour or so. 

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16 hours ago, mwhouston said:

Where to buy Xover parts; chokes at least caps I have.

 

Is there an Ozzy supplier? 

Nigel at SpeakerBug in Qld perhaps.

 

https://speakerbug.com.au/

Edited by BuzzzFuzzz
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7 hours ago, BuzzzFuzzz said:

Nigel at SpeakerBug in Qld perhaps.

 

https://speakerbug.com.au/

Thanks  for the suggestion. Another member suggested Soundlabs which is easy driver and Ive bought stuff from in the past but for $14 I’ll probably have the chokes posted.

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I was asked to compare yet another HP amp from Oatley (the last one never got to production). Same schematic but with two different chips. The OPA2134 and the PT2308. The PT is a dedicated headphone driver chip. In this version there are no output caps as have been when the PT chip was used.

 

To try to home in on the chip in the circuit I went to these lengths. Tidal on my phone, headphone amp with one of the two chips, digitised (24/96) back to a file. Then back on my phone with pro head phones. I couldn’t use a head phone amp because I’m trying to eval headphone amps. 
 

My Samsung I’m told has a DSD DAC and I guessed this way it was a good neutral non-biased way to A/B. With 1 minute of piano only then voice and jazz band recorded from one chip at a time I could flip instantly between the two tracks on my phone driving headphones direct. 
 

I’d say there really is nothing between them but if held at gun point and told to chose I’d go for the PT2308. Reverb just sounded more extended and I felt I had a better sense of the recording venue. Harmonics in the piano sounded better too. But I wouldn’t be my lefty on it.

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19 minutes ago, mwhouston said:

Not mine but a keen DIYer with a Trent toward the retro and timber look. I like.

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Fantastic recycling 

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Way off thread but as DIYers we are often receiving packages from OS.

I was emailed this scam in my junk folder. Australian post is aware of the scam that is when I got this image. 
 

You are asked to pay $1.99 via credit card to a Australian Post. COVID levy. What they are after is all your credit card info. Don’t pay it if it is not obvious by now. 

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17 hours ago, sfdoddsy said:

 

Finished. 3 way passive open baffles. AST2560, Neo10, Satori WO24P. Corian baffle, sealed walnut bass enclosure.

 

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Great design & workmanship, sfd!  :thumb:

 

I have started the process of creating some active OBs.  Drivers are ordered (6 1/2" Satori mid & Satori ribbon tweeter) - the plan is ... these will cross over to my 15" sealed subs @ 100Hz.  Because I'll be basing it around my miniDSP setup, I'll be able to provide some boost at the low end, if the Satori mid finds it difficult to get enough output down at 100Hz.

 

Just waiting for Wagner to supply the drivers - then I can finish off the rest of the design.

 

Andy

 

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My latest project, nelsonnpass aleph mini class a, my goal is to measure how clean it will or will not be using a smps vs the traditional toridial tx with crc psu. 

 

The aleph mini is still my go to amplifier after almost 20 years of running from the first version I helped get done.

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9 minutes ago, itsparks said:

My latest project, nelsonnpass aleph mini class a, my goal is to measure how clean it will or will not be using a smps vs the traditional toridial tx with crc psu. 

 

That will get quite a bit of interest I suspect :) 

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11 minutes ago, aussievintage said:

 

That will get quite a bit of interest I suspect :) 

 

I just uploaded my video to youtube, i'll post the link tomorow. 

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I built a preamp with some 100year old tubes last year during a lockdown. The tubes are DHTs but the DIY PS I was using had the DC filament voltage negative and HT neg joined. With my ear inside the woofer at good listening level there was a 50hZ hum. Three or four tweaks got it extremely quiet, can’t hear it at 1M with my ear in line with the woofer. At my 5M listening distance, nothing. 
 

My new Radi0kit tube PS kits have regulated filament and smoothed HT with seperate earths. Today I removed the three pin power socket to the preamp and put in a four pin. Some rewiring and rebalancing of the voltages was required. Now still quieter but not perfect. No 50HZ hum but maybe 100 but very low in level. Tried bring the chassis to mains earth, same as PS metal enclosures, but that was audibly worse. Filaments have balancing 100ohm resistors across them.

 

Happier though but did find the right channel a little noisier than the left but as I said unless you are flat on the ground with ear in woofer impossible to hear. I’ll checkout why.  90db sensitive speakers will always highly any noise. Fortunately I love the sound of this preamp and smile when I think the tubes are 100years old. 

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2 minutes ago, mwhouston said:

Filaments have balancing 100ohm resistors across them.

 

You need to fit a potentiometer to allow you to balance the filament w.r.t. the HT common/negative for minimum hum

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44 minutes ago, aussievintage said:

 

You need to fit a potentiometer to allow you to balance the filament w.r.t. the HT common/negative for minimum hum

Regulated 12V feeds a 5V regulator. The filament has 100ohm balance resistors which at the centre feed Rk with Ck across it. 

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3 minutes ago, mwhouston said:

Regulated 12V feeds a 5V regulator. The filament has 100ohm balance resistors which at the centre feed Rk with Ck across it. 

 

Yeah, but that's only a fixed point, depending on the 2 "100" ohm resistors.  Also, the physical construction of the valve and filament is never perfect - so the balance needs to be adjustable.  Feed Rk/Ck from the pot's wiper.

 

 

Actually it is interesting, as you are using DC.   I feed mine AC and just balance out the hum.  Probably not as quiet as you want, but inaudible the way I use them.

Edited by aussievintage
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10 minutes ago, Ihearmusic said:

I use rod coleman filament regulators in my build.

http://www.lyrima.co.uk/dhtreg/dhtRegIntro.html

 

No noise on my 99dB speakers.

 

A nice idea, well implemented by the way it reads.

 

11 minutes ago, Ihearmusic said:

Currently got brand new MingDa MC 300 A here. It uses a simple dc supply and a balancing pot. No noise!

 

Yeah, that's what I was saying.  You need a pot to set it for lowest noise pickup.  The sweet spot on mine is very tight - you aren't going to get lucky with just fixed resistors.

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Some rear surrounds that will do some service upfront after an impromptu sale of my VAFs

19mm stringy bark flooring used for the cabinets, patched using auto body filler, couple of coats of high fill primer and gloss white on top and sides. 

 

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