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1 minute ago, Red MacKay said:

Does he make that available as a seperate item?

 

Yep. Bit pricey but has a heck of a lot of features that will come in handy with my new amp build.

 

https://holtonprecisionaudio.com/products/ac-mains-power-controller-holton-audio-power-one-r4

 

Pairing up with these as well as im done with traditional relays....

 

https://holtonprecisionaudio.com/collections/diy-audio-products/products/audio-solid-state-relay-hpa-ss-relay-one

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Stereo Subs & Two Way Monitor Build   It’s been slow going on my two way monitor with stereo sub build but I’ve finally finished finished one of the two subs!!!   The subs are 10inch CSS drive

Finally finished my 6sn7 preamp. 😀 not a bad outcome considering 50% material was recycled. Thanks a lot mwhouston for schematics.

Thanks Pete Sure! Pretty much just used common spray acrylics (cans) for the whole job. Not shy of using 2k but just trying to save on costs.  After the cabs where routed i gave th

21 minutes ago, Tubularbells said:

Hi @Red MacKay another Canadian option would be Hammond transformers. Ordered these 1kv jobbies from my mates at DigiKey and arrived in less than 1 week with free shipping making it a no brainer for me.

 

 

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I also ordered a 1KW 55-0-55 from RS and arrived in a week or so. This went in my Holton build for Jakey77. 

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In the F5 turbo build I used (on the owners suggestion) thermistors on the active and neutral of the mains. These start with a slight higher resistance at turn on and then settle to very low resistance. They act as surge protection. Simple and cheap. 
 

I had not seen these used in this way before. Work well though and very cheap. 

 

STM-CL60A(s). 
 

https://au.element14.com/amphenol-advanced-sensors/cl-60a/icl-ntc-thermistor-10r-disc-19/dp/2915278?st=CL60

 

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36 minutes ago, mwhouston said:

In the F5 turbo build I used (on the owners suggestion) thermistors on the active and neutral of the mains. These start with a slight higher resistance at turn on and then settle to very low resistance. They act as surge protection. Simple and cheap. 
 

I had not seen these used in this way before. Work well though and very cheap. 

 

STM-CL60A(s). 
 

https://au.element14.com/amphenol-advanced-sensors/cl-60a/icl-ntc-thermistor-10r-disc-19/dp/2915278?st=CL60

 

 

Ashly used to do this trick on there pro audio amps

20200516_104831.jpg

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Red, This is the softstart DC protection i use now and has no relays.

Also use 10 ohm thermistor on AC input and another on the earth connection to PCB.

Screen Shot 2020-05-16 at 12.00.37 pm.png

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Hard to believe I’m listening to a 100 year old tube which has probably entertained dozens of families over the years by powering the speaker in their AM wireless. If it could tell some stories. The musical stories it tells now are very engaging. Cohen sounds quite different through the preamp. Not bad or better just different. The preamp - “MWH” - is a real attention grabber. 
 

ive now regulated the heater PS. 

C4DE7259-6CAE-406D-8003-2ECD7E08B40C.jpeg

Edited by mwhouston
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Yes Mark just goes to show how far we have progressed in so called Hi Fi when something made 100 years ago still gives most modern tech a run for it's money.

Here is another example although not quite as old.

2 - 1 (55).jpeg

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Guest iant
5 hours ago, mwhouston said:

In the F5 turbo build I used (on the owners suggestion) thermistors on the active and neutral of the mains. These start with a slight higher resistance at turn on and then settle to very low resistance. They act as surge protection. Simple and cheap. 
 

I had not seen these used in this way before. Work well though and very cheap. 

 

STM-CL60A(s). 
 

https://au.element14.com/amphenol-advanced-sensors/cl-60a/icl-ntc-thermistor-10r-disc-19/dp/2915278?st=CL60

 

See Rod Elliotts full discussion.https://sound-au.com/articles/inrush.htm#s61

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49 minutes ago, kranky said:

Yes Mark just goes to show how far we have progressed in so called Hi Fi when something made 100 years ago still gives most modern tech a run for it's money.

Here is another example although not quite as old.

2 - 1 (55).jpeg

I’ve asked Bruce of  American oddwatt fame to design me a preamp based on a 45. After getting so much audio pleasure from the 71A I thought why not try the legendary DHT 45? Also a amp building buddy nearby is bound to have a few very rare ones (hopefully even NOS) and may like to sell a few.

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43 minutes ago, iant said:

Thermistors as surge protection in power amps are a bit of a concern.They can cause power supply modulation effects along with other potential problems.See Rod Elliotts full discussion.https://sound-au.com/articles/inrush.htm#s61

Nelson Pass uses them....

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Yes sorry for posting the pic.

Have you tried the 4P1L tubes in a pre as i have found them to be excellent, as good as 01A just not as detailed but a dam site cheaper.

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Valve porn :)

 

The easy bits done, I removed some winds and took the opportunity to replace the leads with something a little more friendly. I better pull my finger out and order the wire for the 150v.

 

If this works I might encase it in resin

 

Tran 5.jpg

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5 hours ago, DQ828 said:

Valve porn :)

 

The easy bits done, I removed some winds and took the opportunity to replace the leads with something a little more friendly. I better pull my finger out and order the wire for the 150v.

 

If this works I might encase it in resin

 

Tran 5.jpg

Awesome work!

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9 hours ago, kranky said:

Mark not a 45 but a close cousin.

2 - 1 (56).jpeg

They look really old, around what year would they have been manufactured?

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5 hours ago, kranky said:

Yes sorry for posting the pic.

Have you tried the 4P1L tubes in a pre as i have found them to be excellent, as good as 01A just not as detailed but a dam site cheaper.

Like to stay with tubes I can get at a moderate price. And I never build one of anything, well rarely, generally three. 
 

I’d even go for some modern Chinese 45s if I could find them. I like the modern Chinese tubes. I have used lots and always vely happy. 

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18 hours ago, Guest iant said:

See Rod Elliotts full discussion.https://sound-au.com/articles/inrush.htm#s61

Thermistors should only be used by themselves where the protected equipment draws a relatively constant power after it has settled down after power is first applied.  While very convenient, NTC thermistors have a number of limitations.

 

OK in a Class A power amp then.

Edited by Batty
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Martykt, they are from the 1920s, on one tube there is a sticker with a stamp dated 1928.

These tubes are known as an 01A.

For more info on this tube or most tubes go to.

Vinylsavor Thomas Mayer 

Tube UX201a.

Steve.

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Finally finished my 6sn7 preamp. 😀

not a bad outcome considering 50% material was recycled. Thanks a lot mwhouston for schematics.

B8F0869F-7534-49BE-B780-83FACD942A76.jpeg

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Edited by SumonKabir
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Last night I finally got around to testing the RPi Streamer using 5v power bank. I'll have to say it was a worthwhile experiment as I believe there was a noticable improvement in the SQ. I'm planning to set the Powerbank/Charger up so when I turn the DAC on, the charger for the PB is disconnect from the AC Mains, hence removing the PSU switching element. I'll probably put another trigger outlet in the DAC to achieve this.

 

When I bought the original PB I stuffed up and bought one that wont supply power while charging so in the switchover the Streamer would get turned on and off, not what I wont. So of course I forked out more money get get a BP that does what I need. Just another thing to add to the list :)

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On 16/05/2020 at 5:20 PM, kranky said:

Yes sorry for posting the pic.

Have you tried the 4P1L tubes in a pre as i have found them to be excellent, as good as 01A just not as detailed but a dam site cheaper.

Yes, I was surprised with $10 tube. Amazing 3D imaging and balanced output. There is only svetlana 4p1L what I can find. Looks like not many manufacturers made them.

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10 hours ago, SumonKabir said:

Yes, I was surprised with $10 tube. Amazing 3D imaging and balanced output. There is only svetlana 4p1L what I can find. Looks like not many manufacturers made them.

I am not sure if the 4P1L was made in other plants in the USSR.

Another tube which is similar is the 2P29L but is covered by a metal casing.

$10 dollars a tube is still cheap, I purchased 100 of each around 10 years ago for $1 a pop.

Happy Building.   Steve.

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Had to hunt down a fault in Matt's Muji DAC, of course it turned out to be something simple but it alluded me for a while.

Also changed the electrolytic caps around the digital chips for larger Polymers, replaced the decoupling caps on the TDA1541 for larger value Polystyrene and changed the 10uf electrolytic caps around the Sparko Op Amps to 100uf Silmics.

20200519_115154.jpg.718f6032655843944f101f5aee25464a.jpg

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16 minutes ago, muon* said:

Had to hunt down a fault in Matt's Muji DAC, of course it turned out to be something simple but it alluded me for a while.

Also changed the electrolytic caps around the digital chips for larger Polymers, replaced the decoupling caps on the TDA1541 for larger value Polystyrene and changed the 10uf electrolytic caps around the Sparko Op Amps to 100uf Silmics.

20200519_115154.jpg.718f6032655843944f101f5aee25464a.jpg

Looking forward to hearing this once more.

 

It's a truly wonderful sounding unit after a few mods: NOS reclock module, Holland made TDA1541 S1, rhodium plated brass solderless RCA's with tellurium copper center pin, Sparkos and Burson OPAMPS, some Arizona Blue Cactus caps, Miflex KFPM-1 bypassed with Duelund Silver Bypass caps and the Neotech UPOCC wires. Will be very interesting to see how these other improvements on the digital side change things, Course it's better value for money to buy a DAC from the Abbas Audio range.

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A pair of Jim’s Audio F5 brds I just populated. Apart from matched input FETs and power FETs a pretty standard brd. with standard parts. 

488B7ED1-32CE-4899-AED5-A5C6C634711D.jpeg

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Made too many of these. Universal tube preamp PS. 
 

250VHT and 25v filament. Voltages required for each preamp is configured in the preamp. One PS powers four of my preamp from 5V heater and 100VHT requirement to 24V and 250VHT requirements. Save a few hundred dollars each preamp. Neatest build so far. 

90673300-B08C-4C6C-9A9F-D2AA415BF0F7.jpeg

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17 minutes ago, mwhouston said:

Made too many of these. Universal tube preamp PS. 
 

250VHT and 25v filament. Voltages required for each preamp is configured in the preamp. One PS powers four of my preamp from 5V heater and 100VHT requirement to 24V and 250VHT requirements. Save a few hundred dollars each preamp. Neatest build so far. 

90673300-B08C-4C6C-9A9F-D2AA415BF0F7.jpeg

Seeing only one transformer,  I am wondering,   either you use the transformer backwards and power the board from a 12/24 AC plugpack,       or you are just using the transformer normally for the low voltage, and rectifying the HT direct from the mains?

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1 minute ago, aussievintage said:

Seeing only one transformer,  I am wondering,   either you use the transformer backwards and power the board from a 12/24 AC plugpack,       or you are just using the transformer normally for the low voltage, and rectifying the HT direct from the mains?

24V 1A wall wart then, as you said, backwards into the step down (24V) for HT. Filament voltage directly rectified and filtered. 

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5 minutes ago, mwhouston said:

24V 1A wall wart then, as you said, backwards into the step down (24V) for HT. Filament voltage directly rectified and filtered. 

 

Yes, same as I do for my phono amps then.  Works extremely well and saves on transformer costs.      I usually don't regulate the DC filament/heater voltage btw (you don't mention it either), as a simple power resistor to drop the voltage, due to the constant load, works nicely.

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9 minutes ago, aussievintage said:

 

Yes, same as I do for my phono amps then.  Works extremely well and saves on transformer costs.      I usually don't regulate the DC filament/heater voltage btw (you don't mention it either), as a simple power resistor to drop the voltage, due to the constant load, works nicely.

Should add I choke the HT with a 5H 50mA Hammond which sitS off the brd:-  CLCRC then in the preamp -RC. Total of 400uf+ for HT and 9400uf+ for the heaters.  

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19 minutes ago, mwhouston said:

Should add I choke the HT with a 5H 50mA Hammond which sitS off the brd:-  CLCRC then in the preamp -RC. Total of 400uf+ for HT and 9400uf+ for the heaters.  

Way more than I use, even for a phono preamp :)  

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Made some progress, Iv'e rewrapped the 9v secondary with the original wrap. I now have the copper for the 150v secondary but was silly enough to take the tape off both rolls at the same time and then spent a good while chasing coils around the workshop before I took the photos. Due to the coil mayhem I decided to make a jig to hold both wire rolls. I will be winding 94m of both onto the slender wooden holder and then will use it to wrap the coil.

Tran 6.jpg

Tran 7.jpg

Tran 8.jpg

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11 hours ago, DQ828 said:

Made some progress, Iv'e rewrapped the 9v secondary with the original wrap. I now have the copper for the 150v secondary but was silly enough to take the tape off both rolls at the same time and then spent a good while chasing coils around the workshop before I took the photos. Due to the coil mayhem I decided to make a jig to hold both wire rolls. I will be winding 94m of both onto the slender wooden holder and then will use it to wrap the coil.

Tran 6.jpg

Tran 7.jpg

Tran 8.jpg

Once more, your brave man. 

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2 hours ago, mwhouston said:

Once more, your brave man. 

Nah, he is obviously no fool and knows what he is doing.  Well done.

 

If you or I were doing it Mark - well that would be pure foolish!

No, I am not that brave either.

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