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DIY audio: what are you building?


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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

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

12 minutes ago, mwhouston said:

It works out to $550 Au. without any shipping chargers. How much was it to ship the Bottlehead? 

Cost ~80 USD to ship the crack.

 

The crackatwoa is about ~$120 USD shipped and the mainline is ~$134 USD - these both appear to share the same frame as the moreplay

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3 hours ago, RankStranger said:


Tried both. No change. I wonder if it’s a faulty transformer. Is that common?

Is it a 50Hz hum or a 100Hz hum?

50Hz would be before rectification and it could be eddy currents introduced into the chassis.

If possible you could move the transformer around to see whether proximity makes a difference.

You might also want to try having the chassis earth closer to the IEC socket.

Transformers are not likely to cause hum unless they have loose wingdings and/or are under rated and then it is more a mechanical noise.

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10 hours ago, crtexcnndrm99 said:

https://bottlehead.com/product/moreplay-preamplifier-kit/;)

 

although I am suspicious of the true value for money for such ‘convenient’ kits... but what do I know!

 

This not a conventional preamp.    It mis-uses valves designed as power tubes, for low signal amplification.  Not sure I agree this is a good idea, but is definitely a trend.      I might have to lash one up on the workbench to have a listen for myself.   You could tube roll all the similar power tubes.

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13 minutes ago, aussievintage said:

 

This not a conventional preamp.    It mis-uses valves designed as power tubes, for low signal amplification.  Not sure I agree this is a good idea, but is definitely a trend.      I might have to lash one up on the workbench to have a listen for myself.   You could tube roll all the similar power tubes.

You may have seen my preamp with antique (1920) low power power tubes, UX-171As. They are DHT so maybe there is a difference but the sound they produce is indescribable. I know Red has been experimenting with power tubes as preamp tube for a while. I was and am stunned by just how good they sound. 
 

https://retro-thermionic.blogspot.com/2020/04/mwh-1920s-ux-171a-tube-preamp.html

 

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22 minutes ago, mwhouston said:

You may have seen my preamp with antique (1920) low power power tubes, UX-171As. They are DHT so maybe there is a difference but the sound they produce is indescribable. I know Red has been experimenting with power tubes as preamp tube for a while. I was and am stunned by just how good they sound. 
 

https://retro-thermionic.blogspot.com/2020/04/mwh-1920s-ux-171a-tube-preamp.html

 

 

Yep, I remember us talking about it.       I have all the bits, even a chassis, that I could build one with.   I have so many projects in mind, I don't know what to build next :)  

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Yes, even with all it's faults - I love my 10Y pre.  I have thought about modding it - but no.

 

Inspired by acg here, I am gathering all the goodies needed to make a new DHT pre - this time using a PX25.  Same gain but way less plate resistance which is really important for good bandwidth.

 

Just starting to scratch around with a circuit right now and contacted Mohan a couple of days back to enlist his help.  After all - there needs to be at least one person involved that actually "knows" what he is doing.

Mohan has a dislike for DHTs, but I will not be put off!

 

A great read I discovered on the net last week was DHT Rob in Germany.  A fellow crazy and a great read.

 

Another mate recently received his custom 10Y pre from Japan.  His circuit is completely different to mine and it has a 12BH7 as a driver tube for the 10Y for lower impedance and drive for the 10Y.  Much better and more useful gain too.  In reality, I only have a gain of about 1.3 with my 10Y and it regularly runs out of puff when you want Billy Idol to be going "more, more more!"

The heater supplies on this Japanese unit and the B+ looks so much simpler than what I have done too.  Maybe a case of KISS...  I must get myself a spot in the hot seat at his place soon for a listen myself.

 

The DHT signature is not for everyone, but  to my ears they are in a listening SQ class of their own.

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15 minutes ago, aussievintage said:

 I have all the bits, even a chassis, that I could build one with.   I have so many projects in mind, I don't know what to build next :)  

 

...Sounds like you have one right there to me.

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45 minutes ago, Red MacKay said:

Yes, even with all it's faults - I love my 10Y pre.  I have thought about modding it - but no.

 

Inspired by acg here, I am gathering all the goodies needed to make a new DHT pre - this time using a PX25.  Same gain but way less plate resistance which is really important for good bandwidth.

 

Just starting to scratch around with a circuit right now and contacted Mohan a couple of days back to enlist his help.  After all - there needs to be at least one person involved that actually "knows" what he is doing.

Mohan has a dislike for DHTs, but I will not be put off!

 

A great read I discovered on the net last week was DHT Rob in Germany.  A fellow crazy and a great read.

 

Another mate recently received his custom 10Y pre from Japan.  His circuit is completely different to mine and it has a 12BH7 as a driver tube for the 10Y for lower impedance and drive for the 10Y.  Much better and more useful gain too.  In reality, I only have a gain of about 1.3 with my 10Y and it regularly runs out of puff when you want Billy Idol to be going "more, more more!"

The heater supplies on this Japanese unit and the B+ looks so much simpler than what I have done too.  Maybe a case of KISS...  I must get myself a spot in the hot seat at his place soon for a listen myself.

 

The DHT signature is not for everyone, but  to my ears they are in a listening SQ class of their own.

Hoping to see a few more DHT pre builds by the sounds of it!

 

Do you know what the name of the 10Y pre from Japan was? 

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1 hour ago, crtexcnndrm99 said:

Hoping to see a few more DHT pre builds by the sounds of it!

 

Do you know what the name of the 10Y pre from Japan was? 

 

Otoman Laboratory.  Sorry, no pics at this stage, but it's all on one chassis with a EL34 and 6SN7 as part of the reg circuit for the B+ and just one transformer and choke.  Tango of course!

 

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Ive added a battery external test point. The shinny screw head is connected to the internal batteries and isolated from the Al enclosure. 
 

When on I meter between the test point and the earth of the RCAs. You only ever see half the total voltage as the RCA earth is 0V in the differential +/-9V PS. A fully charged battery will show 9V or a bit more at the test point. At a reading of 7V batteries require changing and are considered flat.

 

With basic 9V inexpensive batteries you should get better than 50hours as the unit draws 10mA. With lithium’s, as I usually use, you get over 120hours.  I buy packets of cheap lithium’s on eBay. 
 

 

0BD1CE33-FDCB-49F8-B3BF-16A796A6F24C.jpeg

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28 minutes ago, mwhouston said:

Ive added a battery external test point. The shinny screw head is connected to the internal batteries and isolated from the Al enclosure. 

 

I had a similar problem with my battery powered variable-eq mono preamp.  I ended up mounting the batteries on the outside of the case.  I can measure them, and replace them easily.

 

Used holder like this.  The pins underneath just go through drilled holes into the case.

PC Mount 9V Battery Holder

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52 minutes ago, Old Man Rubber said:

Anyone got an idea what these might be?  Probably PA or something but might be useful to convert to some kind of wacky horn driven hi-fi speaker?

 

20201129_145201.jpg

 

57 minutes ago, Old Man Rubber said:

Anyone got an idea what these might be?  Probably PA or something but might be useful to convert to some kind of wacky horn driven hi-fi speaker?

 

20201129_145201.jpg

It’s a Goodman’s Midax horn

 

 

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59 minutes ago, Old Man Rubber said:

Anyone got an idea what these might be?  Probably PA or something but might be useful to convert to some kind of wacky horn driven hi-fi speaker?

 

20201129_145201.jpg

Here you go they are very good vintage horns for hi fi.

3A180DE7-C3F9-43EE-BDD9-08E8B48542DE.jpeg

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1 hour ago, Old Man Rubber said:

Anyone got an idea what these might be?  Probably PA or something but might be useful to convert to some kind of wacky horn driven hi-fi speaker?

 

20201129_145201.jpg

You may have some retro gems there. If they work all you need is some woofers for the first K and a suitable Xover. 

Edited by mwhouston
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55 minutes ago, mwhouston said:

You may have some retro gems there. If they work all you need is some woofers for the first K and a suitable Xover. 

I don't suppose there might be plans for such a thing, or a reasonable approach to designing something around them?

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1 minute ago, Old Man Rubber said:

I don't suppose there might be plans for such a thing, or a reasonable approach to designing something around them?

Absolutely. PM if I can help. 

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42 minutes ago, Old Man Rubber said:

I don't suppose there might be plans for such a thing, or a reasonable approach to designing something around them?

These are perfect to go with the horns and cheap. Go super low, very efficient (work with a SET) and cheap. Sealed box - 60ltr - will do 30hz easy. 
 

https://www.altronics.com.au/p/c3070-300mm-12-inch-100w-woofer-polypropylene-speaker/

 

Edited by mwhouston
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3 hours ago, mwhouston said:

These are perfect to go with the horns and cheap. Go super low, very efficient (work with a SET) and cheap. Sealed box - 60ltr - will do 30hz easy. 
 

https://www.altronics.com.au/p/c3070-300mm-12-inch-100w-woofer-polypropylene-speaker/

 

Interesting.. i've seen those but always dismissed them.. maybe they are worth a second look

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After years and years of dissing horns - this is where I have actually ended up!

 

Just a cheap ar*e no name small horn with Peavey drivers - nothing special at all and a pair of 12" drivers of around 95dB.  Nope - way from perfect but dynamics galore and you can "see" into the music.  I have a couple of crappy 18" drivers  in huge boxes that come with them - and I have not even worried about hooking them up yet.

 

So basically what I have found is that if a driver is under 95dB sensitivity - it just isn't going to work for me as it just does not have dynamics.  As I said - far from right - but I love the sound. 

 

With 95dB - any 30w ClassA amp will drive them fine - be it SS or valve.  Happy days!

 

 

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7 hours ago, mwhouston said:

In hifi nothing is perfect. +/-10% is close enough. 

 

I'm way out past 10%!  As long as I like it - no one else matters.

 

3watts?  Nope - for pipes and slippers maybe.  Zero headroom and I like headroom.

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Another Radi0kit tube MM phono preamp. I like the tubes to stick out most of the time and put the resistors on the underneath. Not realising of course that they will never rise above the tube sockets anyhow and the caps, also squat, have to go on the screened side. 
 

Regardless won’t effect quality and at least I did a neat job. Cct. brd. Is complete and the kit comes with JJ tubes - ECC83S - which punch way above their weight. 
 

This is the high end kit; Dales, Vishay caps, Wima, Corneal Dubilier and Nichicon caps. And low noise metal film. Ceramic socket. This kit always sounds good. I also bought the Radi0kit 250V PS kit. Regulated 12V and electronically smoothed 250V.
 

This will go in a Hammond wood cheek chassis with external PS. The hardest decision is the colour? 

C474AB1D-DE6E-4BC3-8D00-BECB11A3D139.jpeg

29560393-CA19-4EFD-8C92-1CCFE2ADA943.jpeg

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On 23/11/2020 at 9:09 AM, Old Man Rubber said:

Went to Jaycar instead and ordered some of these:

Titanium tweeters

 

Now - the description on the Jaycar site isn't quite correct, they are silk/titanium.  I have removed the plastic surround and hacked them into place.  Sadly the mounting holes didn't quite line up with the original ones.  Impedence and frequency response are probably different to the originals as well so I should probably do something with the crossovers.  Now just waiting for some bass reflex ports to arrive from China so I can finish these and start tweaking.  The only original things left are the crossovers and the plastic badges 🙂

 

 

 

20201123_090716.jpg

...and the bass ports finally arrived from China, although being a bit stupid I accidentally ordered 2 pairs instead of just 2.

 

No matter, they fit well enough and it's probably time I had a good look at the frequency response and started fiddling with the crossover since there are no original parts left on these.

 

If anybody wants some ports for a project PM me an address I will send you the unopened 2nd pair.

(72mmX118mm Inverter Tubes Portable For 6"-8" Subwoofers)

 

20201203_142416.jpg

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1 hour ago, mwhouston said:

Bought tube when they first came out. Just ordered this and will provide other components from local sources. 
 

https://diyaudiostore.com/products/korg-nutube-b1-pcb-and-jfets

 

Time to turn it into something useful. Any others built one or used this brd. 

 

I'll be following along.  Still intrigued by this "tube" :) 

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Finished the umbilical cord from PS to preamp. PS is not cased at this point just busting to have a listen. Slight hum through the woofer (can’t be heard at listening position) looks like I need to sort out with earthing. Clear  detailed sound. Needs 50 hours to burn in. New tubes and parts. 

 

64C9C421-6745-4E51-8640-9D70A29B348E.jpeg

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1 hour ago, mwhouston said:

Finished the umbilical cord from PS to preamp. PS is not cased at this point just busting to have a listen. Slight hum through the woofer (can’t be heard at listening position) looks like I need to sort out with earthing. Clear  detailed sound. Needs 50 hours to burn in. New tubes and parts. 

 

64C9C421-6745-4E51-8640-9D70A29B348E.jpeg

Connected mains earth to the chassis now the hum has gone. All quiet  and I can feel the improvement in sound already.

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Test baffles for.my new hybrid open baffles.

 

Satori WO24P sealed bass, dipole BG Neo10 mids. Tweeters are currently dipole Neo3s, but I have a pair of Aurum Cantus AST2560 on a plane headed my way.

63C5AC5A-6149-454F-9C0D-77238E166EA8.jpeg

Edited by sfdoddsy
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