DIY audio: what are you building?

[mwhouston]

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 November 29, 2020 by mwhouston

[oohms]

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

[Red MacKay]

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!

 

 

[aussievintage]

3 minutes ago, Red MacKay said:

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

30 watt?  Way overkill.

 

try 3 watts  

[soundbyte]

3 minutes ago, Red MacKay said:

Happy days!

? Really? Good to hear, just need the next 20 years to make them "right"?

[mwhouston]

At 96db sensitive horns/woofers I find 2W plenty. 

[mwhouston]

2 minutes ago, soundbyte said:

? Really? Good to hear, just need the next 20 years to make them "right"?

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

[Red MacKay]

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.

[mwhouston]

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? 

[Guest Old Man Rubber]

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

 

 

 

...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)

 

[mwhouston]

A mock-up of the finished MM tube phono preamp. External Radi0kit PS and Radi0kit phono preamp. 

[mwhouston]

Completed the preamp stage. PS cct. brd. and Tranni is assembled but not cased. I may do a rough wiring so I can have a listen. Two selectable phono MM inputs. 

[Red MacKay]

On 04/12/2020 at 9:39 AM, Old Man Rubber said:

 

 

 

They look quite good actually.  Very useful.

 

[mwhouston]

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. 

[aussievintage]

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"  

[mwhouston]

Coming together. Just the PSs to box up. Can’t wait to hear it. 

[mwhouston]

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. 

 

[mwhouston]

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. 

 

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

[sfdoddsy]

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.

Edited December 9, 2020 by sfdoddsy

[aussievintage]

5 hours ago, mwhouston said:

Connected mains earth to the chassis

 

ahem...  don't you always?  

[mwhouston]

Not when I have an external PS which carries the mains. My usual PS runs from a 24VAC wall wart. This one uses a Radi0kit PS which connects to the mains. 
 

The light chassis is not grounded to HT- or (or it wasn’t) earthed in any way. I noticed when my hand was near the chassis the hum got louder. Connecting the chassis only to the mains earth has stopped that. If the mains are connected to any of my amps or PSs or any other audio device the metal chassis are always earthed and fused. 

[aussievintage]

10 hours ago, mwhouston said:

Not when I have an external PS which carries the mains. My usual PS runs from a 24VAC wall wart. This one uses a Radi0kit PS which connects to the mains. 
 

The light chassis is not grounded to HT- or (or it wasn’t) earthed in any way. I noticed when my hand was near the chassis the hum got louder. Connecting the chassis only to the mains earth has stopped that. If the mains are connected to any of my amps or PSs or any other audio device the metal chassis are always earthed and fused. 

 

Floating systems tend to give this sorts of problems.  It is difficult when the system runs from a 2 pin mains plug, for example double insulated equipment.  We had one post here recently where a supplementary earth chased the hum away.  The shielding effect of metal chassis requires an earth connection, as you just proved    When I build something with an external power supply, I carry the earth through on the umbilical.  It's just one extra wire.

[mwhouston]

22 minutes ago, aussievintage said:

 

Floating systems tend to give this sorts of problems.  It is difficult when the system runs from a 2 pin mains plug, for example double insulated equipment.  We had one post here recently where a supplementary earth chased the hum away.  The shielding effect of metal chassis requires an earth connection, as you just proved    When I build something with an external power supply, I carry the earth through on the umbilical.  It's just one extra wire.

Agree on all counts. This will cause a stir in the DIY community but I used solid core Cat5 as the power cord between PS and preamp. I use all four pairs to carry HT and filament DC. No spare wires.

 

When the PS is cased it will be earthed. I’ll provide a seperate earth terminal at the back with appropriate wire to run earth to a similar terminal on the preamp chassis. This will allow flexibility in earthing arrangements. 

[aussievintage]

30 minutes ago, mwhouston said:

This will cause a stir in the DIY community but I used solid core Cat5 as the power cord between PS and preamp. I use all four pairs to carry HT and filament DC. No spare wires.

 

 

Be careful.  One spec I checked shows a maximum operation voltage of just  72 V DC

[mwhouston]

2 minutes ago, aussievintage said:

 

Be careful.  One spec I checked shows a maximum operation voltage of just  72 V DC

Agree again. Just looked at the specs and its stated 125V. Never seems to be a problem. I knew this before making the cord but like the idea that’s it’s solid core. Covered the cord in white heat shrink. No that it helps breakdown voltages just looks smarter. Should this be sold I may make a new cord. Easy and cheap enough. For me I’m happy with the current cord.

 

Not sure of the effect on sonics (solid core umbilical) but currently, after a short break-in, the preamp sounds glorious. I would still say 50 hours break-in but it changed dramatically in the first two hours. Best way I could describe it is much more colour from dead new.