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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. 

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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

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.

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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. 

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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

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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.

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Now I may have posted about this before , can't remember but I have just finished building what I am calling the MK2  version of a clone of the venerable AR SP 10. The MK1 worked and sounded great but it had a few issues that saw me reworking the board to the point where I lifted a few tracks and still had a problem with getting the power supply voltages to be the same on both channels. I started with a new pcb and minimal parts kit and rebuilt the power supply and signal board.

The pre amp is now fully built and tomorrow I will begin testing again. Here are a couple of pics:

IMG20201210142757.jpg

IMG20201210142803.jpg

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Just now, awayward said:

Looking good, three square frames, where are they going?

Above the TV, with the triangular ones in the corners on the opposite wall

PXL_20201208_085833149.thumb.jpg.f3b029e9aa6038ffbfcb0990d461bbd9.jpg

 

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Just another quick pic , this time of my PI based streamer :

Oh and I finished rebuilding my Gale 401a's and am busy running them in because of the new caps and midrange surrounds.

IMG20201210142832.jpg

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3 hours ago, oohms said:

Above the TV, with the triangular ones in the corners on the opposite wall

PXL_20201208_085833149.thumb.jpg.f3b029e9aa6038ffbfcb0990d461bbd9.jpg

 


Why? Those little things don’t look like they put out much b-ohhhh...! 😮

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Guess i will chime in here !  I have well, WAY to many projects going on ATM but since Covid has hit, it has given me time to start and (maybe ) finish some projects. 

 

I have almost finished my speakers, altho im not 1005 happy with them, I find the ribbon tweeter off axis response annoying :( 

 

I did finish my test project a big goal for my own designed SSR  circuit ( with some help from two people Anthony Holton and Thomas Larsen ) it works and I'm happy, now onto revision 1.5.

 

Ordered a pile of PCB boards to build some more amplifiers, yes I have way to many, most are class a starting at 20watts up to 100 watts ( heat monsters )

 

 

20201128_161941.thumb.jpg.b36dc537219de99086ac746d2973f9c1.jpg20201129_085554.thumb.jpg.76417f5556b0db71fab631c2d93389aa.jpg

20201124_122713.jpg

20201128_161935.jpg

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30 minutes ago, itsparks said:

Guess i will chime in here !  I have well, WAY to many projects going on ATM but since Covid has hit, it has given me time to start and (maybe ) finish some projects. 

 

I have almost finished my speakers, altho im not 1005 happy with them, I find the ribbon tweeter off axis response annoying :( 

 

I did finish my test project a big goal for my own designed SSR  circuit ( with some help from two people Anthony Holton and Thomas Larsen ) it works and I'm happy, now onto revision 1.5.

 

Ordered a pile of PCB boards to build some more amplifiers, yes I have way to many, most are class a starting at 20watts up to 100 watts ( heat monsters )

 

 

20201128_161941.thumb.jpg.b36dc537219de99086ac746d2973f9c1.jpg20201129_085554.thumb.jpg.76417f5556b0db71fab631c2d93389aa.jpg

20201124_122713.jpg

20201128_161935.jpg

Speakers look good but it’s that test bench which is insane! I’m known to use the dining table so... 

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1 hour ago, itsparks said:

Guess i will chime in here !  I have well, WAY to many projects going on ATM but since Covid has hit, it has given me time to start and (maybe ) finish some projects. 

 

I have almost finished my speakers, altho im not 1005 happy with them, I find the ribbon tweeter off axis response annoying :( 

 

I did finish my test project a big goal for my own designed SSR  circuit ( with some help from two people Anthony Holton and Thomas Larsen ) it works and I'm happy, now onto revision 1.5.

 

Ordered a pile of PCB boards to build some more amplifiers, yes I have way to many, most are class a starting at 20watts up to 100 watts ( heat monsters )

 

 

20201128_161941.thumb.jpg.b36dc537219de99086ac746d2973f9c1.jpg20201129_085554.thumb.jpg.76417f5556b0db71fab631c2d93389aa.jpg

20201124_122713.jpg

20201128_161935.jpg

 

I can't find any info on that Gareth Roberts Hiraga board.  Is there a link you can put up please?

 

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5 hours ago, Red MacKay said:

 

I can't find any info on that Gareth Roberts Hiraga board.  Is there a link you can put up please?

 

I made my Hiraga with Croatian brds. Still available I believe.  

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4 hours ago, mwhouston said:

I made my Hiraga with Croatian brds. Still available I believe.  

 

 

I have a few of the board revisions PLUS i'm working on a SMD version.

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10 hours ago, Red MacKay said:

 

I can't find any info on that Gareth Roberts Hiraga board.  Is there a link you can put up please?

 

The boards are the exact same schematic for the jean hiraga 50 watt version, just his boards are 100% over done! I have plenty if you want a set, all the values are written on the boards and all parts are purchase able from mouser / digikey. Gareth Lives in Australia also.

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6 hours ago, itsparks said:

The boards are the exact same schematic for the jean hiraga 50 watt version, just his boards are 100% over done! I have plenty if you want a set, all the values are written on the boards and all parts are purchase able from mouser / digikey. Gareth Lives in Australia also.

 

...There is a 50 Watt version?  How does he achieve that?

 

Thanks, but I already have purchased a kit from Jim's Audio. My build is still way off, but always interested in what others are doing.

 

Thanks..

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5 minutes ago, Red MacKay said:

 

...There is a 50 Watt version?  How does he achieve that?

 

Thanks, but I already have purchased a kit from Jim's Audio. My build is still way off, but always interested in what others are doing.

 

Thanks..

45V rails and up the bias a little. I'm running 33k for bias resistors on my Green boards with MJE21195/MJE21196 Output drivers.  i got to about 58watts rms into 8ohm before clipping. 

 

I've also tested min with 2 different power supply setups, one with straight through power supply powering the "whole" amp and then one psu for the output stage and one regulated psu for the driver stage. Going to be measuring it soon for thd and other measurements.

Edited by itsparks
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37 minutes ago, itsparks said:

45V rails and up the bias a little. I'm running 33k for bias resistors on my Green boards with MJE21195/MJE21196 Output drivers.  i got to about 58watts rms into 8ohm before clipping. 

 

I've also tested min with 2 different power supply setups, one with straight through power supply powering the "whole" amp and then one psu for the output stage and one regulated psu for the driver stage. Going to be measuring it soon for thd and other measurements.

 

@soundbyte

 

45v rails!!!  But I love the idea of 58 clean watts.  I'm not sure what transistors I went for.

 

Very interested in the results of difference re p/s too.

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5 minutes ago, Red MacKay said:

 

@soundbyte

 

45v rails!!!  But I love the idea of 58 clean watts.  I'm not sure what transistors I went for.

 

Very interested in the results of difference re p/s too.

Attached 2 photos of the amplifier running with the regulator psu.. 

20201021_093631.jpg

20201021_093719.jpg

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PS completed, earthed and fused. Has an earthing point at the rear for the preamp with similar banana connection. Total removal of hum with the phono preamp and line level tube preamp chassis also earth. A jump in clarity too. Didn’t expect that.
 

Called the new tube phono preamp “Mantra”. Has a really live sound I’m not saying sounds like live music but seems to make the music jump and feel alive. 

3A7A9762-ACFE-497C-8CEA-FA3BA25A6C7F.jpeg

7FD8DC66-0AFF-440B-83DD-586F750D75A9.jpeg

B6973343-46A3-4B31-88FD-0554C01A7F94.jpeg

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49 minutes ago, aussievintage said:

 

Well just for embarrassment,  here are my two benches just before I decided it was time to clean up

 

 

2020-12-13_14-54-00_02.jpg.0bb4c164ffa5288127a91762c4babad0.jpg

 

2020-12-13_14-53-49_02.jpg.8550ea696f9d9eaf882916025fca7ef8.jpg

Just move house. I have a room that is about the same. 

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13 minutes ago, mwhouston said:

Just move house. I have a room that is about the same. 

 

Funny you should say that.  My wife thinks it would be a good way to spring clean and dump a lot of junk :) 

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Here's a bit of a challenge to fix.  An old valve oscilloscope.  Sort of works, but takes a long time to warm up (sadly might mean the cathode ray  tube is weak), and I smell hot electrolyte :)   Probably only good for audio frequencies...

 

Anyone have info - especially a schematic.  Seems to use a  12AT7, 6U8 and 6AU6 and a couple of rectifiers (if I read the smudged markings correctly)

2020-12-14_09-10-55.jpg.0c3fc6734c155c0ee1ff844eb294da0c.jpg

 

 

2020-12-14_09-14-11.jpg.7a292e852bcd0c37976358effabf9892.jpg

 

 

2020-12-14_09-14-45.jpg.f52160340478941ca640fbf26cc28065.jpg

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On 09/12/2020 at 8:18 PM, sfdoddsy said:

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

 

 

Hmmm, very nice, where did you get the Neo 10's from

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24 minutes ago, mwhouston said:

Is the wife still looking for the cheese board? 

 

 

Cute.    Son-in-law gets off-cuts from his work and has cut, rounded, and oiled a couple of nice cutting boards from the stuff for her so she is not jealous.  :) 

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19 hours ago, DQ828 said:

 

 

Hmmm, very nice, where did you get the Neo 10's from

I’ve actually had them for years. Two pairs initially. Used them in a fully active system then stored them when that system wasn’t practical in the new house.

 

They are still great sounding, and ideal for my passive crossover/active EQ experiment.

 

Parts Express still sell them (at double the old price) and have cheaper clones of which there are conflicting reports.

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On 16/12/2020 at 5:10 PM, sfdoddsy said:

I’ve actually had them for years. Two pairs initially. Used them in a fully active system then stored them when that system wasn’t practical in the new house.

 

They are still great sounding, and ideal for my passive crossover/active EQ experiment.

 

Parts Express still sell them (at double the old price) and have cheaper clones of which there are conflicting reports.

 

I see what you mean about the price. I used a pair for my main speakers and when you couldn't get them anymore I panicked and bought another pair second hand just in case one of mine failed. Good to you can get them again, as long as you can afford them :)

13-01-20 DQ OB Finished01_3.JPG

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