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 NEW  Bruce Heran outlines the details and construction of his simple DIY 6DJ8 (ECC88) Tube Hi-Fi Headphone Amplifier Project.

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PostPosted: 24 Dec 2010 5:57 am 
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Thought of that, what else you got?

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PostPosted: 24 Dec 2010 7:27 am 
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If you looked away you missed it. Yes the night before Xmas BoZoaC was complete.

1K blocking R and 1M bias R has been added. Would I do it differently. No! Can't think How I would improve. No, I really tried. Most times when I do stuff (Professor Julius Sumner Miller) I can see how I can improve. This time: NO!
Attachment:
BoZoaC8.jpg

This type of construction exceeds all other types. It is beyond PCB, point-2-point. It is component-2-component (C-2-C). If you think with a PCB when two components join there is two solder joints and dissimilar metals. Not to mention the solder. Here there is only one joint where one component joins the next.

Also no additional inter-connecting wires. Only the component wire is on this self supporting cct. brd. All other ccts. on other projects other than where component-2-component wiring is used have interconnecting wires. No straps also (apart from a 1mm thick, polished, 4N pure silver short earth strap).


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Projects: Oatley K272C - headphone amp in a tin can | "K272C" - Oatley's newest headphone amp | "VoXItBassO" - stereo 12" sub-woofers ]
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PostPosted: 27 Dec 2010 12:02 am 
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Case is drilled, gold RCA mounted, battery holders and the BoZoaC engine double-sided taped down, ready for wiring. There are two sets of input RCAs and one output RCA set (on the side). The switch also on the side switches between the two sets of inputs. The double sided tape is extremely sticky and holds the components very well it also provides mechanical isolation. Thick bitumanised Al foil lines the top and bottom of the case.

The bannana style ports on the other side sit directly across the power section. This allows me to test the batteries, with a meter without opening the case, under load conditions. Also if I remove the batteries I can plug an external PS into these test plugs to power BoZoaC OR power another device (e.g.my phono preamp) from tthe batteries (3 X 9V = 27V) in the preamp. I could also recharge batteries in the preamp through this power port.

A mini switch at the front turns the minimalist BoZ on with the usual low level blue LED indicator. The preamp should be finished tonight for a listen.
Attachment:
BoZoaC10.jpg


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PostPosted: 27 Dec 2010 1:48 am 
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Finis: Yes it is complete and in it's hand made plastic case (lel). All wiring is wirewarp wire. Here three lithiums power the preamp. Of course any high performance 9V battery, even rechargables could be used. I like lithiums.

At the last minute I added a 0.01uf poly to the power section right at the input to the BoZoaC engine (I could hear Gio whispering "de-couple"). Just one 0.01uf poly to ensure no HF gets into the PS. I'm pleased with the build and assembly.

I am listening to it now from my new Oppo BDP-83SE. It sounds better than my BoZSE capless-or is it. Though this preamp requires 10 or so hours of use to relax the big 10uf 100V ploypropelene output caps and settle the 2 X 1000uf 35V low ESR electros the sound is very immediate, bass seems to be at full weight (I don't believe it) and in all a very natural balance with, comparitively, mids slightly forward.

I thought BoZSE had added additional bass weight due to its 30,000uf of storage caps. But I am sensing this minimalist BoZ has the same bass performance with a fraction of the storage caps? Is it the 27V battery PS?? And I may have better mids??!!??

I cannot play LPs due to the fact I cannot attenuate my phono preamp enough. I may add a pot or an attenuator switch to this BoZ build. So far I'm very pleased. Very impressed. It sounds very quick!
Attachment:
BoZoaC12.jpg
Attachment:
BoZoaC13.jpg
Attachment:
BoZoaC11.jpg


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PostPosted: 27 Dec 2010 2:29 am 
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Mark,

As usual you can make any case look good. :king:
How many hours can you get out of those lithiums ?

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PostPosted: 27 Dec 2010 2:57 am 
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dtsup1 wrote:
How many hours can you get out of those lithiums ?

I'm running it at the moment or partially used lithiums so not a good test. But I will try with a fresh set some time soon.

BUT I do need to add an attenuator. Some CDs, on the Oppo's lowest volume level, still play too loud. I have a few ideas how to fix this.

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PostPosted: 28 Dec 2010 1:08 am 
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One thing I did discover about BoZoaC is that it really required an attenator.The volume control from the Oppo BDP-83SE was too lumpy and it jumps from mute to quite loud in one increment.

So I added a dual gang 50K B tapper pot to BoZoaC. Pass suggests a 25K but I don't think it is critical. This just fitted in the front panel with sufficient room behind not to touch the BoZoaC engine. On playing the pot is not the perfect fit for this preamp but it works. Listening now. The pot does not seem to have degraded the sound audibly. In fact I think I'm enjoying it more. I left it on for a few hours last night to get some burn in time but I think it needs 10 or so hours more.


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Projects: Oatley K272C - headphone amp in a tin can | "K272C" - Oatley's newest headphone amp | "VoXItBassO" - stereo 12" sub-woofers ]
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PostPosted: 28 Dec 2010 2:18 am 
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Location: Delta, BC, Canada
That's a real nice looking amp you got there, great work.


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PostPosted: 28 Dec 2010 2:27 am 
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Check-out my latest blog entry for some additonal info on BoZoaC: http://mongreldogaudio.blogspot.com/

My next constrcution maybe the other BoZ Gio highlighted. http://www.passdiy.com/pdf/brideofzen.pdf

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Projects: Oatley K272C - headphone amp in a tin can | "K272C" - Oatley's newest headphone amp | "VoXItBassO" - stereo 12" sub-woofers ]
Website: [ retro-thermionic ]


Last edited by mwhouston on 28 Dec 2010 2:33 am, edited 1 time in total.

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PostPosted: 28 Dec 2010 2:28 am 
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Yeah, I love the gold engraved badges. I must follow that style for my front panel of my preamp.
Mark, pls provide some details on how you did the engraving.

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