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HdB

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About HdB

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    melb
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    Australia

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  1. Ah Steffen, you're looking at the well known Hagerman snubber network for transformer secondary windings - a capacitor in parallel to a capacitor + series resistor network - for these purposes it's 10nF in // to 150nF + a measured resistance, yes? Circuit 'snubbers' have been around for a long time and extensively used in power engineering and it works very well indeed as 'acg' mentioned above, to suppress/dampen the ringing in the secondary windings of the transformer produced by the 'reverse charge/back firing 'spike' of the conventional diodes and especially the classic BP bloc
  2. Referring to Steve's post above (Batty - Mar 7) about choosing the M2X amp for the selection of input stages, these same input stages can be used in the F6 too, although these pcbs are designed to fit snuggly onto the M2x pcb and require some 'links' to fit the F6 layout but the original input stages on both amps are simple jfet buffers and Mark Johnson has developed a family of optional buffers to experiment with - the sound of the M2x and the F6 are a bit different mainly due to the different signal transformers and the feedback design. The F6 appeared about 10 years ago and beca
  3. Red's got a low mass unipivot but it's only 9", I think
  4. Thanks guys for you advice, Yeah, I wondered about that stupidly low 150*C and measured the temp of the pcb when inside and it came to about 260, or thereabouts - go figure - I got one of those infra-red 'toaster-ovens' just for the job too! I've taken note of the tips about pre-coating the copper and the solderwick cleaning, Roman too. Yeah, my old weller, excellent iron with quite sharp #7 tips finally gave up the ghost and I got one of those new temp controlled ones and a cheap lower power 'toys' with the temp setting in the handle - it seems to work ok
  5. Thanks for your reply Rockeater, I can handle the smaller resistors without too much trouble (apart from going 'cross-eyed!) but these miniature ICs are a real PIA - I've looked at numerous videos about smearing paste on the copper and positioning the IC on top of that and cooking it in an oven at 150*C for 15 minutes but somehow, the damn things just don't seem to pull straight onto the pads like they say so I've assumed it's the silly bugger attempting things well beyond his capabilities (much as i hate to say it) and looking for someone who has mastered 'the knack'.
  6. I'm looking for someone that is comfortable soldering the tiny surface mount components, preferably in Melbourne but not exclusively. even with magnifiers and following the online videos, these things are quite the challenge.
  7. I have an unused Tortech isolation transformer here - it's their 600VA version in the usual white metal case - I was going to retrofit a line filter to it but never got around to it. I'm in Melb and available for a possible pickup - it's not a light package.
  8. Nicely done - I think there should be a continuous surface between the modules but not sure if it's really significant in practice. What is something to consider is the relative distance between the sound reaching the listening position directly from the speakers and the sound coming from the diffusers - it looks like being about 3 - 4 msec or a path difference about 3 - 4 feet Before securing them to the wall, perhaps you would try them at either on the wall behind the speakers (about 5 feet) or on the back wall behind the listening position (also a space of over 5 feet) to achieve
  9. Hi Rob, I sent you a PM about the copper ribbon Interconnect project awhile back ...
  10. I somehow have started getting blue writing on the Stereonet pages that don't allow posting and is bloody weird - have to find the internet site again - I wonder what's going on? Okay, basic 8mm and I don't think any measurable differences between the "original" 60mm, and this new 56mm considering the benefits of the fractal profile. The local Styrene people here are called "Foam Fabrications Pty Ltd" and contact is Stuart Lown - they're in Rowville here in Melb but pretty sure you'll have a local styrene company up your way that'll do the same thing with a compatible
  11. I got a sample from the guys in Latvia when they were cheap - they are okay but, as you say, quickly add up to considerable amount. The local option surprised me in that it cost A$100 for a program setup fee (just the once) for plain and fractal version, then a further $200 for a dozen panels, mostly the 1200 X 420mm wide size and this will be same cost in future - apparently, it's a simple job for the foam cutters. I looked around for high density styrene foam but couldn't find anyone providing cutting service, or retail sales of 'sheet form' at all but the much of absorbtion of the
  12. Thanks, didn't know they had a specific USB 2 version - interesting. All the best
  13. A very impressive project Steffen, just to router the fractal strips alone is a rather onerous job and I see you've used the basic 7 step version ( 0,40,50,30,50,40, 0mm height) - I did the same - amazingly effective. I made the plain/simple Arqen 'leanfusers' with 60mm flats using plywood, etc but didn't keep the grain of the ply consistent and used average quality ply so they ended up looking a bit 'basic' even after stained and sealed - I made the 2 of the 7 unit diffuser (2940 wide and 1200 high) for across the front wall behind the speakers and they do work very well - it s
  14. I think your "market price" of $75 is the price on the US website - out here they're more like AU$130 - 150 but appear to be in short supply at present . I might be persuaded to loan you mine butdepends ....
  15. I have a couple of the well regarded 25s that were rebuilt by the Garrot Bros back quite a few years ago and were designed to run very lightly on a very stable arm - if interested ...
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