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acg

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acg last won the day on February 14 2018

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About acg

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    I can't jump puddles
  • Birthday 31/07/1973

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    Toowoomba
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    Australia

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  1. Yep. I've already put extra solar panels on the roof to offset the expense...seriously. Dac, preamp, turntable and a couple of computers will probably put the total power draw for the system to a bit over a kW.
  2. Measured the power draw this morning... It's a 4 minute startup protocol. It briefly draws an amp when plugged into the wall and the services LPS fills its capacitors, then settles down to virtually nothing, less than 20w. Then I hit the power foot pedal and the AC filaments/heaters are all lit up and being direct AC there are no caps or other electronics so not much of a spike. The bias and 1st Stages are powered 45 seconds later (just past 1m on the graph) and there is a 5A spike as the power supply caps are filled. That sits at about 150w until three minutes later the DHT, 2nd Stages and Single Stages power supplies are energized. The DMM logs once a second and managed to capture about 11A, which is as much as the mains supply is rated, maybe a little more...perhaps I should put in a soft start. Anyway, after that the amp sits on a pretty neat 400W power draw at idle. Being Class A that should be where it stays even when playing music. So, 400 watts power draw to light up a combined total of 30w-33w of output power...yep, that's definitely Class A operation...haha. Will have to check to see what fuses I have put in the beast and see if they can be trimmed to suit this power draw.
  3. One amplifier chassis per speaker is what I would call a monobloc. Are they still monobloc when there is on power supply box and one amplifier box per speaker? I dunno. It feels great. Let me know when you get away from the Land of the Long White Cloud...I have vinyl withdrawals and need a fix...haha. Seriously though, enjoy yourself.
  4. acg

    Tube + solid state amp in one case

    Truly excellent work! I have a good idea how long this took you from inception to design to crafting, and it is not a simple task. Lots of skills there...
  5. Phwew, the first DSET is operational, finally. It has taken a lot longer than I thought it should have but all six channels in the first monoblock are now operational. It is a thing of beauty to look at and to be honest every time in the last week that I have turned it on for testing I turned off the lights so that the glow could send its good vibes my way. Over on the far left is the DHT driver tube, in this case a 45 globe, but I can put in that socket many 2.5V and 4V heater DHT's from the early part of the last century. Next step is to make it safe, copy the wiring for the second monobloc, and then cart them upstairs for further testing and debugging. Such a relief to finally have one going. As a matter of interest I did a rough noise measurement at the output of each channel to see how my layout choices have been successful: A - 0.2mVAC B - 0.2 mVAC C - 0.3mVAC D - 0.25mVAC E - 6.7mVAC - the DHT Channel - most of this would be AC hum but it was a little dangerous to reach around to use the hum pot to cancel this out, so I did not F - held the 111dB/w/m sensitive RAAL Lazy Ribbon to my ear and could not hear a thing A good start!
  6. It's a pain to wait 10 minutes after shutting down the amp for those massive capacitors to bleed down, but I would prefer to keep breathing at this stage of my life. High voltage electronics is not the kind of stuff to be doing if you tend to rush things...and you guys have seen no evidence of me ever rushing anything (4 years later - now I roast myself too)
  7. DSET Assembly I've also started putting together the first of the 6 Channel SET's. Very excited I am! It's been a bloody grind with a couple of issues which more experience would help me to sort out in a timely manner, but I have perservered and I reckon I can nut it out from here. Four multimeters is not enough and I am tempted to hook off to Jaycar and get myself some more cheapies...six channels is a lot to debug simultaneously. Here she is on the bench with three snake like umbilicals winding down to the power supply on the floor. At the moment I am only testing the First Stages (or driver stages) and the complicated Bias system. I had a problem where the gas regulator tube for negative bias was taking a couple of minutes to ignite plus one of the driver tubes was not conducting and I wasted two days trying to figure out why. Heck yeah ^^^^. These irritating and frustrating couple of days meant I double, triple, quadruple, pentuple (ha!) checked the circuits and while I found nothing really wrong I learned a whole lot about how the circuit works and do not think that it was an entirely hollow effort, because I've gained that little bit of experience that I had lacked at the beginning of the week. So pretty... Tomorrow, I will begin the next round of testing by applying more high voltage to the chassis for the Second Stages, Single Stages and DHT. Wish me luck!!
  8. Fundamentals Horn V2 is underway. First time around I had trouble with the throat so this time I've gone slower and have been more precise. The first 4 rings of 32mm MDF have been done in three stages: 1 ring trimmed and sanded and checked; glue on the second ring then trim and sand; then glue on the 3rd and 4th rings and trim and sand. All a day apart because the glue needs 24hrs to dry. Four rings is twice the length of my fingers so I have primed the throat and will sand it back while I can still reach it...but again it is time because 4 coats of primer brushed on in the course of a day takes several days to properly dry. I'll sand it back tomorrow or the next day and make a call then whether to add more coats of primer. In the meantime I've glued together the remaining rings in two groups based on the length of my cutting tool, so after the throat sanding is complete I'll glue on the next set of rings and trim them to shape and then on with the final group of rings. The outside of the horn is being made balanced and round as I go but is not being cut to the final shape just yet. This horn is about half a meter long so when the final group of rings go on and I get the rollers under the mouth I'll cut the outside profile in one smooth hit which should leave me with less fixing up to do at the end.
  9. Plenty is learned by failures. Not ugly = a whole lot of work. Roast me all you like, I've earned it, haha. I would still like to know what you have tried and why you moved on.
  10. Got a bit of lathe time in today remaking the Fundamentals horn. The throat was not good enough in the originals...too bloody tight to sand properly and I had a paint run in an unreachable area, so they are being redone in a slightly different way so that they end up spot on. It will take a while to get them done but they must be complete before I reconfigure the lathe to turn the front half of the huge 110hz Upperbass horns. I still have about 6 weeks of work to finish that was supposed to be done by Christmas...oh well...so taking all of January off to finish this project is not possible, but I have talked to my clients and am planning to work on and off for the next couple of months to get them out of trouble while giving me some sanity time so I don't burn out. Perhaps week on and week off, or fortnight on, fortnight off for a while, we will see, but this is happening. Might even work the hot days in the office and go in to the shed when the temperature is tolerable. A little more turning tomorrow.
  11. Four years Dave! It did start out as just building the horns and went manic from there. Suddenly I was building the amps and trying to make it look great and it has just got out of hand...everything but the horns are pretty much made....oh my.
  12. ...about to be some progress made Paul...woo hoo.
  13. Yeah, cnc takes a while to cut with the harder materials, and there is a lot of setup time in software and placement as well. As far as enclosures go I build my own. They are designed in CAD and then I have the pieces laser cut and folded locally. A bit of assembly , drilling and occasional trimming with a linishing wheel at home before I send them off for powdercoating. I've never looked at the places such Modushop because they are overseas and I can't see how it could be any cheaper...although cost is not the reason why I build my own cases. There are places that will etch/engrave aluminium for you, and there are places that will make badges or plaques to attach to your boxes. Likewise there are local companies that will cnc machine stuff for you, but it is expensive.
  14. acg

    Port Design Preference

    Paul, personally I would definitely go sealed with the bits and pieces that you have there...port noise is so off-putting and the ports on those big drivers are going to chuff in and out an awful lot of air in the lower frequencies at high SPL. It is also likely you will be able to do the EQ passively with a first or second order filter to suit the sealed response and the room gain. Weight and stiffness is your friend at those frequencies, so build something very heavy that can damp the inevitable vibrations at high SPL. You've seen my big subs...it was a very conscious decision not only to use multiple drivers so that excursion is limited (which reduces the energy sent back into the box and hence box vibrations), but also to house each of those drivers separately so that I could maximise not only weight, but also enclosure stiffness and damping. Mine is an extreme solution, but I think yours is too. I know you'll think it through and go with the best solution for your circumstances and I look forward to reading about it.
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