mdr30
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Posts posted by mdr30
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On 4/28/2022 at 2:55 PM, n_maher said:
1. I know this is a personal preference thing but I do not care for their chosen aesthetic.
2. Straight to cloud 7... What the? I think they meant cloud 9 but it still would be a bizarre statement to make about a headphone. The internets do have some references to cloud 7 but whatever.
3. I'm really hoping Justin didn't write this ad copy.
"Cloud nine" (highest bliss) is not referred to in non-English speaking countries, where as "Seventh heaven" (Aristoteles) is more widely used in different vernaculars; "Sjunde himlen" where I live. Surely something similar in Italian.
A classic mix-up. It's difficult to grade pleasure, it comes in many forms. My most recent sonic one is a renovated SR-X Pro, around 200 bucks in all. I find it hard to believe this Spirit thing provides 50 times more "bliss", but I'm open to new delights.
Any technical information about the drivers?
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Joamat's build reminded me of some problems with balance and setoff on my own Dynahi. I adjusted the amp a couple a months ago, a bit tricky with DC fluctuating, but got numbers down to 3-15 mV with servo in, depending on volume pot position. However, with headphones connected, DC between hot and cold is 50-80 mV. Anyone got theories why this is?
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It's my favourite amp for dynamic headphones, double mono like yours with psu in a separate box. Sounds so good I haven't even bothered to replace the THAT340 with JFETs.
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Opened up a SRD7-SB to see if it needed any updates. Looks neat and tidy, and at least no electrolytics to replace. Is there anything I should consider before it's put into action?
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Late to the party, but here goes. Lured a nice small case off of MLA for a cheap penny, wanted a compact CFA (SE).
Took some time for my slow mind to figure out how to best use the space in three dimensions, but I found a solution that works fine so far, if you're planning something similar. No interfering leads or unwanted nearness of critical components, and bias can be set without problem. In reality, I'm surprised it turned out quite airy and spacious, considering the limitations.
Note the Müller Rhombus transformer device ("Konzept Raute"). This romboid plate interacts wit the circular toroid shape and the electromagnetic waves are forced through the four holes in an endless loop in this electronically confined space, and thus traps all hum in an existant/nonexistant void. This amp is noise and hum free.
I'm particulary happy with the volume control, a 24-position Swiss Elma switch that's been lying in a drawer for 35 years. 15K (why not?), shunt coupled and making as little contribution to the signal as possible. I think this plays a part in the clean, revealing sound of the CFA design.
The odd resistor out is in the position I mostly listen to, a hand selected Syldavian military plutonium component (0,01%) from 1953, made in a numbered series of three of each value (I own the third one as well) and these days sold on ebay in Hong Kong for not less than $1200, if available at all (only one for sale during the last nine years).
Set the bias at first to 150mA, it sank to 135 after some time, which was to be expected. Decided too raise it (why not?) to 200mA. Put the lid on and after three hours it was stable at 175mA after a last fine-tuning. Gets warm, but not too hot.
Like all successful, completed builds it sounds wonderful , but if that lasts only time will tell. If so, I may be tempted to follow up with a CFA3.
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So, finally time to replace the cable of my 007. Birgir and others have probably demonstrated this before, but I thought I'd show some pics for those who, like me, haven't done it before (and, sooner or later it will be necessary).
Off with pads and front plate, and the nylon piece covering solder terminals.
Solderer's best friend: electrical tape. Some sacrifices necessary too - had to buy and eat a bar of chocolate for the cardboard to protect driver from hot solder.
New cable in place.
Also adjusted the headband elastic and put on the pads correctly, wasn't done before.
Now the 007 sits tight on my head, sounds better and is more comfortable. Promised myself to fix the 007 when I finished my Carbon, so here goes. Build without major problems. MLA brought his variac for startup, and there were high voltages on the outputs. My mistake, had missed to solder one leg of a PZTA56, hanging in air. Fixed that and it works fine.
Wanted to keep it simple and clean. Might add a LED when I can afford it.
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On 10/26/2021 at 10:23 PM, kevin gilmore said:
bc546/bc556 starting to get very hard to get even though onsemi says they are going to make more, so this which needs massive amounts of checking.
Anyone order the boards? I'd be interested in a pair.
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On 11/26/2021 at 4:19 AM, JoaMat said:
Just made a third board (right side) of “Megatron something”. Output CCS are T2 style - 3 x 2sc4686 and 2sa1968. All ten LEDs are on top side of board. I’ve to compensate for the missing tubes.
Picture is shoot in weak light, ISO 12800 and 1/6sec.
"City of Tiny Lites".
Tell us the truth: 1.7 or 2.1?
Make sure the salty Kattegatt sea air doesn't corrode the copper.
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21 hours ago, JoaMat said:
While waiting for the replacement I today brought forward my home-built headphone which has been stoved away for a year or so. It sounds really good, even better than I remembered. Perhaps it ages as a good wine. Wonder what happens if I put it away in our wine cellar for a couple of more years?
Original home-built Faulty Stax
A listen now and then might be advantageous. Aren't the bottles supposed to be turned every year or so? About to replace the cable of the 007 when I've got the Carbon together. Gamma will do service meanwhile. Thinking of moving the drivers to a SR-X MkIII, but don't know if it's worth the effort. On-ear not so comfortable.
If the Carbon fulfills expectations the headphone to the right behind may be the next step.
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13 hours ago, JoaMat said:
Well… I’ve finished the work with the new headphone and it ended in a disaster.
I decided to resolder all solder points, so I took the driver package a part. Even removed the small cable connector. After cleaning all solder points, I connect outer stator and put into its position. It was a bit tricky to arrange the short wire in the connector house. Next was the diaphragm and here I made the disastrous mistake and got a scratch on the membrane when I should solder its wire. I guess I’m getting to old and clumsy for this kind of delicate work. Nowadays I have to wear headband magnifier which also makes it more difficult. Anyhow, I finished the assembly and have one good side and one bad with a small defect on membrane.
After visual inspection with good light and magifier I don’t think the lower loudness had anything with dust or any foreign particles to do nor bad connections. So, I really should had waited for this…Thanks a lot, Wachara and Birgir!
Don't buy a lottery ticket this month, Joachim. Is the membrane ripped, or is it only surface damage? If the latter, the driver may reform. And you can always send it back for repair, then you'll have a mint headphone again (even if the cost hurts).
Reminds me to be extra careful when I change cable on the 007, to be done when my Carbon is finished. Something to look forward to.
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Finally completed my Dynahi, an on/off project (like some of them) for five years. Bought the set of boards from Samsie in December 2015, so I thought I'd just let him know that they eventually came of use!
Turned out to be a relatively uncomplicated build, except for a couple of resistors around the THAT340 with too many zeros, discovered by MLA.
Also a problem with the -30V side on one of the PSUs. Turned out to be a malfunctioning rectifier. A BC556 popped, but the supply worked once replaced. For a week or so, then the 556 popped again. After the third time I scratched my head, but some sparks from one of the surrounding caps told me it had taken some beating from the faulty rectifier. Replaced that and the DN2540 and now it has played without incidents for a couple of weeks.
Sounds very nice and has become my go-to-amp, with some competition from a KSA5 I took over from MLA recently. Spoiled for choice.
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23 hours ago, Pars said:
Those caps should run from V+ or V- to ground. The boards have a ground plane (top side of board). Check for continuity to ground on those; if not, jumper them to ground. Sometimes if you use PCB drills and only enlarge slightly, they will still be good.
Thanks, two jumpers did the trick.
I think I'll lower the gain with 50K/5pF feedback, which I think are the parts at the arrow (don't have a schematic).
The PSU is hopefully ok too, did not populate the transistors that popped at turn-on.
Time to test the beast.
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Am about to test my Dynahi boards but have a little probelm.
The holes were to small for the 0,1 uF servo caps so I made them slightly larger wit a drill. Later I realised I may have ruined and inner layer contact (one leg of the caps have no connection on the back of the board). Is there a way to check this, could a jumper fix it?
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Had a Keith Monks unipivot quicksilver tone arm 30 years ago, very interesting design.
Problem was that the pins oxidised in the quicksilver bath, had to be cleaned regularly. But the design without cables from tone arm to turntable and at the same time damping of the unipivot arm tube in the four quicksilver baths connecting cartridge to riia was quite intriguing.
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On 11/24/2020 at 12:09 AM, Grahame said:
Wonderful.
Listened and appreciated it. Only afterwards did I realise she's from my home country - never heard about her before. Shame on me.
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On 2/2/2020 at 9:10 PM, Scgorg said:
The Stax SR-X MK3 (normal bias) measures almost completely flat on EARS but is horrifically bright if you actually listen to it.
No it's not. Generalised opinions like this should be avoided.
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18 hours ago, JoaMat said:
Joans Fjeld - Svaert Nok For Meg
Now isn't that a rare choice. I bought his "Jonas Fjeld Rock and Rolf Band" in the 1970s, on sale at Waidele in Gothenburg. A terrific, original and inspired recording making fun of present trends with a satire twist ("Bridge Over Tonic Water"). A forgotten masterpiece that still excites.
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Ask joamat.
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14 hours ago, jose said:
Yes I have one too... I have not heard it for years but I have very good memories of that amplifier.
Count me in as well. Fine amp, does its duties alongside Dynalo, M3 and Squarewave (and soon Dynahi). Runs it with Russian gold grid 6N1P tubes.
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Anyone got spare CFA boards, dynamic?
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On 4/18/2019 at 12:18 AM, JoaMat said:
Wow, I like that Scanivox box – beautiful.
Thanks. Of course a small homage to the Swedish radio manufacturer 'voice of Scandinavia' (1940s). The vintage knob has the patented double dot feature which guarantees perfect channel balance. On-off switch is a spiffy little Russian thing with nice M1,6 threads. Bought a pair from Bulgaria delivered in oiled paper. Strange thing: manufacturer has the same name as me.
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Gonna start Dynahi next, on board heatsinks and double mono in two boxes, and wonder if anyone konows where I can source two SJ109 jfets to go with the SK389s I got.
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Does anyone possibly have a couple of sj109 to complement my sk389s?
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and now for something completely different part 3
in Do It Yourself
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Nice! Heat sinks ready for a T-bone steak? I prefer rare.