It is a kodak distance sensor window, you know the one on the Polaroid camera 😉 I have a few of these from snow height sensor 😀
I'm curious, how did you make that nice top hole? I'm not sure how I would go about one that big. Maybe drill a center hole big enough for a thin saber saw blade, then cut around a scribed circle? I have some hole punches with a threaded bolt in the center, but none are that large.
That window is looks great. Those two blue LEDs are used as voltage references for the clipping circuit's window comparator. I was originally going to replace the LEDs with zeners, but the LEDs looked too cool to do away with. What I did instead is swap the original narrow 40 degree lens one for the current wide dispersion 130 degree lens.
That window is looks great. Those two blue LEDs are used as voltage references for the clipping circuit's window comparator. I was originally going to replace the LEDs with zeners, but the LEDs looked too cool to do away with. What I did instead is swap the original narrow 40 degree lens one for the current wide dispersion 130 degree lens.
I simply used a hole saw with some cutting oil. It was very easy to drill and it made a perfect hole. I used a black permanent marker to colour the aluminum sides in black. The small window is glued from under with epoxy glue.
The hole diameter size is not perfect, maybe slightly too large but it was the closest hole saw that I had in stock.
The hole diameter size is not perfect, maybe slightly too large but it was the closest hole saw that I had in stock.
Interesting! I looked around a bit today and sure enough, there are small hole saws in the stores. When I think of a hole saw I typically think of something 5 or 8 inches in diameter for recessed ceiling lighting. Well good to know! That certainly produced a nice round hole.
Im about to purchase one of these but im new to the audiophile community I will be owning the Beyerdynamic DT 990 Premiums (600 ohm vers.) by end of the month and wanted something good i can use and not worry about later on so I currently about to choose:
EHP-O2Di Desktop Headphone Amplifier/DAC | Epiphany Acoustics
this or agdrs one since i dont know how to solder etc ill just buy a premade which would be better between the 2? Sorry as im new i dont know too much so i shall trust you guys opinion im based in UK btw
EHP-O2Di Desktop Headphone Amplifier/DAC | Epiphany Acoustics
this or agdrs one since i dont know how to solder etc ill just buy a premade which would be better between the 2? Sorry as im new i dont know too much so i shall trust you guys opinion im based in UK btw
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Hi!
Both will drive your Beyers without a sweat! Buy agdr's should definitely have more power headroom, and be even quieter. Keep in mind that the ODA does not include the ODAC by default, but you could just purchase it from Epiphany and install it into the ODA's case.
Both will drive your Beyers without a sweat! Buy agdr's should definitely have more power headroom, and be even quieter. Keep in mind that the ODA does not include the ODAC by default, but you could just purchase it from Epiphany and install it into the ODA's case.
ah great to hear! how hard is it to install the odac if youve never done anything like that is there an option where it comes with one all ready to go?
Welcome to the forum! 🙂
Given that you need to buy something pre-assembled and you are in the UK, the Epiphany unit might be your best bet. Due to the energy conservation law in the EU the AC-to-AC wall transformers are no longer available. Folks in the EU who build ODAs pretty much have to box up their own 50Hz torroidal transformer, which would be a bunch of DIY work you probably don't want to get into. It looks like Epiphany have special ordered transformers from somewhere that work with the O2 headamp.
The Epiphany unit should just be a regular O2 headphone amplifier in a box with an ODA. You probably have the links to NwAvGuy's blog, but in case not here you go:
http://nwavguy.blogspot.com/2011/07/o2-headphone-amp.html
So it won't be any better - or worse - than an O2, but the O2 is fine headphone amp. In his blog article NwAvGuy shows all sorts of measurements he made with his dScope tester. I think those are what Epiphany is referring to in their writeup on that desktop version of the amp.
Like CHiroshi says the ODA doesn't have a DAC so you would have to do some DIY work to put one inside, or use one that is separately boxed up. With Epiphany's unit it is just ready to go for you.
However your 600 ohm DT-990s would require 12Vrms to hit 120dB peaks, if the 96dB/mW sensitivity specification I'm seeing on their website is correct. Now that is a bit of a problem. The O2 can only manage 7Vrms while running on AC (much less on batteries) and the ODA with the 12.5Vdc power rails is just a bit higher at 7.25Vrms. The ODA can be built with +/-15Vdc power rails for headphones 300R and up, but that still would only result in 10Vrms, not enough for 120dB.
So, suggestion - if you haven't bought those headphones yet I would highly recommend considering getting the 32 ohm version instead of 600 ohm! You will do yourself a big favor. At 32 ohms and 96dB/mW you only need about 3Vrms and 88mA current per channel to hit 120dB, which the O2 (and standard ODA) can easily do. 600 ohm low-sensitivity headphones are just a real problem to find an amp to drive. See this person's thread on the forum here high now with the same problem:
http://www.diyaudio.com/forums/head...mple-high-quality-amp-drive-600-ohm-load.html
Beyer also still has the 250 ohm version as a special order it appears, but at 250 ohms you still have trouble. 250R requires about 8Vrms and 31mA per channel to hit 120dB. The O2 (and that Epiphany desktop O2) couldn't do it (7Vrms max output), but the +/-15Vdc power rail ODA could. In this case with the 96dB/mW specification 250R would be OK, even though it is slightly less than the 300R for the higher voltage ODA rails. But then with the +/-15Vdc ODA you have an amp that can only be used with headphones 250R and up, while most modern headphones are low impedance (like 32 ohms) and high sensitivity so they work with portable audio devices (cell phones, ipods, etc). The 600 ohm headphone is sort of a holdover from vacuum tubes which tended to work best into higher ohm loads that require higher voltages and less current. Transistor stuff likes lower ohm loads that require lower voltages but more current.
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And just for the record I have both, the O2 and the ODA and for me there is no contest, the ODA sounds much better than the O2, even with agdr buffer 😀
Oh snap wow thank you so much for the helpful info!
As of right now the ive purchased the 600 version i dont plan on taking it anywhere other than using it on my pc rig 🙁
I think the main reason you are seeing so many 600 ohm questions is massdrop just did a sale on it for around $250 so i and probably a few others picked it up.
hmm so if i understand right your oda wont work in eu/uk and it doesnt have a dac inside already so its just an amp? Im going to check the links you posted but im still lost as to my best solution to push the 990's
sorry for all the questions just making heads or tails of it all haha
As of right now the ive purchased the 600 version i dont plan on taking it anywhere other than using it on my pc rig 🙁
I think the main reason you are seeing so many 600 ohm questions is massdrop just did a sale on it for around $250 so i and probably a few others picked it up.
hmm so if i understand right your oda wont work in eu/uk and it doesnt have a dac inside already so its just an amp? Im going to check the links you posted but im still lost as to my best solution to push the 990's
sorry for all the questions just making heads or tails of it all haha
I also have both the O2 and the ODA, but my O2 has agdr's booster board and a bunch of part upgrades. I recently posted a review of both these amps on this site in the O2 booster board thread. I found that they sounded very similar, if you want to ready my full review, it can be found here: http://www.diyaudio.com/forums/head...eadamp-output-booster-pcb-33.html#post4323308
I don't have any 600 ohm phones to give the ODA a test, but nobody listens to music at 120db. If you get the 32 ohm version as agdr suggested, I can say you will not be disappointed by either amp.
I don't have any 600 ohm phones to give the ODA a test, but nobody listens to music at 120db. If you get the 32 ohm version as agdr suggested, I can say you will not be disappointed by either amp.
Very interesting! Thank you for the feedback. 🙂
The much improved power supply in the ODA is likely one reason. Two stages with an input CRC filter and the chips properly heat sinked vs just the two LM78xx fixed regulators in the O2.
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You are exactly right! 🙂 In fact I answered a PM for louiebh a couple of hours ago and noted that while the 600R at 96dB/mW headphones can't hit the 12Vrms for 120dB with the +/-15Vdc ODAC, it can hit 118dB at 9.75Vrms. That 120dB sound pressure level is the "threshold of pain" level on most medical noise exposure charts that isn't supposed to be listened to for more than 7 minutes at a time. 115dB is the level at a rock concert. 118dB is still insanely loud and really just for momentary musical peaks if anything.
So scratch my comment above in bold unless the headphones have even lower sensitivity than those DT-990s, like something in the 80s (dB/mW). That 120dB (SPL benchmark is essentially pulled out of the air, although I probably see that level referred to more than any other on the forums. The important thiing to remember is that is just an extremely short maximum-peak level, nowhere near sustained maximum listening levels of probably 70-90dB or so.
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I have the 250 ohms version of the DT-770 with a nominal SPL of 96db, and both my O2s (one with the agdr's booster and one low power version with the TLE2062 output opamps) can drive the cans beyond reasonable listening levels. With 1 X gain on my booster equipped O2, maximum confortable level is reached with the volume knob at around 3 o'clock. I realise this is highly subjective, but anyways... 😊
I listen mostly to classical music, but jazz, soul and funk is also part of the program!
I listen mostly to classical music, but jazz, soul and funk is also part of the program!
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That is correct, the ODA is just an amp and no EU or UK transformer available. I've already PMed this but I'm going to post here too since it might help others. Over on Head-Fi there is a thread about powering 600 ohm DT-990s with this post saying the fiio E09K power booster and E17 DAC worked just fine with plenty of volume.
Beyerdynamic DT990 / 600 Ohm Amp Recommendation and misc. - Page 2
I see the E09K on Amazon right now for $100 and the E17 for $140. They would be a relatively economical way to get an assembled unit.
About the AC-AC wall adapters in Europe, I'm aware about the new regulation, but here in Sweden I have been able to buy these off the shelves at Kjell & Co. Check their web shop, I don't know if they ship outside Sweden. http://www.kjell.com/sortiment/el/s...ac/ac-ac-transformator-15-v-ac-1000-ma-p44207
I don't know if that might help someone here.
I've been buying a few these in different voltages over the past couple of years for different projects, and they were always available.
I don't know if that might help someone here.
I've been buying a few these in different voltages over the past couple of years for different projects, and they were always available.
WOW!! That is a fantastic find. Thank you for posting the link! It even has the correct 5.5/2.1 mm power plug.
For the ODAC the 18VAC would be best. To hit the full 420mA out per channel it would take 2.2amps or greather due to the power supply spikes from the half wave rectifer, but very few headphones would need anything near that. The 1000mA adaptor should be able to provide 200mA out per channel with no problem, which is still above the O2's 140mA per channel maximu.