qusp,
Thanks for your generous offer. Problem is I live in France, so shipping would not be particularly ideal. But still better than ordering two resistors from mouser, so, if my suggestion doesn't come through, i may contact you or Owen.
And yes, i was especially talking about the SE-SE amplifier, although the same could be said about the BAL-SE.
Let 's assume we want a max SPL of 115dB (still below the real sound pressure level of some live orchestras, but enough in most cases)
The Sennheiser HD-600 has a sensitivity of 97dB/mW for a 300ohms impedance. This means that to attein 115dB, it requires a power of 63mW, equivalent to 4.4 Vrms (12,3 Vpp), and a current of 14.5mA.
Now, 4.4Vrms is a seriously hot source, and not commonly found, even in balanced mode. Most common sources are around 2Vrms, which means a gain of 2 would be just enough to handle the headphone. Hence my suggestion to raise the gain to 2X at least.
Worst case scenario: with a standard line level of 1Vrms and a 1X gain, the SPL would only be 102dB.
On the other hand, if ones want to be able to have enough headroom to hit the 120dB, the voltage requirement is 7,7 Vrms (22 Vpp).
Furthermore, the huge current ability of "The Wire" allows to use it with low impedance phones as well. With a 2X or 3X gain, "The wire" would be a truly universal headphone amplifier and preamplifier, while it would be quite lacking headroom with a big crowd of cans with a unity gain.
Also, there would be little to no downside, as the SNR is ridiculously low, so it would still be perfect fot iems, and such.
Thanks for your generous offer. Problem is I live in France, so shipping would not be particularly ideal. But still better than ordering two resistors from mouser, so, if my suggestion doesn't come through, i may contact you or Owen.
And yes, i was especially talking about the SE-SE amplifier, although the same could be said about the BAL-SE.
Let 's assume we want a max SPL of 115dB (still below the real sound pressure level of some live orchestras, but enough in most cases)
The Sennheiser HD-600 has a sensitivity of 97dB/mW for a 300ohms impedance. This means that to attein 115dB, it requires a power of 63mW, equivalent to 4.4 Vrms (12,3 Vpp), and a current of 14.5mA.
Now, 4.4Vrms is a seriously hot source, and not commonly found, even in balanced mode. Most common sources are around 2Vrms, which means a gain of 2 would be just enough to handle the headphone. Hence my suggestion to raise the gain to 2X at least.
Worst case scenario: with a standard line level of 1Vrms and a 1X gain, the SPL would only be 102dB.
On the other hand, if ones want to be able to have enough headroom to hit the 120dB, the voltage requirement is 7,7 Vrms (22 Vpp).
Furthermore, the huge current ability of "The Wire" allows to use it with low impedance phones as well. With a 2X or 3X gain, "The wire" would be a truly universal headphone amplifier and preamplifier, while it would be quite lacking headroom with a big crowd of cans with a unity gain.
Also, there would be little to no downside, as the SNR is ridiculously low, so it would still be perfect fot iems, and such.
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CaféNoir:
Let me know what gain you would like, and I'll toss in an extra set of resistors with your kit (unless you've already made arrangements with qusp) I know that from your end it seems like a small trivial thing, but consider that I have to assemble, pack and ship over 100 kits, and you'll see why I can't offer to "customize" every single order. It's a logistics nightmare.
As for the gain thing, I think you're being a little too academic about it. Grab yourself an SPL meter and turn your loudspeakers up until it reads 115dB SPL. It won't be just a little unpleasant, it's downright painful and physically upsetting. I know real concerts can hit 110-115dB SPL, but that's not because they should, it's because they have to in order to get decent SPL 300 feet back in the last rows of seats. When I go to concerts like that, I always bring ear plugs.
The other issue is that the vast majority of headphones are significantly less than 300 ohms, and significantly more sensitive than the Sennheiser phones you're talking about. If I dialed the gain in for the user with the lowest sensitivity phones who wants to listen at ear bleeding levels, then the other 95% of people will have ten times more gain than they need, and there's nothing that irks me more than wasted gain!
I suggest you give it a try at unity gain first, and see how you find it. If you genuinely feel it doesn't play loud enough with 2VRMS running into your headphones, then I'll put my foot in my mouth. You'd be looking at over 110dB SPL at the ear, and I can tell you from experience, that's loud enough to be seriously upsetting.
Cheers,
Owen
Let me know what gain you would like, and I'll toss in an extra set of resistors with your kit (unless you've already made arrangements with qusp) I know that from your end it seems like a small trivial thing, but consider that I have to assemble, pack and ship over 100 kits, and you'll see why I can't offer to "customize" every single order. It's a logistics nightmare.
As for the gain thing, I think you're being a little too academic about it. Grab yourself an SPL meter and turn your loudspeakers up until it reads 115dB SPL. It won't be just a little unpleasant, it's downright painful and physically upsetting. I know real concerts can hit 110-115dB SPL, but that's not because they should, it's because they have to in order to get decent SPL 300 feet back in the last rows of seats. When I go to concerts like that, I always bring ear plugs.
The other issue is that the vast majority of headphones are significantly less than 300 ohms, and significantly more sensitive than the Sennheiser phones you're talking about. If I dialed the gain in for the user with the lowest sensitivity phones who wants to listen at ear bleeding levels, then the other 95% of people will have ten times more gain than they need, and there's nothing that irks me more than wasted gain!
I suggest you give it a try at unity gain first, and see how you find it. If you genuinely feel it doesn't play loud enough with 2VRMS running into your headphones, then I'll put my foot in my mouth. You'd be looking at over 110dB SPL at the ear, and I can tell you from experience, that's loud enough to be seriously upsetting.
Cheers,
Owen
it doesn't matter even with 300 ohms its academic, you have to go higher than that to make unity gain with such good current delivery not enough and i like to listen quite loud sometimes. according to my chart on hearing protection guidelines 115db below 115db is the loudest level before they say you shouldn't listen at all.
i haven't tried the SE-SE, but i couldn't go past half way with hd600 on the bal-se. basically you just said what i did before edit. i decided i'd send it via pm as it was a really long reply.
i haven't tried the SE-SE, but i couldn't go past half way with hd600 on the bal-se. basically you just said what i did before edit. i decided i'd send it via pm as it was a really long reply.
Increasing Input impedance
Hi Owen,
I don't want to throw this off-topic, but I do have a technical question... Do you think The Wire would be stable (or suffer any performance degredation) if upon building it I replace the 10K resistors at the inputs with 47k resistors (to increase the input impedance?). It would be to play nicer with the some other gear that will be consuming the same signal. Attached is a photo to make my question clear... this is a snapshot of a single channel of the Bal-SE version.
Looking forward to building this puppy
Hi Owen,
I don't want to throw this off-topic, but I do have a technical question... Do you think The Wire would be stable (or suffer any performance degredation) if upon building it I replace the 10K resistors at the inputs with 47k resistors (to increase the input impedance?). It would be to play nicer with the some other gear that will be consuming the same signal. Attached is a photo to make my question clear... this is a snapshot of a single channel of the Bal-SE version.
Looking forward to building this puppy
Attachments
I'll update the list with the additional orders, and post it up here tomorrow!
fualcr:
Running higher value resistors in those location is no problem at all. I just chose 10k since it's a common value for input impedance, but if you're driving this with a tube amp or any other source that wants to see a higher impedance, changing those resistors will have no ill effect.
The only possible downside would be higher thermal noise from that resistor due to higher value. It may or may not be measurable with no input, and shouldn't have any effect once your source is connected.
Regards,
Owen
fualcr:
Running higher value resistors in those location is no problem at all. I just chose 10k since it's a common value for input impedance, but if you're driving this with a tube amp or any other source that wants to see a higher impedance, changing those resistors will have no ill effect.
The only possible downside would be higher thermal noise from that resistor due to higher value. It may or may not be measurable with no input, and shouldn't have any effect once your source is connected.
Regards,
Owen
Hi Owen,
I understand very much how difficult and time consuming it must be for you to organize such a group buy, and I can't thank you enough for the oportunity you give us all to enjoy the wonderful equipment you design.
Concerning your offer, you have a PM.
Also, I have been already testing my HD-650 with a unity gain, using my Dispre-2 and while I agree that my statement was a bit bold and the gain is high enough on most cases, there are times, with low level recordings, that I wish there were a bit more.
kind regards
anybody wants to take my slot for 1x SE-SE PCB + PSU kit?
suddenly i'm in need of cash and cannot afford another expenses
Hi Owen,
I would like a SE-SE + PSU full kit pls. Can take your ifjoel2000's slot but would need the full kit. Thanks for your efforts!
My assistant was suggesting something like this, just to have a bit of headroom
Just to doublecheck, am I still on the list for two PSU ? I subscribed very early in the thread. I may take even kits, if available, whatever is easier for Owen.
Thanks,
Davide
Attachments
Hi Davide,
I do indeed have you down for a pair of power supply boards, so no worries.
As for that transformer, you might want to check in with IanAS. If you have two of them he'd probably take them off your hands to build dual mono supplies for the BAL-BAL headphone amp he bought
If you're reading this IanAS, I'm just poking fun
Cheers,
Owen
I do indeed have you down for a pair of power supply boards, so no worries.
As for that transformer, you might want to check in with IanAS. If you have two of them he'd probably take them off your hands to build dual mono supplies for the BAL-BAL headphone amp he bought
If you're reading this IanAS, I'm just poking fun
Cheers,
Owen