I just finished reading this whole thread, which I discovered today. Thanks, Owen, for everything you have done for the community and I am definitely interested if you decide to do another run of populated SE-SE boards!
Just received my bal-bal board! It looks great!
Does anyone know the current draw of this amp? I a pair of Sjostrom jsr01 +-14v here, and some boards for the SSLV 1.1. Would like to try the sjostrom, but I don't know if its powerful enough.
Does anyone know the current draw of this amp? I a pair of Sjostrom jsr01 +-14v here, and some boards for the SSLV 1.1. Would like to try the sjostrom, but I don't know if its powerful enough.
No losses? I thought it might be efficient being IC, but there is a lot (relative) of heatsinks on it.
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Idle losses are relatively small compared to full power load requirements.
Total current draw depends on the rail voltages, the higher you go in voltage, the higher the quiescent current. See page 8 of the LME49610 datasheet for the graph of current draw vs. BW vs. supply voltage.
In a typical +/-15V setup at idle, with the BW pin tied to V-, you'll be drawing 14mA per buffer and 14mA for the OPA1632. That's roughly 42mA per channel, or 84mA per board.
At full load, the buffers can deliver 250mA peak current per channel, so you'll need to handle peaks of 500mA if you want to be able to run both channels at full power.
It's exceedingly unlikely that you will ever need full power, so I'll leave it up to you to sort out just how much power you'll need for your specific headphones and desired listening levels.
Regards,
Owen
I think so... I was in a hurry, but I think it's correct upon review.
Each BAL-BAL board contains one OPA1632 and two LME49610 per channel, so that should be 14ma + 14mA + 14mA = 42mA per channel. The board has two channels, so 84mA?
Did I miss something?
Regards,
Owen
the 1632 is 14mA typ.
The 9610 is 13 or 19mA typ. times 2 gives 26 or 38mA
That would come to a balanced channel requiring a typical 40mA or 52mA
two channels 80mA or 104mA
Then add on the output current that the load demands.
He needs to know his load.
The 9610 is 13 or 19mA typ. times 2 gives 26 or 38mA
That would come to a balanced channel requiring a typical 40mA or 52mA
two channels 80mA or 104mA
Then add on the output current that the load demands.
He needs to know his load.
Hi Andrew,
The 19mA case is not applicable here since the OPA1632 shares the same rails as the LME49610, and the OPA tops out at +/- 16V, so there's no safe way to run 22V rails.
I'm not sure if the relationship between current draw and rail voltage is linear or not but if it is, you could extrapolate the current draw at even lower rail voltages using the existing two datapoints for 15V and 22V. I would imagine idle current would start to become quite low at +/- 8V.
More to your point though, he does indeed need to know what load he's driving, and at what levels, and then the power supply requirements can be derived.
Regards,
Owen
The 19mA case is not applicable here since the OPA1632 shares the same rails as the LME49610, and the OPA tops out at +/- 16V, so there's no safe way to run 22V rails.
I'm not sure if the relationship between current draw and rail voltage is linear or not but if it is, you could extrapolate the current draw at even lower rail voltages using the existing two datapoints for 15V and 22V. I would imagine idle current would start to become quite low at +/- 8V.
More to your point though, he does indeed need to know what load he's driving, and at what levels, and then the power supply requirements can be derived.
Regards,
Owen
The quiescent current is pin selectable. That is separate from the changes in quiescent current that occur with changes in supply rail voltage.
Hi Andrew,
The 19mA is still for the case where BW is tied to VEE and the rail voltage is at 22V which isn't an arrangement that is possible to run on the BAL-BAL due to the restriction caused by the voltage limits of the OA1632.
Besides that limitation, I would suggest there aren't any headphones out there that require 28VRMS to drive them, so running 22V rails seems a little extreme.
See the attached graph from the datasheet.
The highest possible current draw would be with BW tied to VEE and +/- 16V rails which is still roughly 14mA.
With the BAL-BAL, it would be quite adequate to run much lower rail voltages, as the output voltage swing is twice what you get from an SE setup with the same rails. Most headphones would be more than happy on 7V rails which would dramatically reduce idle losses.
Regards,
Owen
The 19mA is still for the case where BW is tied to VEE and the rail voltage is at 22V which isn't an arrangement that is possible to run on the BAL-BAL due to the restriction caused by the voltage limits of the OA1632.
Besides that limitation, I would suggest there aren't any headphones out there that require 28VRMS to drive them, so running 22V rails seems a little extreme.
See the attached graph from the datasheet.
The highest possible current draw would be with BW tied to VEE and +/- 16V rails which is still roughly 14mA.
With the BAL-BAL, it would be quite adequate to run much lower rail voltages, as the output voltage swing is twice what you get from an SE setup with the same rails. Most headphones would be more than happy on 7V rails which would dramatically reduce idle losses.
Regards,
Owen
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Hello Owen,
This is a very interesting build. It might be the right one for my headphones. My headphones are Sennheiser HD 598 (50 ohm, 112 dB/1kHz/1Vrms, THD <0,1%(1kHz/100dB SPL)). I have a few questions about it:
- I'm searching for some matching amplifier and DAC, can this amplifier swings up to 2.5Vrms into a 50 ohm load per channel?
- Would I have to modify this amplifier for my application or is it Ok like it is?
- I will use it on my PC (Motherboard: Gigabyte H81M-HD3). What kind of decent DAC would you recommend for this application? I'm not an audiophile but I enjoy good sound quality (my music is always 192 kbps or more).
- Can you still provide the pcb's for this amplifier (including power supply pcb)? How much is the price including shipping to EU - Slovenia?
- Is there an option to get a BOM? I would like to ask my local dealer if they can provide me with all the material before I start.
Thank you 🙂.
Best regards, Ziga
This is a very interesting build. It might be the right one for my headphones. My headphones are Sennheiser HD 598 (50 ohm, 112 dB/1kHz/1Vrms, THD <0,1%(1kHz/100dB SPL)). I have a few questions about it:
- I'm searching for some matching amplifier and DAC, can this amplifier swings up to 2.5Vrms into a 50 ohm load per channel?
- Would I have to modify this amplifier for my application or is it Ok like it is?
- I will use it on my PC (Motherboard: Gigabyte H81M-HD3). What kind of decent DAC would you recommend for this application? I'm not an audiophile but I enjoy good sound quality (my music is always 192 kbps or more).
- Can you still provide the pcb's for this amplifier (including power supply pcb)? How much is the price including shipping to EU - Slovenia?
- Is there an option to get a BOM? I would like to ask my local dealer if they can provide me with all the material before I start.
Thank you 🙂.
Best regards, Ziga
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Thanks!
Bought it back in the day when I was looking for a matching enclosure to house the Salas shunt supply I had built to power my M2Tech EVO.
With a little bit (actually a lot...) of digging around I managed to find the exact same enclosures M2Tech are using for their EVO products, namely the "AKG 105" line from Fischer Elektronik. You can see the finished PSU in the attached pic.
The exact product code of my enclosure is AKG 105 46 220 ME, but they come in *lots* of different sizes. You can find them all here. I see they've added more (e.g. the TON line seems nice).
At the time I couldn't find them in stock at any of the usual suspects, so I had to order from the local distributor (had to wait ~ a month for delivery). Maybe things are better now, but haven't looked.
Hope that helps. 🙂
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Absolutely. The BAL-BAL or SE-SE will happily swing up to 8.5 VRMS into a 50 ohm load before they start current limiting.
No need for any modification. If you go for the SE-SE then everything would be exactly as it would with any other headphone amp. If you go for the BAL-BAL then you should make sure you headphones are wired for balanced input (eg. no common ground). This may require an aftermarket or custom made cable. Most of the time though, you can just change the connector from the usual 3.5mm or 1/4" to a 4-pin XLR or Lemo.
I'd suggest a Twisted Pear Buffalo II/III/SE with a good I/V stage like the NTD1, but that might be more than you're looking to spend. I think there are few lower cost variants available now based around some of the mobile ESS DAC parts. Check those out.
All boards are fully available and in stock at the moment. Order sheet with pricing is linked to at the very top of the very first post in this thread. Just add your name and I will send a PM.
Full BOM is on the build Wiki site here:
"The Wire" Headphone Amp Build Wiki - diyAudio
Regards,
Owen
What is the difference between PSU and PSU V2? And what kind of transformer do I need to order for SE-SE amp? Thank you.
Everything is different.
You can use an Antek 25VA 12V or any similar transformer:
AN-0212 - 25VA 12V Transformer - AnTek Products Corp
Regards,
Owen