It is obviously distorted/clipping at less than half of the pot level with the HE-4xx's which is to me a moderate listening level. It's a bad combination for whatever reason. Now that being said I have never been impressed with the HE-4xx's and I don't rule out that there is something wrong with them.
Now I do love the T60RP's with the NOIR, this combination brings a different presentation than the SMSL THD amp that I have been listening to for a while now. There is more pace to the mid base to mid range. Kick drums impact are articulated, bass guitar was more accounted for in comparison. When I listened to Mondo Cane I could hear more room reverb, no check that I could hear the room reverb which I compleatelly missed with the SMSL combo. I've heard other parts of this recording that jump out, and it is great but I have babbled enough about my tin ears. Oh one more thing I have turned up the T60RP/NOIR combo to 11 for no longer than 3 seconds and no obvious distortion / clipping at all, just too loud to listen to.
I do find it weird that two cans that are at least similar electrically on paper give such drastically different presentation. I really do not consider the MassDrop HE-4xx a reference at all.
Now I do love the T60RP's with the NOIR, this combination brings a different presentation than the SMSL THD amp that I have been listening to for a while now. There is more pace to the mid base to mid range. Kick drums impact are articulated, bass guitar was more accounted for in comparison. When I listened to Mondo Cane I could hear more room reverb, no check that I could hear the room reverb which I compleatelly missed with the SMSL combo. I've heard other parts of this recording that jump out, and it is great but I have babbled enough about my tin ears. Oh one more thing I have turned up the T60RP/NOIR combo to 11 for no longer than 3 seconds and no obvious distortion / clipping at all, just too loud to listen to.
I do find it weird that two cans that are at least similar electrically on paper give such drastically different presentation. I really do not consider the MassDrop HE-4xx a reference at all.
Is sensitivity much different for the two headphones? On paper they should be fairly close.
I would suggest taking the multimeter to the HE-4xx and measuring DC resistance at the plug. Maybe there's something silly like a sneaky short. Speaking of which, visually compare the plugs of both cans as well - sometimes a non-ideal plug/jack combination can give you a bad day as well. At times adapting back and forth between different sizes can resolve such issues.
I would suggest taking the multimeter to the HE-4xx and measuring DC resistance at the plug. Maybe there's something silly like a sneaky short. Speaking of which, visually compare the plugs of both cans as well - sometimes a non-ideal plug/jack combination can give you a bad day as well. At times adapting back and forth between different sizes can resolve such issues.
I didn't look at paper until I posted but the T60RP's are 50 ohm with sensitivity of 92db/mw. The HE-4xx are 35 ohm at 93db/mw.
DCR for the T60RP is 49.4 tip to ground, 49 ring to ground, 98 tip to ring
HE-4xx 41.6 tip to ground, 41.7 ring to ground, 83 tip to ring
Grado SR60 is 32.3 tip to ground, 31.8 ring to ground, 64 tip to ring
I have tried different adapters for the He-4xx's both listening and measuring with no difference worth mentioning. It confuses me more with measuring the DCR higher than expected on the HE-4xx, I bet money its sensitivity is much lower than advertised.
DCR for the T60RP is 49.4 tip to ground, 49 ring to ground, 98 tip to ring
HE-4xx 41.6 tip to ground, 41.7 ring to ground, 83 tip to ring
Grado SR60 is 32.3 tip to ground, 31.8 ring to ground, 64 tip to ring
I have tried different adapters for the He-4xx's both listening and measuring with no difference worth mentioning. It confuses me more with measuring the DCR higher than expected on the HE-4xx, I bet money its sensitivity is much lower than advertised.
Thanks for the quick response! Those are in stock. They were also out of the resistors specified, but they have vishay/etc... in the same spec. The one thing I had trouble finding are the ferrite cable cores. This looked compatible but please confirm:
7427216 Wurth Elektronik | Mouser
7427216 Wurth Elektronik | Mouser
Wall wart for UK
The wall wart suggested for Europe in the other thread is out of stock unfortunately (same for the UK version, which I actually need...).
Would this one work? TRE25240-U-11G03-Level-VI Cincon | Mouser United Kingdom
The wall wart suggested for Europe in the other thread is out of stock unfortunately (same for the UK version, which I actually need...).
Would this one work? TRE25240-U-11G03-Level-VI Cincon | Mouser United Kingdom
Ah yes, good catch! I'll check with DigiKey.
Found another one:
VER24US240-JA | XP Power, 24W Plug In Power Supply 24V dc, 1A, Level VI Efficiency, 1 Output Switched Mode Power Supply, Interchangeable | RS Components
More expensive, but free shipments without limit (at least here in the UK) and adaptable to different countries.
Found another one:
VER24US240-JA | XP Power, 24W Plug In Power Supply 24V dc, 1A, Level VI Efficiency, 1 Output Switched Mode Power Supply, Interchangeable | RS Components
More expensive, but free shipments without limit (at least here in the UK) and adaptable to different countries.
Great name.
I think there should be a best diy name award with
'Noir' being an excellent candidate.
Noir's two big-brother headphone amps, Azul and Rojo, were displayed and demonstrated at Burning Amp 2019. Ti Kan of AMB Labs photographed them, see shots # 18 thru 21 on his excellent Burning Amp Festival 2019 web page
https://www.amb.org/ti/audio/burningamp2019/baf2019-18.jpg
https://www.amb.org/ti/audio/burningamp2019/baf2019-19.jpg
https://www.amb.org/ti/audio/burningamp2019/baf2019-20.jpg
https://www.amb.org/ti/audio/burningamp2019/baf2019-21.jpg
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https://www.amb.org/ti/audio/burningamp2019/baf2019-18.jpg
https://www.amb.org/ti/audio/burningamp2019/baf2019-19.jpg
https://www.amb.org/ti/audio/burningamp2019/baf2019-20.jpg
https://www.amb.org/ti/audio/burningamp2019/baf2019-21.jpg
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Stuck at home because the Gouv issued a request for everyone to stay home unless you need to go to the grocery store, I did my own version of the Noir, an intriguing very nice HP amp. Tom of Neurochrome did a detailled analysis of the amp and he identified a few areas where the original design may be improved such as the power supply noise floor, channel separation and a slight oscillation under certain load. I don't pretend to be able to improve an already mature design, but I may try. I still used the same circuit topology but I also added a few twists of my own. No need to mention that it is a private project, just for me. The official project is still on diyaudio store. Here is what I did:
I like integrated power supply, so I added a 24V SMPS power supply, with CLC filter (same as my version of the B1 preamp), followed by one common and then two dual CRC filters (one final RC stage per channel) to try to reduce the noise floor, added two possible ALPS volume pots on the same pcb, reroute the input traces up to the pot to separate them with gnd traces and split VCC layers per channel to try to improve channel separation, added a chassis Ground lifter for the audio ground, reversed the VCC on the positive side, and the gnd as I prefer. Finally I also added a snubber network at the output, apparently the original circuit can oscillate a little depending on the load. The snubber exact values (if they are needed) are still not determined... It still fits into the same enclosure, but it doesn't work with the store included front panel. No problem I'll do my own... Here a picture of the concept.
I like integrated power supply, so I added a 24V SMPS power supply, with CLC filter (same as my version of the B1 preamp), followed by one common and then two dual CRC filters (one final RC stage per channel) to try to reduce the noise floor, added two possible ALPS volume pots on the same pcb, reroute the input traces up to the pot to separate them with gnd traces and split VCC layers per channel to try to improve channel separation, added a chassis Ground lifter for the audio ground, reversed the VCC on the positive side, and the gnd as I prefer. Finally I also added a snubber network at the output, apparently the original circuit can oscillate a little depending on the load. The snubber exact values (if they are needed) are still not determined... It still fits into the same enclosure, but it doesn't work with the store included front panel. No problem I'll do my own... Here a picture of the concept.
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For those who are interested, here are 3 different gain versions of Noir in LTSpice. 6dB (stock), 9dB and 12dB. Only R75 - 78 values are changed. The 12dB version waveform clips asymetrically. I'm planning on building the "hot-rod" 9dB version to see how much it might improve performance on my planar magnetic cans.
Fantastic! I'm glad you're experimenting and I hope you have tons of fun with it.
You might be forced to choose the next-bigger Galaxy 1U chassis (230 mm deep instead of stock Noir's 170 mm deep chassis) in order to create enough room for an IEC mains inlet. If so then you can select an IEC inlet with integrated fuse; that will allow the user to replace a fuse from the outside, without having to open the cabinet and fiddle with the PCB. It also allows you to select an IEC inlet with both an integrated fuse and a mains power switch. I don't see any flywire / external I/O terminals for an on-off switch on your PCB layout. Since Noir consumes 8 watts thanks to class-A operation, you might want to turn it off when you're not actively listening.