Questions.
1) The LL1667 Choke in the BOM states: 810mH / 5mA .. while in the Lundhals document it says: 210H / 15mA. Do I need to specify your values during order ?
2) The LL2765 Output states 60mA in the BOM while in Lundhals document PP or 30mA. Do I need to specify your values during order ?
Oneminde
1) The LL1667 Choke in the BOM states: 810mH / 5mA .. while in the Lundhals document it says: 210H / 15mA. Do I need to specify your values during order ?
2) The LL2765 Output states 60mA in the BOM while in Lundhals document PP or 30mA. Do I need to specify your values during order ?
Oneminde
@Oneminde
With transformer manufacturers, you need to specify the DC current that the iron is going to be used for.
Note for the LL1667/1668 document they clearly state:
So yes, you need to specify that you want an LL1667 choke gapped at 5mA. They will then inform you of the inductance (this can vary slightly from one build to another) , and the saturating current (i.e. the max current). Custom orders requiring larger standing DC currents will result in lower inductances for a given choke design and vice versa.
Same thing with the LL2765 output transformer, particularly since you want the version for a single ended output stage (not push pull). You request an LL2765 that is gapped for 60mA, for single ended operation which will account for the bias current on the EL34 being 50mA in this design. This allows for a little headroom so you are not saturating the output transformer.
Best,
Anand.
With transformer manufacturers, you need to specify the DC current that the iron is going to be used for.
Note for the LL1667/1668 document they clearly state:
So yes, you need to specify that you want an LL1667 choke gapped at 5mA. They will then inform you of the inductance (this can vary slightly from one build to another) , and the saturating current (i.e. the max current). Custom orders requiring larger standing DC currents will result in lower inductances for a given choke design and vice versa.
Same thing with the LL2765 output transformer, particularly since you want the version for a single ended output stage (not push pull). You request an LL2765 that is gapped for 60mA, for single ended operation which will account for the bias current on the EL34 being 50mA in this design. This allows for a little headroom so you are not saturating the output transformer.
Best,
Anand.
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Ahh, okay, thanks a million - both of you. Btw, I live 70 miles from the factory 
..
I was considering the Amorphous core and silver wire on the output tranny, but since Lundhal states:
.. I was considering the Amorphous core and silver wire on the output tranny, but since Lundhal states:
I don't know. I'm thinking that the Amorphous could be an advantage, but with 30% less signal level, the 2W would become 1.4W .. unless I misunderstand what the 30% are a reference to ?
Yes, the amorphous cores will saturate faster, although 1.4W is still plenty for 99% of headphones. Someone on the Head-Fi thread built with amorphous output transformers and liked the sound. I would avoid going amorphous with the anode chokes however.
He described his impressions here: https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/page-30#post-17596299
He described his impressions here: https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/page-30#post-17596299
Thanks for the review. Yes, I have found in most situations that upgrades to amorphous core and nanocrystalline have been sonically quite beneficial.
Curious:
2W into 32 ohms is 8V RMS. 30% less than that is 70% of 8VRMS = 5.6VRMS. 5.6V RMS into 32 ohms = ~ 1 Watt RMS. Not 1.4W RMS. Regardless, 1W RMS is still very loud with headphones.
I agree with sticking with iron core for the anode chokes to provide maximum voltage “clean” swing so the input stage doesn’t prematurely clip because the chokes are saturating.
Best,
Anand.
Curious:
2W into 32 ohms is 8V RMS. 30% less than that is 70% of 8VRMS = 5.6VRMS. 5.6V RMS into 32 ohms = ~ 1 Watt RMS. Not 1.4W RMS. Regardless, 1W RMS is still very loud with headphones.
I agree with sticking with iron core for the anode chokes to provide maximum voltage “clean” swing so the input stage doesn’t prematurely clip because the chokes are saturating.
Best,
Anand.
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Also note that the 2W rating is the peak output swing of the amplifier, not necessarily the peak rating of the output transformer. For the 30mA gapped LL2765, it is rated for 160Vrms into the 5.4K primary, which is 4.7W. So very likely the 60mA gapped amorphous variant can handle 2W peak, someone from Lundahl might be able to speak to that as there isn't a spec sheet specifically for that variant.
Alright, well this is fun .. I will definitely read the impressions thread to fill up on which way to go and the AM-core is only for OPT, nothing else.
I will ask Lundhal for info when I talk to them after the weekend.
Also, before I close this reply: Since I intend to move things around a bit like I mentioned, I wanted to check if I can also close the gap between the tubes a bit and therefore wanted to check with you L0rdGwyn if you have a more conventional schematic and not the SPICE version ? - If not, then I'll work out a std version and you can have a look at it such that nothing is off or weird.
I will ask Lundhal for info when I talk to them after the weekend.
Also, before I close this reply: Since I intend to move things around a bit like I mentioned, I wanted to check if I can also close the gap between the tubes a bit and therefore wanted to check with you L0rdGwyn if you have a more conventional schematic and not the SPICE version ? - If not, then I'll work out a std version and you can have a look at it such that nothing is off or weird.
No problem, I'll work on one
Saw this line from the review: "A more clear / detailed view into the sound. At a serious cost. I lost my lowest octave weight that I liked so much in Aegis.
Now a few months with this amorphous anode choke I'm happy with the sound. But do miss some in the lower regions."
I think that remark is all I need for you don't want an amplifier to lose too much of the bottom end since this is important to the dimensionality of the playback. Listening to deep base, like a footstep, in a recording, can enhance the spacial experience, and upper details can be adjusted via capacitor, headphones used, the tube itself and so forth. In other words, sticking to the OG silicone iron core will probably be most beneficial
I've not heard this amp but its difficult to ignore the rave reviews and I'm a sucker for tubes. Also, with 121 pages in, the other tread is probably super useful for me, so will go over it and take notes.
Thomas Meyer / Vinylsavor is a great inspiration for the chassis design, so heads up, leaning towards that.
Alright, I'll return to my cave for a while and will make some noise when I've made some sch. progress
Saw this line from the review: "A more clear / detailed view into the sound. At a serious cost. I lost my lowest octave weight that I liked so much in Aegis.
Now a few months with this amorphous anode choke I'm happy with the sound. But do miss some in the lower regions."
I think that remark is all I need for you don't want an amplifier to lose too much of the bottom end since this is important to the dimensionality of the playback. Listening to deep base, like a footstep, in a recording, can enhance the spacial experience, and upper details can be adjusted via capacitor, headphones used, the tube itself and so forth. In other words, sticking to the OG silicone iron core will probably be most beneficial
I've not heard this amp but its difficult to ignore the rave reviews and I'm a sucker for tubes. Also, with 121 pages in, the other tread is probably super useful for me, so will go over it and take notes.
Thomas Meyer / Vinylsavor is a great inspiration for the chassis design, so heads up, leaning towards that.
Alright, I'll return to my cave for a while and will make some noise when I've made some sch. progress
I've updated the build document and BOM to reflect some changes made, it is now version 1.1. There is a changelog included on the last page in the build document.
I had two builders who had noise issues in one channel with the output tube heaters referenced to cathode rather than ground. The issue was solved by moving the noisy heater winding to the 6SL7 heaters, which are ground referenced. However, to avoid that issue in the future, in the v1.1 PCB, the output tube heaters are also referenced to ground. The output tube cathode swing should not violate the heater-to-cathode voltage rating, it was precautionary, but given the noise issue I felt the change was needed. The schematics in the build document have been updated as well.
One other change - I had three instances of the Jupiter Copper Foil 400V caps failing for builders, causing a short between the input and output stages. I've included another option in the BOM for coupling caps, the V-Cap ODAM. I have not tried them personally, but I have heard good things. If builders are going to use the Jupiter caps, I suggest going with the 600V rated model. The BOM now includes either one as an option. Of course, many other caps are available, just two suggestions.
At the moment, Dave at Landfall is low on material, so chassis orders may be delayed.
I had two builders who had noise issues in one channel with the output tube heaters referenced to cathode rather than ground. The issue was solved by moving the noisy heater winding to the 6SL7 heaters, which are ground referenced. However, to avoid that issue in the future, in the v1.1 PCB, the output tube heaters are also referenced to ground. The output tube cathode swing should not violate the heater-to-cathode voltage rating, it was precautionary, but given the noise issue I felt the change was needed. The schematics in the build document have been updated as well.
One other change - I had three instances of the Jupiter Copper Foil 400V caps failing for builders, causing a short between the input and output stages. I've included another option in the BOM for coupling caps, the V-Cap ODAM. I have not tried them personally, but I have heard good things. If builders are going to use the Jupiter caps, I suggest going with the 600V rated model. The BOM now includes either one as an option. Of course, many other caps are available, just two suggestions.
At the moment, Dave at Landfall is low on material, so chassis orders may be delayed.
Not necessary, the pcb should have plated through holes and if you are soldering well (good heating element), it should melt into the other side of the hole. As always, a little flux here and there can help.
Best,
Anand.
