[Tom-s]

Here's a link to the Lundahl datasheets:
Power transformer: https://www.lundahltransformers.com/wp-content/uploads/datasheets/2758.pdf
Power supply choke: https://www.lundahltransformers.com/wp-content/uploads/datasheets/2742.pdf
Anode chokes: http://www.lundahl.se/wp-content/uploads/datasheets/1667_68.pdf
Output transformers: https://www.lundahltransformers.com/wp-content/uploads/datasheets/2765.pdf

I know we discussed impedances; however, I’m still struggling understanding this…

what output transformer are you using?
what are the taps on them?

then, what is the understanding on impedance matching? Is it all about having enough wattage, for a given headphone impedance? Also, is it about the the damping needed for the headphones? How do you know what the damping factor is?

The output transformer is the LL2765. Wired for suggested connection A or B in the datasheet.
This results in an output impedance of 5 Ohms on the low impedance connection A, and 17 Ohms on the high impedance connection B.
With Aegis it's possible to switch between this low and high output impedance settings via a switch on the back.
And that's somewhat of an achievement given the complexity of the wiring scheme on a Lundahl output transformer.

See this thread to learn about all about impedance matching.

Hope this helps!

 

[JazzVinyl]

Page 7, post 98 for a pic of all tranny's.

You can link to any message:

https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/page-7#post-17374562

By clicking the link in the upper right of that message...then copy/paste the browser URL, as above.

 

[caryking]

Here's a link to the Lundahl datasheets:
Power transformer: https://www.lundahltransformers.com/wp-content/uploads/datasheets/2758.pdf
Power supply choke: https://www.lundahltransformers.com/wp-content/uploads/datasheets/2742.pdf
Anode chokes: http://www.lundahl.se/wp-content/uploads/datasheets/1667_68.pdf
Output transformers: https://www.lundahltransformers.com/wp-content/uploads/datasheets/2765.pdf


The output transformer is the LL2765. Wired for suggested connection A or B in the datasheet.
This results in an output impedance of 5 Ohms on the low impedance connection A, and 17 Ohms on the high impedance connection B.
With Aegis it's possible to switch between this low and high output impedance settings via a switch on the back.
And that's somewhat of an achievement given the complexity of the wiring scheme on a Lundahl output transformer.

See this thread to learn about all about impedance matching.

Hope this helps!

Ok, I have the Audeze LCD-2 (fazor) at 70 ohms. Based on this article, my output tap should be somewhere around 8-12 ohms, right?

 

[Henrim]

I've been in touch with Dave from Landfall systems. And he's a very friendly guy to work with and super responsive.
Here's a link to their website to get some impressions: https://www.landfallsystems.com/
First have a look at the website to find a color/finish that fits your setup. Having an anodized chassis was about 70$ extra over powdercoat colors.
Shipping to Europe was 65$ for me.
His packaging is great and all panels got to me without any scratches in no time.
Pictures below for inspiration with packaging and sides showing. The color is casper blue powdercoat. Inspired by all great Landfall chassis builds from @carlman14: https://www.head-fi.org/threads/carls-diy-adventures.957646/page-2#post-16548412


Edit: Further more I need to add that apart from the looks; the quality of the finish has been very durable in my opinion.

How much was the chassis itself?

 

[L0rdGwyn]

I know we discussed impedances; however, I’m still struggling understanding this…

what output transformer are you using?
what are the taps on them?

then, what is the understanding on impedance matching? Is it all about having enough wattage, for a given headphone impedance? Also, is it about the the damping needed for the headphones? How do you know what the damping factor is?

Ok, I have the Audeze LCD-2 (fazor) at 70 ohms. Based on this article, my output tap should be somewhere around 8-12 ohms, right?

@Tom-s nicely explained the transformer situation, thanks!

With your 70ohm headphone, it would be used on the low impedance tap, which has an output impedance of 5ohms. So, 70/5 = 14, you would be achieving a 14:1 damping ratio. It is not an exact science, some would say 8:1 is a good minimum target, people (like me) who enjoy single-ended triode amplifiers would tell you 3:1 is a good target. 14:1 with your Audeze LCD-2 will work great, planar headphones benefit from amplifiers with lower output impedances, a higher damping ratio will not be harmful.

 

[caryking]

Thanks everyone for the reply’s…. I understand the damping ratios now! That said, based the Lundahl data sheet, how are you getting 17 ohms out of the second tap. I’m not seeing the connections, for B, equaling 17 ohms…

BTW, yes, I’m a new to this stuff; however, it’s all extremely fascinating and I’m appreciative of everyone’s help…

 

[L0rdGwyn]

Thanks everyone for the reply’s…. I understand the damping ratios now! That said, based the Lundahl data sheet, how are you getting 17 ohms out of the second tap. I’m not seeing the connections, for B, equaling 17 ohms…

BTW, yes, I’m a new to this stuff; however, it’s all extremely fascinating and I’m appreciative of everyone’s help…

I explained in this post: https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17450565

The tap does not indicate the output impedance, it indicates the minimum impedance that should be connected to achieve a appropriate damping ratio. The taps on the transformer are 32 and 150ohm, in a conventional SET design, that would get you roughly a 3:1 damping ratio if using headphones of that impedance on those taps. However, this is not a conventional SET since the output stage is a cathode follower. As such, you get better damping ratios with those headphone impedances, closer to 7:1. Again, the output impedance is dependent on the design of the amplifier, not the transformer taps.

 

[caryking]

I explained in this post: https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17450565

The tap does not indicate the output impedance, it indicates the minimum impedance that should be connected to achieve an appropriate damping ratio. The taps on the transformer are 32 and 150ohm, in a conventional SET design, that would get you roughly a 3:1 damping ratio if using headphones of that impedance on those taps. However, this is not a conventional SET since the output stage is a cathode follower. As such, you get better damping ratios with those headphone impedances, closer to 7:1. Again, the output impedance is dependent on the design of the amplifier, not the transformer taps.

I think this is where my general lack of understanding comes in…. I need an engineering course…. I just don’t get it. Nonetheless, I appreciate the help.

 

[JazzVinyl]

I think this is where my general lack of understanding comes in…. I need an engineering course…. I just don’t get it. Nonetheless, I appreciate the help.

LG said: "The tap does not indicate the output impedance, it indicates the minimum impedance that should be connected, to achieve a appropriate damping ratio."

 

[Henrim]

Just plug your headphones in, play with the knobs and decide what sounds best. My best attempts at predicting what will sound good are futile, listening is king.

 

[JNouw]

I explained in this post: https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17450565

The tap does not indicate the output impedance, it indicates the minimum impedance that should be connected to achieve a appropriate damping ratio. The taps on the transformer are 32 and 150ohm, in a conventional SET design, that would get you roughly a 3:1 damping ratio if using headphones of that impedance on those taps. However, this is not a conventional SET since the output stage is a cathode follower. As such, you get better damping ratios with those headphone impedances, closer to 7:1. Again, the output impedance is dependent on the design of the amplifier, not the transformer taps.

It appears that the problem in understanding arises form the difference between amplifier output impedance and the actual matching impedance. For example, a tube amplifier can have a tap for 8 ohms, but a output impedance of - say 1 ohm. The 8 ohms comes into play when you match the speaker or headphone to the amp, but the output impedance comes into play when you address the damping factor.
IMO CaryKing is confusing the 5 ohm (presumably tap) as the output impedance, and not as the matching impedance. Furthermore, looking at the Lundahl specs adds tot eh confusion, as amplifier designers work with the winding ratios rather than the exact impedances as set out by Lundahl.

 

[L0rdGwyn]

I'll try again. The output transformers have 32ohm and 150ohm taps. These taps are telling you what headphone impedance should be attached to them to achieve a good damping ratio based on the output impedance on that tap, which is not the same as the impedance of the tap or the impedance of the headphone attached.

The output impedance on the 32ohm tap is 5ohms. The damping ratio is the ratio between the attached impedance and the output impedance. So, if using a 32ohm headphone on the 32ohm tap, the damping ratio will be 32/5 = 6.4.

Now, a 5ohm output impedance on a 32ohm tap is lower than is typical for a SET design because of what I've done in this amplifier. So, you could even achieve a 3:1 damping ratio by using 16ohm headphones on the 32ohm tap. The tap is a guideline based on the design of the transformer, it is not set in stone, and I am using these transformers unconventionally.

In a transformer coupled amplifier, the output impedance is largely made up of the internal resistance of the output tube and the resistance of the wire in the transformer. Because this amplifier uses a cathode follower output stage, the output tube has a fraction of its normal internal resistance, so a lower output impedance is achieved.

I think getting any more into the details of amplifier design are going to make things more confusing. The main point is output impedance is a result of the amplifiers design, not the number associated with the taps. The taps tell you what headphone to attach based on the transformers design, but in this amplifier, those guidelines are more loose based on the lower output impedance. On the 32ohm tap, I would say you could use 16ohm to 120ohm headphones. On the 150ohm tap, I would say you could use 120ohm and up and you will have good damping ratios.

 

[Tacuba]

Signed up just to give you some kudos here @L0rdGwyn! Big fan of the DAC you posted over on the DIYaudio forum. Bummer you haven’t posted that walkthrough yet but look forward to seeing this one finalized!

 

[L0rdGwyn]

Signed up just to give you some kudos here @L0rdGwyn! Big fan of the DAC you posted over on the DIYaudio forum. Bummer you haven’t posted that walkthrough yet but look forward to seeing this one finalized!

I appreciate it! Sorry I'm moving slow, want to get this done but have a lot going on right now in life and work. Thanks for being patient.

 

[DenverW]

I appreciate it! Sorry I'm moving slow, want to get this done but have a lot going on right now in life and work. Thanks for being patient.

No one should ever complain about the speed in which they receive a gift . The things you need to do come first and we support that!