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Tom Christiansen Audio HPA-1 Headphone Amp Review

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@tomchr I think for this class of amp your building, it is going to be perfect for the majority of users. Looking forward to trying it out in-person. It also going to be perfect for driving my current piggy headsets. Tested XD05 plus which is 1 watt at 32 Ohms, finally happy with Aeon and HE-560 where they do not sound like mud.
 

tomchr

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I forget if I've mentioned this already: I'll be exhibiting at the Florida Audio Expo in Tampa, FL Feb. 7-10. Tickets are free. Parking is $11/day, though you can probably find street parking for less/free. The Expo takes place at the Embassy Suites by Hilton – Tampa Airport Westshore (555 N Westshore Blvd, Tampa, FL 33609).

I'll be bringing the HPA-1. Hopefully, I will have the prototype for another TCA product with me as well.

Edit: I just happened to notice that the temperature in Tampa, FL (+26 C) is about the absolute value of the current temperature in Calgary (-28 C). :)

Tom
 

restorer-john

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Edit: I just happened to notice that the temperature in Tampa, FL (+26 C) is about the absolute value of the current temperature in Calgary (-28 C).
Your gear sounds better when it's warmed up, doesn't it? ;)
 

tomchr

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Heh... Here I was thinking to put a stack of HPA-1s outside overnight and offer them as "cryogenically treated".

Tom
 

Doodski

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I forget if I've mentioned this already: I'll be exhibiting at the Florida Audio Expo in Tampa, FL Feb. 7-10. Tickets are free. Parking is $11/day, though you can probably find street parking for less/free. The Expo takes place at the Embassy Suites by Hilton – Tampa Airport Westshore (555 N Westshore Blvd, Tampa, FL 33609).

I'll be bringing the HPA-1. Hopefully, I will have the prototype for another TCA product with me as well.

Edit: I just happened to notice that the temperature in Tampa, FL (+26 C) is about the absolute value of the current temperature in Calgary (-28 C). :)

Tom
Lucky you it's -30C up here in Edmonton.
 
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@tomchr Started reading the white papers and Datasheets on OpAmps at TI to better understand what operating voltage and currents the Headphone versions. You have your work cut out for you dealing with this modern bread of headphones. I like this paper Parallel INA1620 Headphone Amplifiers for Higher Output Power http://www.ti.com/lit/an/sboa352/sboa352.pdf. Even if you want to spend a mint on SparkOS SS3601 Aeon Flow going punish even this Opamp as a single device. Now understand your comments.
 

tomchr

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Azeia

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I hope I've shed some light on what goes into the specifications of an amp. If you're now even more confused, just remember that you're not alone. Multivariate optimization is not for everybody... :)
Actually I already mostly understood those things from many of your prior posts on the subject (across various threads)

I was mostly just curious about this comment specifically from an earlier post:
But we'd need 5-pin inputs as well. Too bad Neutrik or Switchcraft don't make a 5-pin TRRRS connector.
I just wasn't sure what you meant by "5-pin inputs" here

I expect to be able to ship before the end of the month.
This is great to hear; I'm very much looking forward to receiving mine :D
 

tomchr

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I was mostly just curious about this comment specifically from an earlier post:

I just wasn't sure what you meant by "5-pin inputs" here
I was pondering a hypothetical scenario where support for a balanced output was needed but the height increase caused by the XLR connectors not desired. No other height constraints were considered or hypothesized about. This should not be taken to mean or imply that no other height constraints exist.

Better?

Tom
 

tomchr

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Pots. So many pots... First 100 of the 500 Alps RK271 I ordered from the Alps distributor are in. 500 is the minimum order quantity for custom orders. You need to order 50000 to talk to Alps directly!
These will go in to the HPA-1.

Tom
IMG_0789.jpg
 

tomchr

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You wanted fine control of the volume, didn't you? Just wait until I get all 500 in there...! :)

Nah. One pot per HPA-1. It's the one and only volume pot in the HPA-1. In other words, the 500 I ordered is enough for 500 HPA-1s. Needless to say, I hope to sell a lot of them.

Tom
 
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@tomchr Just to see what going with a few headphones on market, I pulled this table together. Someone even built a 8 Ohm headphone, the Verum 1 when I was looking around. it started because looking Aeon current needs, then

Personally I have Focal Elex, Hifiman Ananda, Senheiser HD-6xx, Hifiman HE-4xx, Hifiman HE-560 ( it is the oldest in group). Really like the Elex and Ananda. HE-560 is fun with you power right.

Screen Shot 2020-01-18 at 7.54.23 PM.png
 

tomchr

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Excellent. There's a large spreadsheet floating around on Head-Fi as well. That's where the 5 W into 50 Ω "requirement"/desire/wish came from.

Tom
 
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@tomchr I figure I put a few more headphones into the table for you, so you have a list all the kool kid's headphones as well.
I thought it would be good for people to see how much more current the Planner's draw.

Screen Shot 2020-01-18 at 10.34.39 PM.png
 
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solderdude

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I have made a list as well... need to update it as it does not have the latest models in it.

Here is another interesting list as well.

There are also online calculators that give the desired info when you put in efficiency and impedance numbers such as this and this one.
 
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I have made a list as well... need to update it as it does not have the latest models in it.

Here is another interesting list as well.

There are also online calculators that give the desired info when you put in efficiency and impedance numbers such as this and this one.
Thanks @solderdude

I had seen digiZod and Headphone Honesty links, bellow is the first table I created where I was using the digZoid calculator for inputs. RAA link just started looking at. For the spreadsheet above, I decided I want to do my own calculations directly so I could feed data from manufacturers and see what device which normally just report Resistance dB/1 mW. I need to do little more data science on the data about trends. Since there are a number of new 2019 headsets in here.

One thing you notice is I am rank the headset in relative efficacy db/1 Vrms based on the list above


Screen Shot 2020-01-19 at 8.25.52 AM.png



Also looks like I cut off few headphones in the list above,
Screen Shot 2020-01-19 at 8.42.36 AM.png
 

tomchr

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Fantastic! Thank you! I appreciate all the help I can get in getting the word out.

If any of you happen to be active on Head-Fi, I would also greatly appreciate a mention there. Unfortunately I cannot post anything to tout my products on Head-Fi without paying their $12k/year fee (with a one-year up-front commitment). That's their lowest priced option. You can pay more if you want more pixels for your ads on their front page.

The HPA-1 chassis are underway via DHL and I'm putting the final touches on the design of the foam bracing for the packaging. I expect to be able to ship the first two preordered HPA-1s within the next couple of days and the rest by the end of the month or within the first few days of February at the latest. All fingers and other loose-hanging extremities crossed.

Tom
 

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