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Salas DCG3 preamp (line & headphone)
Salas DCG3 preamp (line & headphone)
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Old Yesterday, 05:40 PM   #5061
Antsav is online now Antsav
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Thanks again Salas, will not be the last question
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Old Yesterday, 07:54 PM   #5062
Salas is offline Salas  Greece
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Salas DCG3 preamp (line & headphone)
That Nichicon LKG is 30mmD 35mmL though. If 5mm extra length can't be accommodated you should go with that TDK/Epcos 30mmX30mm cap.
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Old Today, 12:22 AM   #5063
hpasternack is offline hpasternack
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Some new headphone cushions came this afternoon. The originals were open-cell foam and these are closed. I like how they feel, but it drastically alters the frequency balance.

I was expecting the output devices to run hot without a proper heatsink. But the dissipation seems quite good and the transistors are just warm to the touch. I am running the output bias at about 135mA.

Someone on the local audio club mailing list posted some awful IRF9610 curves he measured and suggested I try FQP3P20s instead. I was curious if you have experimented with different types of output devices, and if you've ever seen bad behavior from the IRF9610s.

Here's another picture for you. I love the open-chassis look, even though it's totally impractical. I screwed up and reversed the + and - op-amp terminals on the AD823 footprint, so had to do board surgery. Otherwise, everything has gone smoothly.
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Old Today, 01:29 AM   #5064
Salas is offline Salas  Greece
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Salas DCG3 preamp (line & headphone)
Yes I had experimented. A good portion of development time was about active parts selection. Since its a very simple signal path architecture that must be working with specific parts in careful synergy. For output I had started with those FQP you mentioned. Because I knew about the infamous IRF PMOS gm kink etc. But THD was eventually measuring significantly better with the IRF9610s in this application. Probably due to better driven by the input stage along with output stage style and bias level indifference but the end result circuit total was superior when with them in the equation. Mine are Vishay to be specific.

Cushion types are integral to headphones FR no doubt. Nice sunlight rays through green FR4 perspective photo.
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Old Today, 06:06 AM   #5065
hpasternack is offline hpasternack
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Quote:
Originally Posted by Salas View Post
Probably due to better driven by the input stage along with output stage style and bias level indifference but the end result circuit total was superior when with them in the equation. Mine are Vishay to be specific.

Cushion types are integral to headphones FR no doubt. Nice sunlight rays through green FR4 perspective photo.
Thanks for the information. I have Vishay parts here too. Since International Rectifier is no more, do you have any idea who picked up their semiconductor manufacturing? Or do you suppose the "bad" parts are no longer in production? Either way, I'm not going to worry about it.

I'm enjoying my DCG3 with the PX-100s. I'm thinking seriously about buying some real headphones, but I think I'll stick with these for now and see if I'm still interested in the concept once the novelty starts to wear off.

I'm also starting to work on a mk. 2 version to package in a proper chassis...

-Henry
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Old Today, 10:24 AM   #5066
Salas is offline Salas  Greece
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Salas DCG3 preamp (line & headphone)
IR power products line was acquired by Vishay fourteen years ago. Mosfets have the Siliconix logo. A fat S with an i inside stamped on their bottom left. In which fabs with what newer process or not they make them I have no idea. They must be owning numerous fabs and/or making production partnerships globally. Siliconix belongs to Vishay. Eventually IR as a whole got sold and embodied to Infineon five years ago.

About new larger headphones have a look in the HiFiMan Sundara also.
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