[Huskerbryce]

The Vfet is not mine.  It belongs to my friend.  He has many many boxes of nelson pass amplifier parts/kits in his basement.  We brought this one up today and did some bourbon and some music with it.  As far as what is under the hood, I will find out when I can.  Short answer is I dont know.

[Huskerbryce]

Sweet!  So that is yours?  Is that an N-Channel?

So I just found out that “Yes” it is an N channel.  He also has a P channel one.

[jmimac351]

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[Jaytor]

I don’t think you have the speaker outputs connected correctly. If you have the positive phase corrected to one input and the negative phase connected to the other, you want to connect the positive speaker wire to the positive terminal of the channel that is connected to the positive phase of the balanced connection, and the other speaker connection to the positive speaker terminal of the other channel. The negative speaker terminals from both channels are connected together as you have them.

This is known as a bridge tied load.

This kind of connection can only be done with amplifiers that are not already bridge tied loads which generally means the negative speaker terminals are connected to signal ground.

[jmimac351]

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[jmimac351]

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[Jaytor]

Ok. I was assuming you were trying to get more power into a typical 8 ohm load. With a current amplifier, you can connect then this way to get more current output.

[jmimac351]

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[mkrawcz]

Sticking with the Papa Pass theme, I just got a INT25 with the intent of it being an integrated for my bedroom system, now I think it’s going to be my reference.

[tom739]

Hi mkrawcz,

Do you have any more opinions on the BRZHifi A1S amp? I may get one. Have you done any mods to the amp?

Thanks.

[mkrawcz]

Hi mkrawcz,

Do you have any more opinions on the BRZHifi A1S amp? I may get one. Have you done any mods to the amp?

Thanks.

It has the A1 sound which sacrifices a touch of detail and pinpoint imaging for warmth and wide soundstage. It’s not an endgame amp, but it’s a good deal at that price point for someone wanting to get into class A with a limited budget. The only mod I did was to bypass the volume pots which is as simple as unplugging and swapping some wires. I’m sure if I was to replace all the cheap Chinese parts on the boards such as the steel leaded resistors the sound would get even better, but at that point the time and money goes up and you can build one of the First Watt clones from Diyaudio. I will also mention that I got a BRZHIFI Hood 1969 which is a 10 watt class an amp for the same price. I think it’s a step up from the A1S as long as it’s enough power for your speakers.

[tom739]

Thanks for the info mkrawcz.   

[Jaytor]

Jaytor, yes I love the Iron Pre. I have since converted it to a single 4gang pot,
But at some point I will change all that out to something else with a remote. I bet a similar design using Toshiba JFETs will sound very good.

I finally got around to building my TVC linestage. This uses a similar concept as the Iron Pre, but substitutes a transformer volume control for the autoformer in the Iron Pre. I'm using an Arduino to control latching relays connected to all the TVC secondary taps so I can implement IR remote control.

[mkrawcz]

Dude, That is spectacular!

[Early B.]

I finally got around to building my TVC linestage.

How does this preamp compare to the one(s) you've previously built? 

[Jaytor]

How does this preamp compare to the one(s) you've previously built?

I've only had it in my main system for a couple of hours, but I'm impressed with the sound. It is very clean sounding and dynamic. It may have a touch less soundstage depth and airiness compared to my DHT linestage, but the differences are pretty subtle.

Aural memory is pretty fickle, so I think I need a lot more time to suss out the differences. And I think this linestage could probably benefit from more break-in. It's only been powered up for maybe 15 hours.

[tremrej65]

Wow. Super clean build. And nice chassis. It's crazy the amount of hour you must have put in this build. It looks like you design some PCBs (main board, arduino, ...)? Impressive.

[Jaytor]

Wow. Super clean build. And nice chassis. It's crazy the amount of hour you must have put in this build. It looks like you design some PCBs (main board, arduino, ...)? Impressive.

Thanks. Yes, I designed all three PCBs (the main board, display board which includes the Ardunio, and the 4 copies of the power supply board). I designed these using EasyEDA and had them fabricated by JLCPCB. This company does excellent work (at least for these relatively simple boards) and is very fast and cost effective (even with the tariffs). It generally takes about 10 days from order placed until they are on my doorstep.

[BrandonB]

Thanks. Yes, I designed all three PCBs (the main board, display board which includes the Ardunio, and the 4 copies of the power supply board). I designed these using EasyEDA and had them fabricated by JLCPCB. This company does excellent work (at least for these relatively simple boards) and is very fast and cost effective (even with the tariffs). It generally takes about 10 days from order placed until they are on my doorstep.

You have built two preamplifiers and they both look awesome.  Are you looking for a specific sound?

[YEEEEGZ]

That looks so awesome, brother.