Little HIFI Speed Build

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Meat&Beer
Posts: 243
Joined: Fri Jun 07, 2013 5:37 pm
Location: Coldest tip of NY woods

Little HIFI Speed Build

Post by Meat&Beer »

Dubbed, MiniFi. I really seem to get myself into quite large and time consuming projects. Recently I've been working on a big stereo PP HIFI amp that took quite a turn. Needs to be totally re-done, essentially.

So I needed a break, and I took one. Got some old iron out and built this thing in about a week and a half start to finish. (Of course Matt H helped me, he always does because he's awesome.) The input stage is adapted from an old HIFI schematic, added adjustable LNF, and a CF into a 6BQ5/EL84.

It uses a simple 3 resistor network to sum stereo into mono, and a switch for straight up mono input. Also a treble bleed switch. I have it wired backwards so I can just call it a bright switch.

The transformers all showed their age, so I DA sanded them with 500 and clear coated them. The chassis I hit with 800 and gave it a really quick buff so it all had the same look.

Originally was going for a 12AU7, but the 12AT7 sounded much nicer to my ears, and ended up smack where it should voltage-wise without even modding anything.

PT is from an old defunct Heathkit TV tester thing. It has a ~124v secondary hitting a doubler, giving somewhere around 330VDC after the choke loaded. Choke is from an elder television. For the life of me, I can't remember where I nabbed the little OT from... It's 4.5k at 8 ohm load.

Sounds great, super happy with it! Especially hooked up to a big and or efficient speaker, it really has some booty to it. As well as high end, hence the switch for that. Suppose, I could call it an "old" switch. :lol:
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ampmike
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Nice

Post by ampmike »

Nice job,I have always wanted to do something like that,Have fun,Mikey
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menger66
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Re: Little HIFI Speed Build

Post by menger66 »

That's cool M&B so what do you run into it to listen to music? mark
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Meat&Beer
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Joined: Fri Jun 07, 2013 5:37 pm
Location: Coldest tip of NY woods

Re: Little HIFI Speed Build

Post by Meat&Beer »

Thanks! It takes line level, ~2Vp-p. So, Ipod/mp3 player, CD player, phono preamp output (though I haven't tried that yet).. Since I blew the mic input (more than just the sound card apparently) on my laptop doing a test on a circuit, I got a USB to mic/headphone that I plug into it also. Handles it all just fine!
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