Vintage Silicon

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Ray P
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#1 Vintage Silicon

Post by Ray P »

I've got a few BUF-O3 devices, probably about 30 or so years old (haven't checked the date codes). They were very well regarded back along so I thought I would do something with them.

https://www.stereophile.com/solidpreamps/54/index.html

https://theslowdiyer.wordpress.com/2015 ... revisited/

You can even use it to drive headphones;

https://headwizememorial.wordpress.com/ ... ne-driver/
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Ray P
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#2 Re: Vintage Silicon

Post by Ray P »

Quite topical given Ant's comments about his experience of Ed's B1 buffer; I've now got some PCBs to go with the vintage BUF-03 devices.

The boards are to implement a zero gain buffer to provide some 'drive' to passive preamps. For the first version I'll do a cheap and cheerful build with a spare Alps Blue pot and simple LM317 type power supply. The BUF-03s can be socket mounted so, unless I cock something up, they can be repurposed into an improved version later (I do have four pairs of them but they're getting expensive, if you can find any, so worth preserving).

IIRC the BUF-03 is based on FETs and runs in class A.
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Ant
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#3 Re: Vintage Silicon

Post by Ant »

Well I can't think of a more reasonable and less coarse description of what the b1 is doing than 'giving a kick up the arse' to the overall sound I'm getting. Presumably because the phono stage isn't having to provide the current to drive the power amp, and the b1 is doing that instead. I'm probably wrong in thinking that, but I'm sure someone can explain what is happening. I don't think it's all to do with impedance matching. All the listening I've done has been vinyl as Eds build only has one input so I haven't tried digital with it. Tbh, I'm rubbish at describing sound, which is why I usually limit myself to saying something sound good, bad or ugly, but it's definitely contributing a more fleshed out overall sound, listener fatigue notwithstanding, which as I mentioned I'm sure can be dialled out. It seems richer and punchier, it's the top end where the hardness is coming in after a while
Hopefully you see a similar performance from your boards ray
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Ray P
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#4 Re: Vintage Silicon

Post by Ray P »

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#5 Re: Vintage Silicon

Post by Ray P »

With a recycled 100K Alps Blue pot - cheap and cheerful first build...

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#6 Re: Vintage Silicon

Post by Ray P »

and my collection of BUF-03s - not nearly as nice looking as old valves!

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#7 Re: Vintage Silicon

Post by Ray P »

I've been putting together the cheap and cheerful verion of my Aunt Corey passive attenuator buffer.

I've assembled a little LM317/337 based +/-15V power supply and assembled the buffer PCB. Just waiting on some phono sockets and terminal blocks to hook it up and try it out.

Image

Also in the picture is a little 11-way make before break switch I found lurking in my desk drawer so for the next iteration I'll use that for a series switched attenuator version.

Ant has taken a PCB and pair of BUF-03s off my hands and will be comparing it with Ed's Pass B1 buffer in one of his passives.
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#8 Re: Vintage Silicon

Post by Ray P »

Did I almost do a breadboard build or does using a couple of PCBs disqualify this project?

Anyway, this is my quick and cheap initial build of the Aunt Corey buffer for a passive attenuator, using 30yr old BUF-03 op amps, and it's playing music.

I hooked up the power supply to the buffer and after a quick check left it to warm up before nulling the DC offset. Everything stayed stable so I plugged in my portable HPA player to the inputs and a pair of 32ohm headphones to the outputs. All's well and it sounds very good. Will have to try it in front of the 300B amps later.

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Ray P
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#9 Re: Vintage Silicon

Post by Ray P »

How's your version going Ant?

Don't be tempted to run the BUF-03s without the heatsinks, even with them installed I'm measuring a temperature of about 60C. The heatsinks can be buggers to get on, especially if you don't want to bend the pins. I found the best way to;
  • Place the heatsink on a firm surface
  • insert a small bladed screwriver into the heatsink slot
  • place the BUF-03 over the heatsink (obviously upside down) and twist the screwdriver blade and push down theBUF all in one movement.
  • I used a little heatsink paste on the BUFs before pushing them onto the heatsinks.
Make sure you insert the BUF-03s into the sockets with the correct orientation - the little tab on the can is pin 8 of the BUF-03.
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#10 Re: Vintage Silicon

Post by Ant »

No progress yet Ray, finished all my work builds on Wednesday and got straight on with the new tt build using the Eds 1000 motor and air bearing arm.
I have however got some really nice afromosia timber left over from the last build and I should have just enough to build the case for the buffer.
I'm hoping that the tt build should be done in the next few days, I'll have to wait for the arm anyways, there will be a gap between the deck being finished and fitting it that I 'should' use productively.
Wether that's the case is another matter....
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Ray P
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#11 Re: Vintage Silicon

Post by Ray P »

I think you'll find it's a worthwhile project Ant. I've no idea how it'll measure up to Ed's B1 buffer so will be interested to see what you think.

Did you manage to sort out a +/-15V power supply?

On the basis of what I've heard so far I'm going to proceed with another build using a series switched attenuator and packaged into a nice little metal enclosure I have available.
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Ray P
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#12 Re: Vintage Silicon

Post by Ray P »

As well as working on the 13E1 amp, It's also been a productive day with my vintage silicon project. I've been building a version of the Aunt Corey BUF-03 buffer with a series switched attenuator, packaged into a nice little box;

Image

Image

and I've also done the board assembly for another version though I've yet to decide on the attenuator that I'll use with it, possibly Slagle Autoformers or perhaps a Muse chip based one.

Image
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#13 Re: Vintage Silicon

Post by Ray P »

Ant, you're welcome to give the breadboard build a go if it's of interest? It's not that big or heavy so wouldn't cost too much to send it up to you?
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Ray P
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#14 Re: Vintage Silicon

Post by Ray P »

Thye power supply for my 'proper' Aunt Corey's Buffer equipped passive arrived this morning so I finished the assembly and have been having a listen.

It uses an 11-way switched attenuator (series) in front of the buffer stage, which is based on 30yr old BUF-03 op amps.

The new power supply is one of Jan Didden's SilentSwitcher modules; I'm impreesed with it, it's tiny and runs off a 5V USB supply but is a good improvemnt on the LM317/337 power supply I used previously - it gives an inky black background and reveals more subtle nuances in the music as well as a generally good weighty and dynamic presentation. Eventually I'll run it off a USB battery power pack - I have an Anker one for recharging my phone on the move but it seems a bit too clever as it turns itself off, I think because the SilentSwitcher draws such a low current.

https://linearaudio.nl/silentswitcher

The BUF-03s deliver enough output to drive headphones so I've been listening on my old 32ohm Goldring headphones - about 10yrs old but great sounds.

The whole thing is fitted into a small Chinese-sourced case, for which i made a clear perspec front panel, that I've illuminated with LEDs behind the knob. The only problem was a bit of noise from the old switch but it seems better after using some contact cleaner and rotating the contacts a few times.

A couple of pictures;

Image

Image
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Ray P
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#15 Re: Vintage Silicon

Post by Ray P »

This thing is a great little headphone amp. :thumbup:
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