@tristanc, I was curious to hear about your findings after living with the Engineer’s Baby Huey, next to Pete Millett’s “Real Engineer’s Amp”. Would love to hear your observations, preferences etc.
Folks - quite a response. My two spare boards went in minutes. With a couple more people interested, there'd almost be enough for a group buy. I'd be happy to organise if people are still keen?
Of course, a reminder that the KiCad source and gerbers are available if people want to get their own fabricated. If so, please do share any spares!
Of course, a reminder that the KiCad source and gerbers are available if people want to get their own fabricated. If so, please do share any spares!
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The latest version of the files can be downloaded here.
https://github.com/tristancollins/HiFi-BabyHuey
If ordering get 2oz copper on both sides and 1.6mm FR4. (I used PCBway)
https://github.com/tristancollins/HiFi-BabyHuey
If ordering get 2oz copper on both sides and 1.6mm FR4. (I used PCBway)
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OK, so as I mentioned above, this BH replaced Pete's DCPP in my living room set-up. So both got used daily, for hours on end, for all TV, movies and music etc. I'm a heathen and listen to almost everything via AppleTV - the vinyl and turntable have been relegated to the loft until I have a bigger house.
I was happy with the DCPP, but getting valves was difficult here in the UK (I was going through them...) and I was looking to future proof. I'll fire it back up when I need another sound system, but it's under the bed currently awaiting that day...
The BH is quiet (other than some mechanical hum as I haven't tightened down the toroidal PT...) and runs at nowhere near the temperature of the DCPP. It Just Works. [having typed that, this evening it sounds like a valve in one channel is starting to fail - not bad given the use it's got]
Now, did I spend ages with a spectrum analyser / FFT tweaking the balance and bias of the driver stage to get minimum distortion? No. I just tried to get the plate voltages close. Did I experiment with the 'shunt' resistor that makes the BH design interesting? No. I took @gingertube's recommendation. Life's too short and my free time is precious, so I was pleasantly surprised the BH Just Sounded Good.
With the DCPP I spent quite a bit of time pairing the driver stage (and output) valves trying to get the distortion down to the level Pete reported. But I never had any joy. And in fact, some times I thought I was getting close but realised if was because the valve biased very, very cold and not really amplifying... The only time I noticed when things were wrong was when listening to dialogue - you could hear the distortion on sibilance. That's about as audiophile as I got.
As for actually listening to music, the BH sounded 'bigger' than the DCPP. The bass through my floorstanding Wharfedale Emerald(?) speakers from 20 years ago (purchased after a summer job during uni) sounded great - fuller. One day I'll 'upgrade'. But things sound as I reckon they should. Songs I know to have certain bass lines, or kick drum patterns, are there at the level I'd expect. Stuff I've recorded (and been involved in the mastering process) sound like I remember. To me that's good enough.
So all in all, a fun project and a great conversation piece when visitors are round. Sadly, most people listen to music from their crappy TV speakers or sound bars, and don't appreciate the improvement. e.g., my 15 month year old responds more to the crap music from those audio books (tinny output) than the same classical piece through the proper system!!
I'd recommend my board to anyone looking to get started in hifi (as I did with Pete's big red board). I'd also welcome anyone with better equipment than I have access to, to do some proper readings. Not that the % THD or -3dB point difference would change my opinion. It's great.
Absolutely! But how can you be sure you get genuine parts?
And nothing beats shipping times from Mouser, Digikey or Farnell. Two days from the US or UK to rural Norway is pretty nice.
I ordered some circuit boards a while ago. They arrived yesterday and I have already stuffed and soldered all the components. Tomorrow will see more work on the chassis. I expect to finish the amplifier this weekend.
Also, I have two extra PCBs to give away for free. Just pay postage. PM me if interested.
Thanks to tristanc for making the project available on GitHub!
Also, I have two extra PCBs to give away for free. Just pay postage. PM me if interested.
Thanks to tristanc for making the project available on GitHub!
Started drilling the holes in the top plate. It's very useful to use the holes in the PCB as guides for marking where the socket openings will be. I plan to make the socket openings slightly larger than the sockets themselves, so they can also serve as ventilation openings.
Finished the chassis, connected everything and turned it on for the first time yesterday. No smoke and no fires! I followed tristanc's power up procedure and there was no problem adjusting the amplifier.
I have also built the previous incarnation of the EL34 Baby Huey. This version is in my opinion easier to build. Very convenient with only one PCB and there are a lot less wires to keep track of.
Connected the amplifier up today and have listened to some music. It sounds very good and smooth as expected, and it's very quiet. More quiet than my previous Baby Huey for some reason.
I have also built the previous incarnation of the EL34 Baby Huey. This version is in my opinion easier to build. Very convenient with only one PCB and there are a lot less wires to keep track of.
Connected the amplifier up today and have listened to some music. It sounds very good and smooth as expected, and it's very quiet. More quiet than my previous Baby Huey for some reason.
Thanks! Yes, there is some planning behind it. And triple checking that the holes I'm about to drill actually are in the right positions.
Thanks! Yes, I had planned to check everything one more time before turning it on for the first time, but I couldn't resist ...