I was originally looking for a tube preamp to build, and I found a few designs that I liked, but they were going to be fairly expensive. I still want to build one, but I came across this Accuphase C-3850 clone kit, and it looked like it has really good performance. From what I could find, it performs the best with a 10K alps pot. I wanted a remote control, but most of them come with a 50k or 100k pot. I reached out to one of the vendors in China, and they put a kit together for me with the 10k pot. We will see how long it takes to get, but I thought that was pretty cool that they would customize a kit for me. I put some pics below of what I ordered. I am planning on building the case from scratch using some nice hardwood and sheet aluminum.
I am interested this one too. Do you mind sharing the vendor details and how you went about putting this together?
Edit: Are you getting the prebuilt populated board or the kit parts?
I have followed the videos from Michael Beeny on Youtube to get some of the inputs to the preamp board like the 10k pot and also there is a 100pF cap that should be replaced with a 47pF on the output. I bought the preamp in unassembled kit form from Looyo Tech on Ebay. I had researched the volume control on my own. I may need to modify it a bit to work. The vendor for the remote is GZLOZONE Online Store. I have not received any of the components yet.
Are you planning on swtiching out the op amp? That was the other recommendation, I think
I think you’ll like that kit. It’s a pretty decent board for so little money. I built a similar one after seeing Micheal Beeny’s videos. I added a motorized pot from an old Sony receiver, an IR receiver & Arduino Nano clone to control it. Once I figured out the grounding issue with the regulated power supply boards I used, it measures and sounds great!
I bought assembled version, think was around 60 bucks, or at least 6-8 weeks ago that bought it. Already had 2x18vac toroids on hand (2 more to use up) and I often use the 35 buck motorized alps pot. While not matter for this board since has L and R ground joined at board, i always use the remote pot kit that keeps the grounds separated and I only have 2 sources that use so just simple toggle switch for me.
I have some NOS
opa627’s (single opamp) from back in 2000’s that might drop in here. Some versions of this clone use single dual opamp. I need to find the stock 100ohm resistor so can bring the gain down some as stock it’s 5x/15db and preference for my usage is usually 3-6db preamp, or even 0db buffer. Though may leave it there as might built out another F4 for myself (0db amp).
Sounds good, clear and I was worried my toroid may need shielding being close to board but no issues.
I have watched a couple of other videos where they swapped op amps, and there was no difference in distortion or slew rate. I am only going to swap out the 100pF output cap, and add the motorized volume and input switching. I will also try to add some sort of display for the outputs. I would also like to add a balanced input since my cd player has balanced outputs.
Great, let us know how it goes once you get it. I am going to read up a bit more and get one, though i might go for a assembled board and try to switch out the couple of components.
I saw Michael Beeny just posted a video and the boards for the one he had been working with Ron are now available. Fewer parts, but really low output impedance - under 20 ohms. They say it’ll drive higher impedance headphones. I ordered a pair, so we’ll see how they measure compared to the 3850 clone.
Hi @Tom_S can you please start a new thread once you get the board and stoart working on it? The boards seem to be out of stock now - all 120 boards sold out, but still interested in this build.
Sure - no problem.
Nice thing about electronic kits - high quality components aren’t the budget busters like they are in a speaker : )
You can afford really nice caps, and use the Audio Grade Panasonics and Nichicons in the power supply. May I suggest the Burr-Brown OPA627AP? I used these in an M3 Headphone Amp project and they were every bit as good as a shielded discrete component preamp. It does need a tad bit of very clean power.
M3 was the best electronic project I ever built. Planning on bringing it to the DIY this Spring. With a good source and HD-800’s it was amazing.
Cheers / Robert
What’s the M3?
The AMB M3 Headphone Amplifier. It is a plan with circuit boards. You have to locate the case and most of the parts yourself.
Best Audio kit I ever made. Options depending, app. 300-400.00. Lots of cool tech. Rail splitter chips to ensure perfect balance on the returns, capacitance multiplier power supply for the Op Amp, etc.
I built mine with XL heatsinks and ran the output MOSFETS Class A to (in a set of headphones) ear-bleed level. I also built their high-end power supply, turn-on thump eliminator board, and a Linkwitz Cross-Feed. Also added a ground loop eliminator (was worried about the 3-channel active ground setup), but it wasn’t necessary. I used a small amount of cross-feed and the headphones were way more natural, more like listening to speakers.
The amp is a 3-channel unit, Left, Right, and an Active Ground driven to zero impedance. Not a speck of noise. I used all Dale-Vishay audio grade metal film resistors, and high grade caps.
It isn’t an easy project, but very rewarding. I built it when Wendy and I were living in the small place. No room for a real stereo : / so I used headphones.
I used soffit vents painted black for vents, and blue LED’s. We called it the “Trek Box” lol. If I do another one, it will be orange lights and a brass/wood case with old school knobs for a Steampunk look. If you are at the DIY, you’ll get a listen.
Cheers / Robert