I have built jfet boz, b1, b1 rev2, ba-3, salas dcg3, Juma’s LSK current mirror and the Korg b1.
Amp is F5 turbo...I only listen to vinyl through salas jfet phono. Speakers are KEF R700 3 ways.
I don’t want to comment on the buffers (I preferred original b1) because I don’t like passive preamps.
My favorites are Juma’s current mirror (quite close to pass hpa-1 in topology) and the Korg. Salas DCG3 is very good but somewhat brutal in my system...a little too tight. Killer bass though. Iam currently using it for headphones.
Korg is the most fun out of all of them but the least “hi fi”. But my Korg also has cheap pots and an smps supply. And the pcb is so small I was forced to use Mylar coupling caps. The other preamps have all the good stuff...step attenuators, good psu, etc.
The Korg has the best soundstage and presentation but is the least linear. Juma’s amp is perhaps the best compromise in this area. Great soundstage but still sounds accurate.
Honestly, I have been doing this for a while and Iam at the point where I just want to have fun and could care less about how tight the bass,etc. and the Korg is the most fun. So Iam gonna stick with it for a while.
Amp is F5 turbo...I only listen to vinyl through salas jfet phono. Speakers are KEF R700 3 ways.
I don’t want to comment on the buffers (I preferred original b1) because I don’t like passive preamps.
My favorites are Juma’s current mirror (quite close to pass hpa-1 in topology) and the Korg. Salas DCG3 is very good but somewhat brutal in my system...a little too tight. Killer bass though. Iam currently using it for headphones.
Korg is the most fun out of all of them but the least “hi fi”. But my Korg also has cheap pots and an smps supply. And the pcb is so small I was forced to use Mylar coupling caps. The other preamps have all the good stuff...step attenuators, good psu, etc.
The Korg has the best soundstage and presentation but is the least linear. Juma’s amp is perhaps the best compromise in this area. Great soundstage but still sounds accurate.
Honestly, I have been doing this for a while and Iam at the point where I just want to have fun and could care less about how tight the bass,etc. and the Korg is the most fun. So Iam gonna stick with it for a while.
It's time for you to learn to create your own PCBs. The good news is, this is not especially difficult, and you don't need to be an EE with a degree to be successful. The software is free and there are three dozen PCB fabs that will build your boards at incredibly cheap prices; see pcbshopper dot com for hard data.
Here's a DIYer who had "minimal experience in electronics" yet taught himself to layout PCBs for his first-ever diyAudio project: the Amp Camp Amp. If he can do it, you can do it: post #6029 You've got much more DIY experience than him, and in Seattle you have access to resources that are every bit as good as the resources he had in Pretoria, South Africa. If he can do it, so can you.
You could do it, but if you build them as separate components, you'll be able to use these pieces with other amplifiers and preamps you build in the future. And you will build more, this hobby works like that...
Thanks 6L6, you’re probably right. I was trying to be a cheapskate and save the cost of one chassis. (Typical Scotsman!)
Now that I’m over that hurdle my next question is regarding the power supplies. I thinking about building them into a separate enclosure from the pre and power amps, and trying to figure out whether or not to connect the ground of each enclosure together through the dc power cables or leave them floating. At the back of my mind I’m thinking they should be connected.
If you want to provide grounding to the enclosure, I recommend running a separate chassis grounding wire with your umbilical that connects the PSU to the amp.
In this way, you can ground both chassis directly to PE (Earth Ground / the third prong in the IEC) for safety reasons, while keeping audio ground separately.
You should also connect the audio ground of the PSU with audio ground of the amp.
Now you are flexible with regard to the connection between audio ground and chassis ground. It only needs to be made at one point, and can be directly or with one of the resistor / thermistor / diode bridge techniques to break possible ground loops.
Regards, Claas
In this way, you can ground both chassis directly to PE (Earth Ground / the third prong in the IEC) for safety reasons, while keeping audio ground separately.
You should also connect the audio ground of the PSU with audio ground of the amp.
Now you are flexible with regard to the connection between audio ground and chassis ground. It only needs to be made at one point, and can be directly or with one of the resistor / thermistor / diode bridge techniques to break possible ground loops.
Regards, Claas
Thanks Claas. I’ll run separate chassis and audio ground wires in each of the power umbilicals to the power amp, pre and phono stage. Since each amp will have a separate power supply located within the main psu enclosure I’m assuming that I should tie all the 0volt rails together in that enclosure???
Thanks,
Gary
Thanks,
Gary
That's actually a really good idea. I've built many of these circuits on perfboard but never designed a PCB. And actually, I am a professional graphic designer.
Can you recommend software?
I use KiCad because (a) it's free; (b) it lets you lay out boards with unlimited numbers of layers; (c) there's no size limit, you can make boards as big as you want; (d) at the time I made the choice, the closest competitor wasn't free, and the lower cost "home hobbyist" versions of the competitor software had limits on layer count and board size. Perhaps the competitive landscape has changed, I don't know. But now that I've got KiCad and know how to use it, I see no reason to change.
I feel this is the most important point. All of these solutions have a learning curve. Once you learn one, there often isn't a compelling enough reason to switch.
For me it was EasyEDA - which is a relatively new addition to the market. Its sophisticated enough for what I needed without being overly complicated. For other users, it might be too sparse on features.
Hi Gary,
tying all PSU 0V rails together at the PSUs is certainly a good fist approach. In the end, you have to see what creates the least amount of hum / ground loops.
When I think about my audio chains, the PSUs have not always been referenced to one another (or maybe through a 10R or 100R resistor, or isolated by a diode bridge, ...)
I think what's important is that the audio grounds of the different stages are referenced to one another, unless you run transformer-coupled, where there is no common DC reference.
Best regards,
Claas
Tonight I experimented with additional capacitance in the PSU.
PSU is a big caged meanwell 10A switcher. Way overkill for this application but I had it.
Caps on board are 2700uf panasonic FM.
I added 33,000uf (!!!) bypassed with a 6.8uf poly cap between the meanwell supply and PCB. The meanwell did not shut down, didn't seem to care about the additional capacitance.
Soundwise, not much different. I was surprised. Maybe a tad bit more liquid but not a big difference. Bass was same. Amp did not seem less noisy. Really, nothing different to note.
Maybe the Korg doesn't care so much about PSU quality? This has made me rethink my plans for a well regulated linear supply. Maybe I don't need it.
PSU is a big caged meanwell 10A switcher. Way overkill for this application but I had it.
Caps on board are 2700uf panasonic FM.
I added 33,000uf (!!!) bypassed with a 6.8uf poly cap between the meanwell supply and PCB. The meanwell did not shut down, didn't seem to care about the additional capacitance.
Soundwise, not much different. I was surprised. Maybe a tad bit more liquid but not a big difference. Bass was same. Amp did not seem less noisy. Really, nothing different to note.
Maybe the Korg doesn't care so much about PSU quality? This has made me rethink my plans for a well regulated linear supply. Maybe I don't need it.
Now try some SMD caps, 10uF and 1uF combo in parallel, right next to the SMPS DC-out eyelets. Scrape the lacquer to solder the SMD's properly - see the photos from this post (#677):
https://www.diyaudio.com/forums/dig...ns-upgrades-modifications-68.html#post5922640
https://www.diyaudio.com/forums/dig...ns-upgrades-modifications-68.html#post5922640
Thin bass
My Korg with Aleph 1.7 needs modification. Bass is to weak and there is to much focus on midrange and treble. Brought it to Copenhagen hificlub and there was no doubt. At home I thought it was my Virtual Zero balanced/SE receivers in my monoblocs. So I will change the Panasonic Mkp 6.8 uf at Aleph input to Audionote Kasei bipolar 50 uf 63 v. And the 3.3 ohm film on ceramic plate resistors to some carbon 5 w.
My Korg with Aleph 1.7 needs modification. Bass is to weak and there is to much focus on midrange and treble. Brought it to Copenhagen hificlub and there was no doubt. At home I thought it was my Virtual Zero balanced/SE receivers in my monoblocs. So I will change the Panasonic Mkp 6.8 uf at Aleph input to Audionote Kasei bipolar 50 uf 63 v. And the 3.3 ohm film on ceramic plate resistors to some carbon 5 w.
