Jason,
Once the preorder for Vfet chassis is complete will this become a regular store item? Waiting to see what NP has cooked up for the Tonkin SITs as I don’t a drawer with a hidden supply of Sony parts. Also need to grab 2 chassis for other amps while I wait. if this is one and done would be good to know now I think.
No plans currently. These are non-standard chassis that must be custom cut and manufactured, hence the pre-order so quantities are known. As for the future... 🔮
Okay and thanks for the follow up.
Now I may be forced to release the pair of matched 2SJ28 I acquired here as the financial numbers of adding everything up is somewhat daunting---> ($640.00 as I thought this was going to be a sub $500 project since I had the Vfets already ) and I have a family to support. The total cost wouldn't be so bad except my wife had lost her job back in 2020 because of the pandemic and hasn't been able to find a new job related to her field of expertise.
I suppose I could use a different (cheaper) chassis and do without the front-end cards as Mr. Pass had mentioned where it may be worthwhile to drive the output stages directly from a preamp since the Vfet configuration he designed has high input impedance and no voltage gain if that makes a suitable compromise.
Anybody have a suggestion on what would be a more suitable and less expensive chassis that I could substitute in order to make this DIY more financially feasible for me (and not give the wife a conniption) under our current economic situation so that I could proceed with the desired build.
Kind Regards,
Most of my chassis have come from Aliexpress either direct or via ebay; freight costs from China are fierce, but you can occasionally find end-of-line/warehouse clearance items at attractive prices. As Zen Mod has mentioned more than once, if you place your output devices carefully or mount them on a bracket you can use long bolts in between the heatsink fins, which makes tapping threads unnecessary. I've read of people re-purposing the chassis from a dead commercial amp but never managed to find anything suitable myself. Don't give up - my VFET is my favorite amp by far.
I
here is my 2sk180 choke loaded follower. I probably have less than $50 into the enclosure.. Heat sink was the most expensive part. Wood is easy to work with. I am going to cover it with wood. You can find heatsinks with the t-03 holes in them. I know it looks ugly but I love the sound.
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Provided your LS are quite efficient (say 94dB/W/m or more), your listening distance and loudness level still reasonable, and finally your source outputs around 2V max with non abnormal output impedances... then you could start enjoying the VFET directly without the FEs.
I tried it myself, without any negative - nor positive LOL
Once times are better again for your family, you could give any of Mark's numerous FEs a try and enjoy that way another great project. You could even assemble it while listening to your VFET
I hope this helps a bit
Claude
I tried it myself, without any negative - nor positive LOL
Once times are better again for your family, you could give any of Mark's numerous FEs a try and enjoy that way another great project. You could even assemble it while listening to your VFET
I hope this helps a bit
Claude
Is the VFET chassis will be compatible with the future circuit who will use Tokin VFET device (mine is THF-51S)?
I like the appearance of it but I worry if it has enough space/headsink.
I like the appearance of it but I worry if it has enough space/headsink.
That's what I was wondering too. Will the upcoming round 4 for those of us with the big Tokins be using this same chassis or end up using a chassis with bigger sinks. In other words, preorder the chassis or just sit tight?
I am using the same heatsinks for SissySIT and that works fine. The narrower chassis does make for a tighter fit with a transformer and in my case SLB psu. If you are using T-brackets, only an external PSU (smps or linear) would work, as I don't see how one would mount the transformer.
Haven’t seen your layout (or more likely I forgot) 😀
Just one sink per side/channel, like with the VFET chassis, or did you go longer?
Mine’s pretty warm (24C above ambient) with a 5U/400. If you used only one sink, what Iq, did you use?
Sorry for OT.
Okay thanks guys for some of your advice.Provided your LS are quite efficient (say 94dB/W/m or more), your listening distance and loudness level still reasonable, and finally your source outputs around 2V max with non abnormal output impedances... then you could start enjoying the VFET directly without the FEs.
I tried it myself, without any negative - nor positive LOL
Once times are better again for your family, you could give any of Mark's numerous FEs a try and enjoy that way another great project. You could even assemble it while listening to your VFET
I hope this helps a bit
Claude
Claude, would the Korg B1 be suitable enough to use as the preamp in lieu of the FE boards by Mark?
If I could do away with the $100 plus FE boards for now then I could probably get on with the build.
The B1 Korg has a maximum usable voltage of about 4 to 5V (https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf).
If it feeds the VFET output stage, the power output would be about 1 to 1.5W rms at 8 Ohms. Suitabliity depends on the sensitivity of your speakers and listening volume.
If it feeds the VFET output stage, the power output would be about 1 to 1.5W rms at 8 Ohms. Suitabliity depends on the sensitivity of your speakers and listening volume.
I believe I left it at 160mv so 1A6. Soon to test with new MOSFETs as I screwed up massively when moving to the smaller footprint chassis (install flying lead resistor without jumpering it's position on board). The width is 2cm wider as the Modushop VFET chassis.
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Claude, would the Korg B1 be suitable enough to use as the preamp in lieu of the FE boards by Mark?
If gain is your concern: not really, as Ben Mah just explained. In fact, I will be even harder: I don't consider the B1K an overall gain device with modern sources, although it has a big gain factor (Vin is multiplied of course when reachin the output). Reason being that the B1K is not really suited to output over 2V, so basicaly what most digital gear produce already. Of course you can extract 4V, but at the cost of quite a lot more sugar / distorsions (albeit likely on peaks only, so less dramatic probabaly for most), whereas I, and that's just me, prefer already to bias the B1K at a nominal level that is 25% disortion of the baseline set up.
Of course the B1K is still a gain device, it can boost low level sources, but it is limited in its output. As my DAC outputs 10V and my RIAA stage 1V, in fact I end up reducing a lot the input voltage in a lot of cases.
But back to you: what efficiency have your speakers? Be it advertised or as tested?
What sources do you use and what max voltage output do they provide?
Again, worth calculating IMHO, you may not need a FE to get a reasonable loudness in your listening room... that would bring costs down to enable getting started.
Claude
Claude, would the Korg B1 be suitable enough to use as the preamp in lieu of the FE boards by Mark?
If gain is your concern: not really, as Ben Mah just explained. In fact, I will be even harder: I don't consider the B1K an overall gain device with modern sources, although it has a big gain factor (Vin is multiplied of course when reachin the output). Reason being that the B1K is not really suited to output over 2V, so basicaly what most digital gear produce already. Of course you can extract 4V, but at the cost of quite a lot more sugar / distorsions (albeit likely on peaks only, so less dramatic probabaly for most), whereas I, and that's just me, prefer already to bias the B1K at a nominal level that is 25% disortion of the baseline set up.
Of course the B1K is still a gain device, it can boost low level sources, but it is limited in its output. As my DAC outputs 10V and my RIAA stage 1V, in fact I end up reducing a lot the input voltage in a lot of cases.
But back to you: what efficiency have your speakers? Be it advertised or as tested?
What sources do you use and what max voltage output do they provide?
Again, worth calculating IMHO, you may not need a FE to get a reasonable loudness in your listening room... that would bring costs down to enable getting started.
Claude