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Diy Monoblock SIT/VFET
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Old 8th February 2019, 01:55 AM   #1
AHall1 is offline AHall1
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Default Diy Monoblock SIT/VFET

I am new to the FW stuff, but it seems all I read about them is “after 30years of trying different amps, I’ve never heard one like this”. I really love the idea of a triode tube sound without all the expense and maintenance. My speakers are very large horns and 113db sensitive. So I will not require a large watt amp.

From my reading it seems like the SIT transistors are impossible to find. At this current date is there a possibility to make this a reality? Would I be better off building a pair of monoblocks with a different topology? My room dictates that I must have monoblocks due to how I designed and wired it. I have enclosures in the front of the room with xlr inputs and speaker wire wall plate outlets that run to behind my mains. Be easy on a newbie please. Currently using a vta70 tube amp I built. I found bob’s instructions to be very straightforward and hope to find as much ease in the ss world.

Click the image to open in full size.

Last edited by AHall1; 8th February 2019 at 06:37 PM.
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Old 8th February 2019, 09:45 AM   #2
Dennis Hui is online now Dennis Hui  Canada
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Diy Monoblock SIT/VFET
Nice setup!

I can think of a few possibilities:

1) SissySIT:
SissySIT

Zen Mod has a kit available (minus the SIT and input transformer).
The Tokin SIT is still available, for example, from user Pras1170

2) L'amp:

L'Amp: A simple SIT Amp

You should be able to build one using the Tokin or other still available parts like
the 2sk180. The are three variations depending on the loading (with light bulbs,
inductor, or constant current source)

3) Watch for the release of the next Sony Vfet-based project from Mr. Pass.
That should be in the coming months. The expectation is there will be kits
including vfets available.

Hope this helps.

Dennis
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Old 8th February 2019, 10:35 AM   #3
Zen Mod is offline Zen Mod  Serbia
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Diy Monoblock SIT/VFET
I really like your setup!!

One thing I want to stress : do not expect exact mimic of tube sound with (any) SIT amplifier; even if you make it in same topology as tube one - using high voltages and output xformer , it still wont be carbon copy tube sound ....... nor it can be "tube" amp sans replacing da toobz every other year

if you didn't hear one , you need to read between the lines of all writings in magazines and on the web

I'm augmenting it , of course , good amp is good , from whatever it is made ; what I want to say is that you can have equally good amp made with SITs as made with tubes , with same organic quality of sound , most probably with some virtues even on higher level (easily gotten extremes of frequency band) ....... but you must suppress expectations of having exactly same thing

they are (good one) on same quality level , but never the same

on the other hand , I never heard exactly same two tube amps , even counting on fact that I'm old , lazy and my ears had mishaps with elephants ......

again - I really like that picture ..... even if I have no space for proper horns , I'm always happy to see that someone has

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Old 8th February 2019, 03:16 PM   #4
damuffin is offline damuffin  Canada
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M2x would be a good choice because it is very simple and sounds very good with compression drivers. My SissySIT is on order..... I’m sure both will give you a smile. As far as tubes go I’ve never really had the motivation to jump down the worm hole. It’s expensive to do 45’s. Preamps are much more reasonable and diverse.

Enjoy the journey!
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Old 8th February 2019, 06:09 PM   #5
Nelson Pass is offline Nelson Pass  United States
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Diy Monoblock SIT/VFET
And we do have the last round of DIY Sony VFETs coming up.

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Old 8th February 2019, 07:11 PM   #6
AHall1 is offline AHall1
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Thank you for the compliments. My room isn’t as large as I’d like it to be, but due to the constant dispersion horn design, it controls the sound very well.

I was hoping a couple of these chassis would work due to my enclosures only being 15” wide.
Mini Dissipante 3U – diyAudio Store

I also designed each enclosure to have a high flow bathroom fan that exhausts to the outside. They are very quiet at .5 sone and are not audible. So that will help remove the heat from whatever I end up with.

Ultimately I’m looking for the best fidelity I can achieve within a reasonable budget. Also the lower the noise floor is, the better. The high sensitivity is a bit of a curse as well in that regard.


Quote:
Originally Posted by Nelson Pass View Post
And we do have the last round of DIY Sony VFETs coming up.

How does a guy get signed up to get on the waiting list or buy these? Is there pricing available yet?
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Old 8th February 2019, 07:19 PM   #7
AHall1 is offline AHall1
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Here are some more pictures of the room for anyone interested. I also welcome any constructive criticism that will lead to a better sounding system.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.
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Old 8th February 2019, 07:51 PM   #8
Zen Mod is offline Zen Mod  Serbia
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Diy Monoblock SIT/VFET
not criticism , just a thought .... for me , L and R channel are always enough

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Old 8th February 2019, 07:58 PM   #9
Nelson Pass is offline Nelson Pass  United States
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Quote:
Originally Posted by AHall1 View Post
I was hoping a couple of these chassis would work due to my enclosures only being 15” wide.
Mini Dissipante 3U – diyAudio Store

How does a guy get signed up to get on the waiting list or buy these? Is there pricing available yet?
I plan to use the same bracket size as in the DIY Sony VFET pt 2, which
is 10" long, but this one holds 4 TO-3 devices.

When you see people dancing in the street, then the announcement
will have been made.

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Old 8th February 2019, 09:15 PM   #10
AHall1 is offline AHall1
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Well hopefully I don’t miss the opportunity and find them sold out.

With them being your intended size would this chassis still be a viable option?

Will it be a big deal that my high freq compression drivers are 16ohm? When I switch the diaphragms to the radian beryllium variant, it wouldn’t be a big deal to get the 8ohm version if need be.
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