JoaMat

I’ve got questions about using +/-450V supplies with mini T2. It would probably work alright, I can’t see why it wouldn’t. If using a drop down resistor for +220V there is a Vishay 24.9k/3W that probably will do (haven’t tested it - maybe I should or someone else). One other request is the location of stand of holes. Attached are templates for left and right boards - imperial and metric. I had to print them 100.4% to get scale 1:1. They don’t look nice but that is what I managed to do in Proteus. holes mini T2 Right v.23.PDF holes mini T2 Left v.23.PDF mm holes mini T2 Right v.23.PDF mm holes mini T2 Left v.23.PDF

Folks with DIY T2 are used to “switch off thump”. I don’t know if anyone have solved the issue with the real thing. I use a T2 PSU with my mini T2 and when switching off the sound just dies out nicely without any thump. T2 PSU has much less capacitors than later GR supplies which probably explains the no thump. Glad you solved the switch off thump so nicely and easy.

Bare boards, please.

mini T2 v.23. Changes from v.22 Ground plane at area for brackets removed. Silk screen lines 20mm from long side edges, cut here if you want transistors mounted direct on heat sinks. Then you also have to run wires for +B traces just been cut. Be careful you are now close to other traces - only for DIYers. Regarding wishes for tblocks I want to quote myself (from a private conversation oct. 2018) “I haven’t used them at all with amplifiers and I have never missed them. Advantages are: - you can route the wire to the spot where it’s wanted, – the connection is much safer than with tblock, - saves space, – with a desolder gun or a solder iron they are easy and fast to “disconnect”. This also what Kevin did with his DIY T2 except for the outputs to earphone. With power supplies I use tblocks, then I find them convenient. Bottom line - IMO – tblocks destroys a layout.”

On GRHV regulator board – is there a capacitor C2 between source Q3 and emitter Q4? If so - reason?

Here is a picture of my third mini T2. Area for heat sink bracket screw holes cut away. Board now 160mm x 80mm and transistors mounted direct to heat sink. Inner dimension of case is 200mm x 161mm. This is the way I’ve built my amplifiers for some years now. There simply is no room for terminal blocks – will only make things more complicated for me. The real thing - DIY T2 has no tblocks either (except for output to Stax connector).

OK, time to bring this thread up on the first page. I think this is one of the most interesting threads after “The ultimate DIY? A Stax SRM-T2!“ (alright, there are lots of interesting things on HeadCase). Here Kevin introduces GG, sandwich, DHT, T8000DR etc., etc..

Any chance for a GRHVxxx BOM?

Looks even nicer today. But my brain is about to overheat – how does the probe work?

Here are some files, the best I could find. kgsshvproductiondualmot.PDF kgsshvps8g.PDF kgsshvBOM.xlsx The BOM has to be reworked with the components you want to use. Some might be harder to find. Take look and see if this is useful.

Happy Birthday, Sir!

After looking at posts by Kerry regarding the GRHV boards I think it might be a good idea for builders of the mini T2 to even build Kerry’s regulators. To me those boards seems doable and they aren’t any more difficult than the amplifier boards nor significant higher voltages either. The more you solder the better you get at it.

Good to know that 10th worked for you. I didn’t dare to buy smaller than 15th even it’s a short flute. When I did my digital attenuator I had 10th clearance so I had to make a conventional chemical etching. Same here, no luck with the V shaped things – probably only for the pros.

Looks nice! What tool did you use? I use 15th end mill but as I understand V shaped tools are more commonly used.

https://static.qobuz.com/goodies/39/000101993.pdf

I believe Kevin has made more than a couple of versions of the KGSSHV. If you post good pictures of your boards I’m sure people here can help you.

Nope!

Intention is to have updated schematic and BOM at just on place to avoid different versions floating around. This place is the first post of this thread. The advantage is that I, as the disorganized person I’m, cant publish schematic or BOM whenever I feel for it. I need Michaels (mwl168) approval and he is the only one that can make changes public – in the first post of this thread. Anyhow, please take look at the new files for errors or other issues. Below are 3D prints of the new layouts (them I'm authorized to publish myself) Please check for errors. I appreciate feedback especially regarding silkscreen, if anything seems unclear, let me know. Changes: Some resistors value. Offset balance op amp: OPA197, hopefully more reliable. Balance servo op amp: LF356, is more similar to LF353 in the DIY T2. OP27 seems to be reliable in this position though.

Looks fine. You found smd LED with color mark? One remark according the terminal block. The pad is C120-50 meaning pad diameter 120th and hole is 50th wide. Clearance to ground plane is 40th. When designing layout with terminal blocks I keep the entirely area under the block free from ground plane. It will certainly be alright to solder in a terminal block as done above but be sure to solder properly. You don’t want solder to flow out under the block. I always let wires come in from the other (non tube) side.

Well, I’m back with the original pads and nothing wrong with them. Besides, I don’t like to comment on sonically differences on things I change or modify. On the other hand I like to tell (to much) all here what I’m doing.

Please hurry on! I've run out of money to get them myself.

Today’s mini project. Timer 555 with a few other components. When IN (the empty pad just below left leg of the two color LED) is low then RED, if high then GREEN. Standby/On indicator.

Removed head band and it looks like this. I suspect it will break, probably sooner than later, so I took some of my wife’s elastic band and replaced the original band. I’m using same elastic band with my two kitchen made headphones and I’ve found the elastics quite comfortable.