L'Amp: A simple SIT Amp

[dantwomey]

I tried the Keratherm in my F5 and they worked great. Does anyone have any of these for the SIT?

Hittefolie 70/50 TO-3 0,25mm in de Conrad online shop

Regards,
Dan 🙂

 

[Sven257]

The Beryllium Oxide (BeO) insulators are supposed to be the best...

BeO ceramic conducts heat better than most metals...
Beryllium Oxide Ceramic Products | BeO

https://www.aavid.com/product-group/interface/insulators/beryllium

Regards,
Peter

 

[Variac]

From the Aavid site. Boy they could be a bit more careful in their notation..
Could someone standardize it with good guesses?
Thickness matters, right? or since it's steady state it doesn't?

I've got some of the Alum Oxide ones but they're about 1 mm thick!



The thermal conductivity of beryllium oxide is 221.94 Wm-1 °C-1 (128.2 Btu/hr.ft.°F).

The thermal conductivity of aluminum oxide is 15.06 W/mK @ 75° (8.71 BTU/hr-ft°F @ 167°F).

The thermal conductivity of mica: 0.528 Wm-1°C-1(0.30 Btu/hr.ft °F)

The thermal conductivity of Thermalsil: 0.92 w/m °C

 

[serengetiplains]

That's quite some difference in thermal conductivity. Does anyone know how one might purchase some BeO insulators?

Edit: I found some at Newark.

 

[dantwomey]

That's quite some difference in thermal conductivity. Does anyone know how one might purchase some BeO insulators?

Edit: I found some at Newark.

4003G - AAVID THERMALLOY - THERMAL INSULATOR | Newark/element14 Canada

Availability: 0

 

[serengetiplains]

I think Newark Canada has a 5 week delivery time for this part. They can get them. $30 a piece. I've seen price quotes for as low as $15 elsewhere.

 

[Tea-Bag]

Why are these pads becoming important? Standard mica ones and good, based on the amount of juice we are putting to these things, should not kill them for a long time.
But I apologize if I missed the point. But a pad that costs more than the SIT seems extreme. (Not that I don't advocate that once in a while).

Good show everyone!! Good show!

 

[serengetiplains]

I suspect that removing dynamical heat fluctuations from the device as quickly and effectively as possible will prevent device-parameter changes to the extent the heat is removed. That makes sense to me.

 

[KASUMI]

tried these big old resistors 200w 22ohm,didn't work after an hour or so I'd get a big click and the meter showing Vds would go high indicating the bias had gone,thought they'd be up to it ,they were £18 each

The thick films as an alternative are around £40 each from RS
I can get a run of 10 thick films from Arcol for around £15 each made at 11,12,13 ohm?
Anyone interested ?
Also if I went CLC what value inductance should I use.
Loving these amps😀

 

[KASUMI]

Got my heatsinks from here in the UK,I think mine is a 5640HS

Heatsinks, Custom Heatsinks, Boardmounting Heatsinks, Anodised Heatsinks

 

[generg]

these address looks really good for Europeans.....🙂


Long Live The Queen!🙂🙂🙂🙂🙂🙂

 

[serengetiplains]

Got my heatsinks from here in the UK,I think mine is a 5640HS

Heatsinks, Custom Heatsinks, Boardmounting Heatsinks, Anodised Heatsinks

Thank you, K.

 

[Antoinel]

Beryllium Oxide [BeO] is toxic. Best not to work with it.

 

[Antoinel]

Safety
Like all beryllium compounds, BeO is carcinogenic and may cause chronic beryllium disease. Once fired into solid form, it is safe to handle as long as it is not subjected to any machining that generates dust.[9] Beryllium oxide ceramic is not a hazardous waste under Federal law in the USA

 

[juanitox]

hey gang , i have made a mod on my sit output , a little zobel filter with just a 100nf before the 40ohm parallel resistor . wiithout it i can see a big overshoot with 1khz and 10khz squarewave at the input. and with the zobel filter the square wave looks better and the sound smoother , worth to try 🙂

 

[juanitox]

update , 40ohm seems to roll-off a little too much , i must tune the filter 😀

 

[Telstar]

May I at least suggest that, before you spend the big bucks on fancy caps and whatnot, invest in the right heatsinking, transformer, etc. After all, which one do you think will make the greatest difference?

The PSU, then the output cap, then the degeneration resistor if present.

 

[vdi_nenna]

Can someone tell me if the ground pin on the 7912 goes to ground or is left floating? See attachment.

 

[generg]

Look here,

http://www.diyaudio.com/media/files/articles/michael_rothacher/lamp_2/9th.png


You are right....

Sorry I worked with the iPad..... Something with the picture got wrong...

 

[Zen Mod]

WTF!!

it can't be floating , there is no purpose then of entire 7912 subcircuit !