Pictures of your diy Pass amplifier

Tiroler · 2013-05-21 9:09 pm

Hi Walter, you made a fine amp. Good layout, clean and nicely done! Iwould be interested to hear what you think of the Amplimo tranformers? Did you chose a standard type? Any hum or noise?
Martin

vdi_nenna · 2013-05-21 9:17 pm

The front is an olive chopping board

Love it! Nice grain!

WalterW · 2013-05-21 9:44 pm

Tiroler said:
Hi Walter, you made a fine amp. Good layout, clean and nicely done! Iwould be interested to hear what you think of the Amplimo tranformers? Did you chose a standard type? Any hum or noise?
Martin

Hi Martin,

I think Amplimo is the number one transformer company in the Netherlands.
They were formerly known as ILP and they made 20 a 30 years ago toroids for audio; tube output transformers, amplifier modules and so on.
They do have a focus on audio.
The ones I used are standard, 2 times the 98016, 625VA, 2 x 25V / 12,5 A.
Noise is absent, but I do have some random hum from the transformers. They told me it could be DC at the mains 230 volts, so at the end of the week I will build a anti DC hum circuit and try this.
Walter

WalterW · 2013-05-21 9:56 pm

EUVL said:
> Thermal tracking must be improved with the NTC's,

If you are referring to those in the First Watt F5 circuit to bias the MOSFETs, then I don't use them.
I rather use a lower bias at room temperature. But that is my personal choice.
I will reconsider that, but when I switch on the amp it draws 290 Watts and when it's warmed up, it draws around 350 Watts... My standard F5 with NTC's stays close to 150 Watts all the time.
> I want to build thermal protection on the amp, so that it switches off when sinks get hotter than 60C.

You just need to add a thermal switch on series with the power supply.
I would use 75°C directly at the MOSFET case.
Measuring somehwere on a heatsink is not really reliable.

Thanks, I'll put the switches directly at the MOSFET cases...
But you will, like me, realise that thermal protection is probably not necessary.
You can just put an ammeter to measure the current, or use a current limit on you power supply (not on the F5 circuit).
It is a much better protection for the FETs.

Again, my 2 cents,
Patrick

WalterW · 2013-05-21 10:13 pm

jacco vermeulen said:
Brrrr, your Swiss side, I suppose ?

(really good heatsinks, though. ~1 dm³/W/C )

yeah, my feel good temperature is around 20 C, above 30 C I'm sweating... but I do like it !

~1 dm³/W/C , you mean the amount of heatsink used per W/C ?
Walter

Tiroler · 2013-05-21 10:34 pm

Thanks for the info, Walter.

jacco vermeulen · 2013-05-21 11:47 pm

WalterW said:
amount of heatsink used per W/C ?

Yep.
W/C is a more rational parameter than C/W (you have to excuse me, I like numbers)

Amplimo used to be ILP Holland, manufacture was by ILP UK.
When the English branch go into financial/distribution difficulties, ILP NL renamed to Amplimo and became the main event, happened somewhere around '88 afair. Manufacture is still in England, but main & sub contractor switched seats.
Amusing at the time, one minute the shelves at my electronics store around the corner (aka <100ft) were full of ILP's, then nearly empty shelves for months. Followed by the familiar sight of rows of stacked boxes, with Amplimo labels.
Built one project with ILP's, on the next I got the exact same boxes, identical content, just a different label.

WalterW · 2013-05-22 8:16 am

jacco vermeulen said:
electronics store around the corner (aka <100ft) .

DIL Elektronika?

Abraxas336 · 2013-05-22 10:11 am

Patrick,

Thanks for mentioning your article - very interesting. Especially your conclusion on additional heat spreaders, the minimum thickness they should have to improve the performance of aluminium heat sinks with rather thick base plates and the fact that they might not improve the situation due to the additional thermal interface (if not soldered).

My question: if the objective is to reduce temperature differences between FET case and heat sink, is there any benefit in moving the interface which insulates the FET from the heat sink from directly underneath the FET to the spreader / heat sink interface?

In this case no insulation material would be necessary directly underneath the FET and one could work with a polished surface on the spreader and may be extremely thin thermal grease. The insulation (e.g. Keratherm 86/82) could happen between spreader and actual heat sink with a much larger area.

Could such a setup be superior to Fet / Keratherm 86/82 / heat sink setup?

Thanks
Sven

PS: This is very likely the wrong thread, I'm sure you will point me to the right one

jacco vermeulen · 2013-05-22 12:48 pm

WalterW said:
DIL Elektronika?

Nèèh, import Hague-nese (suck-city), at a 20 minute bicycle distance from the TH (TU).
15 minute HTM tram ride to Stuut & Bruin, occasional train ticket for DIL.

(3 decades later, and Barry Hay is my parttime 'neighbor', no progress, duh)

McQuaide · 2013-05-22 6:19 pm

I bought a VTI audio rack and finally finished my 2-channel rig, so I thought I'd share. Pictured are the Mitsubishi LT-30, Pearl 2 Phono Pre, O2 Headphone amp, DVD-A and SACD players, and the DCB1/F5 integrated on the bottom. Pure audio heaven!

An externally hosted image should be here but it was not working when we last tested it.

vdi_nenna · 2013-05-22 6:22 pm

Very nice!

bcmbob · 2013-05-22 8:10 pm

Beautiful shot... and that Brubeck album cover adds to the warmth and character. One of the first in my collection - 1960. What speakers are you using?

McQuaide · 2013-05-22 8:24 pm

vdi_nenna said:
Very nice!

Thanks!

bcmbob said:
Beautiful shot... and that Brubeck album cover adds to the warmth and character. One of the first in my collection - 1960. What speakers are you using?

Mirage OM-7s. Love 'em.

An externally hosted image should be here but it was not working when we last tested it.

bcmbob · 2013-05-22 9:35 pm

Looks like a marvelous combination. A slight similarity to the open back Sunflower speakers I'm using. I like that approach a lot.

Happy listening !!