Jump to content

The Multi Amp aka Dynalo Mk2


spritzer
 Share

Recommended Posts

Correct. IIRC Kevin made the SMD-layout when On-semi announced that they were discontinuing the MPSW-devices and only keep the surface-mount PZTAs. As it's the same transistors I don't believe there are any difference in performance.

 

//UFN

  • Like 1
Link to comment
Share on other sites

I made a list on mouser.com for parts of the amp boards alone. I included both the 240 ohm and 255 ohm resistors but you could easily remove one. The only thing I don't have are the terminal blocks. Anyone know which blocks I should use?
kgssdynalobal9 - 2 channels

I noticed that most amps that are class A have a lot of heatsinks but this one doesn't seem to really need them. It is because the current is distributed among several transistors which spreads out the heat more efficiently without the need for heatsinking?

Link to comment
Share on other sites

Partly. From memory, the Dynalo runs app. 300mA at +/- 15-20V, i.e. an idle dissipation of around 10-12W per channel. This is not much by class A standards (a 20W/ch speaker amp like the Pass F5 or similar dissipates from 60W/channel and up).

Distributing the heat across many transistors means the Dynalo can use smaller output transistors - the MPSW/PZTA-ones are only rated for 1W dissipation each.

//UFN

  • Like 2
Link to comment
Share on other sites

Here's an update on the mini.

I've got the external regs running now.  This thing does throw off quite a bit of heat.  I've some sinks on the output transformers now, but I'd like to make them a bit larger.  The regulators heatsinks are going to about 140 deg F at their peak and I'm ok with that.

I was testing at +/-14V before I put the heatsinks on.  The bump up to +/-20V seemed to smooth things out a bit on the top and bottom ends.  I'm very happy with this so far :D

 

IMAG00001 (3).jpg

Edited by Kerry
  • Like 20
Link to comment
Share on other sites

Just looking to get the bias back in line with original specs.  That plus the heatsinks I was testing should put us around 110 deg F on the output sinks.  The regulator sinks should also come down to 105 deg F.

Need some parts to test.

Link to comment
Share on other sites

How a about using the whole case as heatsink?

It's rather easy to calculate the distance between case and PCB. Customized aluminum block can do this job.

Or, hollow the case to expose the heat sink. My concern is if the whole PCB is cased and heat dissipation will be a problem after hours of running.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...