Recent content by Arfer

Alternatively, if they all have as much lead length as those in the pics, use the transistors you already have if they are electrically OK. Use a suitably thick wire to make the connections and make a good mechanical joint by wrapping before you solder, there is plenty of space between those...

So 35 x 70mm comes out at about £110 for 100 off, or £140 for 200 assuming 2 layers Ian

I would try Quick-tek for the PCBs, their add used to appear at the top of this forum. What size and how many layers is it? I just had a quick look and as an example a 25mm x 50mm board with 2 layers costs £98 for 100 off, £114 for 200 off, or £128 for 300. 50mm x 50mm board with 2 layers...

Hi I assume you are referring to R88 in the pre amp? As I said in the OP the problem is with the power amp. I have shown this by using another pre amp, and I also saw it on the scope on the bench with nothing connected. Shorting the inputs reduces but doesn't clear it. I am suspecting the...

Hi All I picked up an Exposure VII/VIII pre power combo as a repair/restore project before christmas, the power amp had a badly leaked reservoir cap, and a faulty Pre amp PSU, where as the pre amp had some blown transistors in the phono pre amp. After recapping it, and replacing numerous parts...

The terminal connected to the heatsink is normally the one that offers the best thermal path to the hottest part of the device, in order to give the most effective cooling, and therefore highest possible power rating for a given package.

I would avoid having intentional "limits" in either output transistor or PSU. So, I would think go for supplies between 15 to 20v, but with plenty of current capability, say 200VA per channel. Maybe use medium sized output devices, T0220 size max, with plenty of hfe, and bandwidth. Although...

I was thinking of a scaled back version of this i.e 1/10 of the power, but with regulated/gyratored front end psu http://www.amplimos.it/images/krell_ksa-50_mk2_original_schematic_2.jpg Although I like the idea of minimal component count style amps, such amps can often be fussy of load in...

+1 for low power class A How about a mini krell say 4 watts into 8 Ohm, and aim for as close to 8 watts into 4 ohm, 16 watts into 2 Ohm etc as possible, so impedance dips in the speakers can be handled well Start off with a debate on what would be enough power to drive a good range of...

I used these guys when I was looking for a new tranny to fit in an MF A1 and wanted to squeeze in a few more VA http://www.amplimo.com/ They have a custom service too, and have some audio stuff Cheers Ian

I use DesignSpark which you can download for free from the RS website Cheers Arfer

If tweeking the cap value connected to the decomp pin has an affect, I would say you have cracked it. :-) Arfer

My guess is the opamp2 symbol does not have the decompensation pin defined. There are loads of tutorials on YouTube which may help. I can't get access to tools til tonight but may have a look if i get chance. You may need to modify opamp2 and save as your own symbol. Cheers Arfer

Early plastic case Cyrus 2 amps used doubled up buv28 parts, later metal cased Cyrus 2 used the larger buv48 Ian

It could be configured for use with a PSXR powersupply. There is info on the net on how to reconfigure it, or you can pay a dealer a load of cash to swap some wires.