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PeeCeeBee V4H GB

Shaan, your drill template needs annotation -- please add the length and width of the rectangle in millimetres.

When you use a PDF file as a drill template, you never know whether your software scaled the printed image slightly. To allow the user to verify that the printout is truly 1:1, you need to put the length and width on the PDF, so that he can first print, then check the size with a scale, then use the template for hole punching.

And thanks for the excellent offline conversation. I'm picking up one pair of amp PCBs and one PSU PCB from you. Thanks for those.
 
Shaan, your drill template needs annotation -- please add the length and width of the rectangle in millimetres.

When you use a PDF file as a drill template, you never know whether your software scaled the printed image slightly. To allow the user to verify that the printout is truly 1:1, you need to put the length and width on the PDF, so that he can first print, then check the size with a scale, then use the template for hole punching.

Hi.

Drill template has been tested to be ok. But I understand your points. Will add the suggestions shortly.

And thanks for the excellent offline conversation. I'm picking up one pair of amp PCBs and one PSU PCB from you. Thanks for those.

Thanks for your interest in peeceebee. :)
 
Hi Shaan,

Have a question on the KSE340 and 350 transistors. It's hard to tell what side is up. Is it the side with the writing on it, or the other? The data sheet isn't clear either. Usually, the leads are off-center a bit, and closer to the back means that's the heatsink side. These don't seem to follow that convention. So, thought I would ask before I solder them to the board.
 
Shaan,

I'm finally at the testing phase with my V4H amp boards. For my initial testing and settings, I'm using a +- 45VDC SMPS instead of the matching linear PSU. I'm still weighting my options as to which PSU I ultimately go with for this amp build.

My questions is, would the testing values - as indicated in your setup guide - be the same as when using the V4H PSU at +-56VDC?

I didn't trim the VR1/2 before soldering to the board, so it was a little precarious trying to set them correctly prior to testing. Anyway, using 2R/3Watt resistors (I didn't have 1R on hand), and measuring across R25, I got ~240mv by the time it settled out. Would this voltage reading be related to my lower voltage (+- 45VDC) SMPS PSU? Or, is there some other issue I need to investigate that you could point me to?

BTW, the LEDs lite and the 2R resistors did not get warm, nor did I get any magic smoke upon firing it up! :)

Ideas, comments?

Edit... Testing the 2nd module/channel the voltage across R25 quickly shot up to ~560mV, and the 2R resistors both got very warm, very quickly. No magic smoke though.
 
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Shaan,

I'm finally at the testing phase with my V4H amp boards. For my initial testing and settings, I'm using a +- 45VDC SMPS instead of the matching linear PSU. I'm still weighting my options as to which PSU I ultimately go with for this amp build.

My questions is, would the testing values - as indicated in your setup guide - be the same as when using the V4H PSU at +-56VDC?

Yes.

I didn't trim the VR1/2 before soldering to the board, so it was a little precarious trying to set them correctly prior to testing. Anyway, using 2R/3Watt resistors (I didn't have 1R on hand), and measuring across R25, I got ~240mv by the time it settled out. Would this voltage reading be related to my lower voltage (+- 45VDC) SMPS PSU? Or, is there some other issue I need to investigate that you could point me to?

Yes the VAS bias is somewhat dependent on rail voltage as there is no CCS on their collectors. A lower bias at lower rails is normal.

BTW, the LEDs lite and the 2R resistors did not get warm, nor did I get any magic smoke upon firing it up! :)

Ideas, comments?

All is well in this channel

Edit... Testing the 2nd module/channel the voltage across R25 quickly shot up to ~560mV, and the 2R resistors both got very warm, very quickly. No magic smoke though.

This is most probably due to lower than recommended value of VR1 and 2, and higher than recommended value for VR3 - at fisrt start. Please set VR1 and 2 to max and VR3 to zero then check.
 
Yes.



Yes the VAS bias is somewhat dependent on rail voltage as there is no CCS on their collectors. A lower bias at lower rails is normal.



All is well in this channel



This is most probably due to lower than recommended value of VR1 and 2, and higher than recommended value for VR3 - at fisrt start. Please set VR1 and 2 to max and VR3 to zero then check.

Thanks. I'll check the settings of VR1, 2 and 3 later this afternoon.
 
Hi Shaan,

My second channel is slowly coming to a completed state. I need to solder the mosfets and mount everything against the heatsink.
In the mean time, my first channel has been playing in my main stereo system. The amp is behaving very well. Compared to my Q-Watt amplifiers, the VH1 produces a deeper bass (probably due to the fact that it is DC coupled).

I would like to experiment with the mosfet biasing. Do you know how the amp behaves with half of the suggested bias current (ie 100mA instead of 200mA)?
I'm asking because when the environment temperature is high (last week was crazy over here) the amp gets really hot even at normal listening levels.

Thanks!
 
Hi Shaan,

My second channel is slowly coming to a completed state. I need to solder the mosfets and mount everything against the heatsink.
In the mean time, my first channel has been playing in my main stereo system. The amp is behaving very well. Compared to my Q-Watt amplifiers, the VH1 produces a deeper bass (probably due to the fact that it is DC coupled).

I would like to experiment with the mosfet biasing. Do you know how the amp behaves with half of the suggested bias current (ie 100mA instead of 200mA)?
I'm asking because when the environment temperature is high (last week was crazy over here) the amp gets really hot even at normal listening levels.

Thanks!

Hi.

Sound doesn't change much after 50mA. So 100mA should not change the sonics much.
200mA is suggested so that we can be sure that both N+P mosfet pairs are well into conduction even if not matched and closer to their temperature coefficient inversion point. But yes in warm ambience it does get a little hot with a 56V supply and 22W idle dissipation.
 
In the meantime, my second channel is running. During setup I adjusted the mosfet bias to 110 mV across the 1R resistors.
After setup was complete I let the amp warm up again and checked bias current by measuring the voltage across the source resistors. And sure, about 50mA per mosfet.

Distortion measurements are the same as with the 100mA bias current. And the amp spits out 142 watts into 8 ohms just before clipping. Next up listening test: I honestly can't hear any difference between the two setups.
I think I'll bring down the bias current of my first channel too. The amp runs a lot cooler with 50mA bias (per mosfet).

Love the deeper base that the PeeCeeBee amplifier produces!