PeeCeeBee V5 discussion thread

[shaan]

Hello.

Original V5 group buy thread >here<.

Feel free to post your questions/suggestions in this thread.

 

[gary s]

Hi shaan,

In the GB post you mention DC supply as +/- 50VDC - do you see any problem running this design at +/- 35VDC for lower output power at around 100W into 8R?

 

[shaan]

Hi Gary.

It will run just fine with 35V rails, and we will gain a little more SOA for the power transistors. But RMS power into 8ohm will be limited to 75Watt or so. For 100W you can use 42V rails.

 

[Vunce]

Transistor matching?
There are a ‘few’ transistors on the V5, how critical is matching the different types?

 

[shaan]

Hi Vincent.

All the data I collected are with tests done with no matching between any of the transistors, neither small signal nor power.

Matching will always bring lower THD in a symmetrical amp. But a bit of disbalance might prevent the sonics from going into the clinical zone.

If the pairs do not deviate more than 50% in hFE then we're good.

 

[Vunce]

That’s Music to my ears! Easy peazy parts gathering then. Hfe grade for 5551/5401’s?
Thanks Shaan 😉

 

[shaan]

My bunch gives me between 160 and 230. I used random pairs.

 

[poseidonsvoice]

Shaan,

I’m going to assume the pcb mounting holes for V5 and V4H are the same as such one can just pop the V5 board in place?

That would make my build really two amps in one! It will be nice to hear the differences between lateral mosfet output stage topology versus BJT. I think modern BJT’s have really come forward in their sonics. Looking forward to building this - but V4H first!

Best,
Anand.

 

[shaan]

Hi Anand.

Yes, the mounting holes for the power transistors are identical in placement as v4h. This was done so that members who want to upgrade, can do so easily.

 

[Oracle1]

Hello Shaan, nice amp!! May i ask the wattage for the psu 2x35ac for each channel?
Your pcb rocks!! Peeceebee psu, pre, v4h v1,v2 etc. I have them all

 

[shaan]

Hi Oracle1.

35VAC will give around 50VDC. At that voltage you will get about 140W into 8ohm.

Thanks for the kind words.

 

[Oracle1]

Thank you for your quick response! I ment about the transormer. For each channel

 

[shaan]

Oh! I misread your post! 🙏🏻

250-350VA per channel should be sufficient.

 

[von Ah]

This was done so that members who want to upgrade, can do so easily.

Some would be willing to help out with disposing of those old lateral output V4H boards… 😎

 

[gary s]

Thanks for all the answers so far shaan, looks like there might be a lot of interest. Looking at several vendors, there could be supply issues with the On Semi output transistors through 2023 - have you looked at any other types for Q29 to Q32?

With +/- 35VDC rails ,output power at 75W will do me fine.

 

[shaan]

...have you looked at any other types for Q29 to Q32?

Yes.

TIP35C/36C
MJW21193/94

Both have been tested with the concept build and both perform very well.

 

[gary s]

Several OPT options now - very good.

 

[Oracle1]

The peeceebee psu is suitable for the V5 or needed more mF?

 

[shaan]

It is suitable for V5. Can be used for two channels with 4x15000uF caps.

 

[gary s]

Hi shaan,

Just looking into parts I have, can you answer the following thanks.
For C3,C4 and C15 (2200uF) - what is the voltage rating you are using to suit a can size of 10mm DIA and 5mm lead spacing?
For R49 and R50 at 0.22R / 5W - what part number are you using?
For R55 and R56 at 10R / 5W - what part number are you using?

Also looking at the schematic and board layout - there are some discrepancies with capacitor numbering - I assume you are finalizing this as you put a BOM together.