Hello Billhurst,
are your thermistors in good contact with the plastic case / surface of the Mosfets? Don't bend them to the metal washers on the Mosfets. The thermistors are well known to easily become damaged on the surfacecoating / colour.
If your new JFets have different values like your original ones - this could also explain a difference in the overall bias.
I would check the thermistors. You describe it as heating up equally , then one side goes / regulates down.
Only an asssumption from me.
And 20mV difference in bias is not so far away.
Cheers
Dirk.
are your thermistors in good contact with the plastic case / surface of the Mosfets? Don't bend them to the metal washers on the Mosfets. The thermistors are well known to easily become damaged on the surfacecoating / colour.
If your new JFets have different values like your original ones - this could also explain a difference in the overall bias.
I would check the thermistors. You describe it as heating up equally , then one side goes / regulates down.
Only an asssumption from me.
And 20mV difference in bias is not so far away.
Cheers
Dirk.
Take a look at posts #6982, 6993 & 6996, esprit was able to increase bias using 8 -11mA IDSS JFET's. Since you are NOT using the diodes, and your heat sink temps are OK, your DC offset is close to 0 mV it sounds like the JFET's are limiting max bias.
I am laying out the components for my F5T build. I use a case with with long heatsink fins and the case internal width is relative small. This makes the 2 400W transformers to be placed very close together. Is there a recommended minimum spacing for torroidal transformers? Or I should stack them one on top the other?
Toroidals are fine to be bunched up together given their very narrow EM field, you can put a shield on them too
Stacking is fine too
Stacking is fine too
Hello everybody, I am considering selling a pair F5 turbos V3 (monoblocks) they are well built, in deluxe U5 chassis, the front boards are built with vishay 1% resistors, real toshiba fets, why? I have a X250.8. Big power supplies with 432000 uF of RCR filtering (too much?), Antek 800 VA transformers. How much should be fair to ask for the pair? Thanks.
The DIY Audio Store. Unless they are out of stock, but I just checked and the PCBs show as in stock.
Ok thanks.
The F5T V3 - pcb-set consists of 2x gain PCB and 2x O/P PCB.
What about power supply, are there bare PCBs available ?, I couldn't see any on the DIY Audio Store.
There are actually 6 PCBs: for each channel, 1 driver/front end board, and two output boards. The PCB set is sufficient for 2 channels, unless you are building a monoblock version, in which case you will need two PCB sets in order to get sufficient output boards (ie you will have 2 leftover driver/front end boards).