Hi Shaan,
I’m gathering my parts for the V4, but have a question about which transistors to use (BD, MJE or KSE)? With parts on hand my power supply will yield 42vdc unloaded. I assume a few volts will drop when the V4 boards are connected but still above the 35vdc for the recommended BD139/140 pair.
Should any other components be changed when the V4 is used above +/-36vdc?
With Loafimus’s recent positive results, I’m looking forward to this project 🙂
Thank you
I’m gathering my parts for the V4, but have a question about which transistors to use (BD, MJE or KSE)? With parts on hand my power supply will yield 42vdc unloaded. I assume a few volts will drop when the V4 boards are connected but still above the 35vdc for the recommended BD139/140 pair.
Should any other components be changed when the V4 is used above +/-36vdc?
With Loafimus’s recent positive results, I’m looking forward to this project 🙂
Thank you
Asuslover, thanks for the tip.
Since I’m building both versions, I figured to go with the KSE340/350 and I’ll be covered.
Since I’m building both versions, I figured to go with the KSE340/350 and I’ll be covered.
Attachments
Just a quick update.
I solved all my minor hum problems! The three big things I did:
1. Tied the grounds of the RCA inputs together. This made the most drastic change and basically cut the hum in less than half.
2. I swapped out the transformer with the 300VA 25V shielded Antek with the steel cover. It was a tight fit, the attached picture shows how close the steel cover was to the cap. This basically made it where I had to put my ear to the tweeter to hear a feint hum.
3. Put a CL-60 Thermistor in between the PSU ground and star ground. After this, it has to be dead silent in the room with my ear to the tweeter and really looking for noise.
The amp sounds great, is dead silent, and I couldn't be happier.
I solved all my minor hum problems! The three big things I did:
1. Tied the grounds of the RCA inputs together. This made the most drastic change and basically cut the hum in less than half.
2. I swapped out the transformer with the 300VA 25V shielded Antek with the steel cover. It was a tight fit, the attached picture shows how close the steel cover was to the cap. This basically made it where I had to put my ear to the tweeter to hear a feint hum.
3. Put a CL-60 Thermistor in between the PSU ground and star ground. After this, it has to be dead silent in the room with my ear to the tweeter and really looking for noise.
The amp sounds great, is dead silent, and I couldn't be happier.
Attachments
What about the use of 2SA(KSA)1381 and 2SC(KSC)3503, instead of BD139/140 (Q9 and Q10), as they are low Cob devices?
Shaan,
Do you think there's any advantage of moving the mosfet bias up a bit? Right now at around 115 the heatsinks I'm using don't get too extremely warm and I was hoping to put them to good use =)
Of course, if there's no advantage to doing so I'll leave it as is.
Do you think there's any advantage of moving the mosfet bias up a bit? Right now at around 115 the heatsinks I'm using don't get too extremely warm and I was hoping to put them to good use =)
Of course, if there's no advantage to doing so I'll leave it as is.
These are superb transistors and are most welcome at VAS stage.
Higher bias would have a direct positive effect on sonics if it was Rev1.
As you are using the Rev2 mod, I think the difference will be minuscule to non-existent. But it will be harmless, so feel free to crank the bias up a little if you want to give the sinks some constant workload. 🙂