A new "Baby" (Huey) arrives
At last its completed - this has been about two years in the making, I got distracted by other projects.
This has been my first "from scratch" power amp build. While not a "cost is no object" build I did want to spend a bit more that absolute minimum so it has James transformers, two chokes and all polyprop caps in the B+supply, tube rectification via 6CK3 damper diodes. Chassis is also from James. I plan on replacing the front panel with something a bit more individual.
My other amp is Allen Wright's PP2C input stage (differential, cascode 6H30) driving fixed bias EL34/KT88. Pre-amp is the line-stage bit of Mr Wright's FVP5A. Adding the phono part is the next "distraction". But I also have an itch to try some Directly Heated power tubes and I reckon some 6B4G's may soon replace the EL34's in the other amp.
Many, many thanks to Ian for the design and the help. I've learned a lot.
Rod
At last its completed - this has been about two years in the making, I got distracted by other projects.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
This has been my first "from scratch" power amp build. While not a "cost is no object" build I did want to spend a bit more that absolute minimum so it has James transformers, two chokes and all polyprop caps in the B+supply, tube rectification via 6CK3 damper diodes. Chassis is also from James. I plan on replacing the front panel with something a bit more individual.
My other amp is Allen Wright's PP2C input stage (differential, cascode 6H30) driving fixed bias EL34/KT88. Pre-amp is the line-stage bit of Mr Wright's FVP5A. Adding the phono part is the next "distraction". But I also have an itch to try some Directly Heated power tubes and I reckon some 6B4G's may soon replace the EL34's in the other amp.
Many, many thanks to Ian for the design and the help. I've learned a lot.
Rod
It's early days, Bas, but my initial impression is that the Huey has a more restrained sound with great fine detail but no hard edges at all. But not remotely dull and warm, either. The PP2c I think has greater large-scale dynamics but that may relate to the higher power of the EL34's. Both are fabulous amps for the money.
Us DIYers are privileged to have access to such high-end designs, I can't emphasise this enough!
So this is correct if I have a volume control in a preamp for example. Would it be the same if I want to use a temporary external volume control? So just a box with an input/output and a 100K pot. Would I still need the 100K resistor at the input of the main amplifier, or should I omit it?
Any issue with this set up? the cable shouldnt be more than a couple fo feet.
Cheers
Charlie
I was just checking the schematic again before powering up in the morning. And in Taj's drawings on the WIKI page Baby Huey PP EL84 amplifier - diyAudio, the no GNFB version omits the 470R resistor that is the lower half of the divider for the feedback.
If I decide that I don't want to use global feedback, should I take this 470R out of the circuit? Will leaving it in cause any unbalance in the design?
Cheers
If I decide that I don't want to use global feedback, should I take this 470R out of the circuit? Will leaving it in cause any unbalance in the design?
Cheers
Well ive fired it up, and everything seems to be in order, other than a higer HT than calculated.
I am actually reading about 320v on the anodes of the ecc803s', and on the last build this was around 180v. So trying to figure out the mistakes. The ccs appears to be wired correctly, getting about +18v though....
As for the RLD arrays, they are lit up like a christmas tree, one is drawing 81mA, and the other only 60mA. Can anyone give me an insight into possible mistakes with this please?
Going to double then triple check my wiring, it's been a very long lunch break so far, im glad ive got a friendly boss.
Charlie
I am actually reading about 320v on the anodes of the ecc803s', and on the last build this was around 180v. So trying to figure out the mistakes. The ccs appears to be wired correctly, getting about +18v though....
As for the RLD arrays, they are lit up like a christmas tree, one is drawing 81mA, and the other only 60mA. Can anyone give me an insight into possible mistakes with this please?
Going to double then triple check my wiring, it's been a very long lunch break so far, im glad ive got a friendly boss.
Charlie