FWIW, I have placed a few orders with them since tariffs on Chinese imports began and have never had to deal with any import issues. They must be folding it into the price. However, $39 is a lot more than I remember paying for shipping.
Another Rowe 4359 amp rebuild
- Thread starter nerdorama
- Start date
After spending some time with the Rowe I felt that it got a little hard sounding at higher volumes. My intuition was that maybe a bit higher level of feedback would help. I changed the feedback resistor from 3.9k to 3.3k. Early on I had a 2.7k resistor which gave close to 15dB feedback but had a hard time finding a good tuning. Since getting it looking pretty good with 3.9k I thought I would bump it up a bit. 3.3k give about 13.7dB feedback and I think it's a bit better. I might try the 2.7k again which puts it at 14.8dB.
WIthout any other changes the 3.3k resistor give a pretty good 10kHz square wave. Just a little more overshoot on leading edge than the 3.9k.
3.9k feedback
WIthout any other changes the 3.3k resistor give a pretty good 10kHz square wave. Just a little more overshoot on leading edge than the 3.9k.
3.9k feedback
Getting a very small amount of hum when connected to line stage or direct to DAC which can double as a line stage. With shorting plug it is dead quiet. Haven't quite figured this out. Other amps in my collection are quiet with the same Aikido line stage. The audio common is floating from the chassis which is on the power ground. Each channel has a local common point which is then connected to the ground bus in the power supply. Power CT is connected directly to the bus at the first cap negative. I'm using EFB and IBBA boards which both have ground connections to the power supply bus. RCA's are chassis isolated and connect to the local common in each channel.
so no tie from audio ground to chassis at all? shouldn't be possible to form a ground loop if done that way. Any voltage differential between the audio and chassis ground with vs without the line stage?
not impossible it would benefit from a cap between the audio and chassis grounds. Should be able to just touch it from RCA jack to chassis to see if anything changes. I wouldn't expect value to be too critical, maybe 0.01uF or so, just to give the audio stuff a low impedance path to ground for any RF nonsense that might come in.
not impossible it would benefit from a cap between the audio and chassis grounds. Should be able to just touch it from RCA jack to chassis to see if anything changes. I wouldn't expect value to be too critical, maybe 0.01uF or so, just to give the audio stuff a low impedance path to ground for any RF nonsense that might come in.
I haven't measured it but they are both connected to the same power strip and neither has the audio common connected to power ground. I tried a cheater plug on the line stage but no difference. I can try a cap between pwr and audio grounds tomorrow. I also have ground break pc boards that use a cap, resistor and diodes to provide some isolation. Not sure I can fit one of those into this amp due to cramped quarters in the power supply area.
I can't hear this background noise with music playing but I would like it to be quieter in between tracks. I've had good luck in this regard with previous builds so I thought my methods would be ok. The heater CT is connected to the cathodyne bias resistor in one channel which puts somewhere between 50 and 70v positive bias on the CT.
im curious about those 39uF and 82uF caps--what did u use there? did you restuff a coupla old can caps?