Amp, Preamp, two volume pots, there can be only one!
Hello everybody,
I have a question regarding the two volume knobs in my system and how they
should co-relate.
Here is my gear, both units are tubed:
Amp: Coincident Dynamo 34SE Mk1 (Output power: 8Wpc, Sensitivity: 300mV for full output, Input impedance: 100k ohms, S/N ratio: 92dB)
Preamp: Doge 8 2018 (Output impedance: 600 ohms, Input impedance: 50K ohms, Input sensitivity: 200mV)
Speaker: Proac 140 Mk1 (Sensitivity 91db, Amplifier Power Range 15 - 250 watts)
Now here is the dilemma, Coincident says if Dynamo is used a power amp the volume pot should be left open (heard that some call it a sensitivity pot too) but this introduces noise in the system (albeit when music is not playing) and leaves a very small usable range on the preamp volume knob, and hard to hit the sweet spot as at 9 o clock its already very loud.
So what would be the best way to run things without losing signal quality? And is there any mismatch between my power/pre?
Thanks in advance for any suggestions!
@neverlast Find one that takes 2Volts or more for full output. If the amp is properly designed, that will drop your noise floor about 15 dB and will make your volume control a lot more useful. |
@neverlast With full output at only 300mV your amplifier is far too sensitive. Since it can only make 8 Watts, it has to be used on a high efficiency speaker. So you'll be fighting noise. So yes, that's a bit of a mismatch! Usually SETs (or SEP in this case) have low gain so as to deal with this issue. I rarely recommend a passive setup but this appears to be a situation where it would be handy. OTOH, finding an amplifier of similar spec that has a more real-world input sensitivity would help with the noise and you may notice greater low level detail as a result. |
