noise spec.
- Thread starter overboard
- Start date
I'll take my scope down to the shop with me tomorrow and grab a spec for you.
thank you sir.
I got things put in place tonight to get this measured properly.
Here's a sample looking at what's there from 1V of output from the amp. You can see the 1kHz fundamental which peaks at about -47.6dB and the 60Hz noise is dominant at -101dB, which is a 53.4dB difference, which gives the noise floor as about 2mV. The 120Hz noise is another 20dB down from that (so 200uV), and the 180Hz harmonic is about 1.7mV. This is a bit quieter than an AC heated 2A3 amp, but not extraordinarily quiet like a DC heated Kaiju is.
There certainly is some possibility that DC heating of the 7L7 could reduce the 60Hz component, but on a single ended amp with this much power, 2mV is certainly reasonable.
Here's a sample looking at what's there from 1V of output from the amp. You can see the 1kHz fundamental which peaks at about -47.6dB and the 60Hz noise is dominant at -101dB, which is a 53.4dB difference, which gives the noise floor as about 2mV. The 120Hz noise is another 20dB down from that (so 200uV), and the 180Hz harmonic is about 1.7mV. This is a bit quieter than an AC heated 2A3 amp, but not extraordinarily quiet like a DC heated Kaiju is.
There certainly is some possibility that DC heating of the 7L7 could reduce the 60Hz component, but on a single ended amp with this much power, 2mV is certainly reasonable.
thanks Paul
The 2mv figure is just about at the level where it would be almost dead quiet
my kaiju was 1 mv with the dc conversion and it was dead quiet
the speaker is 105 db efficient so that is saying something!
it is really hard to find amps this quiet
my first horn speaker was in 1975 i went through many amps and i think the only one was a Yamaha
the 30 watts would provide huge head room and that never hurts
thanks again for your efforts
The 2mv figure is just about at the level where it would be almost dead quiet
my kaiju was 1 mv with the dc conversion and it was dead quiet
the speaker is 105 db efficient so that is saying something!
it is really hard to find amps this quiet
my first horn speaker was in 1975 i went through many amps and i think the only one was a Yamaha
the 30 watts would provide huge head room and that never hurts
thanks again for your efforts
You could also use the 4 ohm output, which will knock that down some more.
