Search found 120 matches

by terkio
Fri Sep 20, 2019 7:46 am
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

Ok thanks, this thread can be closed, title topic is fully answered.
I opened a new thread for VCA Multiplying DAC.
by terkio
Fri Sep 20, 2019 7:41 am
Forum: Build
Topic: VCA Multiplying DAC.
Replies: 6
Views: 638

VCA Multiplying DAC.

I am on a VCA design where I need high headroom, high accuracy ( resolution and stability ) I am thinking to use 16 bits MDACs. DAC8812, AD5545. From TI, AD they look the same. The data sheets give -104dB THD at 5Vpp. That is 0.0005%. How do they perform at higher levels ? The AD5545 only mentions A...
by terkio
Tue Sep 17, 2019 7:05 pm
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

I think it is a good trick for analog VCA. Their exponential transfer curve mostly makes H2 harmonics, H2/H1going higher with signal amplitude. The trick zeroes H2/H1 lowering the THD figure, but unfortunately does nothing about H3/H1. The results about bridged amps was not from commercial PA, this ...
by terkio
Tue Sep 17, 2019 2:28 pm
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

THD cancellation. With a differential topology, if the two legs are exactly the same then you have cancellation of all even harmonics. This is from theory and applies at any level. This theoretical result I have seen effective in bridged power amps. Cancellation of even harmonics does decrease THD, ...
by terkio
Tue Sep 17, 2019 11:20 am
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

I looked at a fully balanced configuration, using two VCA circuits as suggested. Compared with balanced to unbalanced input stage, one VCA, unbalanced to balanced output stage. I like the fully balanced for a nicer output stage and the harmonic 2 cancellation and a better S/N. The drawbacks: Cost of...
by terkio
Sat Sep 14, 2019 2:23 pm
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

mediatechnology wrote:
Sat Sep 14, 2019 2:08 pm
I never get timeouts.
How does that happen?
I am extremely slow at typing on a smartphone and checking stuff. I got logged out.
by terkio
Sat Sep 14, 2019 2:06 pm
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

Thanks all, for your inputs, I had typed many answers but lost all cuz a timeout.😣 To make it short, I think of using MDAC like DAC8811 at the VCA stage ( unbalanced ) Balanced XLR output using OPA454 with high voltage rails. Stay with usual voltage rails at the XLR input stage and VCA stage. The re...
by terkio
Sat Sep 14, 2019 10:33 am
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

In line level gear what is considered signal peak value of a given signal rms value ? The answer for a Sine signal is Vpeak /Vrms = √2; What about audio signals rms values ? In line level gear, when considering headroom and clipping, what is the ratio used by pro designers? There is only a simple r...
by terkio
Sat Sep 14, 2019 7:39 am
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Re: Audio RMS versus Peak

I see, in this matter audio rms refers to sine signals. I wanted to make sure. Another related issue ( or same ?). RMS-equivalent (or average measurement calibrated to RMS) using a sine wave . When measuring AC, multimeters display a RMS value. They actually measure the mean value of the rectified s...
by terkio
Sat Sep 14, 2019 5:57 am
Forum: Build
Topic: Audio RMS versus Peak
Replies: 21
Views: 1646

Audio RMS versus Peak

In line level gear what is considered signal peak value of a given signal rms value ?
The answer for a Sine signal is Vpeak /Vrms = √2; What about audio signals rms values ?
In line level gear, when considering headroom and clipping, what is the ratio used by pro designers?