AudioCircle

Audio/Video Gear and Systems => Owner's Circles => Digital Amplifier Company Owners => Topic started by: AvsFan on 1 Aug 2019, 09:48 pm

Title: Stereo Maraschino, question about load resistance and speaker ohms.
Post by: AvsFan on 1 Aug 2019, 09:48 pm

So I have owned the Stereo Maraschino with the 48v power supply, Tommy is working on a 60v version right now, for about a month now and LOVE it! I have it paired with my ZU Audio Omen MKII Dirty Weekends and it's by far the BEST my ZU's have ever sounded. I do have a question though, and the ZU crew has even suggested it in my situation. I guess that's why they offer it as an option when running solid state amps.
But as it stands, the DW's have an odd impedance rating at 12ohms. I don't understand the technical or specifics behind it but something about a higher or lower damping factor with certain amps is better or worse. So ZU offers and option of a 25ohm speaker loading resistor.........  https://www.zuaudio.com/diy/loading25r

What does this do? What is the reasoning behind it? And would this be a good,bad or an option that won't make any difference in my situation with the STM?

Thanks.

Title: Re: Stereo Maraschino, question about load resistance and speaker ohms.
Post by: AmpDesigner333 on 7 Aug 2019, 09:21 pm

Quote from: AvsFan on  1 Aug 2019, 09:48 pm

So I have owned the Stereo Maraschino with the 48v power supply, Tommy is working on a 60v version right now, for about a month now and LOVE it! I have it paired with my ZU Audio Omen MKII Dirty Weekends and it's by far the BEST my ZU's have ever sounded. I do have a question though, and the ZU crew has even suggested it in my situation. I guess that's why they offer it as an option when running solid state amps.
But as it stands, the DW's have an odd impedance rating at 12ohms. I don't understand the technical or specifics behind it but something about a higher or lower damping factor with certain amps is better or worse. So ZU offers and option of a 25ohm speaker loading resistor.........  https://www.zuaudio.com/diy/loading25r

What does this do? What is the reasoning behind it? And would this be a good,bad or an option that won't make any difference in my situation with the STM?

Thanks.

Some amps, more specifically transformer coupled tube amps, don't function as well when they aren't "loaded enough".  I have met some people like that, but I digress....

By placing the 25Ω resistor in parallel with a 12Ω speaker, you get roughly 8Ω (nominal).
    Rp = (R1 x R2) / (R1 + R2)

This is NOT necessary with Cherry Amps.  Cherry Amps don't mind fluctuations in speaker impedance, within reason, even the frequency dependent type.

Thanks.

Title: Re: Stereo Maraschino, question about load resistance and speaker ohms.
Post by: seikosha on 8 Aug 2019, 12:54 pm

Thanks for the answer Tommy.  So is the power that the amp supplies at 12 ohms the same as it does at 8ohms?  I think that's what AvsFan is getting at.

Title: Re: Stereo Maraschino, question about load resistance and speaker ohms.
Post by: AmpDesigner333 on 8 Aug 2019, 05:51 pm

Quote from: seikosha on  8 Aug 2019, 12:54 pm

Thanks for the answer Tommy.  So is the power that the amp supplies at 12 ohms the same as it does at 8ohms?  I think that's what AvsFan is getting at.

The amp will drive more power with the parallel resistance, but the sound should be the same, and the extra power gets dissipated as heat by the resistor.  So, I recommend against using this resistor.