ledmac vs. setspace: Don’t change spacing of critical notes

Question

Normaly setspace tries to set only the stretch of main text an footnotes are unchanged. In combination with ledmac the critical notes are stretched too. Is there a way to unstretch the notes like normal footnotes?

\documentclass{scrbook}
\usepackage{xltxtra}

\usepackage{setspace}
    \AtBeginDocument{\setstretch{2}}
    % without \AtBeginDocument it leads to an arithmetic overflow
    % don't know why ...

% für die Edition
\usepackage{ledmac}
\newcommand{\BNote}[3][]{%
        \edtext{#2}{\lemma{}\Bfootnote{#3}}%
}
\footparagraph{B}

\begin{document}
\beginnumbering
\setstanzaindents{2,0,0,0,0,0,0,0,0,0,0,}
\stanza
inspirat genio. Sed quae depingere vocem &
dextra potest oculisque echo signare videndam? &
\BNote{clarus}{very long text to show the problem\textbf{C}} circa urbes et famae voce lyraeque. &
Illum laetus Hymen plausu iuvenumque choreis &
At tandem \BNote{vergente}{urgente very long text to show the problem\textbf{H}} die festoque peracto &
\BNote{At}{ac very long text to show the problem\textbf{C}} cito colloquio facto dictaque salute &
spondet et oblato sua fata \BNote{paciscitur}{pasciscitur very long text to show  
    very long text to show the problem\textbf{H}} auro.
\&
\endnumbering
\end{document}

After lockstep’s answer seem to work fine it stopped working when using ledparin addition to ledmac. Here’s the new example.

\documentclass{scrbook}
\usepackage{ledmac,ledpar}
\newcommand{\BNote}[3][]{%
        \edtext{#2}{\lemma{}\Bfootnote{#3}}%
}
\footparagraph{B}
\usepackage{setspace}
\begin{document}
    \begin{spacing}{2}
        \begin{pages}
            \begin{Leftside}
                \beginnumbering
                \setstanzaindents{2,0,0,0,0,0,0,0,0,0,0,}
                \stanza
                inspirat genio. Sed quae depingere vocem &
                dextra potest oculisque echo signare videndam? &
                \BNote{clarus}{very long text to show the problem\textbf{C}}
                    circa urbes et famae voce lyraeque. &
                Illum laetus Hymen plausu iuvenumque choreis &
                At tandem \BNote{vergente}{urgente very long text to
                    show the problem\textbf{H}} die festoque peracto &
                \BNote{At}{ac very long text to show the problem\textbf{C}}
                    cito colloquio facto dictaque salute &
                spondet et oblato sua fata \BNote{paciscitur}{pasciscitur
                    very long text to show  
                    very long text to show the problem\textbf{H}} auro.
                \&
                \endnumbering
            \end{Leftside}
            \begin{Rightside}
                \beginnumbering
                \setstanzaindents{2,0,0,0,0,0,0,0,0,0,0,}
                \stanza 1 & 2 & 3 & 4 & 5 & 6 & 7 \&
                \endnumbering
            \end{Rightside}
            \Pages
        \end{pages}
    \end{spacing}
\end{document}

Answer 1

To avoid the "arithmetic overflow" error, load setspace after ledmac. To achieve single-spacing for ledmac's notes, omit \setstretch{2} and enclose the document body in a spacing environment instead.

\documentclass{scrbook}

\usepackage{ledmac}
\newcommand{\BNote}[3][]{%
  \edtext{#2}{\lemma{}\Bfootnote{#3}}%
}
\footparagraph{B}

\usepackage{setspace}

\begin{document}
\begin{spacing}{2}
\beginnumbering
\setstanzaindents{2,0,0,0,0,0,0,0,0,0,0,}
\stanza
inspirat genio. Sed quae depingere vocem &
dextra potest oculisque echo signare videndam? &
\BNote{clarus}{very long text to show the problem\textbf{C}} circa urbes et famae voce lyraeque. &
Illum laetus Hymen plausu iuvenumque choreis &
At tandem \BNote{vergente}{urgente very long text to show the problem\textbf{H}} die festoque peracto &
\BNote{At}{ac very long text to show the problem\textbf{C}} cito colloquio facto dictaque salute &
spondet et oblato sua fata \BNote{paciscitur}{pasciscitur very long text to show  
    very long text to show the problem\textbf{H}} auro.
\&
\endnumbering
\end{spacing}
\end{document}

Answer 2

I ran into this problem once. You have to dig through ledmac.sty to see what's going on. However, the fix is pretty easy:

%% from ledmac.sty:
%% \newcommand*{\notefontsetup}{\footnotesize}
\renewcommand*{\notefontsetup}{\linespread{1}\selectfont\footnotesize}

This worked for me, and worked for your updated example.