A new publication of The True Psalmody is available at a Puritan’s Mind website:
The True Psalmody – The Psalms the Only Manual of Praise from Matthew McMahon on Vimeo.
Are you interested in true worship? Check out this new eBook and hardback at the Puritan shop: True Psalmody by The Reformed Ministers
This ebook is an updated version of the PDF available here free. I am not sure if the update includes any new material or articles. If anyone can provide more information, please let us know.
Exclusive Psalmody 
The book was actually produced by a committee formed of ministers and ruling elders of the Reformed Presbyterian (both Synod and General Synod) and United Presbyterian (the old UPCNA) congregations in Philadelphia. Also, while there were a number of recommendations given by Scottish ministers, the three new prefaces were written by John Edgar and Henry Cooke of the Presbyterian Church of Ireland, and Thomas Houston of the Reformed Presbyterian Church of Ireland.
Does God by sovereign right and command desire you to wear a wig? What a joke. Thanks be to God that I’m a Missouri Synod Lutheran. I’ll settle for Christ’s true Body and Blood in the Sacrament of the Altar, His Words of Forgiveness in the Holy Absolution, His Word preached in the homily, and the sign of the Holy Cross made in remembrance of my baptism into the Triune God’s name. As well as the sacred liturgy as passed down through the ages. You can keep the regulative principle and your wigs.