PyQt - Combining QSlider and QTextEdit - python-3.x

Question

I'm trying to create a QSlider-QTextEdit synchronised pair, such that any change in one is reflected in the other. This is the code I have:
import sys
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
class MainWindow(QMainWindow):
def __init__(self, *args, **kw):
super().__init__(*args, **kw)
self.main_panel = QWidget(self)
self.setCentralWidget(self.main_panel)
grid = QGridLayout(self.main_panel)
self.sl = QSlider(Qt.Horizontal, self)
self.txt = QTextEdit(self)
self._old_val = ""
self.sl.valueChanged.connect(self._sl_to_txt)
self.txt.textChanged.connect(self._txt_to_sl)
self.sl.setMinimum(1)
self.sl.setMaximum(60)
self.sl.setValue(30)
grid.addWidget(self.sl, 0, 0)
grid.addWidget(self.txt, 0, 1)
def _sl_to_txt(self, val):
print("SL->TXT")
self.txt.setText(str(val))
def _txt_to_sl(self):
print("TXT->SL")
val = self.txt.toPlainText()
try:
self.sl.setValue(int(val))
self._old_val = val
except ValueError:
self.txt.setText(self._old_val)
app = QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
However, this causes both signals to be emitted at the same time (due to setValue and setText triggering the respective signals) and also for some reason keeps placing the cursor to the start of the text area when trying to type into it.
How do I change the text/slider value without triggering the corresponding signals?