diff --git a/src/emu/sound/zsg2.c b/src/emu/sound/zsg2.c
index 39ceea22273..0112c82c98b 100644
--- a/src/emu/sound/zsg2.c
+++ b/src/emu/sound/zsg2.c
@@ -48,8 +48,7 @@ Emulation is still preliminary.
 
 TODO:
 - channel volume, 16bits?? need to make a lookup table?
-- how does panning work? it is not simply left/right volume
-- (some) samples are in stereo format?
+- some samples are in stereo format?
 - memory reads out of range sometimes
 - a lot of unknowns
 
@@ -204,7 +203,7 @@ void zsg2_device::sound_stream_update(sound_stream &stream, stream_sample_t **in
 			if (m_chan[ch].step_ptr & 0x40000)
 			{
 				m_chan[ch].step_ptr &= 0xffff;
-				if (++m_chan[ch].cur_pos > m_chan[ch].end_pos)
+				if (++m_chan[ch].cur_pos >= m_chan[ch].end_pos)
 				{
 					// loop sample
 					m_chan[ch].cur_pos = m_chan[ch].loop_pos;
@@ -223,8 +222,8 @@ void zsg2_device::sound_stream_update(sound_stream &stream, stream_sample_t **in
 			//sample = (sample * (m_chan[ch].vol & 0xffff)) / 0x10000;
 			if (m_chan[ch].vol == 0) sample = 0; // temp hack to prevent stuck notes
 			
-			mix_l += sample;
-			mix_r += sample;
+			mix_l += (sample * m_chan[ch].panl + sample * (0x1f - m_chan[ch].panr)) >> 5;
+			mix_r += (sample * m_chan[ch].panr + sample * (0x1f - m_chan[ch].panl)) >> 5;
 		}
 
 		outputs[0][i] = mix_l / 48;
@@ -240,7 +239,7 @@ void zsg2_device::chan_w(int ch, int reg, UINT16 data)
 	switch (reg)
 	{
 		case 0x0:
-			// lo byte: always 0?
+			// lo byte: unknown, 0 on most games
 			// hi byte: start address low
 			m_chan[ch].start_pos = (m_chan[ch].start_pos & 0xff00) | (data >> 8 & 0xff);
 			break;
@@ -252,14 +251,22 @@ void zsg2_device::chan_w(int ch, int reg, UINT16 data)
 			m_chan[ch].page = data << 8 & 0xff0000;
 			break;
 		
+		case 0x2:
+			// no function? always 0
+			break;
+		
+		case 0x3:
+			// unknown, always 0x0400
+			break;
+		
 		case 0x4:
 			// frequency
-			m_chan[ch].step = data;
+			m_chan[ch].step = data + 1;
 			break;
 
 		case 0x5:
 			// lo byte: loop address low
-			// hi byte: right(?) panning (high bits always 0)
+			// hi byte: right panning (high bits always 0)
 			m_chan[ch].loop_pos = (m_chan[ch].loop_pos & 0xff00) | (data & 0xff);
 			m_chan[ch].panr = data >> 8 & 0x1f;
 			break;
@@ -271,18 +278,22 @@ void zsg2_device::chan_w(int ch, int reg, UINT16 data)
 
 		case 0x7:
 			// lo byte: loop address high
-			// hi byte: left(?) panning (high bits always 0)
+			// hi byte: left panning (high bits always 0)
 			m_chan[ch].loop_pos = (m_chan[ch].loop_pos & 0x00ff) | (data << 8 & 0xff00);
 			m_chan[ch].panl = data >> 8 & 0x1f;
 			break;
 		
+		case 0x9:
+			// no function? always 0
+			break;
+		
 		case 0xb:
 			// always writes 0
 			// this register is read-only
 			break;
 		
 		case 0xe:
-			// channel volume, reg 0xc is also related?
+			// channel volume, reg 0xa/0xc is also related?
 			m_chan[ch].vol = data;
 			break;