Unfamiliar tubes for a preamp

The EC88 is a European designation for the 6DJ8/6922/E188CC/7308 family, and is a dual triode. The Holy Grail of the family being the Siemens CCa. The WY4P is a chinese voltage regulator tube like the RCA OD3 (http://cgi.ebay.com/NOS-0d3-VR150-JAN-RCA-MADE-IN-USA-TUBES-OD3_W0QQitemZ330230807107QQcmdZViewItem) Change yours for an RCA, and you should realize quite a sonic improvement. There is a 5Z4/5Z4P full wave rectifier tube, but I've never heard of a 15Z4P.

Thanks Rodman99999 for the info. I knew about the Ecc88 but was in a fog about the others. The 1 in front of the 5Z4P tube was probably given by mistake. I'll check on the RCA OD3 once the pre arrives. Thanks for the link.

One other question comes to mind on the rectifier tube. It looks like a GZ30 tube is the same as the 5Z4. Could someone verify this. Thanks in advance.

I hope some of that info helps you enjoy your music.