The latest project from Bruce's workbench is the Groovewatt, a tube based RIAA phono preamplifier. The Groovewatt is the result of over one year of work and several build iterations. Bruce set some pretty high performance requirements for the tube preamp and he is very pleased with the results.
|Second Groovewatt Build|
The Groovewatt uses a symmetrical SRPP (12AX7) input stage which feeds a passive RIAA equalization network. The second gain stage is nearly identical to the input stage and is direct coupled to the third stage which is a cathode follower (12AT7). Bruce used Gold Pin JJ ECC83S for the SRPP stages and half of a ECC81 for each side of the cathode follower. The power supply is solid state and DC is used for the tube heaters. Total gain of the RIAA phono preamp is about 45 dB which should be sufficient for use with a high output MC cartridge.
|Inside View - Third Groovewatt Build|
|Third Groovewatt Build|
The measured performance of the Grovewatt is excellent and noted in the project page. Bruce reports excellent results with the Groovewatt in place in his system. For the full details of the Groovewatt, see the DIY Vacuum Tube (Valve) RIAA Phono Preamp project page.
More Hi-Fi Vacuum Tube Projects by Bruce