Groove Tubes Substi-Tube 928-PR to EL84 Adapter and Tube Sets

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Converts an AB to Class A and reduces power.

It converts an 8-pin socket allowing use of EL-84 power tubes. This converts class A/B amplifiers to Class A and reduces power. For a 100W amp, output will be lowered to about 40W. A typical 50W amp will be reduced to about 20-25W. Duet includes 2 adapters and 2 EL84 tubes.

These are used in pairs or quads, not individually. These are NOT for use in Class A amplifiers. For Class A amplifiers, use the 928, not the 928-PR.

They will reduce the load on your power transformer, and allow your amp to reach distortion with a nice AC-30 or EL-84 sound and feel at lower levels.

Dimensions - tube tip to amp chassis requires 4-1/4".

Country of origin: Slovakia


  • Country of origin: Slovakia