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 ... Click To Read More About This Product
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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
Reviewed by 1 customer
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Comments about Groove Tubes Substi-Tube 928-PR to EL84 Adapter and Tube Sets:
At last! About three years ago, a friend offered me a a '65 Bassman head at a price I couldn't refuse. I bought and got it rehabbed by a wonderful tech friend. But despite all kinds of good work, the amp just remained too...well...loud. After getting tons of advice from many players (much of it conflicting), the best fix seemed to be tubes with low-power adapters. I only found two on the market, and only one A/B review of them. The review said Substi-Tubes are easier to install and sound better than the other. So I ordered a pair. They popped in easily, as promised, and after one rehearsal with them, all I can say is: at last! These things sound great. Finally, I can turn up to 7, and the sound - at least through and old Bassman - is sweet and full. What's it worth to make a vintage amp playable? Certainly the cost of a pair of Substi-Tubes. A great buy.
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