By Michael Kohn 07/26/11
Besides SUNN, when it comes to
classic tube bass amps Ampeg is pretty much the industry standard. Take a look
at the stage next time youíre at a show. Chances are if the bass player is
using tube gear it is going to be an Ampeg.
The all tube SVT Classics are about as good as youíre going to get but sometimes you donít need 300 watts of earth shaking power! Thatís where the Ampeg V4BH comes in. Instead of using a sextet of 6550ís for power like the SVT, it uses a quad of 6L6ís to produce 100 watts.
Ampeg discontinued these amps a few years ago and they are pretty sought after. I was offered one recently for a trade so I jumped on it since you donít see them too often. They look very similar to the SVT Classic. The preamp section is similar but not exactly the same as the SVT Classic. The V4BH uses one 12AU7 and one 12AX7 in the driver stage and two 12AX7's in the preamp stage. Like the SVT Classic it has a normal and padded input, a gain control, Ultra High and Low switches for boosting your high and low frequencies, Bass/Midrange/Treble controls, a Frequency control that allows you to select the center frequency for the midrange, and a Master Volume control. The amp also has the same tube protection circuit as its bigger brother. Unlike the SVT Classic, the V4BH has a Presence switch on the back panel which adds a high frequency boost to compensate for a speaker cabinet with no horn.
When I received the amp it was loaded up with some tired looking Sovteks. The amp sounded good but I knew I could improve things with a retube. I loaded it up with a quad of JJ 6L6GCís, a current balanced JJ ECC82 and ECC83S for the driver and two standard JJ ECC83Sís for the preamp. I set the bias to idle at 65% dissipation since I was after a cleaner tone. There was a marked improvement in tone! The amp sounded a lot warmer and punchier overall. The lows were bold & stout without getting muddy and the mids & high end were more pronounced without sounding harsh. The great thing about these amps is that you can achieve a really cool overdriven bass tone without destroying your band mates and causing the foundation to settle! Plugged into a SVT 6x10 cabinet, the amp can easily hang with a loud band and sits in the mix well. It is very versatile for a variety of styles. If you can find one, you wonít be disappointed. Kudos to Ampeg!