Vintage vs. Vintage

I was over at Bruce Collins’ Mission Amps shop getting some demon tweaks done to my Masco amp when I noticed he had two very interesting vintage tube amps sitting side-by-side on the floor: A tweed Fender 5E3 Deluxe and a Gibson GA-6 Lancer. Both date from 1958. Both are in perfect original sonic condition. Both have two 6V6 power tubes, 5Y3 rectifiers, and original (or period correct) Jensen P12Q speakers. I was prepared to beg Bruce to let me plug in and play both amps, but no need. He immediately suggested I do a comparison test.

The Fender Deluxe was without it’s tweed covering but was otherwise intact. The Gibson GA-6 was in near mint condition. They were both in the shop for minor age-related repairs: faulty switches or plugs that cause noise.

While the circuits of the two amps are very similar, there are some differences.

Gibson:

Fender:

The preamp in the GA-6 is a 12AX7 wired as a grounded cathode, using a 5 megaohm grid leak bias set up, it is not cathode biased... very old school, same as the 5A3, 5B3 and 5C3 tweed Deluxe but the Deluxe used octal, 6SC7 preamp tubes.

The two volume pots and the tone pot are less than 500k, unlike a tweed Deluxe that uses 1M pots for volume and tone controls. Tone control caps in the GA-6 are the same values as the Deluxe.

The phase inverter in the GA-6 is a 12AX7 wired as a paraphase driver, same as the octal preamp tubed 5A3, 5B3 and 5C3 Deluxes.

In the Gibson the plate voltage to the power tubes is a bit hotter then a tweed Deluxe and the power tubes are idling painfully hot at about 14 watts each. Screen voltage to plate voltage ratio is lower then the Deluxe and the 5 watt power resistor used for biasing the 6V6s is 200 ohms vs 250 ohms for a Deluxe and there is no cathode bypass cap on the resistor while a tweed Deluxe uses a 25uF bypass cap.

Power supply filter caps are all 20uF vs 16uf on a tweed Deluxe.

A good running tweed 5A3, 5B3 and 5C3 Deluxe will make about 10-12 watts clean and this particular GA 6 made about 12-13 watts clean with the same size output transformer as the Deluxe.

So… How does this all translate to tonal differences? There were dramatic contrasts in the sound of the two amps. I used my big red bullet mic – which is extraordinarily hot, putting out 1 volt of current when I hit a loud passage.

Both amps sounded good right out of the gate, but the Gibson was clearly superior. The tone is bigger and warmer, with a much more natural sounding tearing on the notes. The breakup was organic and closely coupled to the pressure I put on the mic. To be honest, it sounded beautiful. I would gig that Gibson amp right now.

The Fender Deluxe had a nice vintage tone, but it just could not measure up to the Gibson. Its tone was thinner and less “connected” to what I was doing with the mic and harp. It sounded slightly boxy. At one point a ghost note popped up –the dreaded boogieman of all harp amps – while I was playing the 2-draw on an A harp. The 5E3 Deluxe amp is legendary among guitar players, and I offer no argument there. This is just about how it reacts when faced with a hot bullet mic and a harp played in second position.

The Gibson had absolutely no issues. No ghost notes or cone cry or nasal tone or noise or anything. You would have to do nothing to this amp to make it a killer harp amp: It is already there.

Small amps with two 6V6 power tubes are among the nicest sounding harp amps. They are too underpowered to carry through a loud blues band, but mic’ed or lined out they are wonderful. I sold a 1947 Gibson BR-6 amp last year and I still painfully regret doing so, especially after playing the GA-6 which sounds remarkably similar.

Many thanks to Bruce Collins at Mission Amps for graciously allowing me to thrash two very valuable vintage amplifiers. Bruce is also the drummer in my blues band, Roadhouse Joe.