Tube Amp Archive

I built an amp based on the 5F11 Tweed Vibrolux, but with 6L6s and a 15" speaker. The tremelo circuit only uses one half of a 12AX7. I've been considering converting to the dual triode (cathode follower) design. This is what Fender used on all their big 6L6 equipped amps (6G16 Vibroverb for example)...

Read my first post for a tone comparison.

The Main B+ on my amp is about 455 Volts and will drop about 5 Volts with one rectifier. But the main thing that affects the different feel and sound is the SAG from using just one 5U4. They have a lot of sag, which is why some people like them and some don't. With the 5AR4, the B+ is about the same...

I built a 5E8-A Low Power Twin with the two Rectifiers. I can tell you that using two 5U4s does sound and feel different than a single 5AR4. It's a fatter, thicker tone and it holds together longer before breaking up. The 5AR4 is a thinner sound and with a bit more immediate attack to the note; a sh...

Well, I figured out what the problem was. There are two 56k resistors that feed the positive and negative sides of the cathodine phase inverter. If they are not perfectly matched you get the "low bass/dominant woofy mids" tone that I was dealing with. The two power tubes were getting unballanced sig...

OK, I disconnected the cap from the fuse holder. Thanks for the info.

I took a look at the new Fender Reissue schematic of this amp and it had a .1 cap across (connecting) the two AC wires just before the power tranny. What is this about... anybody?

I built a '57 Tweed Twin and didn't hook up the ground switch because I used a modern 3 prong AC chord. Now, the ground switch had a .05uF cap on it going to ground. I was told by the guy who sold me the kit to put this cap on the fuse holder tab since I wasn't using the ground switch. I haven't see...

To: Andy Le Blanc OK, I'm going to try jumping the whole section. While looking at the 5D8 that you mentioned, I noticed that there was no negative feedback in the tone circuit. I'd like to try removing just the 10 Meg negative feedback resistor. Could I do that in the 5E8-A tone circuit without any...

Is it really the exact schematic for a 5e8-A? Ive used the pre and post circuits and know your problem isn't there. If it really is a 5e8-A I'd be looking at the tone configuration and the feed back around the chathode follower temporaraly lift the CF and tone control out. put a temporary jumper fr...

Hi, You might want to go through your amp to see how bass is transfered.Excess treble can make bass seem lacking and there are usually a number of filters that can be adjusted for desired response. Also damping in the powersupply might not be sufficient and then bass won't be transfered very clearl...

Mark Baier's explanation on the Victoria website is/was accurate. Most of these old 50's/60's amps we love, had nominally Hi-Fi OT's The Triad OT in the low power twin wasn't interleaved and as such, I have to wonder what it was intended for. It's wound more or less like a power transformer. I look...

It's just the 4ohm tap. All I know is the Mojo Tone part Number 767.

My Fender 5E8-A has a Heyboer Output Transformer that has great midrange detail, but I think it's lacking in the lower frequency range. After trying for a year to figure out why my amp lacked lower frequency response, I was told that Heyboer OT's don't have good low end. I heard 30Hz-30kHz is standa...

I just built a 5E8A Tweed Twin with a Heyboer OT. I thought I could improve the tone with a Mercury OT but was disappointed. The Heyboer had way more harmonic detail and the tone was usable no matter how I turned the tone knobs. With the Mercury, the amp was only playable with both tone controls set...

I just built a 5E8A Tweed Twin with a Heyboer OT. I thought I could improve the tone with a Mercury OT but was disappointed. The Heyboer had way more harmonic detail and the tone was usable no matter how I turned the tone knobs. With the Mercury, the amp was only playable with both tone controls set...