Recent Posts

41

Tube Amp Building - Tweaks - Repairs / Re: Tweed BluesMeister needs a tweak

« Last post by tubenit on September 08, 2026, 08:08:35 pm »

Going back to that post,  Tubenit is saying that the OD in this style of amp sounds harsh

Respectfully,  this could be misunderstood to construe that I think the overdrive in Dumble style amps is intrinsically harsh.
That is not at all the case in my viewpoint!  I have heard "some" that sound harsh.


Exact quote:

"To my ears, not all the original Dumble amps and Dumble clone that I've heard on YouTube (or some sound clip) sound great with their overdrive. Some sound harsh to me. My viewpoint is just because it says Dumble doesn't mean it's a good sounding amp."

I view the Dumblish inspired amps I built like the Tweed Overdrive Special and the Tweed BluezMeister & the Carolina Overdrive Special and the D'Mars  to have all been successful with an OD tone that I liked.  I will say those amps took some tweaking and that was done slowly, small mods at a time over months.


With respect, Tubenit

42

Tube Amp Building - Tweaks - Repairs / Re: First amp build (5F1) would anyone mind double checking my turret board layout?

« Last post by sluckey on September 08, 2026, 05:53:52 pm »

Gotcha, yeah I was just having some trouble finding flameproof 22k's that were 1/2 watt.

There is a 22K 1/2W carbon comp resistor in the same position in my original 5F10 amp. After 70 years it still looks like it did the day it was put on the board.

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Tube Amp Building - Tweaks - Repairs / Re: First amp build (5F1) would anyone mind double checking my turret board layout?

« Last post by HexEnduction on September 08, 2026, 04:49:32 pm »

Hoffman sells 22K 3W metal oxide. However, according to the schematic there is 45V dropped across that 22K. So, the power dissipation is less than 0.1 watts. A 1/2W resistor will last forever.

Gotcha, yeah I was just having some trouble finding flameproof 22k's that were 1/2 watt.

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Tube Amp Building - Tweaks - Repairs / Re: Univox 202R Amplifier making noise

« Last post by astronomicum on September 08, 2026, 04:01:39 pm »

my amp seems to have verb in both channels but I don’t see how that would work in the schematic.

There is a hum when turned up and it goes away l when all the way down.

There can be some cross talk between the two channels due to the close proximity of the volume and tone wires. A little crosstalk is normal. See if the wires feeding the volume pots and returns from the tone pots run parallel and if so, separate them.

A few things to check for hum:

The early 202Rs used an open frame reverb tank with a paperboard cover mounted in the bottom of the cabinet. The later used Belton Gibbs tanks contained in a pouch on the side of cabinet. Univox had a habit of grounding both tank feed and return jacks. If there is continuity between the grounds on the tank and both jacks are grounded, a ground loop is formed. If there is continuity between the grounds on the tank and both jacks are grounded, remove the ground from the tank feed jack to break the loop.

If the tank is mounted on the side of the cabinet in a pouch, make sure the tank feed is at the top of the pouch. You want to keep the tank return as far from the PT as possible.

Make sure that the tank feed wire to the jack, and the tank return wire from the jack to the pot, and from the pot to the grid of the 6AV6 do not run close to the heater wires where they can pick up hum.

Edited 090826 18:32

45

Tube Amp Building - Tweaks - Repairs / Re: Laney Klipp "Fuzz" circuit

« Last post by Helmholtz on September 08, 2026, 03:36:00 pm »

The output signal (V2 pin6) is in phase with the input signal (V2 pin2).

46

Tube Amp Building - Tweaks - Repairs / Re: Tweed BluesMeister needs a tweak

« Last post by Helmholtz on September 08, 2026, 02:41:42 pm »

Oh well,
so just a bad input signal and garbage in -> garbage out.

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Tube Amp Building - Tweaks - Repairs / Re: Tweed BluesMeister needs a tweak

« Last post by acheld on September 08, 2026, 01:22:24 pm »

And the answer is none of the above!  I probed the first triode, and found the notches, and then probed the input signal and saw very subtle notching.   I had been using the signal generator from a Picoscope module -- at low amplitude and low frequency, the DAC within the system is not able to function correctly, apparently a known issue.    I tried to capture the input signal waveform, but the notching is so subtle as to be tough to see in all the noise, so I didn't post an image.   Apologies for the excitement, but a good reminder that test equipment has its own limitations.

Tubenit: thanks so much for the sound clip (and your great ideas over the years). 

Now back to the amp.  I tried the sig gen on my Hantek o'scope, but it is crap.    I do have an old Heathkit signal generator that I rebuilt years ago that should work ok.

As an aside regarding oscilloscope selection, I'd recommend either cheaper FNIRSI or more expensive Rigol units.

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Tube Amp Building - Tweaks - Repairs / Re: Tweed BluesMeister needs a tweak

« Last post by tubenit on September 08, 2026, 12:54:36 pm »

I found a soundclick with a recording of the Tweed BluezMeister I built yrs ago.


https://soundclick.com/song/12803806


With respect, Tubenit

49

Tube Amp Building - Tweaks - Repairs / Re: Laney Klipp "Fuzz" circuit

« Last post by tablebeast on September 08, 2026, 12:53:18 pm »

I just stumbled on this Klipp circuit today in the Faustone pedal. I'm currently trying to wrap my head around it. The "blend" control seems to blend out of phase signals and the original Laney amp seems to further confuse this by mixing two out of phase preamp signals together if both inputs are bridged. That doesn't seem right, so am I looking at this schematic correctly? You ever mess with building something like this? I may have to build it myself just to answer a few questions.

50

Tube Amp Building - Tweaks - Repairs / Re: First amp build (5F1) would anyone mind double checking my turret board layout?

« Last post by sluckey on September 08, 2026, 12:25:38 pm »

Hoffman sells 22K 3W metal oxide. However, according to the schematic there is 45V dropped across that 22K. So, the power dissipation is less than 0.1 watts. A 1/2W resistor will last forever.