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11

Tube Amp Building - Tweaks - Repairs / Re: First amp build

« Last post by Rontone on June 11, 2026, 06:45:50 pm »

Ok I have studied these all day and I do see what you mean, In the fuse page I was sent too it said better to fuse on the AC side than the DC side, After diodes is DC?? is that correct? and it talks about fusing both leads, I have not seen one schematic with that fusing, I see the positive about it, but is it really a must or is it ok to just use the HT fuse already on the amp? the way you and others have it wired up? Thanks guys!

I was away for a few days then,

Yes, good to fuse the HT on the AC side, the diodes are the point where the AC is rectified to DC, in the case of the two layouts from further up the page, the rectifier is a two phase type,

Some manufacturers put the HT fuse in the centre tap of the HT winding, I have a few old amps with that fusing and never had a problem, and some Marshalls do it after the rectifier, so you will see two fuse holders on the rear, one for Primary and one for Secondary, but as mentioned on Merlin's Valvewizard site there are some faults which can still leave current flowing even if that centre tap fuse blows, so ideally on a "two phase" rectifier two fuses, one for each leg of the HT, just help protect the transformer a bit more...

Has the "Triode Electronics" layout above been edited, it looks like the two HT fuses have been added, along with another after the rectifier, so there is 4 altogether, also I cannot see the component legs on the board, feels like I'm going colour blind, are the component legs just a slightly darker shade of red

If the amp is well built, setup and running well you would be fine with the "old" style or the two fuse way, as long as you don't put bacofoil in those fuse holders ever again

[I bought an old Sound City once, poor thing used to run so hot, 6x EL34's in there so I just assumed it was that at first, but then I found a Kitkat wrapper in the fuse holder, there was so much jammed in there I bet it would have done more than 10 amps through it before it burned out, it was like solid metal in the holder...]

12

Tube Amp Building - Tweaks - Repairs / Re: Safe to power an amp with a home backup battery?

« Last post by passaloutre on June 11, 2026, 02:53:06 pm »

I don't see why not, if it's clean and has the power capacity. A tube amp is just an inefficient space heater.

13

Tube Amp Building - Tweaks - Repairs / Re: Any tips for taming a wild 5E3?

« Last post by passaloutre on June 11, 2026, 02:40:57 pm »

To be fair, it's just a fixed L-pad, which surely is older than Robinette, Clapton, or even Fender

14

Tube Amp Building - Tweaks - Repairs / Safe to power an amp with a home backup battery?

« Last post by jacobarber on June 11, 2026, 12:31:48 pm »

I'm just throwing out a hypothetical. I have a couple of EcoFlow Delta2 batteries and was wondering if there are any concerns about using one of these to (temporarily) power an amp. So long as it can essentially provide a really clean 1800w, 120VAC @60Hz on a 13A circuit.

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Other Topics / Re: Meme of the day

« Last post by shooter on June 11, 2026, 12:08:17 pm »

...

16

Tube Amp Building - Tweaks - Repairs / panoverb

« Last post by johnfromcyrene on June 11, 2026, 11:53:51 am »

has anyone made a panoverb?

not sure how they got the reverb in one speaker.

17

Tube Amp Building - Tweaks - Repairs / Re: Princeton Reverb circuit refinements

« Last post by acheld on June 11, 2026, 10:35:07 am »

I don't know what the cause of the "raspy" distortion might be, and I do hear some beating in the overtones. I think you're right to go after it.

Having worked with this circuit several times, my personal approach would be to scope your signal through the path to see where your problem originates.  This approach can take some time, but it does work. 

An alternative easy thing to try would be working your way down the gain chain by subbing in various tubes into V1.    5751<12AT7<12AY7.   (If you get down to a 12AU7, you really have problems! But, you won't. . .)   It's easy to get rid of distortion; the hard part is to preserve the tone and your desirable harmonics.

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Tube Amp Building - Tweaks - Repairs / Distorted sound clip - raspy?

« Last post by tristanc on June 11, 2026, 08:46:07 am »

Here's a quick recording of the amp. The cleans are glorious. The distorted sounds I'm still struggling with. Help lift me out of the 'hyper critical hole' I'm in.

The attached mp3 is zipped to be able to upload it here.

I can hear a 'raspy' overtone on distorted notes that, to me, is a bit much. Could this be blocking somewhere? The cathodyne grid resistor needs increased from 470k to 1meg? Or bigger grid resistors on the 6V6s?

The amp on 7/10, with a tele with high output pickups, boosted with a clean boost set fairly high (2 or 3 o'clock). So I'm slamming the 1st stage to highlight what I'm hearing. I can also hear it just cranking the amp (guitar -> amp). Also, the raspy note seems to fluctuate with the tremolo setting.

I'm recording via a Boss TAE straight to audacity - the sound in the room is very close.

Am I just listening too closely and this would be inaudible playing in a mix?

19

Tube Amp Building - Tweaks - Repairs / Re: Repairs - Peavey Windsor Studio

« Last post by Shrek on June 11, 2026, 07:36:11 am »

Ok, i checked the heck out of the board for voltages before working.  it looks like everything had drained out on its own…. Everything is reading 0.

Im about to replace the c7 cap….
I tested the cathode resistor it was about perfect at 399.

tone stack -
stock im always scooping the eq at crazy settings….

One thing i have beem reading about is moding the tone stack

I was reading about a bright cap clip i dont really want to do that.

I was going to put it back together with a different powertube because it burned the brand new power tube when the c7 blew… i probably should have got a stronger c7 cap instead of one with the same values.  I suspect it blew because of the digital delay overwhelmed the preamp… i plugged it straight into the preamp because i was testing a pedal at low volumn… but i had the attenuator cooking the power tube…when i was twisting the frequencies. It oscilliated and wasnt so good.  The volumn drop was probably the power tube dumping.

And test the juice on the cathode pin

So my question would be can I test the power tube cathode pin live?  And also the bias voltage? 
By the pins from the top of the board. 


 

20

Tube Amp Building - Tweaks - Repairs / Re: Any tips for taming a wild 5E3?

« Last post by pdf64 on June 11, 2026, 04:21:46 am »

Robinette's 1/4 Power switch: https://robrobinette.com/5e3_Modifications.htm#Quarter_Power_Switch

That's Fender's switch - not Rob's. He plagiarises everything and calls it his.


(Fender put it on their Eric Clapton Tremolux)

To be fair, Rob doesn't claim any responsibility for it, rather he writes "This very cool 1/4 Power Switch is from the 20 watt Fender Eric Clapton Tremolux".