Quote from: JonnyDeth on March 31, 2024, 09:14:42 AM

Quote from: RookieRecurve on March 31, 2024, 08:39:55 AMI see these pop up often around me, but not for that price!  There's one I saw for $100 with only one of the two channels working.  I thought about buying it to try and fix it, then flip it.  It would be too loud for me, but they are pretty amazing amps.  The ease of access to incredible schematics makes these a great buy.

I saw a guy on youtube that flips gear for a living and he nabbed one for $40! He said it was his very first amp so he made a video with it then sent it on it's way to someone who had bought it.

I am a shred and sweep player so it's a little harsh in the bass due to the very high, even order harmonics added by semiconductors, but in combining the dirty channel with my modeler and an overdrive pedal I actually designed around this amplifier's dirty channel used to overdrive the modeler, I get perfectly useable lead tones. I also have a Zoom G5 on the way to replace the one I have that some crazy b*t** smashed, and those with the 12AX7 in them turn damn near any amp into a thoroughbred.
That coupled with this and I have a brutal metal amp but really, an every genre amp. It's so friggin loud I could never actually use this much volume and in a live setting, I would definitely be using earplugs.

It's all about gain stage cascades and teaming the right devices. Solid-States have some universal problems shared by 99% of them, but Crate is highly underrated and players with really high standards would rather spend 3 grand on known gear combinations than experiment and get something built for $500 that is every bit as good as the 3 G's arrangement. The Zoom G5 is an example within itself because when you run the processor without the tube engaged, it's very digital and quite truly sounds cheap, but when you switch the tube in and crank it's gain, it makes every single patch you design for modeling whatever amp, pedal and speaker combination sound amazing. The harshness, "swooshing" etc. to your bass is completely filtered out of the signal by the tube's limited bandwidth. The 12AX7 is said to have a maximum of 20Khz for audio, but typical is actually 10 Khz. The semiconductors will add ridiculous harmonic bandwidth like 40 Khz to a 100 Hz bass note!
This trait is why solid-states continue to be the whipping boy of the industry and because digital circuits are still using solid-state semiconductors, 90% of those units aren't designed to compensate so the war wages on! I shutter at the sight of digital modelers and FX I see selling for $1500 and I can hear all those extremely high, even order harmonics still coming out of them and trashing the signal, but not every player is sweeping and shredding for it to matter.
The technology guarantees people will always spend big money on tube amps, and even I'm still guilty of that.

Great explanation of why tubes are still so popular.  Its also a great reminder that great tones from inexpensive SS stuff can be had with the right piece(s) of equipment in front of it.  Sometimes I like to just plug into my fairly stock Valve Jr. and appreciate its simplicity, but other times I love playing around with different tools.  Your talk about having a tube in the signal path makes a ton of sense.  Thanks!

These two ceramics are still hot enough to cook steaks on....

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At least small steaks...well done...

Looks odd but oh well replaced three axial caps with radial (have you seen the price difference between axial and radial)   

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Still I had not an extra angstrom of length to spare on two of them.  On the third I clipped the lead and used the j-hook method.

Still no green phosphor....  

Meanwhile....onward through the fog.  I am still holding out hope that I can get a trace on this Heathkit oscilloscope.  I ordered the four ICs for it and now I thought I would investigate this power supply by removing caps and reinstalling if testing good.

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Unfortunately (or fortunately) I have removed two and both tested (presumably) good

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So back in they go

Except...hmmm no way here to test leakage so I checked DC ohms with my meter and I have one that charged up pretty quick to about 70 kohm but then really slowed down

So idk maybe it's leaky

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But as I type it's still creeping up in fact it's at 130 kohm now so maybe it's ok.

 

Quote from: g1 on April 08, 2024, 08:04:14 PMI think there may be some confusion now about the 'distorted sound'.
You are getting the proper sound of the Boss pedal using the FX return?

Yes, I am getting the proper DS-1 distorted sound as expected from that pedal.
Also, I neglected to mention that I had also tried a patch cord between the Send and Return jacks with no improvement.

Thank you sir I am glad I did not have to touch any power tubes...in the back of my mind I had heard about tube biasing and was dreading having to do something like that.  But I looked it up and evidently preamp tubes are just plug and play...?

The two 12ax7 I switched positions were in there really tight.  To avoid broken glass and blood I put on a leather work glove.

I really appreciate everyone's help with this idk what we did but it's sounding really crazy nice it still has a little hum at low volume but I ain't touching it right now.

Yes it would seem T1 is bad as you verified R5 and D1.  But you also need to check their solder connections.
As T1 and T2 form a differential amplifier, it is best to replace them as a pair.

I think there may be some confusion now about the 'distorted sound'.
You are getting the proper sound of the Boss pedal using the FX return?

It appears to be a power amp issue.

Just remember that big power tubes can get VERY heavy, just pull one out when it's hot and try to hold it in one hand, I bet you can't hold it for too long.
But everyone has to learn that certain things are hot the hard way, I am constantly reminding myself that the soldering iron is too heavy to hold on the pointy end. (The hard way)