Teach Me! Magnatone 260 vs 260A schematic differences = ???

[Yeatzee]

Today I'm looking for some insights and help as I consider picking up a Magnatone 260 to pair with my AC30 for the live rig. Seems like it might be a good pair, 2x12 and ~30w. I've got an old Magnatone 440 and it's a very cool amp, love the vibrato so the bigger 6l6 model I imagine could be very giggable.

As I've started to do research I've learned from a few people that there are two versions of the 260. First year, 1957 is the 260 which has been described to me as more tweed like. Much more breakup / gain, and a warmer tone. That's what I'm looking for. The 260A, 1958-???, has been described to me by those that have compared the two as much much cleaner. Very little gain even high up on the volume, and more "blackface" esque tone vs the the more tweed sound of the 260. To pair with my AC30, a very gainy amp at gig volumes, I definitely want the 260 not the 260A. But here's the dilemma, there are naturally not as many 260's available for sale by those willing to ship, the 260A is easier to get... so I'm considering buying a 260A and just converting it to the 260 circuit. That's where I need some help and guidance.

The 260A schematic is readily available here on the forum: https://el34world.com/charts/Schematics/files/Magnatone/Magnatone_260a.pdf

The 260 doesn't seem to have a scanned schematic anywhere, but I did find this photo of one that was in the amp: https://i.imgur.com/wUGCsod.jpg

I tried to quickly compare the two, and the tonestack is obviously different both in certain values and layout (plus added bright switches on 260A). That seems to be the major difference. And then there are some other differences, specifically I think around the phase inverter if I'm understanding correctly? I tried to draw where I noticed the differences, green check the same value, red different value / added parts on the 260A. I didn't redraw the tonestack layout differences.



You guys know infinitely more than me, looking at the differences do those description differences make sense between the 260 vs 260A? More gain vs less gain, what would be the cause of that difference? As far as I can tell the tube layout and transformers are all identical.

And then a slight aside, but I noticed no cathode bypass caps on the preamp's. I did that mod to my Gretsch Dual Twin (valco) and wow did it liven that amp up. Wonder if that'd be a good method to get more gain as well, if needed. I just added the cap on the dual twin, didn't change the value of the resistor so that's something I need to learn about as well, whether that's required and how to choose.

Thanks as always, you guys rock!

[sluckey]

Sounds like you have already figured it out. As you've seen, the biggest difference is the tone stack. And that is really only minor, certainly not enough to say the difference is like comparing a tweed Fender to a blackface fender.

The PI difference is simply changing from a DC coupled PI to an AC coupled PI. My preference is the AC coupled PI. Not gonna be much tone difference.

The cathode cap on the Vibrato oscillator is a good thing. No effect on tone.

Magnatone amps were not designed with "breakup" in mind. They are clean sounding amps. I would not modify a 260A back to 260 specs. I consider that a step backwards.

[Yeatzee]

Sounds like you have already figured it out. As you've seen, the biggest difference is the tone stack. And that is really only minor, certainly not enough to say the difference is like comparing a tweed Fender to a blackface fender.

The PI difference is simply changing from a DC coupled PI to an AC coupled PI. My preference is the AC coupled PI. Not gonna be much tone difference.

The cathode cap on the Vibrato oscillator is a good thing. No effect on tone.

Magnatone amps were not designed with "breakup" in mind. They are clean sounding amps. I would not modify a 260A back to 260 specs. I consider that a step backwards.

Thanks for chiming in Sluckey! That's what's a bit confusing to me, at least two people I've talked to that have played both a 260 and a 260A both independently said that the 260 was more tweed like and had much more gain. Perhaps I'm missing something else... though photo's of sold listings seem to show the same transformers and the speakers are the same. No videos on the internet of the 260 playing, that I can find, but plenty of clips of the 260A which seem to show very little gain even with the volume way up.

I know, too, that the Magnatone 213 for example is famous for its breakup whereas the later version is a much cleaner amp. It seems like those early/mid 50's amps had a lot of breakup but they sorted it out in the following revisions to better fit the era's requirements. I guess I don't really understand what in the circuit would cause that. If, say the changes from the 260 to 260A don't explain those descriptions perhaps something like adding cathode bypass caps might rock them up enough to get me somewhere closer to those descriptions.

[sluckey]

Adding cathode bypass caps will certainly increase the gain. Maybe even enough to produce some overdrive distortions that you desire. But neither of these amps had any bypass caps and that's a sure sign that the amps were built with a clean, refined sound in mind.

It's easy to add bypass caps and doing so may be all you need to do. If you decide to modify the tone stack I suggest you only do one channel and evaluate before doing the other channel.

Take your time as you always do. These amps are true point to point wiring, and it can be a bit overwhelming for the faint-hearted. I have an M10-A. Take a look. The 260 'may' resemble this style construction.

     https://sluckeyamps.com/magnatone/magnatone.htm

[sluckey]

I found this gut shot pic of the M260-A. Not nearly as cluttered as I had imagined.

[SoundmasterG]

Here is a gut shot of a Magnatone 260. A friend used to have two of these and sold one. This is the one he kept. Great sounding amp!

Greg

[sluckey]

Here is a gut shot of a Magnatone 260.

That's the 260-A. The tone switches are the give-away.

[Yeatzee]

Here is a gut shot of a Magnatone 260. A friend used to have two of these and sold one. This is the one he kept. Great sounding amp!

Greg

Nice! Yeah like Sluckey said, 260A but still cool to see!

Adding cathode bypass caps will certainly increase the gain. Maybe even enough to produce some overdrive distortions that you desire. But neither of these amps had any bypass caps and that's a sure sign that the amps were built with a clean, refined sound in mind.

It's easy to add bypass caps and doing so may be all you need to do. If you decide to modify the tone stack I suggest you only do one channel and evaluate before doing the other channel.

Take your time as you always do. These amps are true point to point wiring, and it can be a bit overwhelming for the faint-hearted. I have an M10-A. Take a look. The 260 'may' resemble this style construction.

     https://sluckeyamps.com/magnatone/magnatone.htm

Over on another forum a member shared this clip with me of his 260 to demonstrate just how gainy it is: http://www.legrandmusique.com/260.m4a

I'd be curious to see gut shots of his to determine if it's stock or not. Would different output/power transformers (obviously they'd be similar as the chassis never changed between 260 and 260A and the rest of the circuit looks very very similar) be a possible explanation? Or do you think that 260 has had mods like the cathode bypass cap addition?

[sluckey]

The transformers are likely identical. That sound clip does not sound like a Maggie to me. Just sounds like any other overdriven amp or maybe ratty speakers.   

Not saying a 260 or 260A can't be made to sound like that, but why? If that was the only Maggie sound clip available I would not own a M10-A and I certainly would not have built a M2 clone.

[Yeatzee]

The transformers are likely identical. That sound clip does not sound like a Maggie to me. Just sounds like any other overdriven amp or maybe ratty speakers.   

Not saying a 260 or 260A can't be made to sound like that, but why? If that was the only Maggie sound clip available I would not own a M10-A and I certainly would not have built a M2 clone.

See to me it does, his 260 sounds like a big 213. I guess I associate with the early ones with mid-y gain and you the cool later clean models haha

[sluckey]

Yeah yeah, I get it. However, most people are interested in the Maggy because of the vibrato and the clean sound. That's why most of the youtube maggy videos focus on clean vibrato.

Do you have a M260-A?

[SoundmasterG]

Here is a gut shot of a Magnatone 260.

That's the 260-A. The tone switches are the give-away.

Thanks for the correction! I always assumed his was the 260 because that is what he said it was, but I didn't look close enough to see the difference in that one. It sounds great anyway.


Greg

[Yeatzee]

Yeah yeah, I get it. However, most people are interested in the Maggy because of the vibrato and the clean sound. That's why most of the youtube maggy videos focus on clean vibrato.

Do you have a M260-A?

The first time I ever heard one was the old Phil x videos where he had a tonemaster 213 as his gainy demo amp, might be partially why that's what I think of! I've got a 440 in need of some love, but I'm in talks with a shop that has a 260a that's willing to ship. I'm also waiting to hear back in a big vintage guitar purchase so in limbo a bit. If the guitar doesn't work out I'll probably buy the 260a :)