EL34 YGL3 -> 6L6 SSS

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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

I guess I'll update this thread, at least to show that I did get enough knobs eventually.

I just re-biased this guy and brought it down a teeny bit and it still sounded good. (I recently got scared by a bit of noises coming out of it when it was on and not being played). It seems to have calmed down. I was worried that I was perhaps burning out the tubes a bit prematurely. It still sounds good.

I also played around with the PI balance pot today with no empirical measurements. I just played notes and tried a bunch of spots on the trimpot. I just tried to settle on a spot that I felt I could convince myself had the note sort of swell up a in volume a bit after it was plucked and then maintained good sustain. It ended up closer to the middle of the trimpot this time and probably closer to the original setting I had where the opposite side was a slightly higher voltage... I didn't care to measure this time though.

But ya, this amp is pretty great. I quite like it. I don't know if it is as magical as a real one or as nice as mHartman's or not... Heck! I've never even spent much time with a Twin Reverb before so I can't even say if it is much better than that, but it is a great clean tone with great reverb and very useable for me. I've had a pretty great DC30 clone that I've used as my favourate clean tone for years and this actually sounds just as nice and 3D to me, but also quite different (and cleaner obviously).

Also, it has become the perfect amp for my Rhodes. Nothing else I have comes close to this for being the perfect amp to handle the Rhodes as well. So, it's always going to get plenty of use even when I'm avoiding super clean amps for guitar for a month or two.

Anyways, I have another YGL-3a that I previously had modded a bit to add the HRM drive circuit to... but it has an oscillation that I have yet to track down... and I am less than pleased where in the circuit I inserted... so I may want to do a more through rebuild on that amp.... but to what? Do I want a second one of these SSSs? Do I want to make an EL34 ODS? Do I want to to make some sort of big bottle Rocket Reverb? Do I want to go back to a stock YGL? I can't make up my mind...
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martin manning
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Re: EL34 YGL3 -> 6L6 SSS

Post by martin manning »

Good to hear it's working out. No surprise these make a good keyboard amp :^) The PI trimmer is pretty subtle. You can look for hints on dialing it in, or at least some suggestions in the files section, I believe.
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JazzGuitarGimp
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Re: EL34 YGL3 -> 6L6 SSS

Post by JazzGuitarGimp »

I'd say if you're running your Rhodes in stereo, build another, identical amp. :-)
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

JazzGuitarGimp wrote:I'd say if you're running your Rhodes in stereo, build another, identical amp. :-)
I haven't been running the Rhodes in stereo.... yet.
I have been using this in stereo with my DC30 (and 6G15 tank) for guitar though... but ya, I'm not ruling out building a second one of these SSSs.

But that would mean buying a choke, reverb transformer, reverb tank and the additional CF transformer again, as well as a quad of 6L6s in addition to incidental components.
I'm wondering if there is something else nice that might utilize this +450V from a FWB rectifier that still uses these old Mullard 6Ca7s. This one doesn't have a separate bias tap on the PT. It doesn't have to necessarily have to have reverb.

I've been preserving this as the YGL for the most part so far, but this oscillation and the general mess inside just begs some sort of major overhaul.
Ideas?
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

I'm thinking a lot about doing a 183 with a built in Dlator. That's assuming it wouldn't be hard to get the right bias voltage off the HT.

I would still have a couple preamp tube positions left that would make reverb tempting, but maybe I could save that as a future expansion possibility if I could keep some real-estate open.


I wondered about doing some sort of 4xEL34 Rocket, but perhaps the voltage is just too high to consider something in that camp...
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martin manning
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Re: EL34 YGL3 -> 6L6 SSS

Post by martin manning »

A 183 would be a nice project, and without the need for the current the the CF driver uses you could capacitively couple to the HT for bias.
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

Just figured out why my amp was so bright (that I had to adjust my high filter options)... I had a 27K feedback resister instead of 2.7k. I discovered it because I was about to try wiring up a presence control to help with this issue when I noticed it. Only because I was obsessing with this value because I was wondering if I would need to alter it to wire up a 5K presence pot with a 1uF cap.

As soon as I swapped in the 2.7K, down came the high filter and much more useable tones.... time to move back to the stock high filter values. Then I'll experiment with a presence control... mostly because it bothers me having a knob on the front panel doing nothing.

First, I'll experiment with the 2.7k going to the 5K pot and then through a 1uF cap. Any suggestions on what I might need to alter from there? The 1uF focuses the frequency that is being played with, right? Should I be starting with something lower like 470 ohms for the resister if I am using a 5K pot?
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

OK, I got the filters back to pretty much stock... well, the full range but missing one of the middle ones since I use a 6 position rotary.

I then went ahead and wired up a presence circuit. Just went from the 2.7K feedback resister to the DPDT slider on the Front panel (so I can switch it in and out to compare)... then to the 5K pot and 1uF cap, back to the DPDT and to ground. It seems to work quite well for the most part. From about 1-4 on the presence knob is pretty indistinguishable from having the presence off (or out of the circuit).... then it adds some useable presence from about 5 to 10. I'm thinking about putting a resister across the pot, but it's not like the pot is overly sensitive, so it's not really annoying or anything.

I guess the DPDT slider switch that brings the presence pot in and out is a bit redundant... so I'd love another suggestion of what to use it for. Just don't say "mid-boost", because that's the other thing I added this afternoon.

I also had another unused DPDT toggle on the front panel. I replaced the 360p cap that feeds the treble pot with a 0.002uF cap and fed it to the DPDT with a bypassable 0.001uF cap which then feeds the treble pot. I wasn't totally sure of those values... but I think they should be close to 300pF when the mid boost is not on.... am I right? I think it sounds like it did... but I don't have the old value on a switch to compare it with. It does work with a recognizable mid boost. I'd be open to any recommendations of something else to try...

So, any suggestions for that other switch? Would there be any value in a PAB in an SSS?
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bcmatt
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Anyone added PAB to SSS?

Post by bcmatt »

So I did the typical ODS PAB switch (but no relays) that is off the Rock/Jazz switch. It seemed to work well in itself, but just interrupting and inserting there caused the deep switch and low filters to now do nothing. Not really a sacrifice I want to make. This is why it would have been useful to draw my changes into a schematic first. So, I'm not sure if there is even a possible way to add the PAB without ruining the deep switch... Has anyone done this? Added a PAB to the SSS? I actually like the tonal option it adds... I'd be willing to sacrifice deep and low filters when it is activated, but not altogether.

I'm about to pull that switch out and revert back, but now I wonder if there is a way and I should draw it out first.
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

Ok, I figured it out. It is possible to keep the PAB switch.
I found my mistake as soon as I was about to draw it onto the Schematic. I noticed that because the 270K resister that goes to the deep switch was right on theRock/Jazz switch, I was interrupting the signal before it could go to the deep switch. I just had to move that end of the 270K resister onto the bass pot wiper... which is nice and close on my particular layout. The resister reached. That fixed it and I have my deep switch back.

As far as low filters go... I think they are always hard to tell if they are doing anything. I seem to recall they are way more obvious when playing the rhodes through the amp.
Mclaughlin.197
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Re: EL34 YGL3 -> 6L6 SSS

Post by Mclaughlin.197 »

Sorry to drudge up a dead on- but I can't quite seem to figure my question out on my own. Is there any reason the Traynor power transformer wouldn't work for an ODS? Such as the 183 Skyliner layout? I turned my Traynor into an SSS and just switched to twin Iron for ease- but it appears the tranny might work in the ODS (and I already have the el34s from the Traynor.)
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martin manning
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Re: EL34 YGL3 -> 6L6 SSS

Post by martin manning »

If you build a power section with similar wattage and filament current requirements you should be fine. In the YGL-3 schematic I'm looking at the PT was supporting 4x 6CA7/EL34 so it is good for 100W of plate dissipation and 6 A of filament current in the power amp. It could also handle 4x 6L6. The three 12AX7 preamp tubes in an ODS only need 0.9 A for the filaments and less than 10 mA of plate current, less than the YGL-3's load of 5x 12AX7 and 1x 6BQ5 so no problem there.
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