Fixing Reverb predicament on HRM'd Traynor YGL-3a

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bcmatt
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

Thanks Tom,

We'll see what happens. My hope is that I can just tweak the HRM overdrive circuit until I get a sound I really like. If I run into great success, I'll consider making the switch into a relay and whatever else.
It would be nice if it all comes together and the OD gets shaped nicely. Then I would be able to draw up the schematic and layout in order to have something to contribute to the world.
Of course, these old Traynors aren't quite as cheap and easy to find as they used to be and that is probably due to jerks like me not keeping their mouths shut about them.

Then again, owning two of them now, this could be my scheme to lure everyone into modding theirs so that my stock one increases in value...
:twisted: Maybe someday it will be worth $500 instead of $300 :shock:
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bcmatt
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

Here's the update:
I brought my later 70s YGL-3a with me on a my trip to the west coast and worked on it here. The other amp will be waiting at my post office when I return in a couple weeks. Anyways, I could not resist trying these mods on the amp I have with me and here are the results so far.

I kept the Master Volume as it is which is after the Trem and Reverb.
I just added a clean volume (1M) where I indicated on the schematic.
I pretty much followed the schematic I had made exactly. (Except I also noticed the pins are numbered wrong on the overdrive tubes). Also, I could only get a 20K trimpot for the OD input level adjuster, so I bumped up the resister to ground after to 8k2.

Problems:
a) Not nearly as much gain available as I expected. (Don't people get a thick tone even with single coils?) I have to use a humbucker and crank the OD Gain in order to get any thick lead tone.
b) Bit of a high pitched squeal if gain is too high or bright before the OD section when OD is switched on. (have to keep clean channel gain at about half and cannot use bright switch)
c) Plate voltages are only at about 150V

Ideas:
Will try reducing OD plate resisters to around 100K each (instead of 120K/180K to bring up the voltage.

I am noticing other ODS models have a bigger OD input trimpot so, I will try the 120K one I have instead of this 20K one.

I'll try those things first. Then I am wondering about cathode resister/cap values after that...

Maybe I need to use a bigger grid resister to get rid of the noise at higher gain...

Any other suggestions? When I get this OD circuit up to around 200V, will it be even LOWER gain? :cry:
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Bob-I
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by Bob-I »

bcmatt wrote: Problems:
a) Not nearly as much gain available as I expected. (Don't people get a thick tone even with single coils?) I have to use a humbucker and crank the OD Gain in order to get any thick lead tone.
Yes, you should get a thick tone even with SC's, but these are not really gain monsters.
b) Bit of a high pitched squeal if gain is too high or bright before the OD section when OD is switched on. (have to keep clean channel gain at about half and cannot use bright switch)
You could have an oscillation that's not audible all the time. This can cause the thickness issue plus the voltage issue in c)
c) Plate voltages are only at about 150V

Ideas:
Will try reducing OD plate resisters to around 100K each (instead of 120K/180K to bring up the voltage.
No, that won't fix the voltage. If you change the plate resistor, Rp, you'll also have to change the cathode resistor, Rk to get the correct bias, and the voltages won't change.

I'd focus on the oscillation problem first, then the voltage and tone issues.
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bcmatt
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

Bob-I wrote: I'd focus on the oscillation problem first, then the voltage and tone issues.
Thanks for the help Bob. I'm trying to follow this advice. How do you usually fix an oscillation?
Rip everything out and try a new layout?

I've been working on this all day. I've chopsticked around and gotten nowhere.
I switched any longer signal lines to shielded cable (to and from the OD circuit) = no difference

I added some 250pf caps between the Cathodes and plates of the OD circuit. = maybe a bit smoother but didn't get rid of that whistle

I've tried a higher value of Grid Resister on OD1(120K instead of the stock 68k). = no difference

I switched the OD trimmer to 100k one and connected the ground lug directly to ground without the resister. But turning the OD trimmer up much more than about 5k from ground will guarantee the whistle anyways.

I can actually get a nice thick solo tone with the OD using humbuckers. I can get it there before I get my steam whistle, but a single coil will not get much of a sustaining note without having to be up in Whistle territory.

I'd think it would almost be ok to just set it for tone and leave it, but the moment you use a different guitar or flip to the other pickup, you are in danger of it being a bit brighter and whistling before you get a chance to re-adjust the amp.

The HRM treble control actually works like a pitch control on the whistle, while the other controls can be used to dial in the whistle in and out and it's strength.

I'm sorta running out of ideas and need some sort of suggestion on how to eliminate the oscillation. I don't have any experience with successfully doing so.

I'm also wondering if the type of capacitor used off of the cathodes to ground is important for this sort of thing. The only sort of cap I could get ahold of without ordering online in the 1uF and 5 uF values were little tiny 50V radial electrolytics.
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bcmatt
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

I didn't give up on this amp. It was put aside for awhile but I did find time to work on it again several times in the last month. I reorganized (with better components) the OD mod section of this amp. I also moved the OD insertion point to where the existing Master Volume was located in the schematic. (It is after the trem and Reverb, so Reverb can get pushed to too much easily if it isn't to subtle when the OD is switched on.)

Another thing I did to this amp was to Decrease the amount of Negative Feedback. I added a 250k pot in series to dial something in that opened up the tone and gave some nice drive/grind to the clean channel if I want it. I'll measure the sweet spot and replace it with the appropriate resister soon (probably around 50-100k). If I had tried this first, I may have never have even bothered with installing an OD... but then I would have missed out on all this fun!

So, I used this amp today for band practice and I must say that it is very versatile and great sounding now. I don't think I've ever had an amp that could pull off so many different tones with such effective controls. I had no problems with it , and I didn't experience any hint of squeals, oscillations, feedback, or unstableness anywhere near the sounds I was dialing in. (I should have tried even harder to find some, but didn't feel the need today. Things are pretty good since I have had this layout cleaned up. I have some pictures now too.
So, everything left of the blue electrolytic capacitor is part of the HRM overdrive circuit:
[IMG:640:480]http://i55.tinypic.com/skukno.jpg[/img]
And so all the controls that used to be for the normal channel are now for the HRM overdrive. Very tweakable with a huge of range in styles of tone. The Master Volume for the overdrive channel is on the very left beneath the toggle that activates the overdrive:
[IMG:640:480]http://i55.tinypic.com/2qi7693.jpg[/img]
So, I'm thinking the next step is to venture into the world of relays in order to put this overdrive switch into foot pedal form. Also, because I now have the overdrive circuit occurring after the reverb and trem in the Traynor circuit (right where the Clean Master Volume is), any significant amount reverb gets sort of too much when the overdrive is clicked in. So, I may think of doing something about this. Not sure if I would just always have the reverb footswitch ready, make another relay for it, or think about moving the overdrive again...
I'm not worried about it right now; because I go light on the reverb anyways.

Any thoughts on the whole relay idea? I've been reading the threads on it and am torn about trying to find a separate Transformer to power the relay or what... It looks like this PT has no centre tap. I also found the more appropriate schematic for this amp. I was using an older one before. Obviously, the normal channel is yanked out and the OD circuit straddles the Master volume pot with a DPDT.
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T Wilcox
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by T Wilcox »

What did you end up doing to clear the oscillation problem?
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bcmatt
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

T Wilcox wrote:What did you end up doing to clear the oscillation problem?
1) I rearranged and tidied up the layout for the OD section.
2) I switched the OD insertion to a later point in the circuit. (to the original MV location instead of before the Reverb)
3) Went from having 3 MVs to 2
4) Found a broken wire at a solder joint in a different part of the old preamp (this was causing a crackling and cutting out at higher volumes- more recent problem that I had to fix)
5) Decreased NFB making it much easier to get more gain without having to really crank controls

So, I don't know if the oscillation is eliminated altogether (I don't think it is), and I don't really know my way around oscillations in general (or understand them), but with regular amp playing and fiddling, it doesn't appear any more. Not sure exactly which thing I did was most effective...
I should note that it got sort of worse when I installed an NFB switch on the front panel with very long routing, so I undid that (but not sure if that was the same oscillation or just a bunch of noise)
T Wilcox
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by T Wilcox »

That's good atleast its not noticeable anymore.
I've been eyeballin this traynor that is at a local music store. Its sittin in the back collecting dust for years. Probably needs new caps and some TLC.
If I can a good deal on it it may be my next amp project.
Zippy
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by Zippy »

bcmatt wrote:I didn't give up on this amp. It was put aside for awhile but I did find time to work on it again several times in the last month...
That's looking great and it sounds like you have dialed ininto something that suits you well.

Have you readjusted the dropping string? The first stages of these amps run pretty low voltages compared to Dumble plate values (typically around 200-205V).

How's the reverb holding up? I think these amps have some of the best sounding reverb around. I would consider moving it tho' rather than running reverb through the OD section. Or perhaps just setting up the relays to turn the reverb off when using OD.
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bcmatt
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

T Wilcox wrote:That's good atleast its not noticeable anymore.
I've been eyeballin this traynor that is at a local music store. Its sittin in the back collecting dust for years. Probably needs new caps and some TLC.
If I can a good deal on it it may be my next amp project.
Is it a YGL-3 as well?
They are really great amps for the price you can usually get them for. Sort of great for everything as well. I have another one with KT88s in it that I use for bass (because the transformers are huge and seem to handle it easily).
Also, in the last week I discovered that same amp through a 4x10 Ampeg bass cabinet sounds amazing with my acoustic guitar. Superb reverb and trem with a clean, warm tone into a hi-fi sounding cabinet seems to beat out anything else I tried yet with my acoustic. I was quite blown away.

Zippy wrote:
bcmatt wrote:I didn't give up on this amp. It was put aside for awhile but I did find time to work on it again several times in the last month...
That's looking great and it sounds like you have dialed ininto something that suits you well.

Have you readjusted the dropping string? The first stages of these amps run pretty low voltages compared to Dumble plate values (typically around 200-205V).

How's the reverb holding up? I think these amps have some of the best sounding reverb around. I would consider moving it tho' rather than running reverb through the OD section. Or perhaps just setting up the relays to turn the reverb off when using OD.
I totally agree with your thoughts on the reverb on these. That's why I really didn't want to compromise that channel. With the OD off now, that channel is EXACTLY the same as before.
Keeping that channel unmolested is part of the motivation of moving the OD to where the original MV is. I had been just setting the Reverb on "1" and it has sounded just fine for clean and OD. If I could figure out a way to keep things tidy and proper for the clean channel, I wouldn't mind moving the OD placement to before the reverb.

I am curious about how a higher voltage would change the sound. I'm not sure exactly how to go about getting it. Would I be trying to just get the OD section's voltage up? I'm not sure how to do that. From people's responses before, it seemed it was not a task for the uninitiated and can get really complicated fast. I'm really interested to learn, but I often draw a blank without reference to a schematic.

Anyways, I'm not sure how accurate to an ODS this amp really gets. It was probably closer before I decreased the NFB. Although, I wanted a bit more gain like the HRM and perhaps is close to that. It just has more aggression than what I expect from a typical ODS (but more suitable for me).
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

Well, it's only been 3 years since I last modded this amp. The truth is, it gets some really great tones. Fantastic clean and probably the most versatile and tweakable distortion imaginable. Every time I play it, I think it is awesome. Yet, it's not my primary amp for gigging because I have a Liverpool that is more appropriate for most of my stuff, and this thing doesn't have any relays installed yet, so the whole whole walking over and flipping a switch is not so practical in a live setting. But, before I fully commit to the relays, I want this thing to do all that it can.
Right now, that means resolving the issue of overdriving the reverb signal. I want to be able to turn up the reverb on my clean tone without having to drive it when I switch on the OD. I've been wrestling with this for a couple days. I've considered a few options:

A) Move the whole reverb to after the current HRM circuit which switches in and out at the Clean Master Pot. This assumes that I don't want to lose the reverb when the OD comes on; I just don't want it getting out of hand like it currently does (overdriving the verbed signal). The downside to this is that the non-OD setting will no longer be the Amp's stock signal path. I'd be stepping into territory of really screwing things around in this amp.

B) Have the DPDT that swaps in the HRM to the circuit move its insertion point to before the Reverb, but exit in it's current location after the clean MV. Assuming this could be done as simply as I marked with the red lines on the schematic, it effectively skips the whole whole reverb/trem part of the circuit. Obviously, I have no idea what this will do to the OD tone to remove so many stages, but it will drop other effects when the distortion starts.

C) Have the reverb also on a switch that turns off or down. Ideally this could be done so that it is simultaneous with turning on the OD. (Possible with relays and footswitches) It could either switch to a separate reverb level pot with it's own setting during OD time, or just switch off during OD time.

There are more options, but these are the ones I'm considering most right now. I think I would like to try option B and see the result on tone and stability. Would just simply interrupting at my red insertion point work, or is there something more to consider? Any other thoughts?
Thanks! I appreciate the wisdom here.
I really don't regret these mods so far. It has made this a pretty cool amp, with way more cool tones, while so far losing nothing that it had before.
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bcmatt
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

I spent the day soldering and rewiring; trying a few things. First I set the insertion point for the OD before the reverb. Just didn't like the OD tone as much, and it was more unstable. It did ditch the reverb while on, but I didn't think it was worth it, when I could just install a switch to turn off the reverb.

I found some big huge long DPDT toggles that I had to dremel down to sort of fit. Replaced my OD switch with one too so I could swat at the amp and turn off the reverb in the same flail as switching on the OD. Unfortunatley, the one for the OD had some problems and wouldn't work properly. I had to put back in the mini-toggle. I swapped the control knobs for something rounder and smaller so that they are less in the way of swatting at the toggles.

So, that long toggle in the bright switch location is attached to the reverb footswitch jack. It's silent (unlike the stock reverb footswitch).

So, this is it I guess, until I install relays. I'll keep it like this for a while to see if I crave more options than turning the reverb on and off. I could do a separate (OD)reverb level if it seems worth it.
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

An interesting development: The reverb doesn't work today. Not sure if it is a tube, cable, reverb pan or what... but whatever it is, seemed to fix the squeal issue that made me have to keep gain and treble below certain levels... the plot thickens...
Now I'm going to dig into this amp again and have some fun. This means that this amp has some real potential all of a sudden. I was planning to gut it and build it into a #183. Now I think we will be going back to mod city with this guy. I quite like what this HRM OD does in this. I'll investigate the Reverb, then figure things out from there once we know what we can get away with without any squealing.
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Re: Fixing Reverb predicament on HRM'd Traynor YGL-3a

Post by bcmatt »

It was the reverb pan (a transducer I think). I had an extra reverb pan from my other YGL (that I completely gutted to build in to an SSS).
Once that was fixed the oscillation came back (at higher gain settings with overdrive on. However, removing the EL84 eliminated the oscillation. It is somewhere in the reverb circuit (whether the reverb is on or not) and it get's amplified when going higher gain.

For now I removed the reverb and wired the amp to alway have the overdrive (HRM) circuit on, and am quite pleased with the tones. I also wired in Preamp out and Poweramp in jacks on the front that seem to work well as well. So, now I can throw effects in post OD if I want to.
I'll leave it like this for the time being and see how much I use it. I quite like these quite tweakable drive tones I'm getting from this... or putting it more on the verge up breakup with the whole pedalboard in front of the amp.

This was the amp I was planning to completely rebuild into a #183 with built-in D-Lator. I may still at some point because it does sort of bother me how cluttered the overly modded Traynor is getting with a bunch of un-used circuitry.

For now, I did buy a piece of Walnut for the front valance that I cut, sanded and am putting an oil finish on.
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