EL34 YGL3 -> 6L6 SSS

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bcmatt
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EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

EDIT: New Plan- Convert to full on SSS in existing cab/chassis/xformers/tube layout



How crucial are the 6L6s or 6550s to that really great cathode follower SSS clean tone? Is it a complete waste of time to consider a 4x 6ca7 or 4x KT88 type build with the hope of achieving that tone?

Has anyone made a successful EL34 based SSS? I've been looking around here recently and doing searches, but not seeing anything...

Any thoughts about the biggest challenges on such a thing?

What are the typical voltages expected/needed on an SSS?

If I hypothetically had amp iron producing about 430V on the power tube plates... 150V preamp plates and 220V PI

Sorry if these are stupid questions.... I spend most of my days hanging out on the Trainwreck side, but come over here intrigued from time to time and quite blown away by some of your guys' SSS tones... just such a different style of clean that Im starting to really hanker for!
Last edited by bcmatt on Mon Feb 22, 2016 7:36 pm, edited 1 time in total.
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

I've still been searching around and found no evidence of any EL34-based SSS. I'm thinking that it's not a venture that most would consider (perhaps counter-productive).

I have 2 early 70s Traynor YGL-3a that only one of sees regular use. The other still has KT88s in it that someone previous installed. I bought this second one for the purpose of messing with but hesitated because it is quite a great clean machine already... but it can never seem to compete for usage compared to my DC30, Express, Liverpool, and my YGL-3a with the original Mullard 6ca7s.

After listening to these SSS examples with the cathode follower driver I've been sort of blown away by this whole other level and type of clean tone that is not at all sterile sounding. However, with my wife on maternity leave and a newborn, the funds for a full scratch SSS build are not really reasonable.

I'm wondering if the chassis and iron from my YGL-3 could be used for a reasonable SSS build. Would the Voltages be too low to support the 6L6 format? How would the sound with about 430V on the plates? Worth it?
tictac
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Re: EL34 YGL3 -> 6L6 SSS

Post by tictac »

With the platform you've got you could use 6L6 or EL34, why fret about one or the other?

TT
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

tictac wrote:With the platform you've got you could use 6L6 or EL34, why fret about one or the other?

TT
Sounds good. I won't fret then. I'll order a quad of 6L6s, probably a new reverb transformer and pan and a bunch more components and get this project started... It's been a year or two since building anything so I am keen!
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

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OK, enough procrastinating. I need to get this sorted out soI can order the parts I need. The Canadian dollar doesn't seem to be picking up, so this waiting is not really helping. I'm just posting so that I am now accountable to get moving on this.
Also, please don't mistake me for someone that doesn't value vintage Traynors enough. Maybe you can tell that this one is not exactly stock (see the KT88s?). Besides, I have another with original British Mullards that sounds better and will remain stock (with the exception of the HRM overdrive replacing the normal channel). Besides, how many of you can claim to have bought a cab, chassis, knobs, tube sockets and Transformers for your SSS for $300 Canadian?

My first task will be sorting out a new layout that makes use of having half the preamp sockets at the front of the chassis... as well as a way to use existing front panel holes that may even make sense with current faceplate labels for the time being.
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

Alright, I finally figured out the parts I need to do this conversion (I hope!), and ordered what I could from AES. I had them shipped to Sumas, Washington, and picked them up last week when we flew to Vancouver for our holidays. Unfortunately, I only had one remaining day off when we flew back so I spent it ripping much of the old guts out. Today I polished up the back of the old faceplate and placed it on. I will be working on this whenever I can steal some time.

I'm trying to decide if I should move one of the preamp tube sockets over to the space on the end at the back....

I'm planning to base off of MHartman's SSS. I really like his take on it. The layout will adapt because of the interesting tube socket layout...
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

I think I would be done this build by now if it was from scratch, rather than a conversion. I spend so much time trying to figure out how to adapt current faceplate holes to fit into an SSS.
I've finally made all my decisions in that regard... and I had to get quite creative, as you can see.
Since 7 pole rotary switches for the filters seem quite unavailable (Mouser demands I purchase at least 1000 pieces). So, I am using 6 pole rotaries from AES and putting a DPDT beside each to activate a "filter activation switch" for each and then I choose between the 6 values. I know it seems silly, but it also helps to fill front panel holes.

Another weird thing I am doing is to put a centre-off DPDT in the FET input location for the purpose of controlling the local NFB right at my V1 location that is right there as well.

I still have one too many DPDTs on the front panel, but I might make one another local NFB switch for V2 if I choose to put it at that other front tube.

On another note, I totally forgot to order a choke... which sucks as a Canadian. I'll just have to pay for more shipping charges... I'll just make sure I don't need anything else first...
I found an old black Dunlop Wah inductor that I replaced with a red Fasel at some point, that I think I will try to use for the inductor needed.

I'm open to any advice on where to mount the reverb transformer as well. I think I see from pics of old Twins that they are mounted diagonally on the preamp side of the OT?
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martin manning
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Re: EL34 YGL3 -> 6L6 SSS

Post by martin manning »

The inductor in the filter section doesn't seem to have any effect, at least as it's shown in the schematics posted here.
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

hmmm, maybe I will just put the inductor on that last unused DPDT right there... if it's going to do nothing anyways, may as well have it actually switch in and out a real thing that does nothing.... so that it has an (almost) purpose for the time being.
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

I changed my mind. Just because I have a wah inductor, it doesn't mean I have to use it. I'd like to keep my controls actually useful and reasonable.

I've decided to eliminate the extra switch for each filter as well. That was a bit of a ridiculous idea. I think 6 filter choices should be fine. Does anyone have any ideas of a value from each filter that seems the least useful (and that I can skip to start?) If no one has any strong opinions, I may start with eliminating the second highest value from each and see if I am using the 1st and 3rd highest values a lot or not.

I'm thinking I will add a presence pot down at the end... I dropped a 5K linear in there that I'll figure out how to incorporate...

Any other controls that I ought to consider? Any of you SSS guys found anything super useful?
My current front is looking like this (SEE ATTACHED)
As you can see I have 2 spots left in the middle that I haven't decided on...
The toggle on the right is a DPDT but it actually is a hole for a pot, so it could be some sort of control like that...

I'm considering a PAB switch, mid-boost switch, a V2 LNFB switch, Reverb on/off switch, inductor in/out switch, I don't know... other ideas?
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

Another question that I have:
Would it make sense to be trying to use the bias tap off my PT since it has one? I guess this would mean saving some of the larger components (that I already bought). Would there be any other advantages or disadvantages?

I suppose a disadvantage would be that I will have nothing solid to follow for instructions (schematic/layout), but I would be eager to learn the right approach and how to figure out what components to tweak, as well as hopefully increase my understanding in a part of amplifier theory that I do feel very weak in. Help?!! Any resources for figuring this out would be much appreciated!
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dreric
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Re: EL34 YGL3 -> 6L6 SSS

Post by dreric »

Seems to me that you have to use the bias taps. Normally you have the bias tap off the high voltage secondaries, the red/blue wire in twin iron. This transformer doesn't have the tap, instead it had it's own secondary bias brown/brown. I know you can create a tap but seeing that to have a perfectly good source I would use it.

Also with the cathode follower, SSS are bias hogs.
Eric
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
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martin manning
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Re: EL34 YGL3 -> 6L6 SSS

Post by martin manning »

In the Hartman layout the bias voltage is coming off the HT, just ahead of a FW rectifier through a 3k3 resistor. Assuming 330VAC there, the bias voltage is probably around -370V. Looking at the -84V shown on the Traynor schematic, your bias winding is not going to do it. Since your PT uses a FWB rectifier, I don't think you can take the bias from the HT either, since you would have to capacitively couple it (like some Marshall's), and I doubt there would be enough voltage or current available. I think you are looking a a new PT, or adding a small mains transformer to provide the bias voltage.
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bcmatt
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Re: EL34 YGL3 -> 6L6 SSS

Post by bcmatt »

Yikes!
That's not very happy news!
I appreciate the heads up though.
I would sure like to not have to buy a new PT if at all possible. I didn't cannibalize a Traynor the same week Pete died just to spite the guy; I was hoping to save some money on the most expensive parts...

Now, I'm not sure how to figure out how to figure out what sort of extra transformer to look for to provide an appropriate bias voltage. What sort of current does it need to provide?
I've been studying grid biasing like crazy for the last day, trying to better understand the whole process. I've watched a lot of Uncle Doug videos lately, trying to get up to speed.

I guess a new PT is not crazy... really is only $90 US... I guess that's not entirely unreasonable either, if it solves a whole lot of headaches...
Last edited by bcmatt on Mon May 30, 2016 8:57 pm, edited 2 times in total.
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Re: EL34 YGL3 -> 6L6 SSS

Post by martin manning »

I think you could use a Hammond 229B230 flat-pack, which is small (~2" x 2.5" x 1" high) and cheap ($15): http://www.mouser.com/ProductDetail/Ham ... 7RMJLfk%3d It's a PCB mount, but you could put it on a small board using eyelets.
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