At it again; '69 SuperLead build

SpiderWars

SpiderWars

Well-known member
I built a Valvestorm '68 Superbass last year but I hate going back and forth between biasing it for 90vac (variac use) and 119vac (my Furman voltage). So I'm building a '69 Superlead for variac use and the Superbass will be the 120v amp. Still with laydown PT but slightly higher B+ (480vdc vs 460vdc) and with filter cans (ARS). And a 2" OT instead of the standard 1.5". But I don't think it is a Drake type, more like a 2" version of the 1.5" Dagnall and still 1k7 primary (not 2k2...long story apparently on that). 3.8H choke. All iron from Mercury. The OT is usually oriented 90* from the Superbass but the 2" thickness forced me to orient it the same. But the OT/PT are spaced even closer together in the SB because there is no garden of filter cans in between so I think it's a non-issue.

My Superbass had non-twisted filaments so I'm doing it that way again. I really don't think it makes a difference in noise and way less wire (which is probably one of the reasons it probably doesn't matter, the untwisted length of wire is almost the same but there is no twisted-pair length running along the back). And it leaves the left end of V1 (the most sensitive area) with zero filament wire to cross, totally open end there.

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Smashedguitarist said:
Are those the heaters? Is it going to be dc?
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Yes the orange are the heaters. Not DC but I will lift the center tap with a node added at that corner can. It is 100uF x 100uF and then I run a 330k across the hots and an 82k from one hot to ground. One node is PI node and the one with the 330k/82k voltage divider on it is the heater center tap node (the green wire coming from PT). I did the same in my Superbass and it only has normal hiss when dimed, no hum at all.

Exo-metal said:
So let's see the irons!
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Here ya go. Those Jalen boxes are so damn handy.

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SpiderWars said:
Yes the orange are the heaters. Not DC but I will lift the center tap with a node added at that corner can. It is 100uF x 100uF and then I run a 330k across the hots and an 82k from one hot to ground. One node is PI node and the one with the 330k/82k voltage divider on it is the heater center tap node (the green wire coming from PT). I did the same in my Superbass and it only has normal hiss when dimed, no hum at all.


Here ya go. Those Jalen boxes are so damn handy.

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I wanted to impress you with my knowledge. I know less than nothing, but that looks really cool, man. I am jealous as shit that i can't do it.
 
Smashedguitarist said:
I wanted to impress you with my knowledge. I know less than nothing, but that looks really cool, man. I am jealous as shit that i can't do it.
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Anybody can do it. Old Marshalls are very simple amps. After this I'm doing a Fender Brown Deluxe (the early ZZ Top amp). Mojotone has a pretty cool kit for it.
 
This was my first build. I used Merren iron. Eventually my tech installed a Variac switch on the rear panel. This amp sounds amazing. But it will kill small animals.
 
Rick Lee said:
This was my first build. I used Merren iron. Eventually my tech installed a Variac switch on the rear panel. This amp sounds amazing. But it will kill small animals.
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I used Merren on the SB but then swapped out the PT for a Mercury. I had considered dual voltage and all that but that doesn't sound the same as a regular amp variac'd down so I decided to just build a fairly standard SL.

Those taller cans for the mains are 100uF x 100uF, the screens and preamp cans are 50uF x 50uF. And the aforementioned 100uF x 100uF can in the corner for PI/Filament CT.
 
I think it's done. I haven't checked anything or turned it on, just finished what I think is last solder joint. I need a break.

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The 0.68uF Mustard is a pull from a Marshall and had short leads so the 2k7 resistor had to make accommodations for it's new neighbor. The mixer and tonestack caps are NOS El-Menco domino 560pF/500v (silver mica).

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psychodave said:
Looks good. What bright cap on the volume pot are you using?
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That's a Murata Ceramic Disc, 560pF/1kv. It's still a lot, but it's not really a Superlead if you completely tame it. I forgot the mid pot was 100k and I was supposed to put a 100k across but even 68k across it is too much. The bass control loses it's already wimpy effectiveness. I put a 47k there for now, so ~32k total.

I also completely screwed something up...its a VERY loud mistake. ;) Easy fix but so much for my color coding.
 
awesome job.... will the 2" output tranny be a little cleaner than the 1.5 traditional Marshall spec? even though its 1.7k ?
 
lespaul6 said:
awesome job.... will the 2" output tranny be a little cleaner than the 1.5 traditional Marshall spec? even though its 1.7k ?
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Possibly and it might be a little tighter when cranked.

I quickly cranked it just to see if it oscillated/squealed or anything...basically standing in another room to play. Noticably more gain than my Superbass. The first plate resistor is a 110k that has drifted to 119k so no wonder why.

Then something vibrated off of another amp and dropped to the floor and I was done. :LOL:
 
Congrats on the amazing build!!

Youll have to post some clips!

I just don’t have the desire to source all new NOS components from all over the world to attempt one on my own. I really like the sound of the sozo caps and could compromise there, but I’ve learned in my 74 that resistor composition makes a huge difference even for single value changes. It was enough of a learning experience to know my own 69 build would be a ways off.
 
Build looks great Spider!

Is that a 330uf cap on V2A I see?

What uf values did you use for filtering?
Mains
Screens
PI
Preamp

Ralle on Metroamp also experimented with the 2" Output transfromer, I can't remember what he though about it but he seemed to like it.
 
Thanks @glpg80! I already had a few things and Valvestorm had some others. Once buttoned up I doubt I could tell Mustards from Synergys.

Thanks @harddriver! The mains are 100x100, screens are 50x50, the PI is 100x100 but only half is used for PI the other half is ground lift for heaters, preamp is 50x50. Those are both 100uF/63v on V1 bass channel and V2. Once its big enough it seems anything bigger doesn't really do anything and I figured 100uF is big enough (by an order of magnitude, 10uF seems big enough).

When I built my SB I loved the clean right off but it didn't hold together when dimed. This amp...the clean kind of sucks but for the short time I had it cranked it held together better.

I'm out of town but hope to make clips soon.
 
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