Dumbleland update (was SSS) :D

[David Root]

Max, no I don't doubt Brandon's info, he has seen inside more Dumbles than I have. But he hasn't seen every SSS.

It just seems reasonable to think that HAD might have used this iron in a 150W SSS as well as in a Dumbleland. The OT could be a bass OT, but even then bass OTs make good guitar OTs.

[David Root]

Roe, 606108 is just the EIA code. 606 identifies the mfr as Schumacher and 108 is the year and week of manufacture. The part no. on it could identify it if someone knows which amp mfr used that part no.

Judging by its relative size next to the Triad PT I would say it is about 15 lbs weight or so, which is about right for 150W.

If Schumacher had an archive like Triad, it would be easy to identify.

[paulster]

And Brandon's info didn't give any hint of which transformers were used for which output tube configuration either, so the Twin and Ampeg iron could, for example, have been used in the 4x6L6 amps and not the 4x6550 amps.

[David Root]

paulster, the Twin iron was used in SSS # 001 thru 004, I believe, which were the 6L6 100W amps.

The Ampeg is I believe (could be wrong here) mostly associated with the 300W models, and was SVT iron.

Dynaco iron was also used.

I have heard that Sunn iron was also used, which could have been Dynaco or Schumacher because Sunn used both manufacturers.

I just sent that pic of the Dumbleland Schumacher OT to the custom transformer division of Schumacher Electric, asking if they could identify it, give me the pri and sec impedances and if it could be duplicated.

[paulster]

I'm wondering if he used something like Ampeg V4/V4B/VT22 iron for the 4x6550 amps as these Ampegs usually ran 7027s but could have 6550s dropped in for an increase in power, as specified by the manufacturer.

Makes me wonder if they were appropriately rated for 150W.

[David Root]

I have a V4B which I modified for 6550Ds. It probably puts out at least 120W. A V4/V4B OT is probably capable of 150W, or 137W which is what the 150W Dumbles measure at.

I do know that with the same Sovtek 6550Ds I have in my V4B, Lord Valve tells of measuring 352W clean out of a '70s SVT.

Either way Ampeg iron was clearly conservatively sized.

[Max]

137W which is what the 150W Dumbles measure at.

Hi David,

for what amount of THD did you adjust the power amp when measuring 137W?

SSS OT: The 150W SSS data sheets I know all list a 4/8 ohm OT. All 150W Dumblelands I am familiar with or heard of - those for guitar and those for bass guitar - are switchable for 4/8/16 ohm (one exception: the pentode DL has a 4/8 ohm OT).

Cheers,

Max

[David Root]

Max, I haven't personally tested a 150W Dumble. I should have added that that info was posted here by Brandon a while ago, and that I trust his number. I believe his post said "clean" but I don't know what that translates to in %THD. As you know the Ancients figured 5%, I would personally figure nearer 2% with little if any significant odd harmonics.

Would you share those "150W SSS datasheets" with us?

I will test mine when I finish it, it should come out close to the same as I am using similar plate/screen voltages, and if necessary, Sylvania/GE 6550s.

[Max]

Max, I haven't personally tested a 150W Dumble. I should have added that that info was posted here by Brandon a while ago, and that I trust his number.

Hi David, I understand.

I believe his post said "clean" but I don't know what that translates to in %THD. As you know the Ancients figured 5%, I would personally figure nearer 2% with little if any significant odd harmonics.

I remember 150W DL values of between 130W and 150W depending on the amount of THD you specify (130W at 1% and 150W more near to 3% or even 5% AFAIR).

Would you share those "150W SSS datasheets" with us?

Because a 150W SSS data sheet has been up on Yukihiro's and later then Bill's "Treasures..." site since around 1995, I thought they are known here. But as this seems not to be the case I'll try to find someone who scans a copy I have and then post it as soon as possible. But perhaps I could also just post its content here as soon as I find the time to copy it word by word. AFAIR it's a data sheet of what Brandon calls the EJ version of the 150W SSS that he derived the "usual" version of the 150W High-Plains Drifter from.

All the best,

Max

[ToneMerc]

I have heard that Sunn iron was also used, which could have been Dynaco or Schumacher because Sunn used both manufacturers.

I just sent that pic of the Dumbleland Schumacher OT to the custom transformer division of Schumacher Electric, asking if they could identify it, give me the pri and sec impedances and if it could be duplicated.

David, that output transformer is from a Sunn 1200S (4x6550) amp. The Sunn original part# is 28-1312, 3-120T output transformer. I'm willing to bet money that Heyboer can make you one.

Mike

[Roe]

Depends on the SSS Some have twin Iron, some have Ampeg Iron, Some have Sunn/Dynaco Iron.

correct me if I'm wrong but wouldn't the dyna iron be the a451 (2k2) OT and the ampeg iron the v4 iron?

[David Root]

Yes, I would think so.

[Roe]

since the v4 ot has a 3k primary impedance, it won't produce enough power with 500v on the plates. with 540v it produces just above 100w, so its not close to the reported 137w.

if the SSS had around 500v on the plates, wasn't ultralinear, and put out 137w, then it had to use a much lower primary. perhaps below 2k

[David Root]

Well, if the V4/V4B OT is 3K primary, that is the loudest 80W I've ever heard. Mine is converted to 6550, I will have to measure its output.

But V sqd/R rules. So that would mean a 1K8 primary for 137W. My selected SSS OT (Bassman 100) is 2K33, which at 520V is 116W. Close but no cigar. Would need 565 Vp.

[Roe]

two different sources stated that the v4 ot was 3k. the early ones had 540+v on the plates, the later ones had even higher plates (585) but much lower screens.

it seems that a SSS OT would have a primary close to 2k. does anyone know the specs of the 3-120t OT used in the Sunn 1200 and 200s? these amp had around 500v on the plates got a rather high output by using ultralinear taps

EDIT:

Triode offers the following info about specs:

"Output Transformer for Sunn, Project - 2200 Ohm 120w / 240w UL 4 8 16 taps MADE IN USA


Output Transformer for Sunn, Project - 2200 Ohm 120w / 240w UL 4 8 16 taps MADE IN USA
Great for HiFi (120w at 20Hz-20KHz), Guitar amps (240W at 30Hz-15Hz)
2.2k Primary, with UL screen taps, 4, 8, 16 ohm secondary.
Great with quads of KT88's or 6550's!
NO LONGER AVAILABLE, LISTING VIEWABLE FOR INFORMATIONAL PURPOSES ONLY
Weight 15 lb 10 oz.

Output Transformer for Sunn, Project - 2200 Ohm 120w / 240w UL 4 8 16 taps"

https://store.triodestore.com/ot2200ul4816.html


This is similar to Dynaco A451a in terms of Z and frequency response (but not weight)