Dumbleland Special 150w ser#009 Schematic

[Max]

... The Dumbleland's Output transformer is equipped with ultra linear taps, this enables you to run the output tubes at higher plate voltages for increased power output, given that the screens of 6550 are not designed to handle these higher voltages under load ...

If I have understood this correctly, then from the transformers of the two amplifiers shown in the two pictures below (when zoomimg in, their transformers look pretty similar on my screen to the ones in the Dumbleland Special 150W #009 ?), one can conclude that the output stages of this Steel String Singer 150W and this Overdrive Special 150W also have such an ultralinear circuit? Or have I misunderstood that?

Best regards,

Max

SSS 150W SRV.png

121_009.jpg

[erwin_ve]

Tony, based on this demo of a Dumbleland Special:

I can vouch for the filter of the Japanese schematic sss002 working the same way as the Dumbleland Special , in my attempt for the sss002 build.
Until someone can confirm, I think this is a good educated guess.

Erwin

[talbany]

Thanks Erwin
I Thought about a reason why he would want to come up with a different filter arrangement from the
D-Land to the SSS and could not think of a good reason as to why he would want to change it? If both were used for guitar..
Tony

[Max]

The fact that Alexander Dumble used different filter circuits in his guitar amplifiers with the type designation Dumbleland Special 150W (for example: seven-stage and eleven-stage filters, some with a trim-pot at the filter-entrance, some without) exists IMO regardless of whether one can imagine his reasons for these differences or not.

By the way: In the schematic proposed here for the Dumbleland Special 150W, the information on the specifications of the inductor is currently missing.

Best regards,

Max

[talbany]

So no one gets confused?
Both SSS #002 and Dumbleland ser#009 have 7 step filters

BTW.Inductor info is added and is considered "Optional"
read here.
https://ampgarage.com/forum/viewtopic.p ... S+Inductor
https://ampgarage.com/forum/viewtopic.p ... or#p414184

Tony

[Max]

... Both SSS #002 and Dumbleland ser#009 have 7 step filters ...

Based on the same number of points next to the two filter knobs of DL #009 and SSS #002, this seems to be correct.

However, the title of this thread is not "Dumbleland Special 150W #009 Schematic" but "Dumbleland Special 150W Schematic".

And due to the fact that obviously not all amplifiers with the type designation "Dumbleland Special 150W" have the filter circuit contained in the schematic proposed here, I personally think it would perhaps be appropriate to either change the title of this thread to "Dumbleland Special 150W #009 Schematic" or to supplement the schematic proposed in the introductory post with the information that there are examples of the Dumbleland Special 150W model whose filter circuits are different from that shown in the schematic proposed here.

... Inductor info is added and is considered "Optional" ...

Just to avoid misunderstandings in regard to “optional”:

So far I have never seen a specimen of the “Dumbleland Special 150W” model - be it in person or on pictures - without an inductor as a part of its filter circuit. And to this day I've also have never heard or read that there would be a “Dumbleland Special 150W” without an inductor as a part of its filter circuit.

Best regards.

Max

[Roe]

Any idea what the specs of the OT should be? 2.4k primary impedance?

Yes.I am thinking around 2k should be about right
Tony

the a451 is 2k2

[Max]

According to the Dynaco catalog linked below, this is correct:
http://knob.planet.ee/kirjandus/books/D ... ormers.pdf

But are you sure that the output transformer visible on the pictures of the Dumbleland Special 150W #009 is actually the A451 known from Winterland #003? I ask because the A451 https://www.worthpoint.com/worthopedia/ ... -108969072 looks quite different from the output transformer shown here on the pictures of the DLS150W #009?

Best regards,

Max

[Roe]

According to the Dynaco catalog linked below, this is correct:
http://knob.planet.ee/kirjandus/books/D ... ormers.pdf

But are you sure that the output transformer visible on the pictures of the Dumbleland Special 150W #009 is actually the A451 known from Winterland #003? I ask because the A451 https://www.worthpoint.com/worthopedia/ ... -108969072 looks quite different from the output transformer shown here on the pictures of the DLS150W #009?

Best regards,

Max

I am not sure no. The dynaco is potted, whereas the schumacher one used by sunn is not potted. it looks quite different. but the sunn power amp was based on the dynaco circuit, so the specs should be close, if not identical

[Max]

I see. Thanks a lot for the clarification.

Best regards,

Max

[talbany]

So far I have never seen a specimen of the “Dumbleland Special 150W” model - be it in person or on pictures - without an inductor as a part of its filter circuit. And to this day I've also have never heard or read that there would be a “Dumbleland Special 150W” without an inductor as a part of its filter circuit.

As far as it being "optional" I included it in the schematic labeled #009 If those building the amplifier choose to not use the inductor this an option they may have given this inductor has little effect on the sound and Martins Filter array does not have the inductor either and it is considered another option
https://ampgarage.com/forum/viewtopic.p ... 33#p412233
https://ampgarage.com/forum/viewtopic.p ... 34#p410934

However, the title of this thread is not "Dumbleland Special 150W #009 Schematic" but "Dumbleland Special 150W Schematic".

And due to the fact that obviously not all amplifiers with the type designation "Dumbleland Special 150W" have the filter circuit contained in the schematic proposed here, I personally think it would perhaps be appropriate to either change the title of this thread to "Dumbleland Special 150W #009 Schematic" or to supplement the schematic proposed in the introductory post with the information that there are examples of the Dumbleland Special 150W model whose filter circuits are different from that shown in the schematic proposed here.

Max
Sure I will update that not all Dumblelands have filters ASAP.

And a comparison of a more legible copy with the handwritten original can of course only confirm that the copy agrees with the handwritten original, but not that the contents of the handwritten original (and thus also its copies) match the reality (reality: circuit of SSS #002).

Here is a LT Spice sim Ryan ran on the filters for those that want to use the ones in #002
The handwritten copy of the filters is clearly legible and AFAIK nobody has complained about not being able to read all the values!..I didn't

https://ampgarage.com/forum/viewtopic.p ... 41#p411041

Unfortunately I've spent more time than planned on this project and unfortunately have some personal issues I need to take care of ,so If you or anyone else wants to post anything directly related to the filters, sound files etc or history of other Dumblelands you might have or any other valuable info so people here can build a Dumbleland inspired amplifier I am sure they and I will appreciate it!
I will check in when I can
Enjoy
Thanks
Tony

[Max]

... I will update that not all Dumblelands have filters ASAP. ...

Please excuse that I expressed myself too ambiguously in this regard: All amplifiers with the type designation “Dumbleland Special 150W” that I have seen personally or in pictures and that I have heard of so far have a filter circuit with two filter controls.

However, these filter circuits are not all identical. For example, there are amplifiers of the “Dumbleland Special 150W” type that have two seven-stage filters and some that have two eleven-stage filters. Some have filters with a trim-pot in the Filter entrance (AFAIU to adjust gain and other parameters of their RLC filter circuits https://en.wikipedia.org/wiki/RLC_circuit ), some do not have such a trim potentiometer.

Due to such differences of the "Dumbleland Special 150W" filter circuits, I consider it rather unlikely that the filter circuit contained in the “Dumbleland Special 150W Schematic” - proposed here as some starting point for further research and individual interpretation - is representative for all amplifiers of the "Dumbleland Special 150W" type.

Therefore I suggested to point out in the introductory article the existence of such individual differences in the filter circuits of the “Dumbleland Special 150W” amps.

But - again to avoid further misunderstandings: AFAIK, there are no amplifiers of the "Dumbleland Special 150W" type without a filter circuit.

Best regards,

Max

[pompeiisneaks]

Thanks for posting it tony! I've stickied the thread too. Sorry was away for a bit on vacation but back in the seat.

~Phil

[talbany]

... I will update that not all Dumblelands have filters ASAP. ...

Please excuse that I expressed myself too ambiguously in this regard: All amplifiers with the type designation “Dumbleland Special 150W” that I have seen personally or in pictures and that I have heard of so far have a filter circuit with two filter controls.

However, these filter circuits are not all identical. For example, there are amplifiers of the “Dumbleland Special 150W” type that have two seven-stage filters and some that have two eleven-stage filters. Some have filters with a trim-pot in the Filter entrance (AFAIU to adjust gain and other parameters of their RLC filter circuits https://en.wikipedia.org/wiki/RLC_circuit ), some do not have such a trim potentiometer.

Due to such differences of the "Dumbleland Special 150W" filter circuits, I consider it rather unlikely that the filter circuit contained in the “Dumbleland Special 150W Schematic” - proposed here as some starting point for further research and individual interpretation - is representative for all amplifiers of the "Dumbleland Special 150W" type.

Therefore I suggested to point out in the introductory article the existence of such individual differences in the filter circuits of the “Dumbleland Special 150W” amps.

But - again to avoid further misunderstandings: AFAIK, there are no amplifiers of the "Dumbleland Special 150W" type without a filter circuit.

Best regards,

Max

Max
This is getting to be a bit ridiculous!
If you wish to clarify which circuits are not accurate in the schematic of #009 I posted show us some evidence and I will update it. I already said it was not verified!!
I never said that all Dumbleland Specials 150W had the same exact filters circuits or I even knew what the filters were exactly in #009 I said we used the filters from #002 and offered a 2nd option.

If you wish to do some kind of historical background as to which Dumblelands have 11 step filters or, which had 7 or none and which ones had trimmers or they all have inductors etc.. Present some kind of evidence for your claim write it up and post it yourself I am sure people will read it and appreciate that... Otherwise I am Done!

Tony

[talbany]

Thanks for posting it tony! I've stickied the thread too. Sorry was away for a bit on vacation but back in the seat.

~Phil

No Problem Phil..I appreciate it!

Tony