Dumble Land/300SL Schematic Starting Here

[Max]

Do you know if the 300SL uses an OT from the SVT?

Hi again, ic-racer,

at least the ones pictured on Bills site do. That is, how the rumour (wrong!!, at least in regard of the specimen described in the datasheet on Bills site) started, that the power amp of 300SLs is the same as the one of SVTs.

Cheers

Max

[Max]

Hi ampdork,

Why do you think so? The SVT poweramp shows a 12DW7 / 12BH7 configuration.

The 300SL datasheet on Bill's site and the pictures on Bill's site show a 12AU7 and 2 x 12BH7 configuration.

Look at the rear of the 300sl. The balance control from the svt is there. ;O)

Hi ampdork,

The ODS 150W do have this "dynamic balance control" too (many ODS 100W too!!), and their power amp has nothing to do with the power amp of SVTs.

I think in regard of the success of a 300 SL cloning project it would be a good idea to distinguish "facts" from "guesses".

Cheers

Max

[dr. who]

Has anyone here actually seen in a 300sl? How many were made? Were they all for bass guitar? Anyone know the tonestack values(skyline?)

[ampdork]

Ok then...good luck

[ic-racer]

A lot of the confusion concerning of the ODS shematics and the discussions about the "right one" you find in www is due to the fact, that they are all different....

Cheers

Max

I agree 100%. As you may know the other 5 schematics that I have drawn done up as a project like this all have serial numbers: #40, #94, #124 (original), #124 (1988), #2xx (are all available in the files section.) So, its a matter of choosing a 300SL that is most well know on the insides.

[ic-racer]

Ok then...good luck

Stay with us; I'm interested in reading everyone's ideas.

[Structo]

Don't get discouraged ic-racer.

Nobody else has stepped forward to take a stab at the schematic.

I don't understand some of the criticism?

If you know something help him out, not just tell him it's wrong.

[dr. who]

I have only been able to find 3 dumbleland amps. Jackson's 150w, chris' 300w orange one, and the black one on bill's page. Any others? On bills page it said that the 300sl is like the v9 so I found some schematics and will provide link. This is exciting.

http://www.drtube.com/guitamp.htm

[ampdork]

On the balance control. I have not seen it on anything but the 300sl and the od150. Not saying it does not exist on any other amp, only that these are the only ones I have seen them on. All 6550 based amps btw...

Also for consideration...
Is there another amp in the world using 6 x 6550 and 2 x 12BH7's besides the ampeg V9 and SVT? (well I guess there is the 300sl)

Interesting to note that the V9 employs an inductor based mid filter.

The V9 sports the VERY same power amp as the SVT too btw!!! ;O)

[Max]

On the balance control. I have not seen it on anything but the 300sl and the od150.

Hi ampdork,

Hmmh, i have seen a "dynamic balance" control inside every (or at least the most) 50W and 100W ODS from the eighties I had a chance to look into. (You can look yourself at the pictures posted here in the last years). You even find them in some ODS from the seventies. They are placed as small trim pots on the preamp board as a part of the phase inverter circuit.

The reason why you find the dynamic balance control of a DL300SL on its backpanel and not inside the amp is obvious: No big fun to remove a 300SL from its chassis to do an adjustment!

Greetings

Max

[Max]

Also for consideration...
Is there another amp in the world using 6 x 6550 and 2 x 12BH7's besides the ampeg V9 and SVT? (well I guess there is the 300sl)

Hi ampdork,

if you really want to derive shematics of the DL 300SL's from "guesses" it may make some sense to consider those similarities.

What I would like to say in my posts is:

a) I have my doubts, if it is wise to start a "Let us clone a DL 300SL" by guesses.

b) I think in such a common forum project perhaps it would be a good idea, if all those, who charm in, make clear, if their contributions are just guesses or facts they are sure of.

Cheers

Max

[ampdork]

They are placed as small trim pots on the preamp board as a part of the phase inverter circuit.

I know what is inside an ODS Max ;O)

If I am guessing .... it is a rather educated guess imo.

let's look at the facts.
None other than the 6550 based amps have the "Balance Phase Inverter" on the rear.
Ampeg SVT and V9 has a "Linear Balance Control" pot....on the phase inverter. Hmmm...


Let's look at more.
Ampeg SVT has "Bias Control" pots.
The 300sl has "Bias Adjust" pots.
Ampeg SVT has test points named K1 and K2...So does the 300sl.

Both amps use 6 x 6550 output tubes.
Both amp use 12BH7 driver for each output half.
Both amps use Ampeg iron.

The Ampeg came first.

I know, offhand, of no other tube amp designs that use 6 x 6550's and 2 12BH7's.

If anyone can suggest any amplifier design that even remotely resembles it let's discuss it.

If this is about D is a genius and would never even think of using the SVT design as part of his thing and he would instead scrap it, not even look at it, bust out the slide rule, figure some load lines and design the thing from the ground up, and by pure coincidence come up with a design using nearly all the same tubes, and pin swappable ones and bias adjustments (2 btw) and bias test points, and balance controls....etc....
Then I dunno what to say....

[ampdork]

Skip it. I have helped way more than I ought to. After all I have amps to build. ;O)

Best to bury the beast and never mention it again.

[heisthl]

If this is about D is a genius and would never even think of using the SVT design as part of his thing and he would instead scrap it, not even look at it, bust out the slide rule, figure some load lines and design the thing from the ground up, and by pure coincidence come up with a design using nearly all the same tubes, and pin swappable ones and bias adjustments (2 btw) and bias test points, and balance controls....etc....
Then I dunno what to say....

Blasphemy! Next you'll be suggesting that he copied a Fender as the basis for the original ODS platform

[ic-racer]

I'll post an updated schematic tomorrow.

Remember, this is just for fun. No one is going to loose their job or be castrated if the guesses are wrong or if the schematic has some deviations from the real thing.