Dumble Land/300SL Schematic Starting Here

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ic-racer
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Dumble Land/300SL Schematic Starting Here

Post by ic-racer »

Well, this is pretty sparse. I wonder if there is enough collective knowledge here to put this together.

Here is a start...
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Last edited by ic-racer on Mon Mar 02, 2009 4:11 pm, edited 2 times in total.
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ic-racer
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Re: Dumble Land/300SL Schematic Starting Here

Post by ic-racer »

For convenience, here is the link to the longest thread on the topic.
http://ampgarage.com/forum/viewtopic.php?t=412&start=0
Max
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Re: Dumble Land/300SL Schematic Here

Post by Max »

ic-racer wrote:Well, this is pretty sparse. I wonder if there is enough collective knowledge here to put this together.

Here is a start...
Hi ic-racer,

none of the DL 300SL I met did have an overdrive. All of them had a reverb. All of them the step filters. So I don't understand in what way this shematic could be a better start for one of a Dumbleland 300SL then a blank sheet of paper would have been? Or didn't I got your point?

Max
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Re: Dumble Land/300SL Schematic Starting Here

Post by ampdork »

The 300sl amps also use 6550 and cathode drivers....

You can get the full power amp directly from an svt.

The filters too are more or less expressed in rdh4.

Good luck.
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Re: Dumble Land/300SL Schematic Here

Post by ic-racer »

So far I have come up with the following additions/deletions:

Needs reverb Send and Return pots.
Needs PI balance pot (on back panel).
Needs only 2 bias test points (K1, K2)
Needs 2 Bias pots (back panel)
Needs 3 prong XLR connector not 5
Needs 3 fuses
Footswitch would be for reverb (PAB also???) and no OD circuit
No manual PAB switch (perhaps 3-position J/R switch)
No AC 'convenience' jack

Can't tell for sure these points:
Number of positions for the filters (4 or 6) and location in circuit.
Anything about the reverb circuit at this point.
Last edited by ic-racer on Sun Mar 01, 2009 4:05 am, edited 1 time in total.
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Re: Dumble Land/300SL Schematic Starting Here

Post by ic-racer »

ampdork wrote:The 300sl amps also use 6550 and cathode drivers....

You can get the full power amp directly from an svt.

The filters too are more or less expressed in rdh4.

Good luck.
Here is the SVT schematic for reference. Do you know if the 300SL uses an OT from the SVT?
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Re: Dumble Land/300SL Schematic Starting Here

Post by ic-racer »

In the Dumble Land thread first post a reverb schematic is mentioned, but I'm not sure if this is the one:

http://ampgarage.com/forum/files/1200dp ... ut_271.pdf

or this one:

http://ampgarage.com/forum/files/odreverb_902.pdf
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Re: Dumble Land/300SL Schematic Starting Here

Post by ic-racer »

I'm going by this "Dumble Land Datasheet" and putting it up for review, in case anyone finds errors in it:
"DUMBLE LAND 300SL"





SPECIFICATIONS

Power Output: 300 watts true power

Output Impedance: 2 or 4 ohms

Input Impedance: NOR = 1M ohm, and FET = 3.3M ohms


TUBE COMPLIMENT

2 x 7025 high-mu twin triodes

1 x 5751 high-mu twin triodes

1 X 12AU7

2 x 12BH7

6 x 6550A beam power


CONTROLS AND EQ SWITCHES

Preamp Controls: volume, treble, middle, and bass

Preamp Switches: bright, deep, rock/jazz, and preamp boost

Filter: Hi and Low step filter

Reverb Contoler: Send, and return levels

Master Section: master volume, and presence


SIGNAL CONNECTIONS

Inputs: NOR, and FET

Access Ports: preamp out, and power amp input (2.5V, 500k ohms)

Outputs: main speaker, and extension speaker


POWER SWITCHES

A.C. mains on/off

A.C. mains grounding

operate/standby

 

ADJUSTMENTS

BIAS ADJUST

 

REMOTE SWITCHING

Reverb on/off
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ic-racer
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Re: Dumble Land/300SL Schematic Here

Post by ic-racer »

Max wrote:... a blank sheet of paper...

Max
Hi Max,
I'm sorry if my thread title comes off like John Lennon's posters:
WAR IS OVER




if you want it...
Anyway, as any of the schematics I have done, it starts with the same Dumble template I have drawn up, so it is indeed not far from a blank sheet. :)

This is, of course, a 'group project' your comments will be appreciated if you care to join in ;)
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Re: Dumble Land/300SL Schematic Starting Here

Post by ic-racer »

For those not up to speed on intelligent collective decision making systems, I will point out that I am a proponent of #3 in the following essay:
3. The collective is smarter than sum of the individuals in the
collective

http://public.lanl.gov/jhw/Publications ... Book-1.pdf

Let's see if I am correct :?:
Max
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Re: Dumble Land/300SL Schematic Starting Here

Post by Max »

ampdork wrote:
You can get the full power amp directly from an svt.
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.

So please explain, why you write: "directly from an svt"?

Cheers

Max
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Re: Dumble Land/300SL Schematic Starting Here

Post by Max »

ampdork wrote:
The filters too are more or less expressed in rdh4.
Hi ampdork,

From what source did you get this info? Could you inspect a 300SL? If yes, do you remember the series #?

Thanks and have a nice weekend

Max
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Re: Dumble Land/300SL Schematic Starting Here

Post by Max »

ic-racer wrote:I'm going by this "Dumble Land Datasheet" and putting it up for review, in case anyone finds errors in it:
"DUMBLE LAND 300SL"





SPECIFICATIONS

Power Output: 300 watts true power

Output Impedance: 2 or 4 ohms

Input Impedance: NOR = 1M ohm, and FET = 3.3M ohms


TUBE COMPLIMENT

2 x 7025 high-mu twin triodes

1 x 5751 high-mu twin triodes

1 X 12AU7

2 x 12BH7

6 x 6550A beam power


CONTROLS AND EQ SWITCHES

Preamp Controls: volume, treble, middle, and bass

Preamp Switches: bright, deep, rock/jazz, and preamp boost

Filter: Hi and Low step filter

Reverb Contoler: Send, and return levels

Master Section: master volume, and presence


SIGNAL CONNECTIONS

Inputs: NOR, and FET

Access Ports: preamp out, and power amp input (2.5V, 500k ohms)

Outputs: main speaker, and extension speaker


POWER SWITCHES

A.C. mains on/off

A.C. mains grounding

operate/standby

 

ADJUSTMENTS

BIAS ADJUST

 

REMOTE SWITCHING

Reverb on/off
Hi ic-racer,

not wrong as far as I know, but there are different ones (Take a look at Bills site). With footswitch for PB and without. With FET and without, with plate reverb, with spring reverb.

Believe me or not: There is not such a thing as a "shematic of a 300SL"! It is the same as with the ODS (and there is no "shematic of a Dumble ODS" too!). Every Dumbleland 300SL has been made for a special client with special features and a special sound (same with ODS). So one allways should keep in mind, that it is not possible to clone "a Dumble ODS". If you degoop an ODS you can at best clone this series # 124 (e. g.) not more not less.

And this is the same with the DL and SSS. If you succeed in cloning the SSS of David Lindley or one of those of SRV, what you get is not "a SSS clone" but in the best case a fine clone of this one specimen.

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. A tech I know has been into many ODS and some SSSs and Dumblelands, and he told me that the differences between different specimens of DL and SSSs are even greater as between two HRM ODS.

So before starting a DL300SL cloning project, it would perhaps be a good idea to make a decision which one you would like to clone. Otherwise chances are great that you end up with the same confusion as with the ODS shematics.

Cheers

Max
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Re: Dumble Land/300SL Schematic Starting Here

Post by ampdork »

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)

Modding to work with other tubes would not be hard at all. The 12dw7 is like a 12ax7 and 12au7 in one tube IIRC. So pinwise they plop in just fine and in some of the ampegs they recommend doing just that.
In the SVT...a two resistor swap iirc for 12ax7.

So I guess my statement may have been off by one triode, since half of the 12dw7 is most like a 12au7. ;O)
ampdork
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Re: Dumble Land/300SL Schematic Starting Here

Post by ampdork »

Believe me or not: There is not such a thing as a "shematic of a 300SL"!
Agreed top to bottom, there is no static state to any of those designs. Emergent and evolving to this very day.
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