Santana's view on his Bludotone

[212Mavguy]

Have not read that book yet, thank you, it's affordable!

Speaking of pins, I use a Dremel to clean them, can't get all the way around each pin but can still do a pretty good job with the 12__7 types. I run it at medium speed with a wire wheel and hold it in my left hand so that the wheel rotates toward the end of the pins.

[alvarezh]

You can download the manual in English here:

http://www.radiostoria.com/Files/Tube%2 ... %20ENG.pdf

All the best Greg.

[Max]

"Trigger" is the name for the adjustable voltage divider at the input to the third gain stage (first overdrive stage). That is implemented as an internal trimmer pot by Dumble, but occasionally brought out to the panel by clone builders (I don't believe HAD ever did that; anybody know?).

AFAIK Alexander did that, too. There are some ODS 100W amps I know of with the trigger control on the back. The ODS 150W #121 has the trigger and taper controls on the front (the silver "LEVEL" ring is the trigger control, the small concentric "LEVEL" knob is the taper control - the silver "RATIO" ring is the OD control and the small concentric "RATIO" knob is the ratio control - see the attached picture). And AFAIR there are some ODS preamps with the same 4 external OD controls (trigger, taper, level, ratio), too.

picture source: http://www.roblivesey.com/dumble/

Cheers,

Max

[martin manning]

Hi Max, as always you are a font of Dumble details; thanks!

I understand the "trigger" controls the input level to OD 1 (most often seen as an internal trimmer), and the Drive (or Level) controls the signal into OD2, and the Volume (or Ratio) controls the output level from OD2. I am not familiar with the "taper." Where does that fit in?

[Max]

Hi Max, as always you are a font of Dumble details; thanks!

I understand the "trigger" controls the input level to OD 1 (most often seen as an internal trimmer), and the Drive (or Level) controls the signal into OD2, and the Volume (or Ratio) controls the output level from OD2. I am not familiar with the "taper." Where does that fit in?

"Taper" is an "overall tone control" for the "standard" OD channel. The "taper" control adjusts the amount of high end in the harmonic content of a "standard" OD channel.

Cheers,

Max

[martin manning]

So, an adjustable version of the "treble bleed" network used by some here to reduce high frequencies and "fizz"?

[Max]

So, an adjustable version of the "treble bleed" network used by some here to reduce high frequencies and "fizz"?

I'm not sure if this is exactly the same in a technical sense. But as you can read in the attached data sheet ("CONTROLS AND EQ SWITCHES") of a 4th generation "classic" ODS with a "standard" (= non-HRM, trigger entrance and snubbers) OD circuit, this internal "h. f. taper" is - just as is the internal "trigger" - a rather usual feature of a 4th generation "classic" ODS 100W (some transition generation "classic" ODS amps have this, too. #0094 is an example for such a transition generation ODS 100W with such an internal "h. f. taper" control.

Cheers,

Max

[martin manning]

I don't think we have yet seen the details of HAD's HF taper here at TAG, only a couple of forms of a treble cut after OD2 attributed to members. Anybody? Tony or Gil?

[alvarezh]

"Hi Max, as always you are a font of Dumble details; thanks!"

Martin, I consider Max to be our "Senior Resident Dumble Paleontologist"!

Cheers!

[Max]

I don't think we have yet seen the details of HAD's HF taper here at TAG

The taper control of the transition generation ODS 100W #0094 ("classic" with "standard" OD) e.g. has been discussed in this thread: https://tubeamparchive.com/viewtopic.php?p=56728#56728

Cheers,

Max

[ER]

Hey Max-

What's the trimmer on the back panel of the 1st gen amps (lindleys ODS)?

Is it an OD stage trimmer as well?

-ER

[boldaslove6789]

Hey Max-

What's the trimmer on the back panel of the 1st gen amps (lindleys ODS)?

Is it an OD stage trimmer as well?

-ER

Its the FET trim pot so he can adjust the level of input when using his lapsteel. Pretty sure the FET Boost is Ftsw'able too.

[Max]

...trimmer... of the 1st gen amps...

In addition to what Greg already posted (I don't know if the FET input of DL's 1st gen. ODS is footswitchable or not):

AFAIK the 1st generation ODS amps (just as the 2nd and 3rd generation ODS amps, too) have originally been built with the older "pre-standard" (or however one wants to call it) OD circuit without the trimmer entrance, without snubbers, without a ratio control, and without a h. f. taper control. So if a 1st generation amp is still in its original condition and without later mods, then it doesn't have a "trigger" and a "h. f. taper" control at all - neither internal nor external.

AFAIK the "standard" OD circuit (trimmer entrance, snubbers, ratio control) was introduced around 1980 in the first "transition generation" ODS amps and AFAIK together with the introduction of the "classic" tonestack. #0075 is an example for the "transition generation" ODS amps with a silver chassis - #0084, #0093 and #0094 are examples for the "transition generation" ODS amps with a black chassis.

AFAIK the "h. f. taper" control was added as a general feature (see the data sheet I posted) to the "standard" OD circuit around the same time, when the 4th generation chassis (full grown ratio control and full grown presence control - both on the front) was introduced (in the early eighties). But you find the h. f. taper control in some of the "transition generation" ODS chassis, too (#0094 e.g.) But in contradiction to this data sheet I posted, you don't find the h. f. taper control in all the 4th generation chassis, #0124 and #0102 e.g. didn't incorporate a h. f. taper control e. g., at least not at the time when #0124 and #0102 have been documented by Gil and Brandon.

Cheers,

Max

[martin manning]

I don't think we have yet seen the details of HAD's HF taper here at TAG

The taper control of the transition generation ODS 100W #0094 ("classic" with "standard" OD) e.g. has been discussed in this thread: https://tubeamparchive.com/viewtopic.php?p=56728#56728

Thanks, Max. I recall seeing that thread but I guess I missed that detail about the cap and trimmer on a small board near the OD pots. If the schematics posted there are correct (at least as far as placement in the circuit and basic form), that is similar to the treble bleed network used by Gil, except I believe he used 250k and 0.001uF, and attached a small board holding those parts above the main board.

[talbany]

I don't think we have yet seen the details of HAD's HF taper here at TAG

The taper control of the transition generation ODS 100W #0094 ("classic" with "standard" OD) e.g. has been discussed in this thread: https://tubeamparchive.com/viewtopic.php?p=56728#56728

Thanks, Max. I recall seeing that thread but I guess I missed that detail about the cap and trimmer on a small board near the OD pots. If the schematics posted there are correct (at least as far as placement in the circuit and basic form), that is similar to the treble bleed network used by Gil, except I believe he used 250k and 0.001uF, and attached a small board holding those parts above the main board.

Martin
AFAIK Dumble has been known to use either a .001 or a .0022 cap in the bleeder network.. I also thought the pot was a 500k instead of a 250k..I like a 500k a bit better..Also AFAIK Robben's #102 did at one time have the internal trimmer (with I believe a .002 cap) before the amp was upgraded to high plate skyliner specs then the HF taper network was removed.

Hope this Helps!!

Tony