Should I use this with built in dlator?

[Max]

Hi Tony, Scott, all,

why do you think this network is at the place where it is?

To recover some lost highs when using the Dumblelator?

Isn't this unlikely?

The Dumblelator has two bright switches and their values of course could have been tweaked for the taste of the #124 customer if the use of a Dumblelator was planned anyway.

The amount of "bright boost" of the bright switches AFAIK is even adjustable to a certain degree, as it depends on the settings of the drive and recover controls. And as most high quality outboard effects have input and output controls, too, there is always a certain range in which you can adjust drive and recover with similar overall input and output levels seen by the effect and power amp.

#124 has a master volume bright cap. The amount of "bright boost" of the master cap can be controlled - at least to a certain degree - by changing the relation of the amp's master, the Dumblelator drive, and the input control of the outboard effect. By this you can adjust the "bright boost" of the master cap and bright switch 1 of the Dumblelator to some extent.

In case the outboard effect has an output control, you can adjust the amount of "bright boost" provided by the bright switch 2 of the Dumblelator to some extent by changing the relation between the output control of the effect and the recover control of the Dumblelator.

The master cap of course could have been tweaked to the taste of the #124 customer, too, if the use of the Dumblelator was intended anyway.

As far as I understand this right, many here feel the need to "soften" the tone of their Dumble style amps and add buffers of a Dumblelator kind and shielded cables in the loop to intentionally get rid of some highs. But as far as I understand this, this network does accentuate the highs a bit. So why did Dumble place it there? Do you think, he could perhaps just have a different personal taste in regard to the "how to soften the sound" topic? (And could this different personal taste of Alexander in regard to the "soft" topic perhaps be the reason, why he provided the Dumblelator with "bright" switches and not with "mid" or "fat" or whatever switches to smoothen the tone?)

BTW: This "soft and sweet" topic is an interesting topic in its own right: Perhaps some of you remember some kind of "amp shootout" in "Guitar Player Magazine" in the early nineties. They had been provided by Joey Brasler of Make'N'Music Los Angeles with a light tan Dumble with a new skyline update and EL34. And the comment of the reviewers was: Great amp with even "Metal tones" if you want them, but lacking sweetness in the OD mode. Alexander's printed comment AFAIR: Strange, as his customers never complain about a "lack of sweetness". So perhaps the personal taste of Alexander and most of his customers in regard to the "soft and sweet" topic is perhaps just a bit different than the one of many members here, and he likes bright amps and does not like it that much when highs get lost in cables and buffers? And in regard to the personal taste of his customers concerning this "soft and sweet" topic it is interesting to note, too, that AFAIK by far the most of them did/do not use a Dumblelator in their loops to get rid of some unwanted highs in order to achieve more smoothness?

But back to this topic: What could be the intended special function of this network in addition to all these possibilities to "recover" highs, that are already there if you use a Dumblelator in the loop - even without this network?

Cheers,

Max

[Structo]

The network is only in circuit when there is nothing plugged into the return jack.
I believe it's purpose was to shape the tone to compensate for when a Dumbleator was not being used.
He abandoned the network after that.

[Max]

The network is only in circuit when there is nothing plugged into the return jack.

As far as I understood this thread up to now, this is wrong. I would suggest that you check again what martin manning has posted in this post:

https://tubeamparchive.com/viewtopic.ph ... 199#130199

"The revised layout is correct- the parallel RC is out of the signal path when the loop is NOT in use."

and the discussion after he posted this.

Cheers,

Max

[Structo]

I stand corrected.
The 220K/250pf is in series with the send jack.
It shapes the frequency on the way to the effects.
The Return plug breaks the circuit so that the effects can send the signal through the green wire to the PI.

I have probably four schematics of #124 that all have that part different.

In this case the network's purpose is to add a bit of brightness to the send, to compensate for long cables.

[dogears]

Actually, the network is before the loop and not in series with the effects send. It is in series with the master wiper and the Dumbleator input. The send is buffered on the other side of the follower and does not see the network.

Just some frequency shaping, yeah. More for the cabling to the Dumbleator me thinks. Or possibly as an RC when attaching a short loop jumper with no 'lator.

I stand corrected.
The 220K/250pf is in series with the send jack.
It shapes the frequency on the way to the effects.
The Return plug breaks the circuit so that the effects can send the signal through the green wire to the PI.

I have probably four schematics of #124 that all have that part different.

In this case the network's purpose is to add a bit of brightness to the send, to compensate for long cables.

[Structo]

This

[dogears]

Yep. Sorry, misunderstanding.

This

[Structo]

I think we can probably all agree that this is a moot point now.
Many of us have tried this network and most have probably removed it.
I frankly didn't hear a difference.
If you use high quality cables (low pf) for your effects runs, then your tone will be fine.

[Max]

He abandoned the network after that.

As "abandoned" could perhaps generate a misunderstanding:

AFAIK #124 is the one and only Dumble amp known with this network.

Cheers,

Max

[Structo]

I agree although some schematics show a 100K resistor in series with the master wiper.
But most likely that is to curb the highs a bit.

[Guitarman18]

Structo wrote:

I agree although some schematics show a 100K resistor in series with the master wiper.

That may be artist licence by the schematic creator, rather than observed in an original. If anyone has observed this in a real deal, then it would certainly help to clarify this mystery.

Paul.

[Structo]

You are most likely right Paul.
I tried it before and didn't really notice any benefit from it.
Some say it cuts some of the hash on the top end off.

What I have noticed in my quest to kill the fizz is if you aren't careful you destroy the bright top end which seems to be characteristic of these amps.
A fine line there for sure.