My #102 Build.

[jazzyjoepass]

I feel my balance between Clean and OD needs some tweaking and Gil's approach is simple and effective mod, set and forget.

Anyone here can tell me at what trimmer resistance did they set if they used this approach?

Or maybe changing the two 270pF plate to cathode puffs to 300pF on V2 might do the trick too? I've seen someone do that.

I believe I put a 30pf on my Master.

No network on the Send Return since I always use the D'lator.

If you don't like the tone difference between the clean and OD, you can add some things that will balance it out.

First is to set the OD trimmer inside, with the amp on measure the resistance between the output of the trimmer and ground.

Set it around +- 25K. Fine tune to your ears.

If the OD seems brighter and fizzier than the clean tone, you can install a little treble bleed circuit like Ayan made.

The great thing about running a D'lator is that you can run the amp controls up high in the sweet spots and tame the overall volume with the output of the D'lator.


Another mod I really like is the Bright on Clean mod.
What this does is turn on the bright cap on the volume control in clean mode.
Then turns off when you switch to OD.
You can still have it on for both since it is a three position switch.
It just takes the place of the bright switch on the front panel.

But, you will most likely need another relay to do this unless you have half of one not being used.

I have a 120pf bright cap, tailor the value to your likes.

[Structo]

You just have to adjust it by ear.

Be sure you are playing at the volume you will most often be playing at.

I have experimented with different snubber caps on V2 and it seems to neuter the tone when you get high enough to kill the fizz.

Do you have a 47pf across the PI plates?

Another option is to put a cap on V2a plate resistor.

Member 10thx uses this method and he says it is very effective.

Try several caps there if you have them, like silver mica, ceramic, film.

Try different values until you get the right one for that frequency.

Be sure the voltage rating of the cap is enough for that position.

If you feel that position for the cap kills the clean tone then you can try this same method on the V2a and / or V2b plate resistors.

Also look at the Technical section and the thread about screen grid voltages.

It talks about how if the screen voltage is slightly higher than the plate voltage it can add some distortion that is not pleasing.

https://tubeamparchive.com/viewtopic.php?t=18855

[jazzyjoepass]

Thanks Structo, I'm aware of some of these tricks myself as I've done quite a few amp mods.

I'm hesitant in taking these approach as they tend to steer away from the "spirit" of the Dumble circuit.

The elegance of the Dumble OD section is its simplicity. And the great advantage of that is transparency. With too much tone sculpting circuitry, the guitar tonal character ends up being compromised.

I might try Gil's trick in the end, though.

You just have to adjust it by ear.

Be sure you are playing at the volume you will most often be playing at.

I have experimented with different snubber caps on V2 and it seems to neuter the tone when you get high enough to kill the fizz.

Do you have a 47pf across the PI plates?

Another option is to put a cap on V2a plate resistor.

Member 10thx uses this method and he says it is very effective.

Try several caps there if you have them, like silver mica, ceramic, film.

Try different values until you get the right one for that frequency.

Be sure the voltage rating of the cap is enough for that position.

If you feel that position for the cap kills the clean tone then you can try this same method on the V2a and / or V2b plate resistors.

Also look at the Technical section and the thread about screen grid voltages.

It talks about how if the screen voltage is slightly higher than the plate voltage it can add some distortion that is not pleasing.

https://tubeamparchive.com/viewtopic.php?t=18855

[Structo]

Yeah, I agree.

The snubbers are like bandaids.

But sometimes you get lucky with the placement of one that really helps.

[ayan]

Thanks Structo, I'm aware of some of these tricks myself as I've done quite a few amp mods.

I'm hesitant in taking these approach as they tend to steer away from the "spirit" of the Dumble circuit.

The elegance of the Dumble OD section is its simplicity. And the great advantage of that is transparency. With too much tone sculpting circuitry, the guitar tonal character ends up being compromised.

I might try Gil's trick in the end, though.

I have to say that...the "trick" is not actually needed if everything else is in place, and for years I went without having everything else in place. What do I mean? Between setting the PI trimmer correctly, picking the right parts in special places and observing cap orientation, you will probably end up with an amp that may be bright but entirely musical, as some might say about a Vox AC30, for example. If you add the "trick" when the amp is finely tuned, you will end up with an amp that's not as bright...but you will probably miss some of the magic. I have done this to too many amps at this point to not be a believer. None of my amps have the "trick" any more.

Cheers,

Gil

[ToneMerc]

I have to say that...the "trick" is not actually needed if everything else is in place, and for years I went without having everything else in place. What do I mean? Between setting the PI trimmer correctly, picking the right parts in special places and observing cap orientation, you will probably end up with an amp that may be bright but entirely musical, as some might say about a Vox AC30, for example. If you add the "trick" when the amp is finely tuned, you will end up with an amp that's not as bright...but you will probably miss some of the magic. I have done this to too many amps at this point to not be a believer. None of my amps have the "trick" any more.

Cheers,

Gil

IMHO, this is the gospel!

TM

[Structo]

Whoa!

(goes back to the drawing board.....)

[jazzyjoepass]

Thanks, that really gave me confidence to stick to my current setup and focus on refining the passive components, speakers and tubes. And maybe a dumbleator.

Gil, do u use a dumbleator too or are you also just using the amp as it is w/o one?

Thanks Structo, I'm aware of some of these tricks myself as I've done quite a few amp mods.

I'm hesitant in taking these approach as they tend to steer away from the "spirit" of the Dumble circuit.

The elegance of the Dumble OD section is its simplicity. And the great advantage of that is transparency. With too much tone sculpting circuitry, the guitar tonal character ends up being compromised.

I might try Gil's trick in the end, though.

I have to say that...the "trick" is not actually needed if everything else is in place, and for years I went without having everything else in place. What do I mean? Between setting the PI trimmer correctly, picking the right parts in special places and observing cap orientation, you will probably end up with an amp that may be bright but entirely musical, as some might say about a Vox AC30, for example. If you add the "trick" when the amp is finely tuned, you will end up with an amp that's not as bright...but you will probably miss some of the magic. I have done this to too many amps at this point to not be a believer. None of my amps have the "trick" any more.

Cheers,

Gil

[ayan]

I use a Dumbleator and I have a 30pF bright cap on the amp's master volume. I use Alpha pots (~15% taper) and set the master at between 6 and 7, so basically at the point where the effect of the bright cap is eliminated.

Cheers,

Gil

Thanks, that really gave me confidence to stick to my current setup and focus on refining the passive components, speakers and tubes. And maybe a dumbleator.

Gil, do u use a dumbleator too or are you also just using the amp as it is w/o one?

[talbany]

Thanks Structo, I'm aware of some of these tricks myself as I've done quite a few amp mods.

I'm hesitant in taking these approach as they tend to steer away from the "spirit" of the Dumble circuit.

The elegance of the Dumble OD section is its simplicity. And the great advantage of that is transparency. With too much tone sculpting circuitry, the guitar tonal character ends up being compromised.

I might try Gil's trick in the end, though.

I have to say that...the "trick" is not actually needed if everything else is in place, and for years I went without having everything else in place. What do I mean? Between setting the PI trimmer correctly, picking the right parts in special places and observing cap orientation, you will probably end up with an amp that may be bright but entirely musical, as some might say about a Vox AC30, for example. If you add the "trick" when the amp is finely tuned, you will end up with an amp that's not as bright...but you will probably miss some of the magic. I have done this to too many amps at this point to not be a believer. None of my amps have the "trick" any more.

Cheers,

Gil

IMO
If you think your amp is a little bright sitting on the bench or in your living room, by the time you get to a gig with full band and can open it up a bit it will be perfect because that is where you LIVE!!..


Enjoy the feedback.

Tony

[bluesfendermanblues]

I fully agree with Gil regarding not to dampen the OD channel's highs with a treble bleed cap.

The only damping I like, stem from the dumbleator and I even compensate by having the 68p cap on the master to regain brightness. My amps are not bright in an unpleasant way.

@ 'jazzyjoepass' a new amp is usually bright and a bit edgy. However, this will change after some burn-in time. You can speed up the burn-in process by attaching a CD player to the amp input and play music or even better 'pink noise'. Let it play non stop for about 1-2 weeks and voilá ...you got a very different amp that is not as edgy, but bright in an pleasant manner. This is not theory but facts.

It doesn't have to be loud and you can put a dummy load resistor on the speaker out.

I wouldnt do any tricks or mods to any amp before it has been played/burned-in properly.

[ayan]

IMO
If you think your amp is a little bright sitting on the bench or in your living room, by the time you get to a gig with full band and can open it up a bit it will be perfect because that is where you LIVE!!..


Enjoy the feedback.

Tony

Absolutely. And when recording, I have even used the Dumbleator bright switches (one or the other, depending on the situation). In my experience, a bright recorded guitar can be mellowed out in the mix, a dull recorded guitar sound is hopeless.

Gil

[amplifiednation]

I fully agree with Gil regarding not to dampen the OD channel's highs with a treble bleed cap.

The only damping I like, stem from the dumbleator and I even compensate by having the 68p cap on the master to regain brightness. My amps are not bright in an unpleasant way.

@ 'jazzyjoepass' a new amp is usually bright and a bit edgy. However, this will change after some burn-in time. You can speed up the burn-in process by attaching a CD player to the amp input and play music or even better 'pink noise'. Let it play non stop for about 1-2 weeks and voilá ...you got a very different amp that is not as edgy, but bright in an pleasant manner. This is not theory but facts.

It doesn't have to be loud and you can put a dummy load resistor on the speaker out.

I wouldnt do any tricks or mods to any amp before it has been played/burned-in properly.

Many people have recommended leaving the amp on for 1-2 weeks, or even as much as a month to burn it in. I did a 40 hour burn in with my 102 and it made a huge difference. 4hrs on 4hrs off for 80 hours.

I was nervous to leave it on continually when out of the house or when sleeping though. Is the thought to just leave it playing like truly "non-stop"? I get worried about a fire, especially with my dogs in the house when I'm not home.

I have a newer 2nd gen, about 6 months old that I didn't burn in at all...maybe it's time for a pink noise session.

[talbany]

IMO
If you think your amp is a little bright sitting on the bench or in your living room, by the time you get to a gig with full band and can open it up a bit it will be perfect because that is where you LIVE!!..


Enjoy the feedback.

Tony

Absolutely. And when recording, I have even used the Dumbleator bright switches (one or the other, depending on the situation). In my experience, a bright recorded guitar can be mellowed out in the mix, a dull recorded guitar sound is hopeless.

Gil

I had the unique honor of visiting several Nashville's elite studios and sit in on some really cool recordings..The amp room was totally separate and just for the guitar amps only so they could set their amps how they wanted them, they all set them pretty bright...When I asked Jeff King (one of Nashville's top 5 recording artists) he told me the same thing..

a bright recorded guitar can be mellowed out in the mix, a dull recorded guitar sound is hopeless.

..There you go!!

All The Best!!

Tony

[jazzyjoepass]

I agree with that too, as I do live sound mixing and I'm always telling the guys give me tones that cuts thru the mix ...

Absolutely. And when recording, I have even used the Dumbleator bright switches (one or the other, depending on the situation). In my experience, a bright recorded guitar can be mellowed out in the mix, a dull recorded guitar sound is hopeless.

Gil