Dumbleland Anyone?

[talbany]

I believe Dumble experimented with tube types for the PI/Drivers on these DL and SSS style builds. For example, I believe SSS #002 came stock with 12AX7/7025 types in the PI and Cathode Follower positions, whereas I believe by SSS #005 he used a 12AT7 in both positions (I'm saying this based on the fact that Bludotone and Taylor at Amp Nation both use 12AT7s in those positions for their #005 clones, and I consider them to be the most knowledgeable in the community with respect to that amp). Interestingly, Brandon does an SRV voiced "Hi-Plains Drifter" amp (his version of an SSS), and he calls it the "Bludoland" voicing, and says it comes stock with a 12AU7/12BH7 compliment (see here: https://www.youtube.com/watch?v=Y95zbzaOfT0. Sure, I suppose you could use a 12AU7/12BH7 for a #002 style DCCF setup, so I can't say with any certainty whether it's true that SRV's SSS amps had the AC-couple DL style driver instead of #002 style DCCF, but it's just food for thought. There's is a quote from Dumble that's been posted often here where Dumble hints that SRV's SSS is "more like a Dumbleland with reverb than an SSS," so that might be the inspiration between Brandon's spec choice. Definitely though with respect to the Dumblelands that Two-Rock has had on their bench, in my discussions with them it was an AC-Coupled Driver setup, 12AU7/12BH7.

Here is the schematic i have of #002 taken from the original schematic AFAIK.
Although Brandon was the 1st to introduce SSS 005 first IIRC 002 was not far behind and both myself and Bill (Sebago) and several others originally built ours with BH7 we quickly changed it to an AT. I vaguely remember other builders using an AT or an AX for guitars. Everyone was talking to everyone else here and in PM's.Not sure what Brandon originally settled on though.

SSS - 002 LTPI & power amp.bmp

Here is a post from Bruce Egnater who was called to service SRV's SSS according to Alexander he said the amp was similar to that of an SVT ie..DC coupled..BTW.Given the volume SRV used to play it wouldn't surprise me if his had an AU and BH7 setup
http://www.ampbuildingclass.com/my-srv-story.html

Tony

[talbany]

Based on my personal perception there's some common denominator - at least in regard to the tone of a Dumbleland Special 150W vs. a SSS 150W:
Dumbleland Special 150W: (in a nutshell) more on the silky side of tone ("Velvet Glove" harmonics)
Usual SSS150W: (in a nutshell) more on the glassy side of tone and a little bit more aggressive
SRV-SSS150W: Somewhere in between: A bit more glassy than a DL Special, but a bit less glassy and less aggressive than a usual SSS150W.
And in my perception the clean headroom of the DL-Special and the SRV-SSS is larger and their attack is a bit quicker and more responsive.

Cheers,

Max

Thanks Max!
I am completely confused now!

[Max]

... My point is that the basic topolgy is the same throughout the series, with differences from amp to amp. But this is true for the ODS and ODR amps as well -- sure, no two ODS amps are the exact same, even those with the same era voicing (Classic, Skyline, etc), but they all share far more in common in basic circuit topology than they do differences. At least in my opinion. ...

A. Dumble in the year 1985:

"Basically, I've kept the Overdrive the same but the other models ... [Max: DL, SSS, etc.] ... are open to flexibility." https://tubeamparchive.com/viewtopic.php?f=4&t=22012

My recommendation: Believe him.

@talbany: Confusion often is where our preconceptions falter and some fresh ideas get a chance. Cognitive bias https://www.youtube.com/watch?v=ZNeD2a95ROE, attention bias https://www.youtube.com/watch?v=IGQmdoK_ZfY, confirmation bias https://www.youtube.com/watch?v=B_YkdMwEO5U, etc. can all be very powerful .

Cheers,

Max

[talbany]

Max
Thanks for the videos as they made me


There you go again taking things out of context! .. I said I was confused about this description you posted and how one is to determine what type of circuits was used in the Dumbleland vs The SSS specifically the driver circuit. So I will clarify..Terms I think he is referring to?? to define the sound of the DC driver could be Silky and the AC driver a bit more aggressive (I guess)

Dumbleland Special 150W: (in a nutshell) more on the silky side of tone ("Velvet Glove" harmonics)

For me he is describing a DC driver

Usual SSS150W: (in a nutshell) more on the glassy side of tone and a little bit more aggressive

This would be a AC driver (SSS's don't have AC drivers)

SRV-SSS150W: Somewhere in between: A bit more glassy than a DL Special, but a bit less glassy and less aggressive than a usual SSS150W.

This one is a little of both

A

nd in my perception the clean headroom of the DL-Special and the SRV-SSS is larger and their attack is a bit quicker and more responsive.

I would put quicker and more responsive under DC driver.I guess..Now he is describing attack time? what happened to aggressive/Silky?

The term "aggressive" is more generally associated in context with some kind of distortion characteristic as to when or possibly how an amp breaks up is a bit of a contradiction, since both the AC and DC drivers are designed to prevent output tube distortion? increase headroom therefore for me is unclear as to what what he is referring too when he uses the word "Aggressive"?
But then again I am not exactly sure what he is talking about when he say's things like this either??

my amps have the low end of feeling of You feel like you're floating on a football field filled with marshmallows.

Thanks for posting an old article i already posted years ago https://tubeamparchive.com/viewtopic.php?f=4&t=22012


Tony

[jfs322]

I'm again confused as to what's going on here. I don't think you can make broad generalizations about the sound/feel any one particular driver type (AC-Coupled vs DC-Coupled), as my understanding from speaking to boutique builders over many years of friendship is a common theme: "It's all about the implementation in the context of the rest of the circuit." If you're sophisticated enough, you can voice either driver style to be whatever amount of silky, glassy, velvety, etc., insert adjective here that you want. So I would caution against any generalizations of AC = Silky, or whatever, and DC=Glassy, or vice versa. "It's all about how you implement it." For example, my DL style build from the guys at Two-Rock uses an AC-Coupled Driver from the DL amps they had on their bench, and yet it's got enough glass in it to take your head off, if you want to set it that way.

And Max, with respect to your comment about Dumble saying he had more flexibility in the DL models, I think his statement is actually consistent with what I have been saying. I've never said every DL amp is exactly alike, but my point is that they likely all share 85%-90% of the basic design, and the "flexibility" Dumble is referring to is the tweaks around the edges, like tonestack, adding in reverb/tremolo if asked by the customer, power section value tweaks. But I don't consider these "flexibility" tweaks to constitute radical changes, perhaps you do. I don't think by "flexibility" he means he threw out the playbook with each Dumbleland and kept nothing similar except the DL name on the chassis, if that's what you're trying to suggest. In any event, I know of at least two Dumblelands that have that 12AU7/12BH7 PI/AC-Coupled Driver network, based on my years friendships and discussions with the guys who actually had those amps on their bench. If you somehow have more inside-knowledge on more DL amps than that, first I'd be surprised, and second, please do share because I am happy to be proven wrong. Something tells me, though, that you don't. So you can choose to take the inside info I'm trying to share with the community or not, but I'm not sure what else to tell you at this point...

[talbany]

I'm again confused as to what's going on here. I don't think you can make broad generalizations about the sound/feel any one particular driver type (AC-Coupled vs DC-Coupled), as my understanding from speaking to boutique builders over many years of friendship is a common theme: "It's all about the implementation in the context of the rest of the circuit." If you're sophisticated enough, you can voice either driver style to be whatever amount of silky, glassy, velvety, etc., insert adjective here that you want. So I would caution against any generalizations of AC = Silky, or whatever, and DC=Glassy, or vice versa. "It's all about how you implement it." For example, my DL style build from the guys at Two-Rock uses an AC-Coupled Driver from the DL amps they had on their bench, and yet it's got enough glass in it to take your head off, if you want to set it that way.

I get your point as to how someone chooses their adjectives to describe the differences is of course debatable especially in the context of entire amplifier and how you set it up.This is what makes this so difficult when trying to determine one circuit out of an amp while in context with everything else that is going on especially one with the hi/low filters with a multitude of different setting variations .So when someone is describing the whole amplifier in 2 words and we are suppose to determine if it's AC or DC coupled is in of itself confusing, impossible and quite frankly ridiculous.
So here are the design characteristics between the 2 circuits and how they affect the sound and feel of the performance of the output section I will attempt to put a face to a name.

Aggressive?=The main advantage to the cathode follower directly into power tube grids (DC coupled) is losing the effects of grid-blocking from the coupling caps recharging and causing momentary distortion when power tube grid current occurs. The amp is overall tighter (electrically) without the time constant of the coupling caps. This is why I think of the DC coupled as being less aggressive than the AC coupled. No coupling caps.

Silky=There also seems to be an added transparency, clarity and overall sheen to the tone with the DC driver due to the elimination of the coupling caps.. Since the driver tube no longer has to drive a bias network or the miller effect of the multiple power tubes, I think overall bandwidth is improved a little bit as well.

3.When you add the coupling caps your also changing the RC time constant of recovery, therefore slowing the response/attack time ..This is what I think Dumble is referring to in his description of speed,so this makes some sense to me
The main effects here being AC utilizes coupling cap and DC does not (direct coupled)

Hopefully this clarifies some of my cork sniffer terminology..
Fascinating discussion

Tony

[Max]

AC/DC? : https://ampgarage.com/forum/viewtopic.p ... 84#p130484

And just in case someone here likes looking for easter eggs :

How many of these amps have DL on the front or back:

Dumble.jpg

Correct answer will be rewarded !

Have fun and all the best,

Max

[talbany]

So doing some digging and ran upon this little "easter egg" from Max describing the reverb type and where it was mixed in the DL-300SL (similar to SSS#005)
Apparently knows the reverb pretty well.

I recall the Reverb recover/mixer and recover from the filters as being the same tube in the more modern incarnations. the early one actually mixed at the master via cathoe folowers!

https://tubeamparchive.com/viewtopic.php?p=66313#p66313

The early SSS 100Watt I know did indeed have more preamp tubes (3 for the reverb-circuit) than the later SSS 150W or the DL-300SL with reverb, where the mixer tube is the recovery amp after the filters too. The blackface 300SLs with reverb from the eighties as far as I know have the same tube constellation (preamp) as the SSS 150 you have worked on.

Reverb's done.
Tony

[Max]

Just to avoid misunderstandings:

... Max describing the reverb type and where it was mixed in the DL-300SL (similar to SSS#005)

This isn't my description, it's Brandon's:

I recall the Reverb recover/mixer and recover from the filters as being the same tube in the more modern incarnations. the early one actually mixed at the master via cathode folowers!

... later SSS 150W or the DL-300SL with reverb, where the mixer tube is the recovery amp after the filters ...

That's just repeating what Brandon wrote in his previous post.

The blackface 300SLs with reverb from the eighties as far as I know have the same tube constellation (preamp) as the SSS 150 you have worked on.

That's just repeating what's written by A. Dumble in the tube complements of his data sheets for the SSS150W and for the DL300SL.

Have a nice weekend!

Max

[talbany]

Just to avoid misunderstandings:

... Max describing the reverb type and where it was mixed in the DL-300SL (similar to SSS#005)

This isn't my description, it's Brandon's:

I recall the Reverb recover/mixer and recover from the filters as being the same tube in the more modern incarnations. the early one actually mixed at the master via cathode folowers!

... later SSS 150W or the DL-300SL with reverb, where the mixer tube is the recovery amp after the filters ...

That's just repeating what Brandon wrote in his previous post.

The blackface 300SLs with reverb from the eighties as far as I know have the same tube constellation (preamp) as the SSS 150 you have worked on.

That's just repeating what's written by A. Dumble in the tube complements of his data sheets for the SSS150W and for the DL300SL.

Have a nice weekend!

Max

I see Brandon quoted the entire page so it was difficult to see who quoted who?

https://tubeamparchive.com/viewtopic.php?p=66244#p66244
In this previous post you wrote

The most important technical differences vs. a Dumbleland are (so far as I remember right now) are:Different use of the two systems of the second - second in the sense of the "signal path without reverb" (if such a thing really exists in an AC frequency amplifier, but it is perhaps a suitable image) - preamp tube, that, as far as I remeber (Brandon, please help: do I remeber this right?) in SSS is both, the recovery amp after the Filters and the reverb mixer. This will make (If I remeber right) of course a difference in sound.

You are still correct however what you are describing is the 3 tube reverb that is in #004 and the one Brandon is talking about is SSS#005 (mixing the reverb before filter recovery) and then there is this one?

I recall the Reverb recover/mixer and recover from the filters as being the same tube in the more modern incarnations. the early one actually mixed at the master via cathoe folowers!

That is now known as the "Tweed Mixer" ie mixed at the followers.
So in this conversation you guy's were discussing 3 different reverb topology's

Back to the Driver!
In an earlier post you wrote this about the "Pentode amp"

"Silver-Aligator" "Pentode-Dumbleland" (the one that came back to US from Japan and was sold at Overland Express) was the "sustain master" (After hitting a chord you always looked around and asked yourself "where is the compressor"?). Ok, I will come back later to these differences in sound.

This to me sounds like you are describing the unmistakable compressor effect that you can only get out a DC coupled Driver (with a little help from EF-86 front end)..IMO Again you wrote

Tubes and their function after what I remember what this tech told me concerning this: 2xEF (input, recovery after EQ), 7247 (reverb mix), 7025 (reverb return), 12AX7 (tremolo), 5751 (reverb send), 7025 (phase inverter), 7025 (driver), 4 x 6550A.

It did put out around 140 Watts without any distortion and had an unusual high plate voltage (output tubes) for a Dumbleland.

7025 PI 7025 Driver..The sustain/compression effect you were hearing was IMO done with the dual 7025 Pi/driver combo.
a 12au/12BH7 combo will not have as drastic a "sustain" like compressor effect due to the much lower gain structure in the Au/BH combo with the AC coupled one..Although this pair would deliver more punch due to it's higher current handling capabilities (better for Bass)
The sound would be cleaner and notes would decay faster and not have the same compression ratio as the 7025..This would for me be rather obvious..How do I know this? because I've built and played both circuits in both bass and guitar amps So a logical question would be? Have you ever played an amp w/ DL written on it(w/ or wo/ reverb) that had this "compressor" like built in quality?
Brandon (describes the same effect)

What I loved about them is that the cleans would sustain endlessly, "Sing" if you will, and I didn't miss overdrive at all.

finally? you wrote

Someone with a bit more of technical knowledge than me, once listening to the "Pentode Amp", later told me, that there must be something going on inside that has the effect of a "generator" of second order harmonics.

DC coupled cathode followers when pushed into clipping generate...Here it comes....2nd order harmonics

Happy Easter!

Tony

[Max]

... it was difficult to see who quoted who?

Indeed. My fault.

... what you are describing is the 3 tube reverb that is in #004 ...

No. I'm describing (at least this was my intention) a difference once explained to me between a Dumbleland Special 150W without reverb and a SSS 150W with reverb. But of course: Perhaps I didn't understand correctly what once was explained to me or/and perhaps I didn't remember correctly what once was explained to me or/and perhaps the people explaining this to me just have been wrong.

... compressor effect that you can only get out a DC coupled Driver ...

I've been told different. But of course: Perhaps I didn't understand correctly what I've been told or/and perhaps I didn't correctly remember what I've been told or/and perhaps the people telling me this have been wrong.

But perhaps all this doesn't matter any longer anyway: AFAIU you correctly, the perceivable difference in tone between AC-coupling vs. DC-coupling is obvious. So after listening again to this track https://ampgarage.com/forum/viewtopic.p ... 84#p130484 you now will be sure anyway what kind of power amp is inside the chassis of at least this Dumbleland Special 150W. And in regard to what's inside Jackson Browne's Dumbleland Special 150W - reportedly used for recording "Texas Flood" - you will of course know anyway just by listening to "Texas Flood".

Happy Easter!

Max

[talbany]

But perhaps all this doesn't matter any longer anyway: AFAIU you correctly, the perceivable difference in tone between AC-coupling vs. DC-coupling is obvious. So after listening again to this track https://ampgarage.com/forum/viewtopic.p ... 84#p130484 you now will be sure anyway what kind of power amp is inside the chassis of at least this Dumbleland Special 150W. And in regard to what's inside Jackson Browne's Dumbleland Special 150W - reportedly used for recording "Texas Flood" - you will of course know anyway just by listening to "Texas Flood".

Happy Easter!

Max

I've been told different. But of course: Perhaps I didn't understand correctly what I've been told or/and perhaps I didn't correctly remember what I've been told or/and perhaps the people telling me this have been wrong.

Max
What I pointed out in my previous post addressed this so called built in compressor effect both you and Brandon experienced. After playing and building several SSS's with this type of driver I too experienced this effect the 2 of you described (perfectly) as well! I did not get this same effect when playing through the BH7 and 12AU7..So again I am simply asking if you've experienced this same type phenomenon with any other Dumbleland amplifier? (not what you know or have been told about it technically?)

As far as the sound clips go it is virtually impossible to detect this "compressor" effect in most recordings due to all the variables involved from things like compression added during the recording and formatting processes/conversion as well as the amp's setup like volume levels trimmer/gain settings pickup output. Speaker types etc..So IMO this is something the player best experiences connected to the instrument that inspires him/her in some artistic direction
So for me to try and speculate on this clip would be just a guess.

BTW In our thread about ODSR #13's reverb I took the time to answer all the questions you asked me about the different reverb designs I knew HAD used in some of his amps for you. I didn't throw clips at you and had you try to guess which was which first
So if you know great! I would appreciate it!. if you don't know thats fine too let us know
otherwise let's move on.
https://ampgarage.com/forum/viewtopic.php?f=4&t=34339

Tony

[Max]

... So if you know great! I would appreciate it!. if you don't know thats fine too let us know ...

I've already posted in this thread (and in others - some you quoted here) my own anecdotal observations and impressions and also - as far as I still remember - what I was told in regard to the more technical aspects of this topic by some (at least AFAIK) experienced professionals.

All the best,

Max

[talbany]

... So if you know great! I would appreciate it!. if you don't know thats fine too let us know ...

I've already posted in this thread (and in others - some you quoted here) my own anecdotal observations and impressions and also - as far as I still remember - what I was told in regard to the more technical aspects of this topic by some (at least AFAIK) experienced professionals.

All the best,

Max

Great Max!
Then perhaps you should ask your

experienced professionals

next time you have a question regarding reverb circuits used in the SSS's and ODSR's

Tony

[pompeiisneaks]

I would like to ask that the high school antics be put somewhere else here, and not in this forum. IF you don't agree that is fine, no need to throw sideways swipes at one another over and over. I've been watching this thread hoping it would mellow out and it keeps seeming to get closer and closer to flame war territory, lets agree to be adults and calm down.

~Phil