Dumbleland Anyone?

[jfs322]

Just to avoid misunderstandings:

AFAIR the individual amps from the "series of amplifiers" (A. Dumble) with DL written on their front or - sometimes - only on their back (e.g. "DL-150VG") are all different: different tonestacks, different feedback circuits (preamp), different filter circuits (or no filters at all), at least one with an overdrive circuit, at least one with a tremolo circuit, with reverb (e.g. price list May 15, 1978: Dumbleland Special 150W with reverb $1,760.00), without reverb (e.g. price list May 15, 1978: Dumbleland Special 150W without reverb $1,410.00), different power amp circuits, different power supplies, different transformers, different chassis dimensions (e.g. long chassis with all tubes in one row, shorter but deeper chassis with all tubes in two rows), different layouts etc.. And because of all these different circuit specs, layout specs, transformer specs, etc. ... , they all sound more or less different, even though you can read DL on all their chassis.

Cheers,

Max

I think the real answer lies somewhere in the middle between my position and yours. Of course, I will admit that my understanding of the one Dumbleland that TR had on its bench doesn't necessarily mean that all Dumblelands are the same, but at the same time, I don't think it would be accurate to assume that all Dumblelands are completely different. I don't think Dumble threw out the playbook with each Dumbleland amp and made each radically different from each other. I think he started with a basic foundation of what he imagined the "Dumbleland" series to be, and made tweaks to each to suit each customer's needs. But I don't think these were radical changes that make each Dumbleland radically different from each other. I think it's similar to, say, a Fender blackface series amp: Some were offered with reverb and/or tremolo; different transformers, different power supplies, and different chassis dimensions were used for the different wattages, and there are different tonestacks/feedback arrangements for some of the larger wattage models. But does that mean that these amps are "completely different"? In my mind, no. They have some differences, but in the end they all share the same basic circuit topology that was set by design for amps of that "series." And in this respect, I think Dumble's "series" amps are no different, given what I have learned of his amps and of the business mindset of current boutique builders who operate similar "custom amp" services. In other words, that they set on a basic topology for the given amp "series," and tweak each amp in the series based on the customer, but the basic topology remains the same. So are all Dumblelands different from each other? Yes, but I think those differences are more a difference in degree not necessarily a difference in kind. I suspect they all share the same basic topology, the customer-specific voicing tweaks nothwithstanding.

[Max]

... I don't think it would be accurate to assume that all Dumblelands are completely different. ...

I'm neither assuming (I'm remembering) nor writing "completely different".

Cheers,

Max

[jfs322]

... I don't think it would be accurate to assume that all Dumblelands are completely different. ...

I'm neither assuming (I'm remembering) nor writing "completely different".

Cheers,

Max

Not explicitly stated, yes, but perhaps I misunderstood your point. My reading of your point that "all Dumblelands are different" and listing all those differences meant that each Dumbleland is significantly different from the next. If I misunderstood your point, I apologize. My point was that sure, each Dumbleland may have slightly different specs (such as tonestack values, etc.), but I think they share far more in common with each other than they are different. 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.

[Max]

... share far more in common in basic circuit topology than they do differences. ...

And what specific "basic circuit topology" do all the Dumble amps with DL written on their front (or back) share in common?

[jfs322]

... share far more in common in basic circuit topology than they do differences. ...

And what specific "basic circuit topology" do all the Dumble amps with DL written on their front (or back) share in common?

As I mentioned above, the Phase Inverter and AC-Coupled Driver topology (mostly 12AU7 PI/12BH7 Driver complement, but there may have been different tube complements over the years) derived from the Winterland/Odyssey line of amps. When I think of Dumbelands, that's the circuit aspect that distinguishes the series in my mind. Of course, I have not been inside every Dumbleland amp, but that knowledge is from a several years long friendship, hundreds of emails, and dozens of phone calls with guys who have been inside of multiple Dumbleland/Winterland/Oddysey amps. Sure they haven't been inside every Dumbleland amp ever built, but I suspect they've been inside more than most on here. And to the extent you've been inside any, I'm happy to be proven wrong.

[talbany]

Here is a Dumbleland "Overdrive Special. a friend sent What looks to be an early 2nd Generation w/ AC coupled follower 12AU/BH7 combination..Judging by the description he gives of the amp in the article? I vote AC Driver for this one although this is still a guess

CCI_000011.jpg

Tony

[talbany]

Just to avoid misunderstandings:

AFAIR the individual amps from the "series of amplifiers" (A. Dumble) with DL written on their front or - sometimes - only on their back (e.g. "DL-150VG") are all different: different tonestacks, different feedback circuits (preamp), different filter circuits (or no filters at all), at least one with an overdrive circuit, at least one with a tremolo circuit, with reverb (e.g. price list May 15, 1978: Dumbleland Special 150W with reverb $1,760.00), without reverb (e.g. price list May 15, 1978: Dumbleland Special 150W without reverb $1,410.00), different power amp circuits, different power supplies, different transformers, different chassis dimensions (e.g. long chassis with all tubes in one row, shorter but deeper chassis with all tubes in two rows), different layouts etc.. And because of all these different circuit specs, layout specs, transformer specs, etc. ... , they all sound more or less different, even though you can read DL on all their chassis.

Cheers,
Max
Max

Max?
Staying within the context of our conversation... So are you saying that you've actually played or know of a Dumble amp that says Dumbleland on it (any Dumbleland) that has a DC coupled cathode follower driver circuit (SVT Style) inside the amplifier..A simple Yes or No is really all we need right now
Thanks.
Tony

[Max]

AFAIU jfs322 correctly, he wrote: AC-coupled = at least one 12BH7 in the PI/Driver tube complement (e.g. DL #009, DL300SL, at least one of SRV's black SSS amps, etc.). Having said this: One of the Dumble amps I know with DL written on the chassis doesn't have at least one 12BH7 in its PI/Driver tube complement (PI and driver both 7025). So - If I understood jfs322 correctly and if the association AC-coupled = at least one 12BH7 is correct - this amp might have a DC-coupled PI/Driver topology.

Cheers,

Max

[jfs322]

AFAIU jfs322 correctly, he wrote: AC-coupled = at least one 12BH7 in the PI/Driver tube complement (e.g. DL #009, DL300SL, at least one of SRV's black SSS amps, etc.). Having said this: One of the Dumble amps I know with DL written on the chassis doesn't have at least one 12BH7 in its PI/Driver tube complement (PI and driver both 7025). So - If I understood jfs322 correctly and if this association (AC-coupled = at least one 12BH) is correct: - this one might have a DC-coupled PI/Driver topology.

Cheers,

Max

Correct -- although I believe the AC-Coupled PI / Driver setup is interchangeable in terms of tube type and not necessarily limited to just the 12AU7/12BH7 combo; I just mentioned that combo because that's the combo I've seen most commonly in the Dumbleland style AC-Coupled Driver. So it's possible that the Dumbleland you referred to, with 7025 tubes, could still be AC-Coupled Driver instead of a DC-Coupled Cathode follower, but I am not familiar with that specific amp so I cannot say for certain. Most of the DL amps I am familiar with are that 12AU7/12BH7 AC-Coupled Driver setup, but it's possible Dumble tried different tubes in that setup as well.

[Max]

If there's no firm association between the PI/Driver tube comlement and AC-coupled vs. DC-coupled (sorry for my misunderstanding), I have no idea, if the amps with DL written on their front or back have an AC-coupled PI/Driver topology or a DC-coupled.

Cheers,

Max

[talbany]

BTW: Isn't it rather obvious from pictures, if there's at least one long nine-pin tube in the PI/Driver tube complement of some Dumble amp with DL written on the front or back?

Yes it's obvious,however this still does not tell us if it's AC driven or DC driven since both use 12BH7 nine pin tube as it's driver.
As far as the LTPI spot goes 12AU/7025 either tube can be used in this circuit as well.It just depends on how you set it up..
BTW...It is my understanding that he prefered the 12 AU in his cleaner type amps for either P.A or Bass and for his guitar amps he used a 7025 for the added gain needed and most guitar players would have preferred..IMO

f there's no firm association between the PI/Driver tube comlement and AC-coupled vs. DC-coupled (sorry for my misunderstanding), I have no idea, if the amps with DL written on their front or back have an AC-coupled PI/Driver topology or a DC-coupled.

Cheers,

Max

Got it Thanks!

Tony

[Max]

... for his guitar amps he used a 7025 for the added gain needed and most guitar players would have preferred...IMO

Tony, IMO the content of the 1986 price schedule leaves no doubt, that a "Dumbleland Special 150W" is a guitar amp. The bass amp is the "Dumbleland Bass 150W" listed in this price schedule.

All the best,

Max

[talbany]

So here is a description of the DC Coupled Driver used in the SVT and SSS Ser #002 by a one Andy fuchs taken from my notes a long time ago. I figure i would post it again here since i think his description is spot on

The main advantage to the cathode follower directly into power tube grids 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.
DC Coupled
There seems to be an added transparency, clarity and overall sheen to the tone with that style of driver for sure. Not sure it's for everyone, but I like it. The amp just sounds bigger and has more authority. 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. It can give a tighter more controlled and extended bass too. I think part of the clarity is the added bandwidth and speed, no capacitor being present (and the sound any cap might bring). When you run regulated lower voltage screens the grid swing and bias voltage is somewhat lower, so I think the power tubes run out of power well before the driver starting doing wacky things.

The AC coupled is slightly different? It has a slower response time due to the added capacitor, you also get the added color of the sound of the cap. The sound is still very clean and helps prevent blocking distortion however as H.A.D puts it doesn’t have the silky or glassy texture that the DC coupled one has. It is however interesting don't you think that S.R.V used a Dumbleland to record Texas flood and yet when he built Stevie his S.S.S's he used the DC coupled driver?
For me personally both serve a purpose however if i were to choose 1 over the other it would be the DC Driver, Mainly due to it's bigger sound and natural compression makes it such a fun amp to play.
the other option of course would be using just the straight LTP PI. Either way these high powered monsters make for wonderful pedal platforms. ( never knew my tube Screamer to be this punchy ) That with a little reverb in front or in the loop will give you an enormous sound and along with the filters can be extremely versatile and for any guitar.

For the sake of authenticity I will draw up a schematic for both AC and DC for the builders/players preference. I still have some more research to do and will get a few more opinions so feel free to comment!!

Thanks everyone for helping out and hopefully we can get some of Ryans chassis made

Tony

[jfs322]

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.

[Max]

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