Kitty Hawk (actual Dumble?) for sale

[oldmacman]

https://reverb.com/item/90631533-kitty- ... ve-special

This looks like an actual Dumble that had a different logo placed on it. Serial is marked as "A048". And they posted a gut shot -- see attached!

The circuit looks a lot like the schematic for #0049 that I posted, including the .047 mid cap. But there are a few differences: the 220k grid resistor on V1b is not bypassed with a 500pf capacitor, and there are some odd values for the resistors following V2a and V2b (these are carbon comp resistors, which I haven't seen Dumble use in many ODSes, so maybe they were modified after the fact?)

[Max]

If I remember correctly, carbon film resistors (e. g. Allen Bradley) are not that uncommon in Alexander Dumble's early ODS and ODRS amplifiers in his 1st, 2nd, and 3rd generation chassis. Here's just one example:
https://www.instagram.com/p/DCjNOPROGIw/

[alnight]

That's very interesting. Thanks!

[Matt J]

Interesting!
Fascinating to see how the output of V2 is set up. There doesn't seem to be a 180k resistor to ground from the 1M/10nf junction and I'm curious what the value is of that mica cap bypassing that 1M?
Maybe it was modded by HAD or Kitty Hawk at a later date where they added in the PI balance pot too?
Matt J.

[Smitty]

Pic from this post:
https://ampgarage.com/forum/viewtopic.p ... d&start=60

Dumble-#40-(1).jpg

And the Kitty Hawk from above:

[Richard1001]

As i'm sure you all know, the story is that the Roy brothers imported Dumble and Mesa boogie amps in the late 70's before making their own amps under the Kitty Hawk brand. They supposedly also imported a Dumble export model which was only the assembled chassis without transformers, tubes and cabinet to save shipping costs. The early Kitty Hawk amps where close copies of Dumble and Mesa amps, although they made quite a few mistakes that compromised the sound and reliability.

I found some pictures of a Kitty-Hawk Dumble clone:

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[Max]

You're absolutely right. The internal components (transformers, cables, electronic components, etc.) of the ODS replicas from Kitty Hawk shown in the pictures you posted do indeed look completely different from the internal components of the Overdrive Special offered on Reverb with (according to the product description on Reverb) the modified logo.

As far as I remember, however, the "Standard" and "Custom" models have more technical and sonic similarities to a Boogie Mark I and Mark II than to a Dumble Overdrive Special.

Incidentally, as far as I know, the reason for producing these ODS replicas, as well as the "Standard" and "Custom" models, was the very long delivery times of Dumble and Mesa in the late 70s and early 80s, which were, at least from the customer's perspective, completely unreasonable, and of course not so great for cash flow either..

By the way: If you want to learn more about the history of Kitty Hawk, you no longer have to rely on rumors since you can now contact the Roy brothers directly via their Instagram account:
https://www.instagram.com/kittyhawk_dum ... s_roybros/

Interesting! Fascinating to see how the output of V2 is set up. There doesn't seem to be a 180k resistor to ground from the 1M/10nf junction and I'm curious what the value is of that mica cap bypassing that 1M? Maybe it was modded by HAD or Kitty Hawk at a later date where they added in the PI balance pot too?
Matt J.

To me, as a layperson when it comes to amplifier circuits, the OD and PI circuits of the Overdrive Special with the modified "Kitty Hawk" logo offered on Reverb seem – at least at first glance – to look quite similar to the two corresponding circuits in this other Overdrive Special with AX7 PI. Or am I wrong?:

special OD circuit.jpg

AX7 PI.jpg

[oldmacman]

To me, as a layperson when it comes to amplifier circuits, the OD and PI circuits of the Overdrive Special with the modified "Kitty Hawk" logo offered on Reverb seem – at least at first glance – to look quite similar to the two corresponding circuits in this other Overdrive Special with AX7 PI. Or am I wrong?:

No, that looks exactly right -- good catch! It's the same OD entrance and V2a/V2b changes that I noticed. I wonder why they made the change. If I get a few minutes, I'll run it through LTSpice -- my gut feeling is more bass and less treble.

Max, which ODS are your photos from?

[Max]

Until now, I've only seen this OD version in two ODS amplifiers. One with a serial number below 20 (which is where the two photos come from) and a second with a serial number between 20 and 30.
So the one now offered on Reverb with the modified logo according to the ad text, is the third one I've ever seen up to now.

[Suckseeder]

Those are from one of those 20 Kitty Hawk Dumble Clones that were made. Sold on Ebay long ago.

[Max]

Thanks for these additional images to show that the chassis, circuitry, components, and build quality of the replicas made by Kitty Hawk are completely different from the chassis, circuitry, components, and build quality of this "Kitty Hawk" Overdrive Special on Reverb, which, according to the Reverb ad text, was exported to Europe by A. Dumble, where the original logo was replaced by the "Kitty Hawk" logo.

… It's the same OD entrance and V2a/V2b changes that I noticed. I wonder why they made the change. …

I don't know why A. Dumble didn't use the OD circuit more typical of his export models (see: https://ampgarage.com/forum/viewtopic.php?f=5&t=12870) in this "Kitty Hawk" ODS or in the two ODS amps I know with with a similar OD circuit and the usual "Overdrive Special By Dumble" logo. But of course, in principle, one could ask the Roy brothers via their Instagram account if they still know.
Because according to the ad text on Reverb, they imported this Overdrive Special to Europe before modifying its logo for their endorsement marketing. And in my personal opinion, the pictures shown in the Reverb ad don't provide any clear evidence that the circuitry of this Overdrive Special was modified by the Roy brothers after it was imported. So perhaps the Roy brothers still remember why they ordered this Overdrive Special from A. Dumble with such an OD circuitry?

[Smitty]

Is there consensus that the Kitty Hawk on Reverb is in fact an amp built by Dumble? Is this the earliest use of Tandy Wire & Cable coax? The amp pic I reposted for comparison has grey coax, which is consistent with other amps from that time period. I don't know why Kitty Hawk would have used Tandy coax if this is a replica.

[Max]

In the pictures from the Reverb ad, I think the gray Colombia Flexfoam cables running from the FET input jack to the FET board and back are clearly visible. However, I don't see a cable labeled "Tandy" in these pictures, perhaps because, as far as I know, over time (and due to dwindling supplies?), A. Dumble initially replaced the other Colombia Flexfoam cables in his Overdrive Specials with an all-black, unlabeled RG59 cable.

Regarding this cable without markings, member GPD expressed the opinion in this thread https://ampgarage.com/forum/viewtopic.php?f=4&t=31940 that this black, unmarked cable is also a Columbia cable:

... Regarding Dumble's use of RG59...yes, many examples have Tandy branded cable inside...but I can confirm, without a doubt, that he used Columbia brand RG-59 in more than one amp...how do I know this? Well, I've seen it with my own two eyes. So you might wish to add this to the encyclopedia on Dumble products that you have been assembling. http://www.electricstringedinstrument.c ... a_1112.jpg

The discussion in this thread was sparked by the question of which details could be used to determine the authenticity of the ODS discussed there at the time.

Over time, A. Dumble increasingly used the black RG59 cable labeled “Tandy” in his ODS amplifiers and then increasingly the white ones.

[Smitty]

Thanks, Max!

[ubikwidus]

Is there consensus that the Kitty Hawk on Reverb is in fact an amp built by Dumble? Is this the earliest use of Tandy Wire & Cable coax? The amp pic I reposted for comparison has grey coax, which is consistent with other amps from that time period. I don't know why Kitty Hawk would have used Tandy coax if this is a replica.

I am not sure this amp was built by Dumble on the grounds that the soldering quality (low) and luster look different than Dumble's work (see especially plate load connections in the preamp), the heater wires are also loosely twisted unlike known specimens of the Dumble ODS export amps of that era, and descriptions of this amp on the Roy Bros insta don't explicitly say this was a Dumble build. It simply says:

"As representatives of Dumble products in Europe, the Roy Bros. were involved in this process and familiar with it, as seen in these photos of a vintage amplifier made for their own use."

See, it says the amp was made for their use but not who made it....it's vague. In that quote there's a picture of the amp in the Reverb ad next to it. The reverb ad says it was originally an ODS so that's worth checking out....I'd be careful with this one though.

P.S. here's a 1977 ODS 50WX currently for sale in Germany; if you compare the gutshot of this one to that on Reverb long enough you'll see the differences I point out above:

https://udopipper.de/shop/dumble-overdr ... 50wx-1977/