S. Hawk Ltd. - Hawk II Tonal Expander  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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apollomusicservice
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Post by apollomusicservice »

McRuff wrote:Just joined this site after seeing posts for S Hawk Ltd II tonal expander. Although I have a great photo component side, tracking down a photo of the solder/trace side has proven tough since there is a foam rectangle covering most of the board so battery cases do not come in contact with it. Does anyone have a clear complete shot of the solder side of the board?

I've owned S Hawk Ltd devices in the past (Hawk I) my first being purchased new (yes, I'm a dinosaur). The second being purchased years later on eBay. I successfully traced that board and built a clone in a more player friendly enclosure.

btw - any idea of the chip used in the II. The 'I' version used a common 741 op amp. I'm thinking that due to voltage requirements the II uses a 4131, but can't make out for sure.
I'm trying to draw the PCB with the help of "jujub" photos. If this device is still
in your property or at least good photos would be of benefit. Specifically on the photos I do not see the value of the capacitors and the inductances would have to measure. In fact I've already made ​​the SMD version of this unit that would fit in the 1590B housing.

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DavidRavenMoon
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Post by DavidRavenMoon »

I used to have one of these. They were REALLY noisy, so I never used it.
"You give a better performance if you skip the eyes" - Raymond Scott
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digi2t
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Post by digi2t »

Cub wrote:Hey Lads,

Another interesting incarnation of the Hawk II is the recently released Maritime Analog Effects Pedal Pistol Slapper - Booster/EQ/Overdrive
http://www.maritimeanalog.com/pistol_slapper.shtml

[ Image ]

Flynn Amps' take on the Hawk II has the low pass filter on a tiny switch, the Slapper has it on a proper foot switch and it comes with a filter pot and rotary switch for different caps.
The Drive and Level pots are welcome additions as well, as the Volume pot on the Flynn pedal goes from "blimey, that's loud" on zero to "are you taking the piss ?" on ten, unity isn't an option.
I've recently come into possession of a Pistol Slapper, so I decided to investigate the inductors further. Using my inductance meter and DMM, I have the following readings (inductors removed from board);

Treble - 27mH / 81 ohms
Mids - 170mH / 287 ohms
Bass - 435mH / 518 ohms

All the pots are C10K. The following R/C combos are used from the inductors to ground;

Treble - 220 ohms / 150nF
Mids - 220 ohms / 47nF
Bass - 120 ohms / 2.2uF

The inductors themselves appear to be visually similar to the Bourns 70F series, however these are now obsolete, and impossible to find. I have found some possible radial replacements, with similar specs, and smaller footprints. The Bourns RLB9012-273KL may be able to sub for the treble inductor. It's spec'd at 27mH / 80 ohms. The mid may be covered by the Fastron 11P-154K-50, which is a 150mH, but might be close enough to work. As for the bass inductor, I couldn't find anything close/cheap/compact, so perhaps a series trio of the 11P-154K-50 might work. The resistance of this particular inductor is spec'd at 205 ohms, so a trio in series would place it at 615 ohms total. Some tweaking of the R/C below might be required to get it just right.

Might be cool if someone could sim these values, and see where they end up.

It's a wonderful pedal BTW. Great boost, with flexible EQ. The newer models have a 3 position filter toggle switch, which replaced the older 6 position rotary. I suppose that perhaps the three additional caps didn't make that much difference. Three settings is more than adequate.
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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jb351
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Post by jb351 »

Good evening,

Hope you all had a good holidays. It's been a long while since I was around here on a regular basis. Attached is a verified and traced schematic for an original Hawk II. Over a decade ago I was on a serious Rory Gallagher kick around the same time I was building pedals and I really wanted a Hawk II. I researched and traced what I could find on the internet at the time and eventually broke down and bought an original one on eBay to trace and compare against. When I made the Pistol Slapper I was slightly obsessed with doing the original justice and remember going from store to store to find the "right" shade of brown for the two piece enclosure I used to use. I used enclosures from Road Rage Pro Gear back then. Superb quality enclosures by the way, I only switched due to the higher cost. The inductors I originally used in the Pistol Slapper were from Wilco before quality and cost issues became problematic. Switched to Bournes after that. The pots are C10K instead of the B25K because they were more responsive and just felt better to adjust. The other alterations I made were primarily to improve it's usability and functionality among other things such as volume and gain controls. I made small changes here and there between the Maritime Analog and Butcher Pedals version of the Pistol Slapper but nothing particularly unusual.

Image

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DavidLuiz
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Post by DavidLuiz »

Hi all.. I’ve been searching for the Hawk ll Tonal Expander circuit for many years. I actually owned one back in the day.

I dug up a 3 band LC based ibanez diagram that might fill in some holes toward a Hawk ll diagram. Unfortunately, it tells me the file is too large, but it’s only 9.6 MB… it’s an AR-500 schematic.

..if someone owns an original box and would be willing to provide a layout..the would be awesome!

Best,
David

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Post by DavidLuiz »

Hi Guys..

I found this schematic for the Hawk II Tonal Expander..credit to David Morrin..This is yet another schematic, but I think with all versions posted..we should be able to create the Hawk ll..

Best,
David
Attachments
IMG_1307.jpeg

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