Michael Frank Braun HSX Circuit Impressions

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Offline mmmguitar

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Michael Frank Braun HSX Circuit Impressions
« on: April 16, 2021, 05:53:10 AM »
Edit: Don’t know what our admin did, but I can finally post again after several months!

For reference:

https://strandbergguitars.com/product/strandberg-hsx-hyper-single-coil-circuit/

https://support.strandbergguitars.com/article/106-the-hsx-module-looks-exciting-please-tell-me-more-about-it

https://strandbergguitars.com/wp-content/uploads/2020/11/el-hsh5-03-r1_hsh_wiring_mf_pickups.pdf

First-off, the HSX (or “Hyper Single Coil”) circuit is just a passive RC filter for humbucker series connections to pass through on their way to ground. What it does differently from most I’ve seen, however, is have a component to it that runs in parallel between the input and output lugs of the volume pot, as well.

The hype on the Strandberg site gives the impression that the HSX is filtering each of the two coils separately; so the resulting series-connected signal processed in parallel adds up to a facsimile of a single coil EQ curve, with minimal decibel loss. In reality, I suspect that the HSX is just two common RC filters - acting as a series connection shunt (As you find in PRS coil splits) and treble bleed (a mod becoming more and more common in production guitars) - gooped together in a $44 disc shape, for the sake of making inferring the dollar’s worth of resistor and capacitor values superficially more difficult.

As novel as the approach is said to be, I’m afraid my first-hand impressions are not positive - In fact, I’d go so far as to say that the MFB-designed “Fusion” pickups currently paired with the circuit in its exclusive offering from Strandberg are the worst set anyone could have chosen to demo this filter; because the two products are not in any way optimized for one another.

In my previous experiments shunting humbucker series connections through C and RC filters, the depth of the desired midrange cut had to be tuned by mating the appropriate component value(s) to the voicing of the pickup being affected. In addition to being a case-by-case basis, the pickup being in neck or bridge position will also dictate how much cut feels necessary to suit each player’s needs.

The HSX, however, is one-size-fits-all. The result, in the case of this unfortunate pairing, is that the humbuckers included in the Strandberg Fusion (hot-rodded with cranked mids and subdued highs for the sake of emulating Allan Holdsworth’s post-amp graphic EQ settings) don’t receive sufficient mid-scoop from the HSX component values to seem in any way “single coil-like.” In fact, even a full coil split results in honky mids from these pickups.

I feel the HSX could shine, so long as it was prescribed for use with a four-conductor PAF or other lower-output humbucker style that suffers from anemic split tones. But why spend $44 + tax on a dollar’s worth of components to share between two humbuckers, when you could just buy the dollar’s worth of components in the first place?

My verdict is that a few cheap components purchased after reading this RC-tuned coil shunting article by Dirk Wacker are a far better investment than a gooped disc branded “MFB”:

https://www.premierguitar.com/diy/mod-garage/jazzmaster-mods

That said, I’ll update this thread after trying the circuit with some “vintage”-output Dimarzio offerings.


« Last Edit: November 14, 2021, 05:48:23 AM by mmmguitar »

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Offline darkbluemurder

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Re: Michael Frank Braun HSX Circuit Impressions
« Reply #1 on: April 16, 2021, 08:48:37 AM »
In my previous experiments shunting humbucker series connections through C and RC filters, the depth of the desired midrange cut had to be tuned by mating the appropriate component value(s) to the voicing of the pickup being affected. In addition to being a case-by-case basis, the pickup being in neck or bridge position will also dictate how much cut feels necessary to suit each player’s needs.

The HSX, however, is one-size-fits-all. The result, in the case of this unfortunate pairing, is that the humbuckers included in the Strandberg Fusion (hot-rodded with cranked mids and subdued highs for the sake of emulating Allan Holdsworth’s post-amp graphic EQ settings) don’t receive sufficient mid-scoop from the HSX component values to seem in any way “single coil-like.” In fact, even a full coil split results in honky mids from these pickups.

First of all, thanks for your detailed review.

What you describe is also the case for any treble bleed as there is also no one size fits all for all guitars and amps. I encourage experimenting with different values.

Cheers Stephan
Area 67, Area 58, Area 61, VV Pro 54, Injectors, VV HB2, Virtual Solo, SDS-1, Area T, Area T 615, Virtual Hot T, Chopper T, Bluesbucker, Breed set, Air Norton, Super Distortion, DLX+ set, DLX-90, DP240, DP198, DP168, VPAF b, AT-1, Mo' Joe, FRED, Super 2; GS b

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Offline mmmguitar

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Re: Michael Frank Braun HSX Circuit Impressions
« Reply #2 on: April 18, 2021, 07:16:36 AM »
Some further experiments/thoughts:

The stock Strandberg wiring is to shunt the outside coils of the MFBs to ground (or, in this case, through the HSX filter that sends some frequencies to ground).

Though a common arrangement with full coil shunting/splitting, this seems an odd choice, here; given that the filtering of the circuit results in single coil simulations in which the neck pickup loses some bass, and the bridge pickup loses some treble (not the frequencies I’d be cutting to simulate a single coil). I swapped some wires so the inside coils would be filtered instead, and...it’s an improvement.

Given I’ve never bothered to check what component values are at play under the goop, I was surprised to find that more mids seemed to be cut, this way (something much-needed to inch these honky humbuckers closer to twang territory). I can only assume it’s due to the Strandberg MFB Fusion humbuckers’ coils being wound to asymmetrical resistance values.

This reaffirms my hypothesis that, due to the HSX circuit’s primary design goal being to minimize volume loss (rather than to minimize hum or affect a dramatic re-voicing) resulting from coil-shunting, the best pickup pairing would seem to be humbuckers in the lower-output realm that would otherwise be unsuitable for splitting.

Considering I’ve previously solved the issue this circuit presents (different R/C values according to each pickup’s needs), I don’t see much point in experimenting with pairing a weaker set of humbuckers with it: This product essentially fulfills a need for an aftermarket solution specific to a problem those of us who prefer 50’s style humbuckers encounter, rather than something needing to be paired with high-output humbuckers at the factory.

If you have something like a Les Paul or HH tele with four-conductor pickups that are firmly in vintage-output territory, this product will get you far enough into the single coil ballpark to avoid having to switch guitars. For everyone else with humbuckers, a 3.9k resistor and .047µF cap in series along the humbucker series connection’s shunt to ground is a few cents’ worth of a starting point that will suffice for more players than this $44 product will.
« Last Edit: November 14, 2021, 05:51:40 AM by mmmguitar »

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Offline buddroyce

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Re: Michael Frank Braun HSX Circuit Impressions
« Reply #3 on: April 23, 2021, 10:08:18 AM »
Edit: Don’t know what our admin did, but I can finally post again after several months!

I have no idea what I did but I'm glad to have you back!
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Offline Guitar74

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Re: Michael Frank Braun HSX Circuit Impressions
« Reply #4 on: May 05, 2021, 07:28:51 AM »
Great review and analysis. I am going to check out the article link. Premier has had some good pedal modding articles that have proven to be a very good jumping off point for my personal pedal mods so I expect that the article you posted will be just as helpful.
If you're having one of those days where everyone is on your case and is just getting on your nerves, it's probably not everyone else

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Offline mmmguitar

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Re: Michael Frank Braun HSX Circuit Impressions
« Reply #5 on: May 06, 2021, 12:44:44 AM »
It was for me. I’d been experimenting with coil tapping/filtering for a while before Dirk Wacker’s article prescribed some good RC values (along with the whys and hows).