Is it just me or is the Simulcast kinda bright?

[HamishR]

Just finished this pedal today. I like it! But I wish it had a treble roll-off tone pot. I spent an hour or two auditioning Ge transistors, and it seems to prefer slightly higher hfes. The highest gain tranny I had which worked was a Russian MP20 at around 90 and it sounds pretty good. Actually all of the MP20s sounded good but the lower the gain got the brighter the tone. I also tried some other "better quality" Ges (can't remember the numbers) but they all sucked.

But even with the good transistors it's still a little crisper (brighter) than I'd like. It's a good sound and I like how it feels to play through, but maybe I'll have to stick a cap to ground on the output! Is it just mine or do they all sound quite bright? And what hfe on the Ge transistors are you fellas using?

 

[manfesto]

I use MP20s with hfes around 50-60 (I bought 50 in two batches of 25 and *all* of them landed in this range with almost no leakage - I was shocked), since apparently that's what Hudson's using now. I don't personally think it's overly bright but I can see how it could be for different setups (especially at 27V).

It must be a relatively common complaint, though, because there does exist a variant of the Broadcast Dual Footswitch with a hi-cut switch:

Hudson Electronics x Regent Sounds Broadcast Dual F/Switch Hi - Cut To

We listened, we talked, Hudson built! The all-new Hudson Electronics Dual Broadcast with mini High-Cut toggle available exclusively at Regent Sounds.

www.regentsounds.com

But afaik, nobody's taken the back off of one and see what value cap is being inserted where in the circuit.

 

[HamishR]

A friend of mine who has recommended this pedal to me many times is bringing his pedal around soon so that we can A/B them. Interesting to know that the hfe is around 50-60. Maybe the hfe is not the main reason for the brightness - I'm sure things like leakage play a role too. I suspect that my hfe90 transistor is just the best sounding one of my lot.

As with your experience, my bag of MP20s has been fantastic. Not one has sounded bad, unlike other, "better" Ge transistors I have which have all sounded badly biased.

I might just try a 22nF cap across pins 1 and 2 of the volume pot and see how that sounds... Thanks for your input!

 

[daeg]

I'm a guy who likes bright but the Broadcast has just been painfully bright in every demo I've heard.

Still on the fence about building one to try it out.

 

[HamishR]

I think I'm incredibly lucky to have the hearing I do, and I think I may have more high-end hearing than most of my guitar-playing friends. When they pick up my guitar they often turn the treble up. Maybe I just like a darker sound?

But rolling a little high end off a pedal's sound must be one of the simplest things we can do?

 

[daeg]

I think I'm incredibly lucky to have the hearing I do, and I think I may have more high-end hearing than most of my guitar-playing friends. When they pick up my guitar they often turn the treble up. Maybe I just like a darker sound?

I'm the opposite. I keep liking the 'too bright' gear, which makes me think I might have some high-frequency hearing loss.

I might just try a 22nF cap across pins 1 and 2 of the volume pot and see how that sounds... Thanks for your input!

So a treble-bleed cap but the opposite. What size cap are you thinking? 2n2 or so?

 

[HamishR]

Yeah, a treble snubber. I just tried a 22nF and a 10nF and they did work but lost some of the immediacy of the sound. Maybe in a band setting it would sound fine. I mean I could add a pot there too but I can't be bothered just now.

 

[Feral Feline]

Perhaps try the Stupidly Wonderful Tone Control

 

[HamishR]

I'm beginning to think it may not be worth it. I have a few ODs I love!

 

[bowanderror]

I think I'm incredibly lucky to have the hearing I do, and I think I may have more high-end hearing than most of my guitar-playing friends. When they pick up my guitar they often turn the treble up. Maybe I just like a darker sound?

But rolling a little high end off a pedal's sound must be one of the simplest things we can do?

I've had the same experience! Always played a Strat, but never really used the bridge pickup (even on my baritone). I always feel like I need to roll off highs on my guitar or pedal tone controls compared to "noon". I have a Jaguar as well, but it turns out I REALLY don't like it.

Funnily enough, I've had the same "too bright" issue on my Broadcast clone as well. I believe I put a higher gain NTE-102A in there, which tested ~260 hFE & Iceo 240uA - but using my cheapo TC-1 multifunction tester. I have a ton of MP42B (50-7- hFE) & GT308V (70-90 hFE) that I might have to try. I mostly keep it on the lowest gain switch setting, so hopefully that will smooth out the sound.

 

[daeg]

Now I'm tempted to build one.

I'm reading claims online that as gain is turned up, the treble is cut. I am doubtful of this, but I think I heard someone at DIYSB once say that parasitic capacitance (ie miller effect) goes up as gain is increased. Looking at the schematic, I'm struggling to understand how the Gain control works.

 

[daeg]

Perhaps try the Stupidly Wonderful Tone Control

R14 would be a good candidate.

Something like:

• Replace R14 with 10k trimpot
• Trimpot wiper goes to 10n cap
• 10n cap goes to ground
• Optional: replace R15 with 21k resistor to maintain similar output volume.

 

[ryland]

I have a pretty large stash of GE transistors that I’ve collected over the decades of building effects. I auditioned a bunch in the broadcast that I built. Some were waaaay too bright (usually the American made ones) and some were much darker and more mellow sounding (UK brands). That transistor has a lot to do with how bright this pedal is.

 

[Markus Kersius]

I build the comparable duocast and tried every transistor I could find in my parts drawers.
Had 2 favourite: AC188 and a GC511.
Never noticed it to be too bright though.
So maybe higher gain transistors help to tame high end?

 

[daeg]

So maybe higher gain transistors help to tame high end?

I believe that's true.

Someone more knowledgeable can correct me if I'm wrong, but I recall that the Miller effect increases with Gain. When people take Germanium Fuzz designs and convert them to Silicon they often put a small cap across the Base and Collector to mimic the capacitance / high-frequency rolloff that Germanium transistors are known for.

 

[bowanderror]

Now I'm tempted to build one.

I'm reading claims online that as gain is turned up, the treble is cut. I am doubtful of this, but I think I heard someone at DIYSB once say that parasitic capacitance (ie miller effect) goes up as gain is increased. Looking at the schematic, I'm struggling to understand how the Gain control works.

That would actually make some sense as you're forcing more signal through the 1n cap down to ground when the gain control is turned up. You're allowing signal to bypass it when turning the gain down.



I believe the Gain control is working as a feedback control.

 

[daeg]

I believe the Gain control is working as a feedback control.

Probably. I don't know enough to tell whether Q2 is inverting or not. If it's non-inverting then there would be a negative feedback path.

So in the High-Gain position, the negative feedback path would be (mostly) eliminated, and the Q1 Emitter would be (mostly) grounded, both bumping the Q1 gain up a good deal.

I'm not a vintage fuzz guy, but this circuit has a unique topology and has caught my interest.

 

[daeg]

That would actually make some sense as you're forcing more signal through the 1n cap down to ground when the gain control is turned up. You're allowing signal to bypass it when turning the gain down.

The parasitic capacitance is actually at the Collector-Base Junction of the transistor, from what I understand. It allows high-frequencies to pass back into the Base, creating Negative Feedback and thereby only attenuating Treble. The effect increases with gain due to some physics at the semiconductor level that are totally beyond me. Guitarists hear it as "wow that fuzz isn't too ear piercing".

Miller Effect

As most amplifiers are inverting, the effective capacitance at their inputs is increased due to the Miller effect. This can reduce the bandwidth of the amplifier, restricting its range of operation to lower frequencies. The tiny junction and stray capacitances between the base and collector terminals of a Darlington transistor, for example, may be drastically increased by the Miller effects due to its high gain, lowering the high frequency response of the device.

 

[HamishR]

I don't understand half of this technical discussion but as a player I find there is something really appealing about how this pedal responds to playing. It's easy to make it sound ugly but if you are careful it can sound beautiful, and responds in a way unlike any other overdrive type pedal I have used. Played gently with gain around halfway up it's not so bright, but once you dig in it becomes annoyingly bright. Which seems kinda contrary to what you fellas are saying but maybe I'm getting gain levels and input levels confused.

 

[daeg]

It's easy to make it sound ugly but if you are careful it can sound beautiful, and responds in a way unlike any other overdrive type pedal I have used.

Now I've got to build one.

Since I started using Vox amps I haven't liked fuzzes, but this one is an interesting crossover with an original topology. I can't say I'm blown away when listening to Youtube demos, but the guitarist demoing it always seems to be in a state of bliss.

When the boards are back in stock I'll get a build going and try a couple of different methods off treble attenuation.