Hermida Audio - Dover Drive

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bucksears
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Post by bucksears »

Anybody cracked one of these open yet?
Sounds a lot better to me than the MXR FET Drive.

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Post by MoonWatcher »

It was just released, right? Probably will be a little while before someone takes one apart.

If Hermida was really involved in the design, and it's really supposed to borrow from a Tube Driver, I think what's in it might be a little more straightforward than we realize. It really wouldn't surprise me if it looked like the actual Tube Driver, just with something in place of the preamp tube, and everything else possibly left as-is.

After all, isn't the Zendrive 2 basically a regular Zen pedal that has the clipping diodes replaced with a preamp tube? Some sort of nuvistor or something? Or that's the Nuvalve. The Zendrive 2 has a 12AX7 in place of the 1's clipping diodes.

So Hermida seems to have a grip on substituting out one for the other, and seems to have no issue with it being solid state, 12AX7, or nuvistor.

So the Dover Drive might kind of be like this is happening in the inverse - take an existing overdrive circuit with a tube and maybe substitute in more conventional diodes?

This is a whole lot of guessing, but why would anyone have to re-invent more than necessary - we know what this pedal is supposed to sound like.

It also has a sort of fuzz/crunch that reminds me of germanium diodes shunted to ground near the output, kind of like that sort of "tearing" quality that you hear with a Foxx Tone Machine or even a dimed Distortion +.

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Post by roseblood11 »

Is this identical to the Hermida Dover Drive?

Does anyone have a schematic?

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Post by modman »

I found not one picture of a Lovepedal branded Dover Drive. They all carry the Hermida Audio name. You clearly didn't google, otherwise you would have even found a gut shot
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Post by sinner »

And what this gutshots is telling you Modman? All I see is massive ground plate

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Post by MoonWatcher »

sinner wrote:All I see is massive ground plate
I see 8 pins for an op amp, and pin 4 is clearly grounded.

Not too many other through-hole parts, and two of those solder dabs are probably for the LED.

Just guessing, but I'd think the SMT components on the other side are probably not too many. It really does seem that the op amp is probably configured to be similar to how the Tube Driver is set up, and then something other than a tube is obviously substituted. I think I did some google-search thing awhile back, but nothing for a component-side of the pcb came up.

Looked around at some other links, and it looks like the Unomos and Unimos might be similar to the Dover Drive. The Lovepedal description calls it "a new FET design." MOS in the name makes it clear that it's a mosfet.

So I could see these pedals as using an op amp driver into a mosfet or two. Hermida has used the 2n7000 in other pedals, so it might be natural to use it again with these.

The accent control with the Unimos/Unomos seems like it would be similar to the Zendrive's voice control. I'd guess that Hermida would probably try to find ways to re-use some bits and bobs of what you find in his other pedals.

Interesting that export to Japan has the pedal named Uno__ instead of Uni___. I guess it's something with translation that is not so good? :hmmm:

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Post by sanfi4u »

MoonWatcher wrote:
sinner wrote:All I see is massive ground plate
I see 8 pins for an op amp, and pin 4 is clearly grounded.

Not too many other through-hole parts, and two of those solder dabs are probably for the LED.

Just guessing, but I'd think the SMT components on the other side are probably not too many. It really does seem that the op amp is probably configured to be similar to how the Tube Driver is set up, and then something other than a tube is obviously substituted. I think I did some google-search thing awhile back, but nothing for a component-side of the pcb came up.

Looked around at some other links, and it looks like the Unomos and Unimos might be similar to the Dover Drive. The Lovepedal description calls it "a new FET design." MOS in the name makes it clear that it's a mosfet.

So I could see these pedals as using an op amp driver into a mosfet or two. Hermida has used the 2n7000 in other pedals, so it might be natural to use it again with these.

The accent control with the Unimos/Unomos seems like it would be similar to the Zendrive's voice control. I'd guess that Hermida would probably try to find ways to re-use some bits and bobs of what you find in his other pedals.

Interesting that export to Japan has the pedal named Uno__ instead of Uni___. I guess it's something with translation that is not so good? :hmmm:
Here's how Sean himself describes the Dover Drive design:
"We use Si based on my Dragon fuzz for the first section. Then we use germanium diodes and FETs in the output stages"
http://www.thegearpage.net/board/index. ... n.1619987/

But I wonder what DIP8 is for on the board then? I tend to believe MoonWatcher's guess was right. It could be configured alike Tube Driver first section, maybe diode clipping added and then FET stages at the output. I'd still like to see the opposite side of the DD board.

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Post by sinner »

Hermida Audio is owned by Lovepedal, right?

How many Lovepedal original designs have you ever seen?

The only thing that guy is good at is recycling old, proven designs

My guess? Joe Davisson's Dual Mos

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Post by sinner »

Breadboard worthy

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Post by Jack Deville »

Um...

Totally incorrect but hey, if it sounds good whatever.
I'm a "professional."
Buy my products and make me rich.

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Post by sinner »

Put your puzzle in, Jack

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Post by sanfi4u »

Dover Drive was released in March 2014. I'm surprised nobody cared to take it apart since then. Here are some pics posted below.

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Sean explanation is quite close to a real schematic. It's a Lovepedal Dragon Fuzz stacked into Tube Driver circuit with the dual triode tube substituted with 2 FET trannies. Dragon Fuzz is a cascaded 2 Si SMD tranny stages located under the Gain pot on the upper left. The same schematic including its Bias trim pot in the collector of the second transistor. Next goes NE5532AP Dual OpAmp. I think it is configured the same way as in Tube Driver: follower stage + gain stage driving the rest of the circuit). It's a good OpAmp but I doubt it can shine in this SMD environment. At the end of the circuit we have 2 FET stages emulating the original Tube Driver tube (see them under the Volume pot). Tranny part numbers are sanded off. I'd expect to see J201 here or probably bs170/2n7000. Tube Driver tone stack is swapped with more simple high freq roll-off control.
I'd say this pedal is overhyped and over mystified a lot. I was never quite impressed with its sound. Now I know the reason why.

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Post by Jack Deville »

Hehehe.

Y'all wrong. :)
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Post by Dirk_Hendrik »

sanfi4u wrote: It's a good OpAmp but I doubt it can shine in this SMD environment.
Above quote alone makes the value of sanfi4u's post doubtful. And that's apart from the poor resolution and unsharp pictures as well as a proper foundation on all claims made based on these pics
Sorry. Plain out of planes.

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Post by MoonWatcher »

sanfi4u wrote:At the end of the circuit we have 2 FET stages emulating the original Tube Driver tube (see them under the Volume pot). Tranny part numbers are sanded off. I'd expect to see J201 here or probably bs170/2n7000.
It looks to me more like those transistors are simply used as clipping diodes - they look to be in the negative feedback loop connected at pins 1 and 2, at ic1a. Most likely a 2n7000 anti-parallel to a 2n7000+1N270, for asymmetrical clipping.

Gain/drive is 1k reverse-log, and connects to pin 8 of op amp, which is for Vcc+. That indicates use of pnp transistors for Fuzzface-based part of circuit. Also a business as usual 22uf connected to q2's emitter.

Tone pot connects to pin 5, which is a non-inverting input. So the tone circuit seems to fall somewhere in between Fuzzface-based circuit and ic1b. It looks like c9 is input cap to ic1b. It looks like the tone pot value is 50k, so I guess that part is a Hermida contribution - a Zendrive-like tone control.

So my best guess based on the shitty photos is probably something like:

input -> Fuzzface-like circuit for gain control -> ic1a with diode clipping that is a variation of Zendrive -> tone control like Zendrive -> ic1b as boost/line driver -> volume control -> output

or:

input -> Fuzzface-like circuit for gain control -> Zendrive-like tone control -> ic1b (probably for boost or line driver) - ic1a with diode clipping, probably in negative feedback loop -> volume control -> output

The first one seems to make more sense design-wise, since the r&d would be reduced to putting a Fuzzface into a Zendrive, and altering things where necessary to make it work together. So when you roll down your guitar's volume, you get the Fuzzface's cleanup effect. And when you set the gain low, it should be more like an overdrive only, since the fuzz wouldn't really be clipping much.

It looks like this has nothing to do with trying to emulate the Tube Driver's circuitry at all - it's more like two stacked pedals that are hardwired together in one box. That would make sense if someone would expect to try and copy some Eric Johnson sounds - silicon Fuzzface into Dumble amp. And I guess it could be extended to a Gilmour type of sound too, because it could be thought of like a combination of Big Muff and overdrive, whether David was using a combination with a Chandler box or a Colorsound box. Kills two birds with one stone.

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Post by sanfi4u »

MoonWatcher wrote:
sanfi4u wrote:At the end of the circuit we have 2 FET stages emulating the original Tube Driver tube (see them under the Volume pot). Tranny part numbers are sanded off. I'd expect to see J201 here or probably bs170/2n7000.
It looks to me more like those transistors are simply used as clipping diodes - they look to be in the negative feedback loop connected at pins 1 and 2, at ic1a. Most likely a 2n7000 anti-parallel to a 2n7000+1N270, for asymmetrical clipping.

Gain/drive is 1k reverse-log, and connects to pin 8 of op amp, which is for Vcc+. That indicates use of pnp transistors for Fuzzface-based part of circuit. Also a business as usual 22uf connected to q2's emitter.

Tone pot connects to pin 5, which is a non-inverting input. So the tone circuit seems to fall somewhere in between Fuzzface-based circuit and ic1b. It looks like c9 is input cap to ic1b. It looks like the tone pot value is 50k, so I guess that part is a Hermida contribution - a Zendrive-like tone control.

So my best guess based on the shitty photos is probably something like:

input -> Fuzzface-like circuit for gain control -> ic1a with diode clipping that is a variation of Zendrive -> tone control like Zendrive -> ic1b as boost/line driver -> volume control -> output

or:

input -> Fuzzface-like circuit for gain control -> Zendrive-like tone control -> ic1b (probably for boost or line driver) - ic1a with diode clipping, probably in negative feedback loop -> volume control -> output

The first one seems to make more sense design-wise, since the r&d would be reduced to putting a Fuzzface into a Zendrive, and altering things where necessary to make it work together. So when you roll down your guitar's volume, you get the Fuzzface's cleanup effect. And when you set the gain low, it should be more like an overdrive only, since the fuzz wouldn't really be clipping much.

It looks like this has nothing to do with trying to emulate the Tube Driver's circuitry at all - it's more like two stacked pedals that are hardwired together in one box. That would make sense if someone would expect to try and copy some Eric Johnson sounds - silicon Fuzzface into Dumble amp. And I guess it could be extended to a Gilmour type of sound too, because it could be thought of like a combination of Big Muff and overdrive, whether David was using a combination with a Chandler box or a Colorsound box. Kills two birds with one stone.
Thanks, @MoonWatcher! Inspired by Jack Deville's comment I finally found time to have a closer look at the Dover Drive PCB, came here to correct my first guess and ... found your post. :) You are absolutely right. Tube Driver marketing references actually have nothing in common with a Dover Drive schematic. Yeah, it's a Fuzzface-like gain stages stacked into slightly modified Zendrive. More detailed signal chain looks as you have described in your first option (with minor corrections):

input -> Fuzzface-like circuit for gain control -> ic1a with MOSFET/Si/Ge diode asymmetrical soft clipping that is a variation of Zendrive -> tone control like Zendrive -> ic1b as boost stage -> volume control -> output

Soft clipping engine in a feedback loop is a bit different from Zendrive: SMD Si diode->MOSFET (2n7000?) in one part of the engine; SMD Si diode->Ge diode (1N34a?)->MOSFET in another one.

As I said no similarities with the Tube Driver.
Last edited by sanfi4u on 05 Apr 2016, 20:57, edited 1 time in total.

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Post by sanfi4u »

Dirk_Hendrik wrote:
sanfi4u wrote: It's a good OpAmp but I doubt it can shine in this SMD environment.
Above quote alone makes the value of sanfi4u's post doubtful. And that's apart from the poor resolution and unsharp pictures as well as a proper foundation on all claims made based on these pics
Recently I had a chance to snag a so called old school version (THD based later edition) and compare it to the first, SMD based Dover Drive face to face. Same schematic, just different PCBs and parts. As I expected SMD version is noticeably inferior to the old school one soundwise. So I still believe there's nothing wrong with my earlier statement.

Image

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Post by deltafred »

sanfi4u wrote:As I expected SMD version is noticeably inferior to the old school one soundwise.
Would you care to explain why?
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Post by sanfi4u »

deltafred wrote:
sanfi4u wrote:As I expected SMD version is noticeably inferior to the old school one soundwise.
Would you care to explain why?
Because real life components are not ideal. They have their imperfections (non-linearity, noise, losses) that affect the sound quality. Going smaller usually makes the situation even worse. In particular in electrolytics department. Nothing new actually.

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Post by deltafred »

sanfi4u wrote:Because real life components are not ideal. They have their imperfections (non-linearity, noise, losses) that affect the sound quality. Going smaller usually makes the situation even worse. In particular in electrolytics department. Nothing new actually.
If you are going to make statements like that you need to back them up with references to relevant data to support your argument.

Having your own opinion is fine but that doesn't make it an undisputable fact.
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