Valhalla vs Original Diezel VH4

[somethingvague]

I built the Valhalla, which is a Diezel VH4 clone. I didn't want a large pedal, especially compared to the comically large original, so I fit it inside of a 125B enclosure. Getting around the notorious squeal from this PCB was a hassle, but I managed it.

Anyway, I got a hold of an original VH4 to do some comparison testing and found that they differed more than I would like. My clone is substantially darker and more muffled, in a way that I can't really EQ away to achieve the crispness in the original. Has anyone else done a comparison test between the two? Does my layout have something to do with it?


Thanks.

 

[somethingvague]

One thing I’ve noticed is just how much more potent the bass knob on my clone is. If I match volumes and gains between the two pedals and turn every other knob to zero except for the bass knobs, which I max out, my pedal is much more boomy than the original. What might cause that?

 

[owlexifry]

much more boomy than the original. What might cause that?

lol sorry i dont really have any helpful suggestions.

bear in mind - parts tolerances is a thing (pots 20%, films caps 5% electro caps 20%, resistors 1%)

when comparing the two pedals are you running them on the same power supply / same voltage ?

 

[somethingvague]

View attachment 91346

lol sorry i dont really have any helpful suggestions.

bear in mind - part tolerances is a thing (pots 20%, films caps 5% electro caps 20%, resistors 1%)

when comparing the two pedals are you running them on the same power supply / same voltage ?

Both pedals are being run at 12 V from the same power supply, which has two 12 V isolate outputs. I plan on returning the original pedal, which I bought just for comparison, so unfortunately I can’t take it apart and start checking component values. But I usually have a terrible ear for hearing differences, and this is very clear to me, so it’s considerable.

I don’t know much about this sort of stuff, but does turning a given tone knob to zero remove that part of the circuit?

 

[owlexifry]

does turning a given tone knob to zero remove that part of the circuit?

nah, not in this circuit.

 

[somethingvague]

nah, not in this circuit.

Rats. I was trying to isolate why mine is so bassy and was hoping that I could isolate the cause that way. Is there a single capacitor I could try a new value with?

 

[lowpitch]

I'm only seeing two 1/4" jacks, but the pedal should have three. Is your output jack connected to the guitar or power amp output pad? The guitar output has additional filtering (lower volume and a substantial low pass filter).

 

[Paradox916]

there are a couple of things I can think of that might be helpful, on the PPCB circuit, the power amp out is quite a bit different than the standard out put like @lowpitch said, and how it sounds at 9v 12v and 18v are very different the pedal really needs to see above 12v (like 14v) for the regulator to work as designed. This has a big big impact on sound.

 

[somethingvague]

I'm only seeing two 1/4" jacks, but the pedal should have three. Is your output jack connected to the guitar or power amp output pad? The guitar output has additional filtering (lower volume and a substantial low pass filter).

I only wired up the one because I didn’t have plans to use the pedal into the power amp (and there’s literally no space for it). I thought about moving those connections over on the PCB, having read what you just said in this thread, turning my one output into the other kind. But since I have the original pedal at the moment, I thought I’d test that out with the original by using the Power Amp Out into the front of the amp. The problem is, when you do that, no signal gets through unless the pedal is turned on. So effectively, you can’t bypass the pedal at all.

I’m not sure if the clone PCB is wired that same way, but that’s obviously a dealbreaker since I’m going to use the pedal into the front of the amp and I don’t want it on all the time.

 

[somethingvague]

there are a couple of things I can think of that might be helpful, on the PPCB circuit, the power amp out is quite a bit different than the standard out put like @lowpitch said, and how it sounds at 9v 12v and 18v are very different the pedal really needs to see above 12v (like 14v) for the regulator to work as designed. This has a big big impact on sound.

See my reply above about using the Power Amp Out.

The issue is, though, I’m using the two pedals side by side: the clone and the original. They are both going off of 12 V and both using the front of amp output. Mine is substantially darker, and I suck at hearing differences.

So my thoughts are one of the following is true

1. The circuits aren’t actually the same

2. Some component value is wrong, either from being incorrect altogether or tolerances. I really don’t think this is the case as I double-checked every component obsessively before soldering it in, so it would have had to be incorrect from Mouser. I also chose 5 or 10% tolerance parts.

3. Something about my layout is affecting the sound. But I don’t know anything about this stuff.

 

[somethingvague]

I'm only seeing two 1/4" jacks, but the pedal should have three. Is your output jack connected to the guitar or power amp output pad? The guitar output has additional filtering (lower volume and a substantial low pass filter).

I found this post on freestompboxes, where one guy describes his build as sounding “shockingly dark”, which is what I’m experiencing:

“For anyone that finds this pedal dark, I would recommend looking at the output resistive voltage divider. I found my build shockingly dark.

From Bajaman's schematic R36 = 150k and R37 = 100k. I changed to 47k/15k and kept C23 at 2n2. Cable capacitance can range from 75pF for a patch cable into a buffered delay pedal to 2nF for a low-quality 20 foot cable. Lowering this ratio may help keep the tone consistent. Your resistor ratio may vary, and you may wish to increase C23 in value to cut some top end which can be nice depending on your style. 150k/100k is a very large output impedance and will lose top end driving most anything. Initially, I removed C23, but that was not enough since it was driving a 1nF cable. Decreasing the ratio got me to a place where I re-installed the 2n2.

I also bypassed the 78L12 to get some more voltage on the rails. Cheers!”

 

[somethingvague]

there are a couple of things I can think of that might be helpful, on the PPCB circuit, the power amp out is quite a bit different than the standard out put like @lowpitch said, and how it sounds at 9v 12v and 18v are very different the pedal really needs to see above 12v (like 14v) for the regulator to work as designed. This has a big big impact on sound.

One thing that is also worth mentioning is that with all tone and gain knobs at, say, noon, my pedal’s volume knob needs to be turned up to 50% to match the 25% position of the original in volume. I don’t know what that means, but part tolerances seem like they would have to be really out of whack.

 

[lowpitch]

I thought maybe you were comparing the preamp out on the clone to the power amp out on the original, but if that's not it I'd suggest opening up the pedal and confirming parts values. Could also be that the trace of the original pedal simply isn't accurate. I'm not sure if Robert did his own trace or used the one from the freestompboxes.org thread (https://www.freestompboxes.org/viewtopic.php?t=28011). The latter is based on a handful of gut shot pics only, which certainly leaves some room for error.

 

[somethingvague]

I thought maybe you were comparing the preamp out on the clone to the power amp out on the original, but if that's not it I'd suggest opening up the pedal and confirming parts values. Could also be that the trace of the original pedal simply isn't accurate. I'm not sure if Robert did his own trace or used the one from the freestompboxes.org thread (https://www.freestompboxes.org/viewtopic.php?t=28011). The latter is based on a handful of gut shot pics only, which certainly leaves some room for error.

I might try the resistor change I mentioned above. I haven’t seen anyone else mention doing a side-by-side comparison of the pedals. I really wouldn’t have given the issue a ton of thought without doing a comparison — I would have just thought the original pedal sounded that way. I would like to get a hold of someone else’s clone and see if they sound like mine.

 

[Paradox916]

One thing that is also worth mentioning is that with all tone and gain knobs at, say, noon, my pedal’s volume knob needs to be turned up to 50% to match the 25% position of the original in volume. I don’t know what that means, but part tolerances seem like they would have to be really out of whack.

Well you have the real circuit right in front of you crack it open pull your meter out and start tracing to see what’s different… it all comes down to how bad you want it.

 

[CR0SSBL4DE]

Both pedals are being run at 12 V from the same power supply, which has two 12 V isolate outputs. I plan on returning the original pedal, which I bought just for comparison, so unfortunately I can’t take it apart and start checking component values. But I usually have a terrible ear for hearing differences, and this is very clear to me, so it’s considerable.

I don’t know much about this sort of stuff, but does turning a given tone knob to zero remove that part of the circuit?

Closes to flat setting:
Presence and deep in 0.
Bass and Treble at 0.
Mids at 10.

 

[bechbox]

Well you have the real circuit right in front of you crack it open pull your meter out and start tracing to see what’s different… it all comes down to how bad you want it.

somethingvague, did you do this?

 

[somethingvague]

somethingvague, did you do this?

I did not. I wouldn’t even know where to begin to trace the circuit. I ended up doing a resistor swap mentioned in a previous comment of mine that I found on a different forum. It’s where the 150k/100k resistors on the output are swapped with 47k/15k. After I did that, it brightened up considerably. The pedal is still not as loud as the original, but they are tonally very similar to my ears now. That was not the case with the original components.

 

[CR0SSBL4DE]

I suspect the first versions of the Diezel pedal may be different from the later units.
A good start point could be opening the pedal, and just take pictures. No warranty or devolution policy should be affected by doing this, and we will be able to help you from the pictures a lot more

 

[somethingvague]

I suspect the first versions of the Diezel pedal may be different from the later units.
A good start point could be opening the pedal, and just take pictures. No warranty or devolution policy should be affected by doing this, and we will be able to help you from the pictures a lot more

I kind of view it as a solved problem for me personally, but if there is interest from others to see if the circuit now differs from the original trace, I would be happy to take the back off and photograph that side of the PCB.