Moodring 18v

[claytushaywood]

With the LED limiting has successfully allowed a deep blue delay clone more headroom on the input by running it at 18v... this is now my 2nd favorite delay ever only short of the deluxe memory man. 

With the moodring now having the LED limiting on the pt2399 would running it at 18v be a good improvement?  i had a ghost echo that distorted a bit with humbuckers when picked hard

[Jopn]

Both the PT2399 and the brick are behind a 5v regulator.  I'd worry about taxing that regulator even further by making it drop 18v down to 5v.  But, I must add, that I probably worry because I don't know for sure how bad it might be.

[claytushaywood]

does voltage matter on the regulator?  i thought current was what blew those things out.  i know the modules run at 5v but the ghost echo, deep blue delay, and other reverb and pt2399 effects i've had problems with the gain stages clipping.  like running the deep blue delay at 18v with the LED limiter has increased headroom significantly when using high output

anyone?

[madbean]

Haven't done that myself but it should be safe to try. Let us know how it turns out.

[midwayfair]

>does voltage matter on the regulator?

The extra voltage has to go somewhere, like all energy. It's converted into heat. Applying too much voltage could damage the regulator and subsequently other parts of the circuit. But people have certainly done it in the past. You might consider using the 7805 with a heat sink to be safe.

[RobA]

You may be able to get to the same level of headroom increase by going to a new op-amp type and leaving the voltage at 9V. Using something like the TS912, TS922, TLV2372, or TL972 could get you a couple of volts of swing over the TL072 and probably give you well more headroom than anything in the 5V section will let you get by with. It'd be pretty easy to try it out too.

[GrindCustoms]

78L05 can take up to 24V supply, spec wise there's no risk. Physically, go for it, that's how i run all my Belton and PT2399 pedals... the more stuff i can plug on 18V the best it is.

What makes the Vreg heat up is the current draw of what is following it, way more than the Input voltage you subject it too.

Edit: It does'nt always work well with delays in wich you have have modulation with an optocoupler....

[claytushaywood]

78L05 can take up to 24V supply, spec wise there's no risk. Physically, go for it, that's how i run all my Belton and PT2399 pedals... the more stuff i can plug on 18V the best it is.

What makes the Vreg heat up is the current draw of what is following it, way more than the Input voltage you subject it too.

Edit: It does'nt always work well with delays in wich you have have modulation with an optocoupler....

so you hear a difference in headroom with belton reverbs running at 18v?

[midwayfair]

78L05 can take up to 24V supply, spec wise there's no risk. Physically, go for it, that's how i run all my Belton and PT2399 pedals... the more stuff i can plug on 18V the best it is.

What makes the Vreg heat up is the current draw of what is following it, way more than the Input voltage you subject it too.

Edit: It does'nt always work well with delays in wich you have have modulation with an optocoupler....

so you hear a difference in headroom with belton reverbs running at 18v?

The Brick and the PT2399 run on 5V. Unless your power supply is giving you less than 7V, they will never see less than 5V, and unless the regulator is dead, they will never see more than 5V.

You will NEVER get more than 2.5V peak to peak out of a PT2399. The supply voltage is your limit. In reality, you probably can't get more than ~2V before it clips (this is why a green LED is enough for the LED limiter). The headroom before it clips is the maximum voltage that will come out. The Brick involves PT2399s, so we can apply the same principals to it.

In a typical simple PT2399 delay, your signal is sent through a single op amp stage with 2x gain before it's split off to the PT2399 and the mixing stage. The mixing stage is usually 0.5x or slightly higher. This was probably originally done because it very slightly increases the signal to noise ratio for the delay line.

This is where the trouble with most delays comes: If your pickups are hot and putting out something like 2V, and you amplify that to 4V, and the PT2399 amplifies it again even a little bit ... well, you've just hit the headroom of the PT2399.

Note that the Moodring's input stage is 1x. This trades a (IMO) meaningless tiny increase in noise for the delay line for more headroom on the repeats.

But you're wondering what happens when you run one of these circuits on 18V.

The mixing stage and the repeats are basically unaffected. There is no situation under which you will gain more headroom for the repeats, and the mixing stage usually isn't adding any gain. The only place you will gain any benefit is whether the op amp distorts due to a very hot input signal.

So really, it's just your input stage that's getting any benefit.

The Moodring has one exception to this: It has variable gain in the op amp preceding the mixing stage (it has a trimmer). This means it IS possible to gain additional output from the repeats, and running the pedal on 18V would let you push that op amp a little harder without introducing clipping.

But I just want to be really clear that 18V is not going to improve the PT2399 or brick themselves.