Delay and Batteries: Match (NOT) made in heaven.

[aettin]

Hi guys- I'm looking for a really simple delay pedal that will run the best/ longest on batteries. I know these circuits suck current and that they're best when hooked up to a wall wart or something, and so this is really why I was looking for some help to find the one most suited to this particular use.

I was thinking about the cheapo Behringer VD400? Carbon Copy? Does anyone have any estimate of the life I can expect from these pedals with a 9v? Other suggestions?

Really appreciate it folks.

[R.G.]

I think it depends on the battery more than the pedal.

[Mark Hammer]

One more time....with feeling.

The MN32xx series was devised for this very reason. 

As you are hopefully aware, the bias voltage on the input signal to the BBD has to be set just right or else the sound is distorted or even unable to pass through the chip.  That bias voltage is generally derived by dividing down the supply voltage with a trimpot.  Now, if the supply voltage is rock solid (i.e., wallwart or similar external power supply), then that division and bias voltage remains valid.  IF, however, one is running off a battery, and the battery voltage starts to slide, what the trimpot is set to may not be the appropriate bias voltage, and the sound will suffer.

The MN32xx series is able to run off 5v.  Since those little TO-92 style 3-pin regulators run fine as long as you feed in 2V more than you hope to get out, a 5V regulator, "powered" by a 9V battery, will be good (i.e., provide a stable 5V at its output) until the battery drops down to around 7V.  What this allows the manufacturer to do is set the bias voltage ONCE, using the derived 5V.  By the time the battery has dropped to 7V, it probably isn't supplying enough current for the overall circuit anyway.

How much LONGER this sort of arrangement allows a delay pedal to run off a fresh 9V battery and deliver optimum sonic performance, I couldn't tell you, but the change in technology from the MN30xx to 32xx series was clearly to provide that sort of advantage, so I'm assuming there was some benefit.

Keep in mind that current drain will also depend on stuff like how efficient the status LED is, whether there is also an LFO circuit for modulation, whether there is a compander circuit on-board, choice of op-amps, and so on.  In other words, there is more to the circuit than just the delay portion.

[waltk]

I was thinking about the cheapo Behringer VD400? Carbon Copy? Does anyone have any estimate of the life I can expect from these pedals with a 9v? Other suggestions?

According to the VD400 user manual, the VD400 consumes 30ma.  You can estimate how long a fresh 9 volt battery will last by dividing the battery's rated mah by the consumption.  So you would expect a fresh standard 9 volt battery (@200 mah) in a Behringer VD400 should last about 6.7 (200/30) hours.

This is kind of a rough estimate, but good enough to get you in the ballpark.  I have a Behringer DR600, and the manual say its power consumption is 90ma - but I measured it at 115ma.  So a 9 volt battery will last less than 2 hours in it.

If you really need to run a pedal off of batteries, and it consumes too much current, you can always make your own external battery pack.  Get a battery holder that holds 8 AA batteries (in series) and load it with rechargeable NiMH batteries.  Wire it up with a power plug for the pedal.  The battery pack would give you 9.6 V.  It's pretty easy to find 2000mah AA NiMH batteries - and you would expect the battery pack to last 10 times as long as a 9 Volt battery.  Bonus - they're rechargeable.

[DavenPaget]

I was thinking about the cheapo Behringer VD400? Carbon Copy? Does anyone have any estimate of the life I can expect from these pedals with a 9v? Other suggestions?

According to the VD400 user manual, the VD400 consumes 30ma.  You can estimate how long a fresh 9 volt battery will last by dividing the battery's rated mah by the consumption.  So you would expect a fresh standard 9 volt battery (@200 mah) in a Behringer VD400 should last about 6.7 (200/30) hours.

This is kind of a rough estimate, but good enough to get you in the ballpark.  I have a Behringer DR600, and the manual say its power consumption is 90ma - but I measured it at 115ma.  So a 9 volt battery will last less than 2 hours in it.

If you really need to run a pedal off of batteries, and it consumes too much current, you can always make your own external battery pack.  Get a battery holder that holds 8 AA batteries (in series) and load it with rechargeable NiMH batteries.  Wire it up with a power plug for the pedal.  The battery pack would give you 9.6 V.  It's pretty easy to find 2000mah AA NiMH batteries - and you would expect the battery pack to last 10 times as long as a 9 Volt battery.  Bonus - they're rechargeable.

Verified , this is a valid solution , i have seen new 9v carbon zinc's at 10.7V unloaded before O_O

[waltk]

Also...  There are two kinds of NiMH batteries.  You can find the standard kind rated up to 2600 or 2800 mah.  That's a lot of power, but there's a downside.  Standard NiMH batteries have a high self-discharge rate.  If you take a fully charged NiMH battery and just let it sit on the shelf (or in your stompbox) for a few months, it will be virtually dead.

The other kind, known as "pre-charged" has a different chemistry/construction.  They only go up to about 2000mah, but the self-discharge rate is much lower.  After a year on the shelf, they will still have ~75% of the initial charge.

I like the standard kind for things I use a lot, and the pre-charged kind for things that aren't used as much.

There's a review of a pre-charged brand here: http://www.stefanv.com/electronics/sanyo_eneloop.html

[aettin]

Thanks everyone for your replies. I really appreciate you folks taking the time.
Also, thank you for explaining how to check current draw. This helps a lot.

The MN32xx series was devised for this very reason. 

So all in all, I'm looking for a BBD delay pedal that draws as little current as possible? The Memory Toy has 18 ma reported-- is that about as good as it gets? Is there a way to estimate how much the mod circuit will affect the current draw (trying to compare the EHX one with Behringers no mod circuit @ 30 ma).

Cheers.

[Mark Hammer]

The Bossarea site lists the DM-2 as drawing 11ma and the DM-3 as drawing 18ma, so yeah I imagine that 18 is pretty darn good, comparatively.

[DavenPaget]

The Bossarea site lists the DM-2 as drawing 11ma and the DM-3 as drawing 18ma, so yeah I imagine that 18 is pretty darn good, comparatively.

It's VERY good already ... my dist pedal consumes 18mA