Anyne know how low a 9v battery can go in a tube screamer B4 it affects the tone negatively?

[pdf64]

It’ll depend on whether the ecaps bypassing the power supply rails are degraded.
I changed the ones in my TS9 (from about ‘83), as it started howling a higher settings as the battery ran down (thereby increasing its ESR).

[daz]

would that be C37 and 38?

[Helmholtz]

Not all 4558 chips perform the same - especially at low supply voltage.
The minimum supply voltage for the NJM 4558 is specified as +/- 4V, but the datasheet values are given for +/- 15V.
Some authors have found that the NJM 4558 is not a good choice for the TS.
At low supply voltage some chips tend to latch sporadically, which sounds awful.

I could verify that the RC4558 performs noticeably better than the NJM 4558 in a TS.
With this chip I like my favorite TS best with a battery voltage around 8V.

[pdf64]

would that be C37 and 38?

Yes

[daz]

[Mark Hammer]

If you're making a Tube Screamer, note that many people prefer the TS-808 over the TS-9. The primary difference between the two is the nature of the output buffer, Where the TS-9 uses a 470R and 100k resistor, the 606 used a 100R and 10K resistor.

Why the change? Well, remember that Ibanez, like so many other commercial pedals of the era, used electronic switching, such that effect cancellation is not bypass around the circuit but is internal to the circuit. That means the output buffer is in-circuit all the time, in both effect and "bypass" mode. I suspect the 808 buffer values load down the output in a way that nicely smooths out the overdrive signal, but tends to suck tone from the bypass. So I imagine Ibanez changed to the higher resistor values to arrive at a less objectionable bypass tone. However, if you are using a mechanical true bypass stompswitch to completely remove the circuit between input and output jacks, then you may find you prefer the 808 values without having to suffer the tone-sucking in your clean signal. Just a thought.

I will also note that some diode-clipper overdrives can be "double-clippers". That is the op-amp is pushed beyond its headroom limits, given the supply voltage, and the output of the op-amp is then clipped by diodes to ground. So the signal is effectively clipped twice. The TS is not like that. The clipping diodes are in the feedback loop of the op-amp such that the signal can never be cranked up to the maximum voltage swing of the op-amp. As such, I would not expect the quality of the tone to vary all that much unless the biasing gets mucked with or the battery's current delivery has dropped a lot. Conversely, I would not expect a TS to show much tonal difference if you upped the supply voltage.

[Helmholtz]

In the early 80s I had a first generation TS-808. When the TS-9 became available, I compared them for a couple of weaks and kept the TS-9, because I liked it better. The difference was small, though. Never regretted my decision.

Around 1985 I had the chance to see SRV on a small stage in a TV studio. He used a TS-9 (+ an old Vox Wah) and 2 Vibroverbs (second one only as an extension cabinet for the extra JBL E130.) Never heard him sound better.

Later I also bought a second TS-9 and a reissue TS-808.
After I replaced the NJM 4558 in the second TS-9 with an RC4558 it became my favorite TS.
(All 3 of them now have the RC4558.)

[daz]

If you're making a Tube Screamer, note that many people prefer the TS-808 over the TS-9. The primary difference between the two is the nature of the output buffer, Where the TS-9 uses a 470R and 100k resistor, the 606 used a 100R and 10K resistor.

Why the change? Well, remember that Ibanez, like so many other commercial pedals of the era, used electronic switching, such that effect cancellation is not bypass around the circuit but is internal to the circuit. That means the output buffer is in-circuit all the time, in both effect and "bypass" mode. I suspect the 808 buffer values load down the output in a way that nicely smooths out the overdrive signal, but tends to suck tone from the bypass. So I imagine Ibanez changed to the higher resistor values to arrive at a less objectionable bypass tone. However, if you are using a mechanical true bypass stompswitch to completely remove the circuit between input and output jacks, then you may find you prefer the 808 values without having to suffer the tone-sucking in your clean signal. Just a thought.

I will also note that some diode-clipper overdrives can be "double-clippers". That is the op-amp is pushed beyond its headroom limits, given the supply voltage, and the output of the op-amp is then clipped by diodes to ground. So the signal is effectively clipped twice. The TS is not like that. The clipping diodes are in the feedback loop of the op-amp such that the signal can never be cranked up to the maximum voltage swing of the op-amp. As such, I would not expect the quality of the tone to vary all that much unless the biasing gets mucked with or the battery's current delivery has dropped a lot. Conversely, I would not expect a TS to show much tonal difference if you upped the supply voltage.

I'm not making one, i have 2....a TS7 and a TS5. The 5 sounds great, as good as any TS i have had or tried. The 7 had the 100r and 10k which i had done years ago after i saw that was a mod that was supposed to make it sound great, which had me scratching my head because it sounded like crap. It's been in a drawer ever since because the 5 sounds infinitely better. Recently i started using both, one as high gain boost slamming the other. Both used as clean boost with dist knob all the way down. I got in there and put the 470R and 100k back and now it sounds close to the 5, tho the 5 still sounds a bit better. As for the diodes, i don't think they will have any effect for me regardless of what they are since i don't use them as distortion, just level boost with as i said the distortion knob all the way off. The TS7 has a JRC4558 and if i recall so does the TS5. In fact, gonna check that out right now and if i am wrong i'll post back and corrct that.

[J M Fahey]

Some Boss or Ibanez pedals incorporate a LED, plus a series Zener, donīt remember the exact value (look at schematics) but the combination made the LED turn OFF below 7.2V supply, so thatīs your minimum Factory recommended value.

Mind you, it might still "work" but when a zinc carbon 9V reaches down to 7.2V under a couple mA load, it means itīs in its deathbed, and it can easily die within a 1 to 2 hour show or rehearsal, so, play it safe and replace it.

, does a battery at 8 volts only allow each pedal half that or 4 volts?

Of course not, they are in parallel so both get the same 8V

[Helmholtz]

^^^^That's a good point.
In fact I always change the battery when the LED indicator gets hard to see.

[daz]

I tried recharging a alkaline. I know i said i wasn't gonna go there, but i had some alkalines but they were all around 8v and i wanted to see how the reheargables sound compared to a full alkaline and didn't wanna go pay 5 bucks to find out. So i put a energizer alkaline in my powerex charger and was surprised at what happened. I kept felling it to be safe but it never even got warm let alone hot in about 40 minutes. i took it out to check and see where it was expecting it to read maybe 8.5 but it read 10.5 ! But heres the question...is it normal to charge up that high then drop like that? Should i have left it longer so when it settles down to a stable number it;s high as a new alkaline or what? Also, how many times can you recharge a alkaline?