Magazine Archive

Home -> Magazines -> Issues -> Articles in this issue -> View

JHS Rock Box

headphone amp for rock, man

Noticed how 'personal' the gadget business has grown in the last handful of years. There's the personal computer, the personal hi-fi, the personal video, all of which have little to do with the JHS Rock-Box other than to introduce it as personal volume — a newcomer in the list of stereo, effect equipped headphone practice amps.

Like the Rockman and Boss Playbus I before it, the JHS is based on the Stowaway or Walkman philosophy of self contained, battery powered, fully portable units with an output for lightweight 'phones. After coming from the Playbus (or HA-5) the immediate contrast is one of weight. The Rock-Box has a heavy, black metal case that will take a lot of knocks. The paint may not survive but nothing is going to get at the circuitry with the possible exception of rain, if you're deranged enough to strum in a downpour. There is the option of a leather carrying pouch and that should help protect the controls which do stand out boldly from the top panel.

Speaking of such, we have a slider for output level, a rotary switch for six different sound settings and green, LED accompanied push buttons for the built-in, slapback delay and chorus (both analogue). There are two standard ¼in jack inputs for the main signal and auxiliary — this stereo aux is reserved for higher signals (1V compared to the main input's 45mV) and does not pass through the effects chain. With juggling you could play back tapes from another cassette machine and play along, or take the output signal from a mate's Rock-Box.

But presuming you're more interested in blasting your own ears, 'personally', we'll fiddle with the rotary switch. First position is an A440Hz tone superimposed over the sound of your guitar so you can tune up — smart move. But beware of relying too strongly on tuning over headphones as they make it harder to spot small but embarrassing variations. Next there's a normal option without effects followed by two clean choices and on both of these you can switch in the slapback and chorus. The second clean position also supplies an EQ boost lifting middle and top and stealing away some of the bass. There are no other tone controls on the Rock-Box.

The chorus is gentle, slightly wobbly with a touch of ADT yet didn't sound quite right until I checked and found that the test 'phones had been wired into a mono plug. After substituting an old pair of Walkman jobs, the sound opened up and guitars sounded not just richer but reinforced in 3D. The real stereo surprise doesn't come until you drop in the slapback echo — the original, dry part of the signal stays in the centre of your head while the echos appear on the extreme left and right as if they really were bouncing off the walls around you. I'd guess the two echo signals are from the same circuit but at different phases to make them stand apart and drive home the stereo image. (Many rack mounted delays have this phase inversion and it's very effective). The slapback time is fixed but you can alter the amount via a small, pre-set potentiometer sunk below the panel which you get at with a screwdriver.

Next stop on the rotary is Overdrive — a cruncher, good on chords, already featuring a strong edge of distortion and fuzz yet fine for chomping out two or three string chords with the palm of your right hand damping them at the bridge. The final Distortion position doubles the amount of fuzz supplying plenty of sustain for solos.

Though convincing enough on their own, both sounds turned mammoth when you knocked in the delay and chorus. Now we are not living in a town where a letter addressed 'subtle' is likely to find us. The JHS goes out-and-out ROCK guitar at this point-screaming solos, wild chord thrashes, floods of volume from one note (it does get loud). I thoroughly enjoyed myself, even though the doctor had advised against it. Just don't expect delicate tastes of valve overload or moody, low thrums of distortion because the JHS is built to bellow.

It can be used with an amp as a straight in-line effects box with stereo or mono outputs, and there's a pair of send and return sockets at the side for adding external effects such as a longer echo, perhaps. That deserves a bonus mark.

The Rock-Box takes eight HP7 batteries (not supplied) in a compartment at the bottom and these apparently powered the review sample for two full days at a recent guitar festival.

Complaints? The aux input socket is just a touch too insensitive to easily cope with a drum box, for example. On the other hand, I often found myself bringing down the volume on the guitar because the clean settings seemed prone to input overload. Heavy whacked out chords could be undesirably fuzzy, but that can happen when batteries are past their initial strength. Officially speaking, when you push the volume slider past 6 on the 1 to 8 scale, you're beginning to go into distortion, but I found it happening a lot sooner. And the unit itself is hissy, the noise seeming to live in the final output sections when the volume slider is high — switching in the chorus and slapback doesn't increase the noise, so they're not at fault. There is a lot of extra volume waiting in those two notches past six, so that's probably where it comes from.

Liked the sound a lot, even though it was paced purely for the HM advocate. Admired the ruggedness, too. A definite 'back-of-the-van' survivor.

JHS rock-box: £99

Also featuring gear in this article

Browse category: Preamp > JHS

Next article in this issue

Are You A Musician?

One Two Testing - Copyright: IPC Magazines Ltd, Northern & Shell Ltd.


One Two Testing - Dec 1984

Gear in this article:

Preamp > JHS > Rock Box

Review by Paul Colbert

Next article in this issue:

> Are You A Musician?

Help Support The Things You Love

mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.

If you value this resource, you can support this project - it really helps!

Donations for October 2021
Issues donated this month: 8

New issues that have been donated or scanned for us this month.

Funds donated this month: £56.00

All donations and support are gratefully appreciated - thank you.

If you're enjoying the site, please consider supporting me to help build this archive...

...with a one time Donation, or a recurring Donation of just £2 a month. It really helps - thank you!

Small Print

Terms of usePrivacy