JBL GTO 6528 Coaxial Loudspeakers

A two-way coaxial from the JBL Grand Touring series, with a 12dB per octave passive crossover system built in, plus a single FRONT SWITCHABLE resistor to attenuate the tweeter by 6dB should you wish to by use of the tiny switch on the tweeter housing itself. This tweeter is also angled on its pole and can be swivelled through 350 degrees. The pressed steel chassis has sixteen holes around its circumference to fit many kinds of cars’ stock locations as custom replacements. For ‘feature’ fitting, they come with smart grilles made of metal mesh and two plastic mouldings and a tasty JBL badge on the front. They feature a hole for the tweeter to play through. Being a TWO Ohm impdedance loudspeaker, these will draw more current from a headunit or regular amplifier than a ‘normal’ 4 Ohm one.
– Power Handling 60w RMS, 180w peak
– Impedance TWO Ohms (normally four, this low load will pull more power from an amp so be careful.)
– Sensitivity 92dB 1w/1M
– Passband 50Hz to 21kHz
– Crossover slope 12dB
– Mounting Depth 59mm
– Cone: Plus One® design for greater surface area
– Tweeter: 25mm, edge-driven Mylar-Titanium My-Ti® balanced dome in Unipoint„¢ rotating housing
– Chassis: Pressed Steel with lug terminals
– Complete with: eight screws and eight panel screwclips
– Flux density: 4.02T-m
– Suspension compliance CMS (µm/N): 233
– FS: 93.3Hz
– QES: 1.05
– QT: 0.95
– QMS: 9.75
– Moving Mass: 12.5g
– VAS: 5.58 litres
– Piston Area SD: 130.6cm2
Review by Adam Rayner
These speakers are quietly slightly fabulous, right out of the box and represent a game changer for me. They have been around some time and yet I had no idea quite how evolutionary they were. For these have a super-duper crossover on them, pretty much as good as many small off board passives, with a really pretty chunky 60w capable Iron-cored inductor choke and chubby wee capacitor, making this a 12dB ‘network’ as against a simple cap to keep the bass out of the tweeter with just a 6dB slope. Also, right under the tweeter is a resistor and there’s a microswitch on the front of the 350-degree swivel Unipoint„¢ tweeter housing to put this in or out of circuit. This acts as a -6dB attenuator like in a posh off board passive box and means that these are likely to be voiced so you can use them behind grilles made by car makers as evidenced by their wide-compatibility hole-filled outer edges on their chassis.
The magnets are a decent size and the tweeter housing is very solidly mounted and swivels only with some force and is slightly detented, so holds position well.
To test them, I pulled one of the very best produced bits of pop in all time, produced by a nutter who used splooshy recordings of his kids in the bath as background to avant-garde introduction sequences. It was the very last ever true Jukebox Hit in the history of UK pop music. (Mad Rayner digression, skip at will: In the Sixties, many records got their hit sales by jukeboxes playing in coffee houses and pubs and clubs rather than the radio and TV. When BBC Radio 1 banned ‘Relax’ by Frankie Goes To Hollywood, young girls in fruit machine companies all over the UK, who were put in charge of choosing singles for the few jukes they were still running with vinyl records in the Eighties put them in their boxes. As there was no airplay, these jukes got played to death and machines that were lying mostly on idle suddenly had their coin boxes bursting, the single went to number one and my wife-to-be went from a formal warning for putting a banned record in the juke boxes, to getting a commendation from the MD over her stroppy line manager’s head. She’s been a medical secretary ever since, though.) Frankie was amazingly over-produced and was made at the dawn of the digital era when there was a thing about quality and Trevor Horn is a genius.
The stuff going on is huge and detailed and a good tester is that in the very beginning, there is a super-deep wobble that goes all the way down to sub-bass quite quietly in the introduction to the album. These speakers did a big slice of that and I was impressed. They had been hooked to a Genesis Stereo 100 being driven by a Pioneer DEH-P88RSII competition-grade CD deck of high purity.
First, I put them in the lovely new plywood sealed test boxes with a new set of front baffles as they have a wider than Euro-standard cut out hole needed and plugged in the Neutrik Speakon plugs. Very nice and short-circuit proof versus banana plugs. I positioned the tweeters to point right at me with the boxes toed so I would be as close to on-axis and then attenuated the tweeters after having heard them upon connection, just to know they were hooked up correctly.
I was quite pleased but found it a way better for detail with the attenuator resistors switched back out. You really can hear the sound not just get made a bit quieter by the resistor, you can hear it smear the edges and detail off a tiny bit. So, realising that a £40 pair of speakers that are stock-hole equipped, simply are never going to be built custom-love into on-axis footwell audiophile installs so listened to them stood such that I was about right for an off-axis sat-in car listener.
There’s no doubt about it, these speakers have balls and present aggressive music aggressively. You may find them a bit tiring if played loud and I found them a bit sharp and spitchy for the posh stuff. But that, as ever with audiophillia and lower cost product, is to be to be harping on about a question that hasn’t been asked. Do they rock? Bloody hell yes and they do it with a scale and weight that is about double their cost. Again, I am limited by the Joomla template as there aught to be a loony-VFM score of eleven for these.
After all, Spinal Tap made the ‘One More’ score famous and these JBL’s do use a technology named (in my personal opinion) by way of Homage to the Great Nigel Tufnel, The Tap’s guitarist who said, ‘ Eleven. Exactly. One louder.’ For these stonk.
I played the same music then through the Bowers & Wilkins LM1 Leisure Monitors I have here on the bench by way of a speaker lead quick-connect system (with idiot-proof connectors so I cannot cock-phase them without really trying hard) and yes, with that less-than-eight-second reference gap you can hear the hike in sound quality on the ‘posh’ speakers. But to be positive, what you can hear on the JBL GTO 6528S is amazing.
Trills and tinkles, edges and all sorts of bits going on, even when playing with some muscle and that’s a huge point too, as never ever before have I seen a two ohm speaker in full range. Yes, lots of woofers of all sorts and even some that can look like a single Ohm load all on their dual-two-Ohm-voice-coil ownsome. But these are coaxes and if you put them on a normal amplifier, or a headunit power chip, they will suck like a Dyson on your amp. This means more music for less rated amplifier power, as again, no one will be putting a three hundred and eighty pound amp on these babies. Thus, you get a bunch of compo features for the low price, a slice of bass that has no real right to be there in such a small cone (Plus One really helps noticeably here) and although cheap and a bit brash sounding, a really powerful tweeter that can be used to enable the marriage to a bass system in the boot, without ever being at risk of being drowned out.
A collection of excellent little ideas that add up to a properly ballsy piece of JBL affordable bang for the buck and you can quote me!
Sound Quality 7.0
Build Quality 8.0
Power Handling 7.0
Efficiency 9.0
Value For Money 10.0
Overall rating 8.2