Ashdown AGM-484H Head review

Ashdown’s Guitar Magnifier head features a deceptively simple preamp that delivers a wide range of tones into the classic quartet of EL84 output tubes – all at real-world prices

Ashdown AGM-484H head
(Image: © Future / Olly Curtis)

Guitar World Verdict

Aimed at serious amateurs and pro users, Ashdown’s AGM-484H has the tone and power to get your point over on any stage. And for a product that’s handmade in Ashdown’s UK Custom Shop, we think it’s very good value for money.


  • +

    A great-sounding, compact and portable all-valve head with plenty of punch.

  • +

    Ideal with effects pedals.

  • +

    Built to last.


  • -

    The fully enclosed steel chassis makes quick valve replacement difficult.

  • -

    It’d be nice to have an on/off switch for the fan.

You can trust Guitar World Our expert reviewers spend hours testing and comparing guitar products so you can choose the best for you. Find out more about how we test.

Ashdown Music is well known all over the world as an industry standard in bass amps, with a huge user-list that reads like a who’s who of the world’s greatest bass players. It’s such a strong reputation that Ashdown’s equally impressive guitar products sometimes tend to be a little unfairly overshadowed.  

Launched back in 2020, Ashdown’s Guitar Magnifier heads and combos take their inspiration from the best-selling Bass Magnifier range. Designed by amp guru Dave Green and made in the UK at Ashdown’s Essex Custom Shop, the AGM collection promises great tone and real-world versatility at affordable prices. 

We previously looked at the AGM-5C combo back in February, now it’s time to zero in on the AGM-484H head. Ashdown’s ultra-compact AGM-484H isn’t that much bigger than a box of cornflakes, but it’s considerably heftier, of course, thanks to a pair of generously sized mains and output transformers feeding four JJ 12AX7 preamp valves and a quartet of JJ EL84s inside.

Ashdown AGM-484H head

(Image credit: Future / Olly Curtis)

The 484H is presented in typical Ashdown fashion, with a satin-black steel cabinet and smart brushed gold control panel featuring the company’s trademark illuminated VU meter at the far right.

A heavy-duty leather strap handle is bolted to one end of the cabinet and enables easier carrying. The electronics live on two high-quality printed circuit boards: a large one near the front holds the preamp components, while a second board in the middle of the chassis accommodates the power stage components, including the valves, which sit horizontally in a gap between the AGM-484H’s transformers.

The wiring is all neatly routed and the soldering is clean and bright, with short flying leads to the front-panel controls and switches for improved reliability and ease of servicing. There’s generous ventilation to keep things cool thanks to the large slotted grilles on the top and bottom of the cabinet and a small permanently-on fan on the rear panel.

Ashdown AGM-484H head

(Image credit: Future / Olly Curtis)

The AGM-484H is essentially a single-channel head, with a switchable boost stage that has its own gain and master volume. There’s a non-boosted gain and master volume as well, together with bass, mid, treble and presence EQ controls.

The gain stages are cascaded, so with the boost engaged both gain controls are active. The boost can be activated remotely with a footswitch or from the front panel. Meanwhile, a second toggle called Clip changes the gain structure for more tonal variation.

Near the VU meter, there’s a pair of sockets for the amp’s series effects loop, which is valve-driven and valve-recovered. Rear-panel features include a pair of 16-ohm and eight-ohm speaker outlets and a footswitch jack on the far right, plus an integrated mains socket, fuse tray and power switch at the other end.

Overall, the AGM-484H exudes the typical Ashdown vibe of solid reliability and classy styling, with military-spec components and tough construction ready to handle the rough and tumble of regular gigging and touring. Having said that, paint finishes on steel cabinets are easily scratched and we’d recommend investing in a padded cover to keep your AGM-484H looking pristine.

Ashdown AGM-484H head

(Image credit: Future / Olly Curtis)

Feel & Sounds

The Ashdown purrs into life with a gentle whirring from the rear-mounted cooling fan. We tried out the AGM-484H with our usual Les Paul and Strat test guitars, which are fitted with regular output pickups: a pair of PAFs and a trio of Duncan Alnico Pro single coils.

The AGM’s Brit-flavoured voice is a heady blend of Vox and early Marshall, with a hint of Fender Tweed, for versatile lead and rhythm sounds that work well across a wide range of genres.

Used unboosted, you can go from spanky funk and reggae cleans to chiming AC-inspired jangle and a slightly gnarlier pushed crunch, which sounds great for blues and country. There’s no favouritism for guitars; humbuckers and single coils both sound great thanks to a smooth, predictable passive EQ. With a little practice, it’s easy to dial in any instrument; there are no annoying midrange peaks or treble fizz.

Ashdown AGM-484H head

(Image credit: Future / Olly Curtis)

Flipping the Boost switch adds a significant chunk of filth, going from crunch up to screaming leads with both gain controls maxed out.

Engaging Boost mode keeps both gain knobs active as the signal cascades from one stage into the next, generating subtle shifts in colour and dynamic response as the controls are tweaked relative to each other. Meanwhile, the Clip switch alters the gain structure for more versatility, tightening up the low-end and adding upper-mid harmonics.

With a respectable 30 watts of power behind it and a pair of heavy duty transformers to deliver it, there’s no shortage of headroom, making the AGM-484H a great platform for pedal users. That said, it’s particularly rewarding to use with just a guitar and a lead, where the dual master volume arrangement makes it easy to balance overdrive and clean sounds.

To deliver the decibels, we hooked the AGM-484H up to one of Ashdown’s AGM-112 cabinets, which is loaded with Celestion’s excellent G12M-65 Creamback driver. This proved to be an ideal partner, with a resonant woody midrange and sweet treble combined with a tight bass, emphasised by the semi-open-back lightweight ply construction.


As live music makes a tentative return, so does the need for amplification that delivers great tone at proper gig volume levels. Ashdown’s AGM-484H is an ideal choice for the working guitar player, with compact dimensions that make it easy to transport and fit on the smallest of stages.

There’s plenty of volume to handle the average un-mic’d pub gig with ease. However, the slightly elevated background noise levels mean this head is perhaps less well-suited to home use and recording.

An on/off switch for the fan might be useful, too, although in fairness the 484H is clearly designed to be turned up, at which point all you’ll hear are great guitar sounds that flatter any style – with the punch and dynamic response that only comes from a premium all-valve circuit.

Ashdown AGM-484H head

(Image credit: Future / Olly Curtis)


  • PRICE: £999
  • TYPE: Valve preamp and valve power amp
  • OUTPUT: 30W
  • VALVES: 4x 12AX7, 4x EL84
  • DIMENSIONS: 80 (h) x 400 (w) x 220mm (d)
  • WEIGHT (kg/lb): 12/26
  • CABINET: Steel
  • CHANNELS: 1, with footswitchable boost
  • CONTROLS: Boost, gain, bass, mid, treble, presence, volume, boost volume. Boost on/off switch, clip switch
  • FOOTSWITCH: Single-button latching footswitch toggles boost function, not supplied
  • ADDITIONAL FEATURES: Series effects loop, footswitchable boost
  • OPTIONS: None
  • RANGE OPTIONS: Ashdown’s Guitar Magnifier collection includes: AGM-5C combo (£749), AGM-30 Offset head (£1,099), 45W AGM-684C combo (£1,599) and 15W AGM-284C combo (£999). Matching speaker cabinets include the AGM-112 featured here (£349), AGM-210 and AGM-212 (both £599)
  • CONTACT: Ashdown Engineering

Thank you for reading 5 articles this month**

Join now for unlimited access

US pricing $3.99 per month or $39.00 per year

UK pricing £2.99 per month or £29.00 per year 

Europe pricing €3.49 per month or €34.00 per year

*Read 5 free articles per month without a subscription

Join now for unlimited access

Prices from £2.99/$3.99/€3.49

Nick Guppy

Nick Guppy has been a regular contributor to Guitarist magazine for over 20 years, mostly writing reviews on guitar amps and related products. He built his first valve amplifier at the age of 12 and has since bought, sold and restored many more, with a particular interest in Vox, Selmer, Orange and tweed-era Fenders, alongside Riveras and Mark Series Boogies. When wielding a guitar instead of soldering iron, he’s enjoyed a diverse musical career playing all over the UK, including occasional stints with theatre groups, orchestras and big bands as well as power trios and tributes. His favourite musical genres are ‘anything that’s good’.