Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems 551 + 555 bi-amp

My first post on here, I hope this isn't something which has already been discussed (I couldn't find much on search).

I've had my 551 (and 506.24) since new in the 1990s, the 551 was recently re-capped by Russell which transformed the sound.

I recently acquired a 555 power amp cheaply and am now bi-amping my PMC TB1's.

Russell recommended the 551 driving the bass and the 555 the mid/treble however I think it sounds better the other way around.

Does anybody else have a similar combination?

The rest of my system is Pro-Ject 2 Xperience deck with Ortofon Bronze cartridge. I listen mostly to vinyl but also CD's with a fairly broad range of music.

Going forwards I'd like to try some speakers with more bass welly, maybe even going out of my PMC comfort zone but I love their detail and delicateness.

Welcome to the forum!How does it sound different in each configuration?

Logically, you’d use the more powerful 555 for the Bass, so I’d say you’ve got correct!

All the best,

Steve

Back in the day when I was using Linn components, I was told that I should use the most powerful amp for the treble/mid. I can't remember the reason why, but it didn't matter in the end as I ended up using the same amps for treble, mid and bass sections. I must admit, it did seem counter intuitive.

+1

Usually, the more powerful amp would make a better bedfellow for the bass drivers as they draw the majority of the power.

As always, though, your ears should be the deciding factor

I wonder whether this could have been down to the frequency response of the more powerful amp

I'll have to try it with several different LPs - it's hard to do the test objectively, different isn't necessarily better!

I could remove the bi-wire/bi-amp and try out each amp in turn I suppose!? Not sure what it'd prove but useful to hear if I can tell the difference I suppose.

The 555 is more powerful than the 551 (65W v 55W) but otherwise identical - the only thing is that the 551 has been re-capped.

Any suggestions for beefier speakers to go with this combination? I like the sound of my TB1's but they don't do rock as hard as I'd like (they're superb for most other music to be fair).

You could consider a re-cap on the 555 if it hasn't been serviced.

The only reason I can think of using the more powerful amplifier for the tweeter, is slew rate, how quickly the amplifier can change voltage in volts per micro-second. This would directly affect the gain bandwidth product, so in theory a power amplifier used at lower power will have an extended high frequency response.

In reality, most solid state amplifiers should have a 50kHz response at full power, so the above may be moot.

ATB,

Steve

Couldn't you just move up in the PMC range? Most PMC speakers I've heard seem pretty respectable in the bass region.

Yes, Bee - I've been considering it... I realise I'm challenging the laws of physics but GB1 is about as large as I dare go before I fall foul of the decor police

it's on my to-do list at some stage...

I ran my 551 (treble) + 555 (bass) into my A500’s. My choice of VanDenHul Teatrack speaker cables really made the difference.