Second hand high end amplifiers - Reccomendations

[moustachebandit]

Looking to upgrade my current Onkyo TXNR626 to something better both audio quality wise but also with more power.

The Onkyo has performed brilliantly, but it is now running a pair of Linn Isobariks and whilst everything still sounds great, I cant help but think it doesn't have the clout and audio quality to get the most out of the speakers as they are supposed to be very power heavy.

I am by no means and audiophile, so I am a little clueless in terms of the brands and models to look for when considering an upgrade.

So I was wondering what suggestions people had for older models / brands that might be a step up in terms of power and quality without putting me in the poor house?

Thanks

[P700DEE]

Budget? A six pack of Naim 250s active crossovers and a serious Naim Pre will set you back huge pennies
Isobariks are known to be demanding of amps especially re control and power on the bottom end.

[moustachebandit]

Budget wise was thinking £500 / 750 - I appreciate it can get out of hand very quickly and in the scheme of things thats not a huge amount.

[legzr1]

At that budget this is hard to beat:

https://www.avforums.com/threads/price-drop-krell-...

[anonymous-user]

I bought a used NAD C275BEE power amplifier from eBay for £500. Very punchy and decent levels of detail. You will need a pre amp though.

https://www.whathifi.com/nad/c275bee/review

[moustachebandit]

Just realised one big feature the pre amp needs to have - HDMI in and HDMI out. Thats going to thin the selection a bit.

[anonymous-user]

moustachebandit said:

Just realised one big feature the pre amp needs to have - HDMI in and HDMI out. Thats going to thin the selection a bit.

Assuming yours is an AV amplifier, all you need is pre out connections to plug into the power amp. If not, you’ll need a new AV amp. If that is the case, I can recommend the Yamaha Aventage range.

[DavidY]

moustachebandit said:

Just realised one big feature the pre amp needs to have - HDMI in and HDMI out. Thats going to thin the selection a bit.

Linn Isobariks like a good high current output amplifier, Integrated AV amplifiers on the whole do not meet this criteria. You might be better considering an AV Amplifier that has pre-outs and a separate power amplifier to drive the Isobariks, and if you are using surround sound as well, you would need an AV amplifier that has pre-outs (for power amplifier) and some internal amplification for the satellite speakers

Your budget isn't really up to what the Isobarik's derserve (eg Naim, Exposure or old skool Meridian amplification, and to these you would need an AV pre-amp or AV Amp with pre-outs).

Personally I would live with what you have until your budget is bigger, otherwise any 'upgrade' may actually just be 'sideways' !!!

[Crackie]

I agree that an AV amp with pre outs is the way to go. Amps capable of pushing high currents into low impedances is what the Isobariks need. A Rotel RB-981 ( RB-1070 ) or RB-991 ( RB-1090 ) will do that for you and both have excellent reputations for sound quality. I use several of the 981s to power my active system at home.

http://www.audioreview.com/product/amplification/a...

A 991 will put out 281.5W into 8 ohms, 539W into 4 ohms, 974 W into 2 ohms, and 1615W into 1 ohm. The latter corresponds to an RMS current of 40A !!!
A 981 will put out 200W into 8 ohms, 372W into 4 ohms, 684 W into 2 ohms, and 1128W into 1 ohm. 33.6A current.....

https://www.stereophile.com/content/rotel-rb-991-p...

https://www.stereophile.com/solidpoweramps/899rote...

https://www.ebay.co.uk/itm/Rotel-RB-1070-Power-Amp... ( This is the model that superseded the 981 but has the same guts inside )

The RB-1090 superseded the 991.

Edited by Crackie on Saturday 27th January 23:25

[theboss]

You wouldn’t go far wrong driving Isobariks with one of Linn’s own higher end stereo power amps - a Klout (sold until about 2002) or its successor the 2250 will come in around your budget - there are a bunch of 2250’s currently listed on eBay at £799

[red997]

I've got a pair of Isobariks;

However, I only run them active (3 power amps per speaker)

Used to have Naim amps, but I actually prefer the sound of the Rotel power amps. They have a good amount of 'clout' to them. ( I run fully active too)

I'd stay away from AV amps TBH, they just dont have the grunt needed to get the best out of these brilliant speakers

[Zod]

You could go for an AV processor and separate power amp(s) for the speakers, but that would be a bit of a budget stretch (to say the least).

[telecat]

The Obvious solution Linn LK1 Pre and LK2 or LK280 Power. Most Meridian Amps should be up to the Job as well. Pricey though even second hand.

[Crackie]

red997 said:

I've got a pair of Isobariks;

However, I only run them active (3 power amps per speaker)

Used to have Naim amps, but I actually prefer the sound of the Rotel power amps. They have a good amount of 'clout' to them. ( I run fully active too)

I'd stay away from AV amps TBH, they just dont have the grunt needed to get the best out of these brilliant speakers

Hi red997, we're both using Rotel amps to run active setups. Which models are you using ? and do you use them stereo or bridged mono?

I have a stereo RB-981 running 2 different ULF subs below 30Hz, a stereo RB-981 does L/R bass up to 175Hz, a bridged RB-971 covers left midrange up to just over 3kHz and another mono RB-971 does the other mid channel. A stereo RB-971 does the top end. Until recently another stereo RB-981 was doing 100 - 600Hz wasn't ideal though. I was never happy with the phase integration 'cos every the speakers are open baffles and room reflections caused big issues.

Edited by Crackie on Monday 29th January 18:41

[red997]

I originally had the Active / Dirak / Bingo active crossover, but sold it as I thought it was pants.
Factory Crossover frequencies & slope:
200Hz 2nd order
2.7KHz 4th order.

I'm using a modified Behringer DCX2496 for crossover and phase correction, and a DEQ2496 for RTA

Be aware - the 'pairs' of drive units when connected together (in parallel) will present a load less than 4R.
If you're using bridged mono Rotel amps, check the spec - the ones I used didn't like driving 4R loads when in mono mode.
I had one go pop on me - it sent the full rail DC voltage to the bass drivers - which went pop. luckily I had a friend who could source me a replacement pair.

I'll have look at the models of the amps when I get home - I cant remember !

Edited by red997 on Monday 29th January 15:55

Edited by red997 on Monday 29th January 15:56

[Jaguar steve]

Look at the cost of having Naim amplification serviced and recapped. It's recommended every 10-12 years and makes a staggering difference to sound quality once the new components have burnt in.

Something to bear in mind if you're going secondhand with Naim, but curiously never seems a consideration with any other brand - apart from old QUAD valve kit.

[red997]

applies to all electronics using electrolytics
heat is their enemy, along with high ripple currents.
plus, new caps have significantly better performance than the older types.

its not sufficient to just swap on voltage and uF - look at temp & ESR values at the frequencies you're interested in

[Jaguar steve]

red997 said:

applies to all electronics using electrolytics
heat is their enemy, along with high ripple currents.
plus, new caps have significantly better performance than the older types.

its not sufficient to just swap on voltage and uF - look at temp & ESR values at the frequencies you're interested in

I can see why it would and have heard how it does.

There's a number of companies servicing Naim kit but as far as I've seen up to now nobody doing the same to anybody elses.

[moustachebandit]

Thanks for the suggestions everyone - definitely some food for thought. Totally new to all of this so a little clueless on it all!

I didn't realise I could use my AV amp and using pre outs run the Isobariks off a separate power amp. That would have kept things pretty simple. I had assumed I needed a new pre amp processor and then a power amp. Annoyingly the Onkyo I have doesn't have any pre outs.

Crakies suggestion of the Rotel RB1070 is interesting, seemingly very well rated and also affordable for a good condition unit second hard. If I could source a second hand AVR with pre outs this might be a good way to go.

Out of interest though - If I use a power amp, run through an AVR would I still retain the surround sound for when I am watching films?

Thanks

[Crackie]

moustachebandit said:

Thanks for the suggestions everyone - definitely some food for thought. Totally new to all of this so a little clueless on it all!

I didn't realise I could use my AV amp and using pre outs run the Isobariks off a separate power amp. That would have kept things pretty simple. I had assumed I needed a new pre amp processor and then a power amp. Annoyingly the Onkyo I have doesn't have any pre outs.

Crakies suggestion of the Rotel RB1070 is interesting, seemingly very well rated and also affordable for a good condition unit second hard. If I could source a second hand AVR with pre outs this might be a good way to go.

Out of interest though - If I use a power amp, run through an AVR would I still retain the surround sound for when I am watching films?

Thanks

The surround sound should still work fine for films.........should just be a case of changing the processing on the AV amp.