Where do I go from here?

[jerryo]

Hello to everyone on this forum, I am hugely impressed with the level of knowledge out there and it is for this reason that I come to you all for advice. I am using Linn Isobarik DMS ( bought for £50.00) with NAD 2100 power amp and matching pre amp. They do sound very impressive but seem to be lacking in some areas. They are also complex beasts and difficult to drive; my NAD amp seems to cope fairly well however. Where do I go from here? Turning the "Briks" active will get expensive so what are my alternatives? Keep the Briks or change direction? I am drawn to the simplicity of fullrange drivers using low powered class A amps or even Nelson Pass F1,F2,F3,F4 style amps. What do you all think? There is a phrase that I personally apply to life generally and that is "The law of diminishing returns". In other words Iam trying to keep the costs down as much as possible!! Thank you all in advance for your advice. Cheers.

[BHTX]

NAD 2100? Would this happen to be the same amplifier as the 3 AMC 2100 amps that I have? They're all in storage. One of them blew completely up brand new after 15 minutes of use, connected to one of my Eminent-Tech LFT-8A's. After that, I put the other 2 in storage...and there they've sat for the last several months. Never even opened the boxes.

I bought them because it seemed like a very good deal at the time, brand new for around $200-$250 each. Boy was I wrong. They were horribly cheap amplifiers. Can't do anywhere near their rated specs.

[sreten]

Hi,

I'd try another power amp to drive the mid/treble.
Gain must be matched to the NAD.

/sreten.

[Brett]

Originally posted by jerryo
I am using Linn Isobarik DMS ( bought for £50.00)

Great price.
I have a real soft spot for these speakers. I had a pair a long while ago on loan and Sara's of my own. Both models do a whole lot right, and some of the best music listening experiences I've had were with them.

I'd suggest an active xover (build it) and a quality pro power amp to drive the bottom end. Lots of pro amps are going quite cheap these days as newer models are going with SMPS and class D modules in some for weight, which is an issue in a mobile rig, but not in a static setup at home. Briks need power to get up and boogie.

[jerryo]

Hello BHTX, sorry to hear about your amps; no I do not think they are the same ones as mine. Mine are NAD 2100 and although they are not the last word in audio they do have a high current capability and drive my Isobariks satisfactorily- for the time being. Hello streten, your idea is one of the options I have considered but of course this path leads to more amplifiers which in an ideal world I wood like to avoid. Hello Brett, yes a fully active set-up would be nice but I am concerned with the amount of amplification needed, not to mention wall sockets! The other method that I have heard that brings good results is the "split barik" where you have one power amp for each pair of crossovers thus reducing the load for each amp to 8ohms. By the way, can you recommend a good crossover kit? Thank you for your replies. Lastly if I were to go active what would be the easiest and best way of building 4-6 mono class a amplifiers. Cheers.

[BHTX]

I know it's an NAD. I've owned NAD in the past as well. AMC is very much like NAD, and some of their products appear almost identical at first glance, but I've never owned any others to compare, so i can't speak any further than that. Despite all of this, I'm not sure whether or not there's any real corporate relationship between the two. However, I do remember reading somewhere a while back that the person who started AMC was a previous employee for NAD, or something like that. Regardless, the Eminent-Tech LFT-8A's I was driving with the AMC 2100 that blew up are terribly inefficient at around 83dB/watt. The AMC 2100 amplifier was in bridge mode to one of these speakers when it blew up after about 20-30 minutes of jazz music, which wasn't even continuous. That amplifier was rated for 250w into 8 ohms when bridged. Bruce Thigpen recommended 75 watts minimum for these speakers, and a maximum of 200w. In my experiences, 200w barely gets them going. Mainly, as far as you're concerned, that AMC 2100 not only went up in smoke like that, but it sounded very thin and cheap while playing before it blew.

Since then, I no longer bridge amplifiers, even if they're underrated. On top of that, I also won't run less than an 8 ohm nominal load anymore, unless I absolutely have to, with the exception of subwoofers, and that's only because a large majority of the good subwoofer drivers out there are 2-4 ohms with dual voice coils.

Oh and...I just remembered you asked about active amplification for your speakers. In that case, grab yourself a DCX2496 for around $250 or so, a few well-built amplifiers...preferrably QSC RMX clones (for value), then get some decent XLR cables. Afterwards, prepare to be amazed, in comparison to the previous sound. If you're running a multi-channel HT setup, just run passive on everything else besides the front L&R channels, unless you're willing to buy more active crossover units and go from digital to analog and from analog back to digital again, and then back to analog, as well as spending a ton on a ridiculous amount of amplifiers...silly and not worth it in most applications, IMO.

You mentioned 4-6 mono class A amplifiers?? Have fun with that electric bill.
Although I suppose if you can afford 6 class A amplifiers all at once, the electric bill won't be a problem.

[Brett]

Originally posted by jerryo
Hello Brett, yes a fully active set-up would be nice but I am concerned with the amount of amplification needed, not to mention wall sockets! The other method that I have heard that brings good results is the "split barik" where you have one power amp for each pair of crossovers thus reducing the load for each amp to 8ohms. By the way, can you recommend a good crossover kit? Thank you for your replies. Lastly if I were to go active what would be the easiest and best way of building 4-6 mono class a amplifiers. Cheers.

First of all, an active crossover is easy to build. Rod Elliot at ESP has a PCB both for the power supply. Simply fill the boards and do the calculations for the xover frequencies using the ones that Linn used in their active version.
http://sound.westhost.com/project09.htm
http://sound.westhost.com/project05b.htm

Get a decent Pro amp as stated above for the LF. Use the NAD for the MF. Build a Gainclone (search here) for the HF; you can probably build the latter into the xover enclosure to save space.

Don't use the DCX - sounds awful (stock) and you need 6 x volume controls unless you want to do it in the digital domain with all it's problems. If you want to buy something, see if you can find a secondhand Rane AC23.

Wall outlets? Are you kidding? Buy a high capacity pro/industrial powerboard and use that. Don't buy an 'audiophile grade' device unless you like wasting money.

By going active, you don't reduce the load on the amps to 8R as easch will still see two nominally 8R drive units in parallel.
For the benefits of going active, read these two articles.
http://sound.westhost.com/bi-amp.htm
http://sound.westhost.com/bi-amp2.htm

The crossover and Gainclones (or one of a variety of other types and designs) are simple and quite inexpensive to build, and if you're unfamiliar with electronic construction make great starter projects. You'll get a lot of support here too. After all what's the sife called.

For a Pro power amp for the LF > 300W/ch at 4R. Brands include Yamaha, QSC, Crown, Perreaux, Tapco etc. If unsure, ask. More power usually doesn't cost much more and weight is a good thing in these design. Usually indicates a bigger PSU and they tend to sell for less for the reasons stated earlier.

[BHTX]

Just FYI, if you can get them where you're at, the Mackie FR series and Tapco Juice series amplifers are the same, as Tapco is a division of Mackie geared towards the DJ market. They're by far the heaviest of all the QSC RMX clones, even the QSC RMX's themselves. That said, they're the best bargain on Earth as far as new pro amps go. I got all of my from Guitar Center for $100 off each amplifier. The Behringer EP's are junk in comparison, IMO.

As for the DCX, I've used mine for a bit over 6 months now with the AES/EBU input, and haven't noticed any degradation or deterioration of sound quality. However, my midrange and tweeter drivers are still passively crossed. So, although my DCX2496 is used on all drivers for the L&R channels, it's really only used at lower frequencies...so that might have something to do with it. Also, I can't say I've ever compared with analog, or any other crossover units.

As for AC power to your amplifiers, I've had a big rack mount Tripp Lite surge suppressor that I've used for a long time now that works great. I believe I got it for under $250 brand new. No audiophile snake oil crap with this one.

[BHTX]

Hrmmm.. That Rane AC23 looks nice, specifically the A23B with balanced XLR inputs/outputs. I have a good friend that's in pro audio, has a ton of equipment. I know he has a thing for Rane gear. I'll see if he has one laying around for me to try out and play around with. If he doesn't, I'm sure he has something very similar. Anyway, we'll see. New Rane equipment can get pretty expensive though. I've seen a few of these units for sale used, some of them in OK condition, but they're all the older models with only TRS connections. As for a new AC23B, $420 is about the lowest I could find online.

[Brett]

Originally posted by BHTX
As for the DCX, I've used mine for a bit over 6 months now with the AES/EBU input, and haven't noticed any degradation or deterioration of sound quality. However, my midrange and tweeter drivers are still passively crossed. So, although my DCX2496 is used on all drivers for the L&R channels, it's really only used at lower frequencies...so that might have something to do with it. Also, I can't say I've ever compared with analog, or any other crossover units.

Run from a digital source, I can see it might be OK, but when i tried it from an analogue source, it noticeably degraded the signal to my ears.