4BSST too quiet. Buy 14 or 7's?

guest2521 · « **Reply #20 on:** 26 May 2005, 03:26 pm »

Have you considered the fact that your preamp may be distorting? Which one are you using and is it a CD or vinyl front end? For the latter better isolation could help. I am using PMC MB2 with trimaped Bryson (2*7bst and 2*4bst) and it is clean all the way up to one kilowatt.

pauldixonuk · « **Reply #21 on:** 26 May 2005, 05:46 pm »

It would be clean as your splitting the effort between three amps, so each one is cruising effortlessly. I'm sure you would have settled for one 4B if that was sufficient.

I listened to the hardening vocals at higher levels through a 25 Bryston pre. Looking to get a valve AR LS25mk2 anyway.

Paul

pauldixonuk · « **Reply #22 on:** 26 May 2005, 05:55 pm »

P.S I bet that sounds quite amazing - well done

guest2521 · « **Reply #23 on:** 26 May 2005, 07:46 pm »

Hi,

Triamping doesnt affect the cleaness in that way. I have tried a single 4bst and even at full volume it sounds totally clean. The benefits of triamping are somewhat different. Everything sounds more defined and controlled. Yes there is more headroom and dynamics but it doesn't mean the 4bst sounds strained at full volume - quite the reverse. It sounds great but trimaping sounds better, but the 4bst still has no shortfall in it's performance. It isn't a power issue. A 4bst st and a pair of 3bst triamping mb2s sounds better than a single 14bst or pair of 7bsts. Its due to individual control of each driver not power. The 4bst/3bst triamp arrangement sounds just as good as the 4bst/7bst that I have but just has half the power. I have heard all of these combinations and I only bought the higher powered arragment as I got such a good deal 2nd hand and it made it easier to put the amps behind each speaker if the bass power came from monoblocks. As you say - a single 4bst was not enough for me but not becuase it solved the issues you have noted. I would point the finger at the Bryston preamp. To be frank I dont like it much at all it's pretty average and sounds worse as the volume level is increased in exactly the way you described. Which is why I don't own it! Something like a avi preamp is much better - second hand you can get them for about £400. New they are about a grand and wipe the floor with the Bryston pre. I think you will find that solves all your problems. I used to own one in my previous system and my friend has one now. They are one of hifis great unsung bargains. In a straight dem I have heard them beat top of the range krell and mark levinson, bryston, naim etc etc. Alternatively I can give you details of the custom built unit I am using. It cost about £700 and is several notches up from the avi.

Regards,

Nick.

pauldixonuk · « **Reply #24 on:** 26 May 2005, 08:52 pm »

Bio,

Thanks for the detailed reply. I was starting to think I was all alone in my experiences. That's very helpful that you point the finger at the pre amp. I will cross it off my list then. I'd be interested to hear which specific unit your using. Is it valve? I recently used a valve pre into some ATC50 actives and found it awesome - huge soundstage, live and exciting sound. By comparison the ATC CA2 solid state pre was dull, flat and lifeless. However this particular (diy) valve pre had the usual valve soft blurred bass. I have it on very good authority that Audio Research have rock solid bass control, together with the upper valve benfits. This is why the LS25mk2 is top of my list to demo / buy. Only downside is mega price tag. Oh well.

I take it your tri amped arrangement is passive? I wonder how you rate yours compared to the active ATC's? In summary I'd say size for size the PMC's have double the low end bass output, extension and even more control. The ATC's have about 5% more clarity in the upper ranges though. For my music the PMC is just more fun. I'd say ATC is better for classical fans. What do you think? What made you go the PMC route?

guest2521 · « **Reply #25 on:** 26 May 2005, 09:24 pm »

Hi,

The ATC's arent more detailed they just emphasise the treble up from neutrality (despite what atc claim). During a short dem it sounds more impressive but it soon becomes very wearing. Just listen to them with rock and you will see. Like nails down a blackboard. They are used as mixing desk monitors so they are designed to emphasise the treble so you can pull the mix apart and analyse it - this is not the same as listening to music for fun. PMC are mastering suite speakers they deal with the presentation of the finished product in the best way possible. I compared MB2 with ATC SCM100A. It was no contest. Once the Bryston pre was replaced by AVI the ATC was just blown away in every area. You haven't really heard the best the system can do yet

. With the pre changed you will write off the atc.

My unit is custom built solid state - I find tubes usually add too much to the signal. What they add sometimes masks problems elsewhere in the system and makes the system warmer (adding lushness to the rather abrasive atc for instance, or to a cd player). However I want accuracy not warmth - otherwise I would put a "niceness" knob on my amp to add 2nd harmonic!

. In a more balanced system the defects of valve kit stand out. A lot of SS is bad but then a lot of tube kit is bad also. The truth is the engineering is the important part not the components. SS and tube can be equally good if designed for accuracy. But tubes are more expensive to buy and run and more hassle and lower powered - not to mention high domestic voltages so why bother if you can get as good a result with SS? So why do high end dealers love valves? Its the money as always - you can sell a valve intregrated for £10K - try doing that with solid state kit! Just like megabucks power and interconnect cables. I have tried nordost valhalla and my custom cables sound better at 5% of the price. The emperor has no clothes!

My triamped arragement is passive currently. When the warranty runs out I will convert using custom crossovers. The pre and phono are based on a diy design but much modifed to my own specification. There is still some way to go but I have never heard a commercial design that comes close and I have heard a lot. Eventually I will also replace the brystons. If you are interested I can give you details. I have spent maybe £2K on the phono and pre together ... maybe another £500 but the time I am finished and that's a bargain for top flight performance. I picked up the amps 2nd hand - 7bst pair from a studio and pair of 4bst used to drive a von neumann cutting lathe. I got the speakers at cost. Phono and pre are diy. Paid an arm and a leg for the deck though!

Pick up an avi pre for £400. Try it out and see what you think. Use it to compare to other preamps at home in your system. If you decide to change it then the tradein will cover the purchase cost and if you decide to keep it then you have a bargain and can spend funds elsewhere.

Just my opinions - feel free to disagree!

Regards,

Nick.

guest2521 · « **Reply #26 on:** 26 May 2005, 09:34 pm »

Also I recommend using 4b and 2*3b to triamp will give you best results.

Preferably ST over SST.

pauldixonuk · « **Reply #27 on:** 27 May 2005, 07:26 am »

Bio,

Interesting to hear your respones with the ATC's. I demo'd the 100's against the IB2. At the time I thought the same - the ATC's have a lot of detail, although it was slightly bright by comparison. Pretty much like the presentation of my previous wilson benesch speakers actually. I thought the PMC were a touch smoother in the top, not as highlighted. Funny, I went to the demo expecting to buy some ATC's, then was blown away by the PMC's lower octaves.

I've also sold off my old nordorst cables and am getting custom studio cables. Was looking at mogami, although I'd have to buy a 50m roll! (Anyone want a group buy?). I may get van damme with decent connectors assembled. This guy is really nice and helpful, posting back long emails full of explanation. Was reccommended by Andrew.B on PFM, an ATC50 owner. http://www.orchid-electronics.co.uk/

Your words on pre amps mirrors my sentiments. However, what I heard with a valve pre on ATC was staggering. I would be amazed if an ss could come close. I've heard nothing similar yet.

I'm going for a very long trip over to the AVI factory soon anyway. I've been told I MUST listen to their Brio speaker. Uses the same volt bass driver as yours btw. Their designer worked at ATC for 10 years too, although they reckon they sound more like PMC, but maybe better. In fact I spoke to one dealer who did an A-B with the Brio and the £18k active PMC mega speaker, and he preffered the Brio! Crazy but true. That's why I'm going to travel so far to check for myself. I think it will be impossible for this sealed box design to emulate the awesome PMC sub bass. But this dealer swears they do. I'll check out their components when I'm there. Supposedly they have some 500w monoblocks coming out as well. May be interesting.

As for tri amping - I don't understand how the hell this makes any difference in passive mode. At the end of the day all amps still have to go through the same passive cross over. It seems to me like this - you have three lanes of motorway traffic (3 amps) flowing along thinking it's better than one lane. However they all have to merge back down into one lane right at the end (cross over) causing a bottle neck. How on earth does this make any sense at all? Is there an explanation, or is it just a case of trusting your ears?

Similar thing happened on my IB2 demo. We put a Whest gizmo in between the cd and pre amp. Immediately the soundstage became twice the width and sounded 'live'. No possible explanation other than trust your ears. I thought it was going to be a gimmick. It made an ss pre sound like an open valve. Check one out!

guest2521 · « **Reply #28 on:** 27 May 2005, 07:37 am »

Hi,

Bryston has a split crossover - if you triamp then each driver is driven completely seperately and there is no interaction between the drivers or the 3 parts of the crossover. It makes a big difference. Its three lanes all the way! There is no bottleneck.

I have seen the brio - it has the same tweeter and bass unit as the mb2. However it is not TL and cannot possibly match it in term sof bass pwoer and control. This also will knock on into the mdirange. I suspect the dealer is over egging the pudding somewhat. Most are little better than used car salesman. I have only heard the old avi kit not the latest stuff.

There are SS pres that will match and surpass valves. Just not the bryston pre. My custom unit beats all preamps I have heard even those up to £20k regardless of wether they are SS or valve. Also be careful that what the valve is adding sounds initially impressive. Same goes for the whest. I read about it and I am a bit dubious - it's addng something that is not meant to be there - it can't just summon valid information from nothing.

Let me know how you get on!

Nick.

pauldixonuk · « **Reply #29 on:** 27 May 2005, 10:39 am »

So your using a Bryston 10B cross over, effectively making them fully active. Which 10B do you use, as there seems to be a few on their site? I don't think this tri amping is an option for the passive IB2. I don't really have the space for anything larger really. The MB2 are huge. This much larger than the IB2: H 10cm, W 5cm, D 7cm. This is a rather bulky mo fo! Tempting though.

Have you ever heard a Benchmark DAC1? This seems to be the biggest bargain 'high end' sound ever. I suspect it will beat the AVI cd.

Just had a mail back from Ashley at AVI. I asked him if their Brio could match the TL PMC designs for sub bass output / extension / impact. In a roundabout way he seems to admit it won't. However he also implies the PMC's bass will sound less accurate. In principle, looking at the on paper design, I might agree with him. However I have heard the IB2's recently and doubt anything can match their sheer bass accuracy. Scary tight and controlled at full volume. Made my old REL sub, and to a lesser extent ATC, sound blurred. Anyone who doubt's the PMC's for bass is having a laugh. I've never heard anything close.

pauldixonuk · « **Reply #30 on:** 27 May 2005, 10:58 am »

Further to just checking out the difference in size, there are much larger differences in output:

IB2 v MB2 specs:

Peak db - 116 v 124!

Sensitivity - 89 v 91!

Sub Hz - 25 v 20.

guest2521 · « **Reply #31 on:** 27 May 2005, 11:51 am »

The PMC TL design couples the bass to the room more effectively and also acts to damp the bass unit making it much more precise and accurate. Ashley is just trying to avoid the issue by making some unsubstantiated claims. The brio will not match the mb2 in the bass in any respect. I will bet he knows it.

No I am not using an active crossover. Just the internal three way passive crossover. It's in three parts which don't interact (otherwise the amps would blow) if you triamp. The ib2 can also be triamped.

I haven't heard the benchmark dac - but the avi is a giant killer. One of the half dozen best players made regardless of price.

The mb2 has more headroom and better bass than the ib2 - with knock on effects into the midrange but appart from that they will sound pretty similiar. Unless you have a huge room the ib2 will likely sound better.

pauldixonuk · « **Reply #32 on:** 27 May 2005, 09:42 pm »

Bio, thanks for all your help and detailed explanations over email!