Great Forum!

As a freshly minted, soon-to-be McIntosh owner, I was recently stung listening to two setups:

1. MC275 driving a pair of B&W 704 (2.5 way floorstanding speaker)

2. MC275 driving the HF terminals on the 704 with MC402 driving the LF terminals on that same 704

Experience:

1. I was actually hoping not to hear a difference between tube and solid state, fearing the slippery and expensive slope into audiophile territory. The gentleman at the store was kind enough to perform blind tests for me.

Bloody hell, I could hear an immediate difference. Beautiful live-like sound on guitars, standing bass and vocals. It did struggle a bit with electronic bass and drums at higher volumes.

2. Goose bumps! Even though there was no active crossover, and you could tell something in the volume was off...some sort of layer effect, the sound was soooooo much better. Same sparkly/live sound with the guitars, standing bass and vocals but you could now feel the bass, it was much tighter, and I could really distinguish the various drum sounds better. Amazing.

Questions:

After reading hours of forum materials I remain with a couple of questions that I was hoping your collective experience could help me with.

1. Are the passive crossovers in the B&W 704 discrete and separated by the LF and HF binding posts? All I could find were the fact that there are 2 crossover points, at 150Hz and 4kHz, and there are separate binding posts for HF and LF. Does that mean that connecting to the HF binding posts will filter out any frequencies 150Hz and lower, with an additional crossover sending 4kHz and up to the tweeter? And that connecting to the LF binding posts will filter out anything over 150hz?

2. How do you tweak the volume of each individual power amp to get that overall gain balance between the two power amps? McIntosh's pre-amps can not do this, as per their tech rep. The power amps do not have a gain knob or setting. Is the only way an active crossover?

3. Is this banding or layer effect(for lack of a better phrase) on the MC275/MC402 that I heard purely due to volume differences in the amps or other effects of bi-amping?

4. When putting an active crossover in between the Pre and Power amps, which ones do not degrade the soundpath? I have read nasty reviews on the likes of Behringers and Dbx, even though they are used in audiostudios. Pass Labs (XVR1) and Bryston (10B) are the same if not more expensive than the amps themselves. Rane or Marchand are also mentioned. Suggestions?

5. The last thing I want to do is rip out the finely tuned passive crossovers in the 704. Perhaps a good combination is as follows:

A - Active crossover sends 150Hz and below to the MC402, which is connected to the LF terminals of the 704. The passive crossover in the speaker takes over and hardly has to filter out anything, sending 150Hz and below to the 6.5" Paper/Kevlar bass cone.

B- Active crossover sends 150Hz and above to the MC275, which is connected to the HF terminals on the 704. The passive crossover in the speaker sends the 4kHz and above to the 1" alloy tweeter, and the rest to the 6.5" kevlar bass/midrange cone.

Will this setup alleviate the increase in heat and distortion I have read about that bi-amping the MC275 will cause? Is this the best of both worlds; "pseudo-active" bi-amping without ripping out the finely tuned passive crossovers that make the speakers what they are?

I was looking at the MC352 as a substitute for the MC402 in this same setup.

Have I gone absolutely stark raving mad? Please help before I plunk down a ridiculous amount of cash.

Sorry for the long post.

Thank you much for your inputs!

Hi there,Glad to hear you have been seduced by the McIntosh sound !

Just a suggestion, but since you seem to really like the tube sound (and before you make things very complicated by going down the active route and mixing solid state and tubes) have you thought about simply going back to the dealer and seeing if you can audition a pair of MC275's connected as monoblocks ? - you may be surprised at the difference compared to a single MC275...

Also, check with the dealer whether the MC275 was used on 8 or 4 ohm tap - if the dealer used the 8 ohm tap, you may get better bass by experimenting with the 4 ohm tap (although you would lose voltage headroom - using the MC275's as monoblocks would ameliorate this somewhat due to the increased power available).

Let us know what you end up with...

Good luck !

Welcome tr@nz :)

My that's a long first post. :D

My first thought for you is to leave active/passive bi-amping for later. You could always do these advanced audio setups later.

I would think you would get better results by putting the money into one good amp and a pair of speakers. I have heard many of the B&W speakers and I like the 703s, 803Ds and 800Ds the best. I thought the 703s for the money sounded great but if you can swing it the 803Ds are much better. At the local stereo shop it is very common for customers to buy the 703s and trade them in for 803Ds a year later.

How loud you listen and the size of your room would determine what amp/amps would work best for you.

If you do passive bi-amp with McIntosh amps you could use the solid state speaker taps to help match the amps outputs. On the amp the 4 ohm speaker taps will be 3db louder than the 2 ohm taps and the 8 ohm taps will be 3db louder than the 4 ohm taps. I would not recommend using the tube amp taps in this way, just the solid state amp.

Also in a passive bi-amp system, usually the bass is where you need to make the adjustments so you could hook up an equalizer between the preamp and amp for the bass speakers only. This will not hurt the sound to the mid/high frequencies and you can set all the settings above the bass crossover point to full minus (usually -12db) this gives the bass amp more power because it won't have to amplify the mid/high frequencies. Then use the low equalizer adjustments as needed. I am doing this in my system with great results.

What are you using for amps and speakers now?

Victor

Thanks wolfclub.

I read a number of reviews that compared MC275 in stereo versus bridged and stereo came out tops in most of them. Naturally it is all in the ears of the beholder. It will be very difficult finding a shop that has 2x MC275s hanging around though, but if I find one I will certainly try.

The tube sound was so good, I actually ordered the MC275 to start the McTrip.

Appreciate the note on the 8 or 4 ohm taps, as I do not remember which one was used. My speakers are rated 8ohms, so I will have to research whether I could do damage to them using the 4 ohm tap on the MC275.

Victor,

Yes, I got a little carried away and am probably boring many to tears.

Thank you for responding.

On a number of occassions I listened to the 804S, 803S, (not sure about 803D) and they irritated my ears somehow. Very tiring to me. A high frequency perhaps? There are a few others I have heard say the same thing, but most people are not bothered. Then I compared the 703 v 704 and liked the detailing better on the 704. 703 was a little boomy for me. Now the 800D and 801D is a different story, but the price......

I ended up buying the 704s a while back and am running them with a .....cough.....cough.....Denon receiver. Am I allowed to say that out loud in this forum?

....but the MC275 is on its way!

Thanks for the suggestions.

Congratulations on ordering the MC275 - Once it arrives and you have had time to get used to the sound, you could always then ask your dealer to lend you his demo model for the weekend and experiment with a mono set up.

PS, you won't damage the amplifier if you run your 8 Ohm speakers on the 4 ohm tap - but you may find that the bass quality improves due to the higher damping factor this will offer (you will, of course, lose voltage headroom compared to the 8 ohm tap -which may mean that you don't find there is enough power available compared to the 8 ohm tap) - try both 8 and 4 ohm taps and see what seems best to you).

On a number of occassions I listened to the 804S, 803S, (not sure about 803D) and they irritated my ears somehow. Very tiring to me. A high frequency perhaps? There are a few others I have heard say the same thing, but most people are not bothered.
I agree, I often find listening to B&W speakers fatiguing but for me the diamond tweeter in the 803D speakers is much smoother and easier to listen to. The 803D is a HUGE price jump over the 704, I think the new retail price on the 803D is $9000 for a pair.

Then I compared the 703 v 704 and liked the detailing better on the 704. 703 was a little boomy for me.
It is great that you found a speaker that works well for you, and it's the lower priced one at that. :thmbsp: Ported speakers can often be boomy, careful positioning and room treatments can often help. For positioning try to give the speakers some room behind them (at least 3 feet) and keep the distances behind the speaker to the wall and to the side walls different. I actually like to put port plugs in ported speakers, this usually gives better bass detail and reduces the boom but it will also reduce the bass response.

I ended up buying the 704s a while back and am running them with a .....cough.....cough.....Denon receiver. Am I allowed to say that out loud in this forum?

....but the MC275 is on its way!
Of course you can say Denon here, It was just keeping your speakers warm until you found McIntosh. :huge: I think you will be impressed with the improvement the MC275 will give you. Let us know how the MC275 works out for you.

Victor

I have 2-MC275 on the way. I am going to Bi amp them with a pair of Tyler Acoustic PD 80. I just read this article on Bi amping http://sound.westhost.com/bi-amp.htm#common-question and it said that you need to disconnect the passive crossover and go electronic to get true bi amping, and also recommended tubing the HF and SS the LF. It is interesting that it is what you heard!? Tyler at TA is going to put Electronic crossover for LF and keep the active for the HF. I will also be able to use the Passive crossover if I want. I cant wait to experiment with the Bi, Mono, Active and Electronic... I will hold off on the SS for now...$$$$ I too would like to know how to set the gain on the MC275?
Thanks

Thanks Victor,

I will try auditioning those 803Ds. It is interesting that the 704s are so much cheaper yet sound so good. I guess there is a reason they keep showing up in the Absolute Sound's Editor's Choice Awards...even this year.

The placement is a good point, and I will start playing around with that more as well.

When I listened to the 800Ds my thoughts were, that it was a good sound but $20K more......maybe not.

But perhaps now with the Mc gear, the 704s are outclassed. I keep reading that your speakers should be the biggest percentage of audio costs.

Like I said....slippery slope!

Luckily I do not buy the cable hype.....yet. Just Blue Jeans Cable product that uses precision machining and Belden 10 gauge wires.

Hi Chiroman,

Exciting stuff. I had read that article and quite a few others before posting here. Very good info.

But the amount of R&D and fine-tuning of a speaker's passive crossover network that goes into getting a speaker to sound just right makes me very wary of ripping that out. One of Sonus Faber's designers purposely does not provide separate binding posts for LF and HF as he does not believe in bi-amping.

So I am contemplating getting the 'best' of both worlds, if that is even the case. Getting an active crossover. Not touch the internal speaker passive crossovers, and send only the frequency range to the LF and HF binding posts that those passive crossovers would have filtered.

One main reason for putting the active crossover in the soundpath as well would be not to get the added distortion and heating problems that the MC275 has been reported to get in a bi-amp setup.

There is an article that I will try to attach written by Ron Cornelius of McIntosh that provides valuable information and caution about bi-amping the MC275. He warns about possible distortion and overheating of the tubes.

There are also a few posts I have read that did tests of 2xMC275 versus 1xMC275, and 1xMc275 sounded better.

But like you said experimentation.

MC275 mark4 has gain control, the mark5 does not.

Are the new ones mark 4 or 5? If you are going to add an active CO is it better to have it outside the cabinet or built in? Tyler can do either or in my case.
Thanks

I have 2-MC275's driving my LaScalla II's.
I started out with 2 but a simple test one day told me that bi-amping them
sounded far better than stereo. It was like the soundstage increased in size by ten. And remember that my Klipsch are way less power hungry than your B&W's. Bi-amp the 275's, you won't be sorry.
I agree on your choice of the 704's over the 703. I have been auditioning them for a second room to use with a MA6500. But in my case the room is small (15 x 15), and it's just for casual listening.

Good luck

I also have a pair of La Scalas. What kind of crossovers do you have?
Thanks

Hi dirtbag,

Thanks for the feedback.

Did you not have any issues with distortion or heating of the amps when bi-amping them?

Are you using an external crossover?

chiroman,

The new MC275s are the mark 5.

Regarding the crossovers, I have no idea, but hopefully some experienced users can provide us with some info.

An interesting article came across my laptop today which describes a THX Ultra 2 certified pre-amp for $1700 msrp, that advertises the following interesting features:

1. Bi-amp Capability For Front (their words, not mine)

2. Adjustable Crossover by channel pair (Bi-amping anyone?) Frequency: 40,45,50,55,60,70,80,90,100,110,120,130,150,200 Hz.

3. 7.1 Balanced outputs (XLR) - Of which, in their words, the two balanced rear channel outputs can also be used in a bi-amping solution

Could this be another good option for a bi-amping solution, and a balanced one at that?

Here is the link to the Integra details:

http://www.integrahometheater.ca/model.cfm?m=DTC-9.8&class=Separates&p=f

Here is the link to the review from Dec 2007 that I mentioned; they awarded it the Surround Processor of the year 2007:

http://www.hometheaterhifi.com/processor-receiver-product-reviews/ssps/integra-dtc-9.8-thx-ultra2-7.1-ssp.html

No issues of any kind with my set-up. My plasma makes more heat than the amps do.