Equipment does not match

Hello all been away for a while busy with work just got a Job 225 paired with my audio research sp17 and Burmester B25 speakers sounds really good

Thanks Dick will let you know how the experimentation with the placement of speakers goes!!

Dereck, Don't worry too much about the amp. From the Stereophile review:

"Fig.8 shows that the RB 1080 clips quite suddenly. However, this is at very high power levels. Using the conventional 1% THD definition of clipping, the Rotel puts out 291W into 8 ohms with one channel driven (24.6dBW), 558W into 4 ohms (24dBW), and even 800W into 2 ohms (23dBW)! Considering its modest price, this is one powerhouse of an amplifier. But, as Rotel recommends in the handbook, the RB 1080 is best used with speakers whose impedances don't drop much below 2 ohms.—John Atkinson"

Your amp has PLENTY of power for those speakers (especially in that lively room you have!). Earlier comments about the amp refer more to the overall refinement and not its ability to power you speakers. I truly believe that most of your problem lies in the room and speaker positioning. Best of luck and let us know how it goes. Dick

oscoeiii/Almarg/Dick

Thanks i will move the speakers around over the weekend and let you guys know.
With regards to Dicks question what sound did i envision, i have a pair of B&W XT8s that i use as a backup so with the same setup i get a good crisp sound , when i purchased the B25s i expected the results to be infinitely better (more natural sound with a good deep base and clear treble)
However as many of you have pointed out i have not optimized the placement of the B25s so hopefully with some experimentation should get there.
The 8ohms rotel power amp paired with the 4ohms B25s still bothers me but will get to that in the next stage thanks all!!

Dereck, Sorry to have left the conversation for a while but it's been a busy weekend. I think the marble floors and the close wall placement are a big piece of the puzzle. I agree with Mapman and Al - you need a rug at the floor reflection point. You didn't mention what you're unhappy with sound-wise but I'd be willing to bet that you're getting a lot of reflected sound. This is going to create a very lumpy in-room frequency response and a lot of sounds arriving at different times from different directions. Some reflected sound is necessary to provide a sense of space but too much is not a good thing. Another thought - are your speakers pointing straight ahead? A little toe-in toward the listening position will change those sidewall first reflection points (although it sounds like that may not be a problem with the left speaker). Dick

Roscoe, thank you most kindly.

Best regards,
-- Al

Yes, I think suggestions like Almarg's are very good ones. Pay attention to any post that Almarg makes. He is a superb resource whose responses never fail to impress and educate me.

And yes, if not the room and placement, I would look at that amp. Try to audition a number of amps, and find out what amps have worked well with your speakers from your dealer or other folks on audio forums.

Thank you all for the very positive feedback, appreciate all your comments. i have already spent quite a bit on my audio kit so wanted to learn about options to improve sound without going in for more expensive kit.
I will try the following
1. move the speakers further away from the wall
2. get a couple of rugs placed in front of the speakers
3. acoustic panels
4. the final option is to upgrade my power amp (Rotel RB 1080)which seems to be the weakest link.

Mapman beat me to it :-) I was composing the following when he submitted the preceding post:

As many of the responses make clear there are numerous possibilities, and chances are that there are multiple factors contributing to the less than optimal sound. However, my instinct is that the two factors that are likely to be the most major contributors are referred to in this excerpt from one of your posts:

I have a marble floor and no rugs. Speakers are placed abt 5-7 inches away from the wall but the left speaker is just next to the open passage at the entrance.

While there are some notable exceptions, the performance of the majority of high end speakers will be severely compromised by close to the wall placement. I see in Stereophile's review of the B25 that they placed the speakers five feet from the wall behind them.

I would urge you to try, at least as an experiment, moving the speakers several feet out from the wall. And then listening from a variety of distances. (The position of the listener relative to all four of the walls in the room can make a significant difference, as well as the distance from the listener to the speakers).

And do consider putting a thick rug on that marble floor!

Good luck,
-- Al

Have you tried placing a rug in front of teh speakers at the
main reflection point to where you liten from? Bare marble
floors sound like something that might benefit from a bit of
acoustic treatment. If bare walls also, an acoustic panel
on each side wall at main reflection point to your listening
position might be worth a try.

Also before that, sound like speakers might be too close to
the walls for best results.

The Sereophile reviewers positioned them 5' from the front
wall:

"I positioned the Burmester B25s 5' from the front wall, 6'
apart (measured from the tweeter centers), and toed-in 45°
to focus on my listening chair 7' away."

I'd play with the placement aways from walls a bit for good
soundstage and imaging and then perhaps try floor and/or
wall treatments from there as needed. Maybe try the toe in
as well. definitely get speaker placement optimized
before anything else.

Only one response about the room,interesting.
I went the upgrade route with gear and (god forbid cables)spent 10's of thousands on the above.
The most immediate and huge improvement was using acoustic panels(especially bass trapping)which give you a tight punchy bottom end and also freeing up the mids and highs,a non muddied clean sound.
Speaker position,seating position and if that doesn't do it,the room,heck you can go to a hardware store and put unopened bags of insulation in your corners to hear what happens and its free as you can take them back as they are unopened.
Haven't heard a cable yet that even touches what acoustic panels will do for sound.
Even put a radio or boom box and play a track in the bathroom and then put it in your room and you'll hear a HUGE difference or even run your speakers to a different room and the sound WILL CHANGE.

Dereck -

a much better power amp match w/ your ARC pre, would be, Bryston 3B ST /SST or 4B ST/SST.

likly, your cables!, cables play a profound part of every systems sound.

i am still learning about this stuff, so the specs of the equipment might help;
B25s Description: Three-way, reflex-loaded, floorstanding loudspeaker. Drive-units: 30mmx40mm Air Motion Transformer tweeter, 5.25" (130mm) Kevlar-cone midrange unit, 9.1" by 6.5" (232mm by 165mm) air-dried paper-cone woofer. Crossover frequencies: 180Hz (third-order Butterworth), 2.7kHz (second-order). Frequency response: 35Hz–45kHz, ±3dB. Nominal impedance: 4 ohms. Sensitivity: 88dB/2.83V/m. Recommended amplification: 200W. Maximum SPL output per pair: not given.

Pre amp SP17 / 17L Specifications:
FREQUENCY RESPONSE:
Line: +0-1dB, 0.6Hz to 80kHz at rated output. -3dB points below 0.3Hz and above 120KHz.
Phono: +/-0.3dB of RIAA, 10 Hz to 20KHz
DISTORTION: Less than .005% at 2V RMS output.
GAIN: Main output line: 11.1dB Processor: 0dB.
Phono: 58dB at 1 KHz.
Record output, line: 0dB. Phono: 47dB.
INPUT IMPEDANCE: 60K ohms line, 47K ohms Phono, (0.7 to 7mV High output cartridge recommended). Inputs (6): phono, CD, tuner, video, aux, processor. Model SP17L has no phono input.
OUTPUT IMPEDANCE: 210 ohms Single Ended main; 20K ohms minimum load and 1000 pF maximum capacitance. Outputs (3): 2 main, 1 record (Single Ended RCA connectors). Record output 60K ohms minimum load and 100pf maximum capacitance.
OUTPUT POLARITY: Non inverting.
MAXIMUM INPUT
Line: 9V RMS.
Phono: 40mV RMS 1KHz, 100mV RMS 10KHz.
RATED OUTPUTS: 2V RMS into 100K load. (Maximum output 15V RMS at 1% THD at 1kHz.)
POWER SUPPLIES: Electronically regulated low and high voltage supplies. Automatic 25 sec. warm-up/brown-out mute. Line regulation better than .01%.
NOISE:
Line: 12uV RMS IHF weighted at main output with volume low (104dB below 2V RMS output).
Phono: 0.3uV RMS IHF weighted equivalent input noise, shorted input (76dB below 2mVRMS 1KHz input).
TUBE COMPLEMENT: (2)-6H30 dual triodes.
POWER REQUIREMENTS:100-135VAC 60Hz (200-270VAC 50/60Hz) 39 watts.
Power amp
The RB-1080 rests close to the pinnacle of Rotel's two channel power amplifier designs. Power output of 200 watts per channel (20 Hz to 20 kHz @ 0.03% THD into 8 ohms) is extraordinary. The Rotel-made toroidal transformer feeds separate power supplies for each channel, each with its own rectifiers, voltage regulators, and capacitor banks. Damping factor, at 1,000, shows this amplifier's unparalleled ability to lock onto the most difficult speakers to precisely control diaphragm motion and give you the best sound quality. Switchable balanced (XLR) and unbalanced (RCA) inputs provide flexible system interface. Front panel heat sinks add a strikingly dramatic look and serve a functional purpose by enhancing heat dissipation even in cramped environments. And a separate input and output for 12 volt "trigger" signals makes this amplifier well suited for fully integrated systems with total remote control capability.

Thank you all for the comments
the input impedance of the Rotel is 8 ohms while the B25s Nominal impedance is 4 ohms. Could this be an issue??
The room dimensions are 15.5 feet by 12 feet however i have a open passage at the entrance, my speaker facing the 15.5 feet length of the room next to the open passage. I have a marble floor and no rugs. Speakers are placed abt 5-7 inches away from the wall but the left speaker is just next to the open passage at the entrance.
Dick mentioned jitter i do have my home theater set-up in the same cabinet one side houses my B&W MT 30s with the base unit behind the right speaker in the corner, and the other side of the cabinet houses my AR/Rotel/Camb Audio

WOW: Where to start....

First have you ever heard the Burmister 25 speakers sound the way you invasion?

Second: Any first rate speaker needs the utmost attention to placement. Away from the rear wall away from the side walls. Six feet to eight +- feet apart. An appropriate sized listening room, not to big not to small.

Once you are sure you have those issues dialed in and still not the sound you know your speakers are capable of. you can move on to cables, amplifier, source etc...

Get back with us........we are here to help......no dealer involve here I am guessing...

best
Jim

Mapman, I wasn't referring to exaggerated high frequencies but the ability to transparently reproduce what is passed to them. Ive never heard them but, from everything I've read, the B25s are pretty transparent. Dick

I've heard modern AMT type tweeters recently in Goldenear Aon3 speakers off Rotel class gear compared to other speakers/tweeters a/b. The GOldenears were the most "polite" in teh high frequencies actually. Some will find that nice but some used to more oonventional tweeters like soft domes for example might miss some of the "bite" that other tweeters may be more prone to. Dynaudio Esotar tweeters are a good example I think.

Dereck, Did you mean the Rotel is 125W? The SP17 is a preamp and doesn't power the speakers per se. However, my research indicates that the RB 1080 produces 200W @ 8 ohms. In one review, the measurements indicated that the Burmester could be a tough speaker to drive. The AMT tweeter in the B25 is very revealing and many amplifiers can become hard sounding when driving difficult loads - the AMT will convey this in a heartbeat. There's also the possibility that what's bothering you is jitter from the source component.

There are many possibilities here. As mentioned above, we still need some info about your listening environment and what is is that you're unsatisfied with in your system (I know it can be hard to put into words sometimes).

I'm not disparaging the Rotel amp - it's a nice, solid component but I don't think it's in the same league as the SP17 and certainly not the B25s. More refined downstream components will reveal flaws in upstream components in most systems. Dick

It could be equipment, but it's probably not. Could you please describe your room (dimensions, type of surfaces, rugs, etc.) and how you've positioned your loudspeakers and listening area.

Actually, that looks to be a pretty well matched system that should perform quite well.

The Rotel amp would seem to be a pretty good match for the speakers. The ARC tube preamp woudl also seem to be a good pairing. WHat is the input impedance of the Rotel? If less than 30000 kohm it might not be the best match for a tube pre-amp, but should still sound pretty good in that setup.

Whenever tubes are involved and sound heads south, always check and make sure the tubes are good and performing as they should. Either keep good spares to swap in and out to see which work best. Have the tubes tested if possible.

Next I would suggest confirming if speaker placement might be tweaked for better results.

Some more detail on what does not sound right exactly would help.

It is highly unlikely but possible that your pre amp and amp have a impedance mismatch but one I would investigate along with the correct toggles in place and that your room acoustics support the music your are playing. I will leave this with the more experienced hands. Could you be as specific as possible regarding the power suck ou and which point it occurs at.

Thanks for the response Dick, i listen to Jazz and slow rock and a bit of country. I think the problem is the Audio research preamp is 125w while the speakers are 200W hence i am not able to power it up beyond a certain point. I use flac files on the cambridge audio to listen to music i don't have a CD player
thanks for your help!!

Dereck, Tell us a little about what you envision the sound should be. What do you like, what do you think you're missing, etc. Also tell us about the type of music you listen to and the room/environment. And what are you streaming? Internet radio, mp3s, or CDs and high res files? All these play a part.

Just looking at the list of equipment, I would say that your speakers and preamp would benefit from a better amp and source but before we can recommend something we need to know where you want to get to. Sorry for the 64 questions. Dick