Sound question

[Harley]

Hi all
I'm relatively new to hifi and have fallen head first down the hole.
I have a very modest system for our small two bedroom unit- Rotel A11 tribute - Polk bookshelf R100 speakers- rel tzero sub and Project essential 3 TT with Ortofon 20 stylus.
I only play vinyl, atm.
This setup makes me happy, nice and defined and natural but lacks punch.
So I decided to grab a power amp (this is the start of the system upgrade for when we are in a larger living area) and run the tribute as a preamp,for now. The one I choose was again a modest Rotel RB1552 Mk2.
I'm running it unbalanced with rca's.
It has added more punch and air into the sound but I am finding acoustic guitar fills to be very metallic sounding to the point of harsh. IE Tom petty- Running down a dream and The Cult -She sells sanctuary.

Question is, is the 1552 producing the harsh sound or are the Polk R100s not handling the highs well?
Rotel RB1552 MK2 rated 130w per channel @8ohm
Polk R100s rated 30w-150w at 8ohm? I know the R100s can dip as low as 3.6ohms.
Listening volume is 75ish dB.

Anyone experienced something similar?
Any help or info is appreciated.
Cheers

 

[Sergeauckland]

I've left this for a few days in the hope that somebody else might answer with some experience of the actual items you have.
As I hate to see a reasonable enquiry go unanswered, I'll do my best to help.

Firstly, the terms 'harsh', 'metallic', 'punch' and 'air' - all subjective terms which may mean different things to different people, so hard to know exactly what YOU mean by them. It's possible it's distortion, or a peaky frequency response.

There's nothing wrong with the power amplifier, plenty of power, and at the levels you play at, there shouldn't be any issues of clipping. The amplifier is 4 ohms rated, but not below that, but even if the R100s dip as low as 3.6 ohms, and at the levels you play at, I would be most surprised if impedance was the issue.

Although turntable is your only source, it would be as well to try another source, the easiest is to use a 'phone (if yours has a headphone socket) with a jack to 2 RCA cable. Play some Radio Paradise, which we know is sent as FLAC, so uncompressed, and if that sounds OK, then it must be the turntable system. If that too sounds bad, then you'll need to investigate 'speakers or amplification.

On the assumption that it's the turntable system that's the problem, the first thing to check is the cartridge alignment. Have you got the tracking weight set correctly and overhang correct, and is the stylus clean and unworn? Also, what condition are your records in? Worn records will sound 'harsh' due to distortion. Getting the tracking weight wrong can mean excessive distortion - too light due to mistracking, too heavy due to non-linearities in the cartridge's generator. Also, check the bias setting, as if that's wrong then you'll get mistracking on peaks causing distortion.

Overall, I don't see anything essentially wrong with your system, but I would spend a bit of effort on checking the alignment.

S.

 

[Harley]

Hi Serge, thanks for the tips and ideas.
I have completely removed the RB1552 from the system and went back to using the integrated A11 tribute as standalone and everything sounds as it should.
I think what I am hearing with the 1552 is a bump in the tweeter of the R100, I will need to test this once I can purchase some floor standers.

 

[Harley]

Update for people who are interested... I put the Rotel 1552mk2 back into the system and I put the speakers onto stands, there were previously on the same surface as my TT, also I changed my speaker cable from 16AWG to 12AWG. Doing both of these things fixed the issue. (I'm pretty sure having the speakers on the TT surface was the problem though). anyway amp sounds great now and I am a happy man.

 

[devinchin]

Update for people who are interested... I put the Rotel 1552mk2 back into the system and I put the speakers onto stands, there were previously on the same surface as my TT, also I changed my speaker cable from 16AWG to 12AWG. Doing both of these things fixed the issue. (I'm pretty sure having the speakers on the TT surface was the problem though). anyway amp sounds great now and I am a happy man.

I think you got your solution!

 

[Sergeauckland]

Indeed. It never occurred to me that the 'speakers would be on the same surface as the TT.

The change in 'speaker cable will be inconsequential unless the cable is very long. On a tabletop system, even bell wire will do, as what matters isn't the gauge of the cable, but the total loop resistance which should be less than 10% of the loudspeaker's minimum impedance, and ideally not more than 5%.

S.