Worn RB-35 speakers?

[iamvos]

Greetings to all, as I am a new member on your community.

I am writing to share my impressions after upgrading my WD Kel84, a 15W, push pull

stereo intergraded amplifier with four El84 on the power amp.

http://www.world-designs.co.uk/acatalog/kel84.pdf

It was bought as a kit 14 years ago from World Audio Designs in UK.

First years was a truly success, matching it with a pair of Klipsch RB-35, (8 ohms / 96dB).

I still can remember the warm and detailed sound I had for the first time in my life.

Then after some years of great listening I got married , so the amp wasn’t fitting well on the

small apartment we rent for some years….

After 5 years that my Kel84 and RB-35 were sitting (well protected) on a

basement, I decided to bring them back to life. I notice that my low frequencies

were not so present and tide as the old days, so as the middle frequencies were a

bit muddy. I decided then to replace the electrolytic capacitors on the power

supply unit, with doubling their capacity to 220uF/450v for better stability.

The tubes were from the original order from WD with not so many hours on their

back. Also I change my cables (speaker and interconnects) with quality ones.

These changes were for better of course, but did not achieve the sound I

remember.

So I decided to go for the XL Upgrade that the World Audio Designs

still offering. That upgrade contains almost everything, except the transformers and the

chassis, with audiofile components as said. From new improved PCB to high quality

capacitors and wiring. After a succesfull (technically) upgrade, I have notice that the sound for

sure it has changed in many ways.

First I have more 'solid body' on sound and more tighten low frequencies

with a 'booming' feeling some times. I used to have a lack of low frequencies.

So far so good.

The problem it concerns me is the 'muddy' picture on sound with an obvious

lack in details, plus a noticeable roll off in high frequencies.

My aesthetic feeling is that it gives me a very very sweet and tight, but seamless (lack in

details) sound.

In audition, things are satisfying in easy listening, like classical or smooth jazz piano trios,

but when music becomes more complicated, like classical or jazz big bands things are getting

really muddy. The same occures in Rythm and blues or Rock music.

Just to mention that I had to use an EQ even for the easy listening part.

Also to mention that the same feeling applies to all of my inputs (cd, pc, turntable).

As far I am aware, when we talk about 'roll off or cut off in high frequencies' in amplification,

usually we care about capacitors, because El84 valves are capable in handling a lot higher

band of frequencies than the acoustic spectrum.

So I wonder if the upgrade (mainly in capacitors) was succesfull or not.

Just to be sure I tested my speakers on a different amplifier (Yamaha DSP AX-620) and

hey… I got the same effect…. Now I am totally confused.

Is it the amp or the speakers?

Is there a possibility for a burned out tweeter or a worn component in crossovers?

The speakers are in excellent cosmetic condition and at a facile optical and aural test

everything seems fine. Any suggestion would be very helpfull and just to notice that I am

an electronic technician my self, so I will be capable for some tests or a simple repair.

Any help or suggestion would be very helpful.

Best regards

Nikolaos Markopoulos

Athens Greece

Edited April 9, 2014 by iamvos

[derrickdj1]

Tell the forum what amp/avr you are using, setup the speakers and room. Hopefully some other will come along with some advice.

[Dennie]

Welcome Nikolaos, We are glad you are here.

Yes, it is possible that the capacitors in your RB 35's are out of spec.. We typically don't see that happen in a approximately 10 year old speaker, but it is possible.

Your description of "Muddy" seems to fit what happened with my 25 year old (at the time) La Scalas. I didn't realize it until I replaced the crossovers, but it was like a blanket was lifted off of my speakers and the bass came to life. The Muddiness in all frequencies went away.

I think it would be relatively inexpensive to replace the caps. and then see what happens.

Keep us posted and again, Welcome.

Dennie