Need some Kenwood expertise

Hi guys and gals. Relatively new to Audiokarma. I've been reading things on here for a while and have learned a bunch but I'm still pretty much a noob when it comes to vintage gear. In the last year I have been fortunate enough to purchase 2 Kenwood receivers, KR-6600 & KR-6340 Quad. I used the quad for a couple of months before I stumbled on the 6600. I liked it a lot but going from 35w RMS to 53w RMS seemed like a no brainer. I hooked the 6600 up and never looked back....until this week. I wanted to take the lid off the 6600 and clean the pots / dust out the interior. I hooked the 6340 up in its place, fired it up for a test run and couldn't believe my ears. The 6340 made my speakers come alive! I'm not sure was I was hearing before but it wasn't close to this. The 6340 out performs the 6600 by a long shot. The difference is really incredible. What I'm trying to figure out is this the 6600's way of telling me it's time to recap? Could it be simply be a better pairing to my speakers? If the 6600 needs recapped am I better off parting with it? There is only one "expert" vintage repair guy in about a hundred miles from me and he is uber slow, expensive and has some poor customer service ratings. I'd attempt to recap myself, but there is a bazillion of those things in this beast. Suggestions / Guidance? If this is posted in the wrong place I apologize. Thanks in advance for any assistance you can offer.

 

Your post contains a few unknowns which make it difficult to steer you in the right direction. First off, where are you located? There may be a qualified tech close to you who can respond. Secondly, define "...made my speakers come alive!" What, specifically, are the differences in sound quality, tonality, etc. that you're experiencing as a difference? What speakers? More data points are good.

 

Ok, My bad.
Kenwood KR 6340
Power output: 35W/ch (stereo), 15W/ch into 8Ω (quadraphonic) Frequency response: 20Hz to 20kHz Total harmonic distortion: 0.8% Damping factor: 20 Input sensitivity: 1.5mV (MM), 150mV (DIN), 150mV (line)
Signal to noise ratio: 60dB (MM), 75dB (DIN), 75dB (line) Output: 150mV (line), 40mV (DIN) Speaker load impedance: 4Ω to 16Ω
Kenwood KR - 6600
Power output: 56 watts per channel into 8Ω (stereo) Frequency response: 20Hz to 50kHz Total harmonic distortion: 0.3% Damping factor: 45 Input sensitivity: 1.5mV (mic), 2.5mV (MM), 150mV (line)
Signal to noise ratio: 65dB (mic), 70dB (MM), 90dB (line) Output: 150mV (line), 30mV (DIN) Speaker load impedance: 4Ω to 16Ω
Polk Monitor 70 II towers

• Driver Complement
  • (4) 6.5" (16.51 cm) d (Round) Mid/Woofer - Tweeter
  • (1) 1" (2.54 cm) d (Round) Tweeter - Tweeter

INPUTS

• Audio Inputs
• Ethernet
  Yes
• Speaker Inputs
  (1) Dual 5-way Binding Posts - na

AUDIO QUALITY

• Total Frequency Response
  30 Hz → 25 Hz
• Nominal Impedance
  8|||| ohms
• Lower and Upper -3dB Limits
  40 Hz → 24 Hz

EXTERNAL AMPLIFIER

• Recommended Amplifier Power Per Channel
  20 watts → 275 watts

I run in 2 channel only, primary source is vinyl. Sound w 6600 - Decent separation, clarity & depth, improves at louder volumes. Sound with 6340 - Exceptional separation, clarity, and depth at all volumes. Have run both on same speakers only.
If there is something I'm leaving out let me know. THx

 

Also, I am in the St Louis area. If someone knows a good tech please let me know. They are certainly not advertised anywhere......

 

After scanning the schematics -- and unless the 6340 has been worked on/upgraded -- nothing jumps out to me why the 6340 would sound better. In fact and as a gross generalization, the 6340 has more circuitry which could possibly contribute to more coloration. Here's what I do know...replacing 40 - 50 y/o components (capacitors, etc.) does clean things up in the aggregate. IOW, changing one cap won't make a sonic difference (unless it's faulty), but changing all of them tightens up channel tolerances, quiets things down a bit and in theory, gives whatever will now be the "weakest link" cap, a new MTBF (mean time before failure) date.

Whether or not recapping the 6600 solves your dilemma will only be for you to decide. Imho...unless you like collecting vintage gear as a hobby, pick and keep one, sell the other, and put the proceeds into the one you kept. OR, sell'em both and go for something closer to 100W/ch. And depending upon your budget, maybe a Marantz 'B' series receiver (e.g., 2270B) is an option. Fwiw...

 

Thanks for great answer. Gives me some things to think about. My biggest issue is no repairmen in this area. I've done some minor soldering, but skill level is definitely not anywhere near what is needed to tackle this job. What is the advantage is to the higher watt receivers othen than just raw power? The higher watt vitage receivers are becoming ridiculously priced. 500$ and up for units that have not been serviced or restored. That may not seem like much to a lot of people but I have 2 kids in college! Audiofrugal...

 

Also, with the 6340 having less power you're running it more in its schveet spot so to say. At any given volume level you're turning the smaller amp up just that much more to achieve the same output. You'll find many here prefer the sound of amps in the 35watt range over its larger siblings, that is until things get nasty. In example, hard to drive loads, or large power demands when the party's in full swing and you need that extra little bit the amp can't give.

 

This doesn't make any sense to me. I would think that regardless of one amp's power output capability vs another, they are both putting out the same power at a given loudness (with a given set of speakers).

The difference will be that the one with a lower power rating is running closer to its maximum output (thereby with less headroom to accommodate transient peaks). I am of the understanding - perhaps wrongly - that an amp's distortion levels generally go up as it is pushed closer to its limits.

To the OP...I like older Kenwood gear quite a bit, and have owned the 6600 (and two others from that series...the 7600 and 9600). I've never had the 6340 quad (not a quad guy!), but I can think of no reason why it would sound so much better, other than the 6600 having some issues that need to be addressed.

Unfortunately, a general complaint of "doesn't sound good" will not be much for a repair shop to go on. Ideally, they would put it on a scope and look at its output, and then work backwards from there to trace any problems/distortion they see. You could start the process by opening it up and just carefully examining the boards for any suspicious-looking components (leaking/bulged caps, charred resistors, etc), cold solder joints, and other obvious problems.

Does the 6600 have specific issues with how it sounds (hiss, static, poor low-end, poor high-end, etc)? This could help provide guidance for troubleshooting.

 

Don't take my word on this, search AK you'll find many threads on this.

 

It would be great if you could explain it to me. You seem to be saying that higher-power amps don't sound as good as a lower-power amp at moderate volumes. Do I have this right?

Thanks.

 

I already did, you didn't like my explanation, maybe you can find the response you want by searching the archives.

 

That makes total sense. I haven't really pushed ther smaller amp with a lot of foreground noise. I have with the 6600 but really didn't pay close attention to how it performed. I really haven't seen many convincing arguments to go up to 75-100w amps other than to say "I have a really expensive high watt amp" I'm not

The 6340 is so loud with volume set on 1/2 max there is no reason to go any louder. Crystal clear and warm with Bass & Treble at 1 o'clock and 11 o'clock respectively. I played in a metal band for 7 years so I have somewhat a grasp on what loud is.

 

Not a matter of liking it or not...I didn't understand it. At any given level of speaker output (again, assuming same speakers), it seems to me that both amps are delivering precisely the same amount of power. Agree or disagree?

If disagree, please explain.

If agree, then what is it that makes the one that is running closer to its max output perform better?

 

Well I don't know if he is even in the business anymore, but there is a long time AK member who has not been here in a while that lives in thew KC area who is likely one of the best Kenwood techs around. He worked magic on my Kenwood 700's a while back. He goes by the name EchoWars, but as said, I really don't know what if anything he is doing currently... Maybe someone has current information here.

 

I'm certainly not questioning your definition of "loud". And frankly, the difference in power output capabilities between these two Kenwood amps (receivers) is so small as to be pretty much irrelevant; it's only around 2dB...and 3dB is generally defined as the smallest change in sound pressure/loudness to be clearly perceptible to most listeners.

Agree or not, the argument for higher power amps is a function of speaker sensitivity, room size/distance from speakers, and headroom. A set of speakers with a sensitivity of 87dB will require 4 times the power needed to drive a pair of 93dB-rated speakers to exactly the same loudness.

As for transients....different people have different points of view on how much headroom is needed to minimize clipping distortion, but for well-recorded music I think most would agree on a minimum of 9-12dB. 9dB = 8 times the power vs 1 dB. 12dB = 16 times the power. 15dB = 32 times the power. Etc, etc.

I shoot for having 12-15dB to spare when listening at the far-end of my personal loudness range. So, for example, if average/RMS output at my desired volume = 3 watts, for example, my amp needs to be capable of delivering 48-96 watts to avoid (minimize) clipping. If 4 watts, I would need 64-128 watts.

Listening distance is a big issue because loudness drops by a bout 6dB for each doubling of distance from the speakers. So those 93dB-rated speakers will measure 87dB at six feet, and 81dB at 12 feet...etc, etc.

Combine all these variables and you can see how/why some folks need a serious power amp (or two!).

 

Higher watts usually translates to headroom (clipping avoidance) and control (damping factor). If for instance, you're watching a movie and the soundtrack is quiet and then suddenly BOOM!, that loud transient is what consumes watts. Most of the time when listening at normal volumes, you won't be pushing an amp that hard, but a deep bass note, or movie special effect, can dig deep for more power and spare watts is what reproduces those sounds with less distortion. Clipping of a waveform is what happens when your amplifier output section is looking for more power than the power supply can produce, and it cuts the edge off a square wave which manifests itself as audible distortion. In its grossest form, it can fry loudspeakers and/or your amplifier. More watts = more headroom before clipping. That's kinda the simplified version. I would simply go with what's in your budget and most importantly, what sounds good to you. That may be the 6340.

 

As I said, do some research, here's a thread started Friday on just this subject.

http://audiokarma.org/forums/index.php?threads/can-you-have-too-much-power.809241/

 

That thread is all over the map...it certainly doesn't reinforce your seeming belief that a lower-powered amp inherently sounds better than one with higher power capacity. In fact, I'm still not even sure what point you wete trying to make...which is why I asked you to explain it.

In any case, the OP's two amps are so close as to make specious any claims based on differences in power output.

And of course, as I said above, both amps are delivering precisely the same amount of power at a given level of loudness (clipping issues aside).

 

As I stated, "many here prefer the sound of a 35watt amp" and their reasoning, take it for whatever it's worth to you.

I never said it was "my" belief or not, you just skipped over that part.

This might help if you can answer this question for yourself, "why do you think manufacturers give amplifier specs at rated output?"

 

This is your statement that I was questioning. I simply asked that you explain it You seem to be saying that running an amplifier closer to its maximum output delivers better sound quality (which is what I assume you mean by "its schveet spot"). Do I have that right? And if so, what is the basis for your conclusion?

On a related, but different, point - you also seem to be saying that at a given volume (loudness level), one amplifier is turned "up" more than the other. This is not true. As I've said several times now, the amount of power being output from either amp will be exactly the same (assuming same speakers and same level of loudness).

As for "the sound of a 35 watt amp"...the power rating has little to do with an amp's sound quality. Yes, it is easier to build a low-powered amp with great performance than a high-powered amp with equal performance, but that does not make 35 watt amps intrinsically better. It does, however, make them more attainable.