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New to the Forum and have some general questions.

Jesse W.

Jesse W.

New Member
JVC QL-A2
Kenwood KR-4070
Polk T-15's



Good day all! Jesse W. here. New AK though I have been reading posts from this site for some time. I have been a musician and music lover all my life and I have an affinity for analog audio. Vinyl, tubes, tape, Moog, 808, etc. I finally have what I would consider a decent setup for listening to my growing collection of LP's. I worked as an A/V tech in my youth, in the '90s, and was exposed to live gear and met some great and knowledgeable folks. I have some experience with electronics, building a few guitar pedal kits and trying to read articles, however, there are some serious gaps in my understanding. I am hoping to fills these gaps with the knowledge base on this site. It seems this is the place to go for information on this wide and varied subject. I thank you in advance for any help you can offer. Also, thank you to the unnamed posters who helped me pick out my current gear and walk me through cleaning my receiver. I greatly appreciate it.

My first questions are about the relationship between the receiver and amplifier in a classic setup. Right now I'm just running with the receiver and it seems to have plenty of power. Would I need a component amp if I wanted to run a bigger speaker? (I don't I'm just curious as to the role of the dedicated amp) What class is the amp in my receiver? (Kenwood KR-4070) How many watts per channel would this unit have? what is the norm for these types of home systems? How else can I find this info out? I don't see it printed on the unit and I don't have the manual.

Once again, thank you. I hope to learn and pass along any info I may have in return.
 
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I didn't think to search it here. I'm not at all familiar with the AK database. That's excellent! In the manual, there is no mention of an extra amplifier component. I guess this system doesn't use one. I can remember as a kid we got this big Fisher system with tape, CD, turntable, had a huge remote for it. It had a receiver and an amplifier. It had large floor speakers and smaller ones on top of the particle board frame. In my early searches, I was looking for a stereo amplifier and was not finding what I wanted. Once I started searching for receivers I found this Kenwood. I guess I still don't understand when an amplifier is appropriate or am I getting too caught up on the names of the components. Obviously, there is an amplifies in the receiver.

Also, as a matter of circuit layout, Is there a preamp, tone section, phono preamp, all inside the receiver? Does the term receiver only refer to units with AM/FM?
 
Thank you as well! My background is more mechanical and I've little experience reading schematics but I impressed myself with how well I did with this diagram. It must be easy to read if I can follow it. I can see the layout. Would my Kenwood KR-4070 be considered an "integrated amplifier"?
 
Jesse W. said:
Would my Kenwood KR-4070 be considered an "integrated amplifier"?
Click to expand...

No, your Kenwood KR-4070 is a receiver.
An integrated amplifier contains both a preamplifier and power amplifier. Any inputs (radio tuner, turntable, tape, etc.) need to be plugged in to it.
A receiver contains preamp, power amp, and radio tuner.

A separate power amp is usually used with an external preamp. No need for one with your receiver. It already contains its own power amp. The Kenwood KR-4070 is rated at 40W per channel. That should drive most speakers without any trouble.
 
welcome to the beginning of your new mental illness!

To answer some questions about your 4070 - its a class A/B at around 40 watts into 8 ohms and it has some 4ohm mettle.

Fairly resilient machine, I have rebuilt one that was killed by a bug (literally) and another one was killed by a snowstorm (literally) where it was playing on fire.

Does your stereo light light up? if not, make sure it is ok and if it still does not light, we can tell you how to make it light...(a little variable resistor gets gummy in the FM section)

as for loudness, 40 watts is enough to harm your hearing and will sound even better if you have efficient speakers. 90db/w/m or higher shall suffice.
 
Thank you quaddriver. I am very happy with my set up. Played CSN de ja vu for my wife and she “got it”. Pure sonic immersion. It is plenty loud. The Polk T-15 are clear but not complete on the bottom end. Are these speakers considered efficient?
 
Jesse W. said:
Thank you as well! My background is more mechanical and I've little experience reading schematics but I impressed myself with how well I did with this diagram. It must be easy to read if I can follow it. I can see the layout. Would my Kenwood KR-4070 be considered an "integrated amplifier"?
Click to expand...
You can think of a receiver as basically an integrated amplifier with a built in tuner. Many receivers have pre out amp in connections allowing you to use the receiver as a preamplifier or as a power amplifier.

As to when you need to add a separate amplifier to your Kenwood, that depends on the sensitivity, not size, of your speakers. The volume(loudness) that you like to listen plays a role too.

The higher the spl of the speaker the less wattage you need to make it play loud. I have a pair of Infinities that are large tower speakers, but only need around 20 watts to get real loud.
 
Jesse W. said:
Thank you quaddriver. I am very happy with my set up. Played CSN de ja vu for my wife and she “got it”. Pure sonic immersion. It is plenty loud. The Polk T-15 are clear but not complete on the bottom end. Are these speakers considered efficient?
Click to expand...

Efficiency is one factor, and performance is another. Efficiency is measured in sound pressure (DBa per watt) whereas performance is measure in resonance and frequency response. The T-15s are reasonably efficient, specified at 89 DB/W. That means that they will make a fairly substantial amount of noise with a 1 watt input, but is it the RIGHT noise? Here are the general specifications: https://www.cnet.com/products/polk-audio-t15-speakers/

Like many currently marketed bookshelf speakers, these use undersized drivers with nearly pathetic VEs and bass response which is actually more in the range of the "full range" category. This began in the 1990s with the advent of "personal" audio systems and multi-channel devices.

If you dispute this, perform some historical research and show evidence why that prior to this erosion of quality in audio systems, there was NO SUCH THING as a "sub-woofer" and only true woofers/bass drivers existed. This was done as a band-aid response to low-grade, compromised performance of the pathetic consumer-grade offerings in the market.

As a counter-example, I have several sets of speakers which have a BETTER bass response and VE than today's "sub-woofers" and they were provided in the full-range speaker cabinets as a matter of course - Because they are NEEDED to qualify a speaker as full-range. This has been the case since tube amplifiers were the only option.
 
I would advise connecting your KR-4070 to a good set of speakers to evaluate its true performance. I believe you will be impressed. If you know someone/somewhere that you can take your receiver and connect it to a pair of 12x6x1 full range 8Ω speakers, it may be very revealing. It may actually be more economical and even more effective to search for a pair of vintage full range speakers with at least 12" woofers, at least 90 DB/W efficiency, and a true LinkwitzRiley active crossover. If the drivers need re-foaming and the crossover needs updating, that's a small cost compared to buying new, GOOD 3-way speakers.

This is not an advertisement, but simply an example of the kind of thing you might want to look for (there are probably better examples out there for less) : https://chicago.craigslist.org/wcl/ele/d/batavia-vintage-sansui-sp-way-speakers/6870151690.html
 
A23gt said:
You can think of a receiver as basically an integrated amplifier with a built in tuner. Many receivers have pre out amp in connections allowing you to use the receiver as a preamplifier or as a power amplifier.

As to when you need to add a separate amplifier to your Kenwood, that depends on the sensitivity, not size, of your speakers. The volume(loudness) that you like to listen plays a role too.

The higher the spl of the speaker the less wattage you need to make it play loud. I have a pair of Infinities that are large tower speakers, but only need around 20 watts to get real loud.
Click to expand...
 
Thank you Watthour and everyone for all you knowledge and willingness to share.

Please excuse my ignorance but what are VE’s?

Also, space is an issue in my home so large 3-way type speakers are not desirable right now but I’m open. I’ll start looking as I’ve seen some stuff similar to the link you sent. I guess all of the “high end” set up I’ve seen have just had book shelf type speakers. I’m sure this is my own misconception. Also, yes quaddriver my lights work well.
 
I like receivers that allow you to use as a preamp or power amp. You can upgrade your system by adding just a power amp and you can see the difference it makes. Then, when funds are available you can buy a proper preamp and again you will be able to see the difference it makes.

Its also nice having the pre/power jumper in the amp for troubleshooting if an issue were to occur.
 
Welcome to AK! If you would rather not go with the suggestion for larger speakers you could also keep your eyes open for a subwoofer. Just make sure that it has the ability to be hooked up with a speaker level connection as it does not appear your receiver has pre-outs to connect via line level.

Just make sure that it has adjustable crossover and volume settings. Since you seem to be fairly happy with the sound from the little Polks with the exception of the bottom end (these appear to be 3db down at 65Hz so I am not surprised you feel this way). Just another option and you may be able to tuck a sub in an out of the way spot more easily than accommodating a pair of large loudspeakers.

What ever you decide have fun! Messing with this stuff is part of the fun, but most importantly...enjoy the music! :music:
 
Ve (equivalent volume) is more modernly expressed as "Vas" but is the same measurement. It is one of the commonly referenced "Thiele-Small Parameters" which define speaker performance.

A speaker with a low equivalent volume essentially moves very little air, and faithfully reproducing lower frequencies requires a lot of air movement to transmit the original program information (in this case, music) in the correct proportion to the other frequencies. In short, small bass drivers are about as annoying to me as political candidates - They make a lot of squealing, whiny noise but really have no meat to them. The approximate equivalent to a single 12" woofer in comparison to the currently marketed 6½" or 6" woofer would require at least half a dozen to come even close to moving the same air.

For example, an Eminence 3012LF 12" woofer has an equivalent volume of 3.77 cubic feet. Their 6½" "woofer" has an equivalent volume of 0.20 cubic feet. That's 20 times more volume with the 12" woofer. It's a function of area, inasmuch as any speaker can be manufactured with a long displacement (throw) and it's actually easier to do that with a larger speaker. And for reference, 0.20 cubic feet is actually pretty good for a 6½" speaker.

Taking the comparison a couple steps further, a similar 8" woofer (Alpha-8A) might have a volume of 0.63 cubic feet, and a 10" woofer (Delta-10A) might have a volume of 1.08 cubic feet.

Eminence is pretty honest about their drivers. They don't even call 6", 8", or 10" speakers a "woofer" but instead a "mid-bass driver" which might be more realistic. Others who sell those sizes with even worse low frequency performance call their offerings "woofers" even though they are nothing of the sort. The fact that speaker manufacturers sell "full-range" speakers with a 6-8" bass drivers is the whole pathetic reason that sub-woofers exist.

Since you have a space issue, it might be useful to search for speakers with at least a more appropriate low-end curve, which is likely to involve longer displacement drivers with smaller magnets and larger diameters in a sealed enclosure. There are some fairly small speakers that do a reasonable job on the low end, despite their inherent disadvantages.
 
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