No Respect! The Kenwood KA-7300

EchoWars

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Got this one in on trade for some work on another amp. Came to me with a blown output module due to a rather silly and easily avoidable foul-up. Our esteemed AudioKarma member Stene found a pair of modules in an electronics shop in Stockholm, and was kind enough to buy and ship them to me...for which I am immensely grateful. :thmbsp:

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I pulled the handles off my 9100 to see if they fit. They do...
 
Overall, the 7300 is a cool piece. It has preamp-out/main-in jacks that the 7100 does not, via a switch on the rear panel. The 7300 has one of the best preamp sections of the 70's mainstream Kenwood gear. It uses an output amplifier module, a TA-80W, similar to the KA-9100 (which uses the TA-100W).

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Here's a pic of the module. You can see the new large 1.5µf Matsushita metal polypropylene input cap at the amp input stage, replacing the stock .47µf job.

I wanted to hear what a 7300 was really supposed to sound like, so this unit got a total recapping. The only original electrolytic caps are the four large power supply caps.
 
Here's a hover-shot of the insides. The 7300 uses a dual supply, including dual transformers, and for filtering has four 10,000µf caps, which is as much filtering as the supersized 160WPC Kenwood KR-9600 receiver. Well done...

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I like it. Nice unit, very clean sounding. Don't seem to see a lot of them on eBay, at least not as many as the 7100's. I have kept this one stock except for the replacement of the electrolytic caps, and the new amp input film cap. The only thing that bugs me is the lack of an offset adjustment, and I'm toying with the idea of perhaps adding servo's to this one, even though offset is at about 10mV and 25mV.
 
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Looks sharp! Another Kenwood I don't see to much of. Glad to see it got a proper update by a qualified tech. :thmbsp:
 
The 7300 is a perfect candidate for a servo...there's already +14V avaiilable on the amp board, and a perfect place to mount it, with excellent access to the points on the PC board needed to make it work.

Here's the servo I added to Danamc's 7300 a year or two ago...

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That amp looks like a poor man's Model 500/600... :scratch2:

Do you think this one compares to the above Glenn?

Is this one for sale?? :naughty:

Scott
 
Gotta love those rack handles. Nice photography work, Glenn. She looks very clean.

That amp looks like a poor man's Model 500/600...

They do have a similar layout, but again, not even the KA-9100 can touch the 500/600/700 series.
 
SPL db said:
That amp looks like a poor man's Model 500/600... :scratch2:

Do you think this one compares to the above Glenn?

Scott
It's a nice amp, and IMHO superior to the 7100 in many ways, and I like the 7100 a lot. Maybe you could call it a 'poor man's 500/600. Certainly has the power supply for it.
Is this one for sale?? :naughty:
Haven't decided. I really should sell it...Lord knows there's enough gear here already.
 
Nice work EW! :yes: With all the work you put into her, I'm afraid its out of my current budget.

How does the phono section compare to the KA9100?
 
The phono of the 9100 is hard to beat. The 7300 phono section is very good...IMO the phono section of ALL the Kenwoods that used the FET input stage sound great, and that includes even the lowly KA-3500 and KA-5500. Mostly they differ in how they bump the voltage up...some use a single-stage / one-transistor voltage amp after the FET differential input and call it good, some use a buffer and then a voltage amp, and a few use a bipolar differential after the FET differential (like the 9100). All of them sound pretty good, but the 9100 is the best sounding. This 7300 is close...
 
I don't see you mention anywhere - what kind of power output does that baby push? Have you benched it (that's probably a stupid question to ask you) for power and distortion. Numbers, I need numbers!
Also - in general, and not necessarily related to the above questions, functionally what does the increased value of the input cap do for it?
 
Reduces phase shift in the bass, and lowers the bottom end cutoff point. Plus, it's just a better cap than the stock one.

The amp benched 88WPC at clipping. At the rated 65WPC, THD+N was about 0.03% @ 1KHz.
 
If ya want to sell that unit Glenn... drop me a PM... :yes:

Scott :thmbsp:
 
How about those output modules? Are they near-Unobtainium? or Expensivium?
 
Thats a great looking piece of gear inside and out. How much send a pm(Just thinking outloud). EW whats so different about Kenwoods that make them sound so open?
 
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