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Anticipating my KA-7100

mg196

mg196

Johnny Thunders - LAMF
Hello everyone, I am extremely excited over my soon-to-be-shipped KA-7100. AK'er ARMY picked this puppy up for me and transfered it to EchoWars at the AKfest. It has been in the Laboratory ever since...

Here is the teaser picture. More info to follow in the coming weeks!

And EW, if you wanna comment at all on the unit, please do it here! Hate to toot my own horn, but...
 
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I'll try to get a better pic tomorrow if I can, but here's my thoughts...

KA-7100's are as common as fleas on dogs, but that does not keep them from being one of the best bargans on eBay and elsewhere. I've said before that all the 7100 lacks to be a real contender is pre-out/main-in jacks. I added them to hpsenicka's 7100, but mg196 passed on it, as not everyone has a real use for 'em. My only criticism of the 7100 besides the lack of seperate jacks for the preamp/amp is the low filter...it uses a simple RC filter with such a gentle slope as to be near useless.

Army found this one..........and snagged it for all of $30. The front panel and knobs and all are flawless. The wood case is an easy 9 out of 10. This is the nicest 7100 I've ever seen.

All the electrolytics were replaced with the exception of the large power supply caps, which were fine and given 2.2µf film bypasses. The signal path caps were replaced with BlackGate caps (including the phono stage), and the rest are Panasonic FC caps. The relay was pulled and cleaned, the transistors pulled and cleaned and new HS grease applied, and the bias 'n offset pots replaced with 25-turn Bourns units. I also fudged with the turn-on relay timing so slow it down a bit...helps keep the speakers from getting a 'thump'.

The unit clipped at 83WPC, and distortion at 60WPC measured 0.003% @1KHz, which is essentially the residual of my analyser. Very nice.

It it's decent out tomorrow, I'l see about getting a pic in natural light. Flash pics of silver gear never look good.
 
mg196... that is a very handsome looking wood case!!

I am very pleased with the sound of my "new" KA-7100, although I have to confess I only have a few hours of listening under my belt since I got it back from EW earlier this week. The results are well worth the wait!!
 
I have a 7100 myself and right now it's my daily driver... I have
other amps and receivers both bigger and smaller (wattage-wise)
and I always seem to go back to the 7100!

You'll love your 7100... and if EW has worked his magic on it, it
will surely be a keeper! :thmbsp:

Hope you enjoy it!

Scott
 
Considering how these seem to go for around $70 on eBay w/out any work done on 'em, sold AS-IS, what is the value of a beauty like this, that has been completely refurbed and brought BEYOND specs?

Not that I would EVER consider selling it, EW!!

The reason I am asking is because I have a hypothesis: Yes these are as common as anything right now, but in another 10/20 years, not only will there be fewer altogether, but of the remaining 7100's, I'm guessing that under 10% will have been refurbished and serviced.

I am not saying that one day these will be some type of Audio Holy Grail, but I AM theorizing that in the next 10 years, units as common as this are TODAY will be significantly more valuable.
 
I have watched the value of these skyrocket over the last year. A while back, you couldn't GIVE them away, now they fetch $70 easily on ebay. I had one that a guy at work gave to me. I loved it and used it for a whole summer til I got my 9100. Great looking and sounding amp, hope you like it!
 
EchoWars has a cult following!

mg196.... we need to have some kind of "certificate of authenticity" to document the fine work done by EchoWars.... perhaps particularly in my case because of the additional mods performed to the amp. :D

Seriously... from a strictly collectible standpoint, modifications will normally reduce the resale value of an item, but in the case of audio equipment, modifications or upgrades performed by a well respected technician may have the opposite effect... any thoughts?

From a practical perspective, if I were shopping for a vintage piece of audio gear, I would be assuming that I need to spend at least $100 -200 (in addition to the purchase price) to have it serviced to make sure it is performing to spec. Finding one that has already been serviced could be a bonus... although there is always the the nagging "was the work done right" question!

An interesting example... a few months ago I bought a Kenwood KT-6500 tuner that had been recapped, aligned, and mildly modded within the past 2 years by Bob Fitzgerald of www.fmtunerinfo.com fame. A stock tuner like this could typically go for around $50 or so on Ebay.... I happened to scoop this one for $99. We all know that recapping and aligning a stock tuner will likely cost well in excess of $150 unless you can DIY, so I figured it was still a very good deal even though it was a premium price relative to a stock unit.
 
EchoWars said:
My only criticism of the 7100...is the low filter...it uses a simple RC filter with such a gentle slope as to be near useless.
Click to expand...

Echo,

Should/Can this issue be easily rectified? You are just speaking of the operation of the low filter switch yes?

If that is the case - I don't even use it, and this message will self destruct in 30 seconds! :thmbsp:
 
What it needs to be effective is an active filter...which means incorporating an active device, such as a transistor or an opamp to allow a slope of 24db/octave or better. Would be a PITA to add, and the cost would certainly outweigh the usefulness.
 
Good camera

EW I see you are putting that new camera to good use. . . GREAT PICS. . .

I am finding great pleasure with "Baby" amps and receivers. . . In my small room (9x9) I cant use big power anyway besides the bigger they get the heavier they get. I would think it reasonable to expect a 7100 or the like to have an easier journey on the shipping trail besides costing much less to ship. . .

There were a lot of people back then who bought smaller high quality amps and plenty are out there in exceptional condition that have very few hours on them. Good buys for sure.
 
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Hey Gyush,

Yeah, I will be using it in a pretty small room to drive my KLH Model Fives. I get one free hour a day before I pick up the little one from Day Care. So I have just enough time to crack the drywall!
 
EW,
Nice work, and a really pretty amp! I like these lower powered amps, but I've never had a Kenwood - but I would like one one day. I do have an Akai AM-2600 which has a single power transformer and is also about 60 watts as well, and looking inside it would be easy to work on or upgrade - a real positive thing for a novice like me.

EchoWars said:
......
All the electrolytics were replaced with the exception of the large power supply caps, which were fine and given 2.2µf film bypasses. ....
Click to expand...

Why not replace the PS caps? They are also 30 years old, and I thought (well, have been told) that these are the caps to replace first. I have a Marantz MR 1130 that really pops on turn on, and the advice was, replace the PS caps (still getting to it...).

Also, is the lettering printed on, or engraved on these amps?

thanks,
Packrat
 
packrat... the faceplate lettering is engraved on the KA-7100.

As for the main PS caps.... the main reason they were not replaced was that because of the manner in which the original ones are mounted to the circuit board a close match was not readily available, and EW recommended that we avoid trying to kludge in substitute unless there was a clear need to do so.
 
I would have loved to replace them, but Kenwood made it tough.

Unless they have vented, I'd leave them. I can find no way to do it an not have it look like a drunken monkey did the work. Certainly if the caps had vented, we'd have no choice and I'd do it, but otherwise I hate half-assed-looking solutions and that's exactly what you'd end up with.
 
EW and mg196,
I have a KA-8300 that I bought on eBay when my other KA-8300 was zapped by lighting. Only problem that it has is the balance control is not working and it looks like someone went into it and did some "fixing". The volume part of this same ganged pot works fine. If you don't mine could you give me a rough estimate or range on what it cost to do the recap etc and work on the balance? I know we're not comparing apples to apples but it would give me an idea.
 
did you keep the old one?

It might be useful as a parts donor if the previous "technician" buggerred the balance pot...
 
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