Echowars--- Ka 5500

rew15951

Active Member
Tell us about the ka 5500. Seems i'v got every amp kenwood makes but that one, as you know from working on most of them!
 
Well, although I need to get back to work and put gearhead's 2330B back together (been on the 'puter for too damn long tonight), I'll answer this and then get back to work. :D

The KA-5500 was my first amp, and I saved for it all summer of '76. Tough to do with car expenses and all, but I finally bought it on sale for $200 at Burstein-Applebee. :banana: I even sprung for the (now rare) D5 carrying handles at $35.

No matter what, I could never break this amp, and it got dragged to many a party. At several of these, it ran for hours on end blasting out tunes at close to 40+ watts of output. Unbreakable. The only issues I ever had was from dirty switches.

This amp has a very basic phono stage with a FET differential pair feeding a PNP driver/buffer, and a simple RIAA feedback loop. The phono board is mounted directly on the rear panel, so there is no long length of wire from the input to the first amplification stage. It sounds very good.

The preamp uses a TA7136P opamp. Kenwood was known for good build quality while keeping prices a tad under the competition, and simplifying the preamp with the use of an opamp was one way to do this. While the original opamp is 'adequate', the use of the opamp actually gives a tech with an eye towards modification a lot of options. With a little bit of juggling, the original opamp can be replaced with about any modern opamp you care to experiment with. I own two KA-5500's (one is my original from 1976), and both have the opamps replaced with Burr-Brown OPA2604's. Certainly you could use anything here you wanted, but the 2604 is a very nice sounding amp and in my experiance is not too fussy about lead length and bypassing. So in my view, Kenwood's use of the opamp is a positive, not a negative.

This unit, like most of the Kenwood integrateds, has no pre-out/main-in jacks. However, the use of the opamp in the preamp section allows the addition of the jacks very easily, and the 5500 has a nice place to put 'em.

The stock low filter is set to take place at 40Hz, and is easily changed with the swap of four film caps to 20Hz. Unfortunately, the location of the filter means that if you add pre-out/main-in jacks, the low filter stays on the amplifier side, whereas it would be more desirable on the preamp side. But Kenwood did put a tone defeat switch on the 5500, which is very very nice, and a feature missing from a lot of low-end integrated amps.

The amp section is beautifully simple and sounds wonderful. A PNP diff-pair with only a resistor current source feeding a VAS stage, and a Vbe-multiplier bias setup feeding the drivers and outputs. The only other real criticism here is the lack of a DC offset adjustment, typical for midrange and lower end Kenwood's. Both of mine have a diode and trimpot offset added to the unit, but this was before I started fooling around with servos. I may someday add servos to them, but not exactly in a rush to do so.

As an aside, the KA-3500 amplifier section is identical to the KA-5500, and also is wonderful sounding, but the KA-3500 is hindered by an inability to bypass the tone controls. Other than that, and the lower power, it also is a nice amp.

The power supply is also nothing outragous..a single EI-core transformer with a two secondary windings..one for the lamp lighting the power meters (yep...a winding that does nothing but power one single lamp), and the other for everything else. The power supply filter caps are nice and hefty for a 55WPC amp...10,000µf x 2.

I wouldn't have hung onto this for so long if it didn't continue to impress me with its sound and build quality. Kenwood didn't seem to sell a lot of these...seems that the KA-3500 (the model below the 5500) and the KA-7300 (the model above) were too close in price and squeezed the 5500 out. But the KA-5500 still is a great little amplifier, and has very good potential for those who like to tinker...

ka5500nh1.jpg
 
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Thats why I don"t see many on e-pay, some day I"ll pick one up somewhere. But then I will have to have another pair of speakers for it to drive! This has got to stop sometime?
 
No, it won't, at least, not in the foreseeable future. You will get the KW, then look for a pair of speakers. you will find TWO pair that you just cannot let go by, so you purchase them both. Then you look for another amp, around which to build system number three (four?), maybe tubes. Then you need another speaker, as the others are not efficient enough for tubes, or you want a different sound...

You see where this is going, don't you? It is exactly as you fear. That's the fun part! :banana:
 
Yah, I know. I got so many amps in my shop that the lights dim when i turn them all on, and thats with a 200 amp main. but they almost heat the shop with out the heater turned on!
 
Hi ecowars my kenwood 3750 still sounds disorted and slightly weaker the other channel. i think it the opamp cos i cleaned it with isp and good scrubing on the phono board and it sounded better but still disorted and this board has the op-amp some people changed this when sound is disorted do you think this is the problem and needs replacing.
 
The 3500 (same as the 3750) does not use an opamp in the preamp section. See your thread about the 3750 for my opinion.
 
The 3500 (same as the 3750) does not use an opamp in the preamp section. See your thread about the 3750 for my opinion.

Hey echowars, the 5500 was my first amp as well. Nice little amp, no trouble over the years, with the exception of the scratchy switches.

Russellc
 
so what the six legged thing in the board that has the input phono leads connected.
'Tis a FET. A dual-FET to be specific. Used as a differential pair for the phono input. It is certainly NOT an opamp.
Hey echowars, the 5500 was my first amp as well. Nice little amp, no trouble over the years, with the exception of the scratchy switches.
Oldy-moldy thread, but it all still applies.
 
'Tis a FET. A dual-FET to be specific. Used as a differential pair for the phono input.

The advantage to putting the diff amp in one package is both transistors are likely to be better matched and they will operate at the same temperature which would minimize drifting.
 
Hi echowars,

I have a KA5500 which I have used in the past but which has come from the attic.
I am thinking of giving this amp a workover.
started with the volume control today, which creaked a little. Used some de-oxit and now it runs clean.

but when I had it open i noticed one of the condensors had corrosion on it (on the bottom), should i replace this? Am I correct that they are 10.000uF?

Also I was thinking of changing the opamps to the model you suggested, OPA2604, which will improve sound quality. where are the opamps located in the amp?
Also want to change the speaker connectors to bananaplugs (thats what we call them in holland).

Do you have any other tips for modifying/improving this amp?

Thanks already

Aram
 
The stock opamps are SIP jobs (Single Inline Package), and replacement is a fairly complex project, since you have to adapt either one or two DIP opamps to work. I simply did it to see if I'd like the change, but I would not recommend tackling such a project without the possession of some well-honed technical skills.

The two power supply caps are 10,000µf 56V. I think they are 35mm diameter, but a replacement that fits the stock clamps (probably 63V, since the stock 56V is an oddball size) should not be too tough to find.
 
thanks.

So I will just stick to the caps and the speaker plugs.
That seems fairly simple.

I also noticed the light was broken, but the lampfitting looked a little odd.
Do you know what to replace it with?

Thanks Aram
 
As an aside, the KA-3500 amplifier section is identical to the KA-5500, and also is wonderful sounding, but the KA-3500 is hindered by an inability to bypass the tone controls. Other than that, and the lower power, it also is a nice amp.

This is nice to know. I've got a KA-3500 sitting around here doing nothing. It has the handles too. I'd like to find a use for it. I brought it to a house party once, but that's the only time I ever used it. That's the problem with having more stereos than rooms in the house! It's a great looking amp.
 
The 3500 has a nice sound...I'm using a slightly modified 3500 to power the Heil's in my biamp setup. I also added the pic of the 5500 with handles to the original post...seems the original pic got lost in the server changes.

Original post was started by Rex about 4 years ago...a semi-local from the northern part of the state. He's gone, and will be missed.
 
Thought I'd chime in here and maybe get a bit of advice as well. I was lucky enough to pick up a 5500 in very good shape for $10 at a garage sale in May of this year. The lady running the garage sale had no idea what she wanted for it and gladly accepted my $10 offer. Here's the kicker: The purchase of this amp is what has gotten me involved in the hobby - I had no prior experience/knowledge of what to look for when shopping nor what to pay! All that has changed over the past few months though and my level of knowledge is considerably better.

I've hooked the 5500 up and am using it to power a pair of Klipsch Synergy B2's (A speakers) and Boston Acoustics HD10's (B speakers). I set it up with both as it's a nice way of listening to the difference bewteen these to speakers by flicking between the A to the B pseaker selector. My findings: Two distinctly different sounds: The HD10's have great clarity - When playing Chuck Mangione I can almost hear him inhale when playing the horn (trebble adjusted two clicks to the right). With the Klipsch's however I have to provide max trebble to even come close. Is the reason for this merely the difference between the speakers or is there something else? I love the Kenwood and condider it a great find to get me rolling into this hobby!
 
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