Harman Kardon A50K/A500 tube amp advice needed!!

I think I might have found something. A friend of mine has one of these Harman Kardon A50K integrated tube amps. It's the kit version of the A500. I am pretty sure it's from 1962 and is 25 wpc (but someone who is selling one on ebay claims it's 50 wpc using 7355 output tubes??). Here are a couple of pics I've found on the web. There is the one on ebay and one in Japan, although my friend's is cleaner:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3017608991&category=3282

http://tubelink.com/audio/inteamp/hk/A50K_1.html

I would upgrade the speaker connections with binding posts that will accept banana plugs, RCA terminals(silver or copper Bullet plugs for the phono and aux/cd), and new power cord, and replace the caps with Black Gates and all wire with solid core silver if possible.

Would this be an absurd amount of modification to do to such an inexpensive amp? Would such mods greatly improve the sound; enough to be worthwhile? Am I going to be disappointed when I try to crank this baby with some heavy rock or pulsing electronica? Any general comments/advice???

 

Yeah, I'm afraid of the HK sounding thin, but back then HK was a high-end manufacturer. I would think that going through this amp, doing the upgrades and replacing all the caps would make it really sing. I don't know what to do here. How are Scott amps? How many watts are the Dynaco ST70s? Maybe I should just pick up a pair of those and use them as monoblocks.

 

I have a Citation II, 60wpc class A power amp (currently waiting for me to make repairs. And waiting... and waiting...) I think it sounds just fine. I certainly wouldn't describe it as thin.

I have been given to understand that the transformers are a good part of what makes one of these amps good, and that being the case I'd think the modifications would be worthwhile (assuming they do good, rather than harm, of course). And depending on how much you enjoy/hate doing the mods, of course.


My Citation used to live in the sound booth at Hill Auditorium, where it was used for monitoring concert recordings. One day I went up and hung mikes as usual, and then turned up the faders to get a balance during rehearsal, and... there was no stereo image. I couldn't hear what was happening at all. I looked over at the rack where the amp used to live, and found that it had been replaced by a Crown D75. (Crown has made some fine products, but if you ask me the D-series was not among them.)

 

So you are suggesting that I may want to upgrade the transformers on this amp? With what? Vintage? New?

 

prix,

Try the HK vintage group at this link

From AA - Vintage

Posted by philo1 ( A ) on February 03, 2003 at 20:05:27
In Reply to: Re: Vintage harman/kardon site posted by D-A-N on January 31, 2003 at 14:43:30:


I have set up a message board for Vintage Harman Kardon at "Yahoo Groups":
http://groups.yahoo.com/group/vintageHarmanKardon/

It is a fledgling group!!! More participants are needed to make this a productive group. Personally, I own (or have owned) only the Citation II, III, IV & V and the Award A500 and the FM reciever that goes with it. Others in the group are interested in the solid state gear. The more the merrier!!!

Regards,
Geoff

 

Sorry, I seem to have given the wrong impression. I was saying that the H/K probably has good transformers, and would be worth while upgrading.

 

I like the idea of the Scott 299C and 299D because of their higher power rating. Would these be the ones you are speaking of? I know there is a 299A, B, C, and D. Can these Scott amps rock? The Fisher stuff scares me because of the FM receiver on-board. Every time I get an amp with a radio the FM leaks into the other inputs. Never fails. I really want to go with an outboard tuner. I'm going to be paying $50 shipped for the HK, so I might as well check it out. If it doesn't sound good, I'll pickup a Scott at your recommendation. At the very least, it will be fun cleaning up and refurbishing the HK. I'll post some before and after pics when it's finished.

 

Prix,

To view specs on vintage Scotts, go to the link shown below. It's a very informative website.


http://www.hhscott.com





Ed Hurdle
HeavyDistortion

 

I've been thinking of doing something like this too.
I found this guy through the klipsch forums and he seems very knowledgeable and personable.
His name is Craig and he started this site a few months ago NOS Valves after receiving countless requests for info and rebuilds from the klipsch members. Kinda turned his hobby into a business.

In many cases the buyer has the unit shipped to him right from the seller. He rebuilds them then sends them on to the buyer.
Seems reasonable at $125 plus parts. He might even have a few things laying around that that you could buy directly from him.

 

So do any of you have any experience with loud rock through older tube amps? I'm wondering what would happen if I were to blast Judas priest through a Scott 299? The reason I ask is that I was once told that low wattage tube amps wouldn't do this very well.

 

What Steve says.

Also realize that tube amps tend to clip more gracefully than solid state amps, so, while clipping is not recommended, you might get more out of it than you expect.

(My Citation II (60 wpc) never went into hard clipping until I played a digital recording of a choral group rather too loudly. Of course you can clip anything if you really try.)

 

I see. My speakers are 90 or 91 db efficient, I think, so they should be fine in other words. Hopefully, I can acheive my goal of warming up the sound of my system with a tube amp. I'm really realizing lately that a somewhat bright, extremely detailed sound is not what it's about for me. I want a little honey coloration and some natural feel for my hi-fi and I'll leave the rest to the monitors in my studio.

 

Yeah, I realize this. There's no distortion like tube distortion. No more square soundwaves here.....

 

Hi,

I have a great vintage HK receiver. Alas, it is only mono but has one of the best FM sections I have ever heard. I am sure the HK would work great for you.

I wouldn't however dive in and do all the mods right away, but would suggest a tune up. Get to know and like the amp first and see what works and what needs work. In any event, vintage amps can and do rock.

Just look at Paul Mcartney rocking at this site with Leak.


http://www.beatlesgear.com/

Jeff

 

May I assure you that you will listen a a lower level with a GOOD tube amp than solid state. I found before that i was trying to go louder to get more prescence, and instead was getting a lot more brightness. And my neighbors NEVER seemed to appreciate it!

 

There's watts and there's watts, and for the majority of people listening needs, not a lot of watts are actually needed. I get buy just fine with 10 watts a side. Mind you, I am using Tannoys. But the same amp can get any reasonably efficient (87-90 db) speaker to sing. Jeff

 

I'm a big fan of vintage HK amps. I own 2 Citation II's that have both been upgraded and rebuilt with kits from Jim Mcshane (He is the HK Guru!, search google with his name to find him).

The Cit II has fantastic output transformers which really have great woofer control. It isn't very pretty (dark brown) but it sure sounds sweet! It uses 6550 or Kt88 output tubes. I am currently using one in a bi-amp setup with a Mac 240 and the combination is unreal.

These are well worth seeking out and unlike most vintage amps, the value of them go UP after you upgrade them.

 

Gary, The HK is doing the Bass duties with the Mac on top. A great combo as the Mac's only weakness is flabby bass.