h/k Chorale.

[WopOnTour]

Wow, that is a "money shot." How was it taken? Spaceman, I like the look of those HK tube amps and receivers. I also like their older copper faced ones too.

I took them with a basic digital camera (Canon A40) on a tripod in a darkend room using a long exposure and using a shutter timer so there was zero shake during the exposure. They all turned out excellent.
There's some more similar shots of this same amp (with RCA black plate 6L6GC) in this old thread:
http://www.audiokarma.org/forums/showthread.php?t=110243
WopOnTour

 

[NYListens]

I took it with a basic digital camera Canon A40) on a tripod in a dark room using a long exposure and a shutter timer so there was zero shake during the exposure. They all turned out excellent.
There's some more similar shots of this same amp (with RCA black plate 6L6GC) in this old thread:
http://www.audiokarma.org/forums/showthread.php?t=110243
WopOnTour

Nice shots. Too bad I don't have the equipment to do that digitally.

 

[WopOnTour]

I couldnt work on these old amps anymore without a digital camera. Memory isnt what it used to be. I take dozens of photos then ID the components and label everything in MS paint so that along the way I wont lose my place. LOL
Sad perhaps, but it works for me!
WOT

 

[NYListens]

I couldnt work on these old amps anymore without a digital camera. Memory isnt what it used to be. I take dozens of photos then ID the components and label everything in MS paint so that anlong the way I wont lose my place. LOL
Sad perhaps, but it works for me!
WOT

That is very wise. I think I will be doing that if and when I rebuild my 340B's MPX section, which is many capacitors burried under resistor and wire spaghetti.

 

[spaceman]

Heh, that's a BIG part of why I finally got a digicam, for working on them. I like to think I'm pretty careful, but it just seems a lot smarter to save a "before" pic, just in case. :yes: WOT, I'll definitely share more once I get going on it, an "up the skirt" shot sounds fun, lol.

 

[WopOnTour]

:yes: WOT, I'll definitely share more once I get going on it, an "up the skirt" shot sounds fun, lol.

ALWAYS up for those LOL.

Here's some shots of my H/K A260 modifications:
-Mcshane'd power supply (revised rectifier with "stacked" 2x 820uf ultra low ESR caps in the doubler, JJ 2x100uf, and CP Manufacturing 3x40uf all mounted top-side)
-Totally rebuilt and reloated bias generator to achieve minimum -40VDC (you can see it on the far left of the under chassis shot)
-Total recap of ALL coupling positions -Russian K40Y PIOs(4), Mcap Supremes(2), Auricaps(2), 716P Orange Drops(2), Hovland Musicaps(4)
-Individual bias pots with 10 ohm cathode resistors
-Top-side bias test points with rotary switch
-Triode<> Pentode Switch (added 200ohm resistor to screen for stability)
-Added new RCAs for AUX1 AUX2 and Mag Phono (after photo obviously)

I basically removed the two stock 5K balance pots, and installed the triode switches in those empty holes, then drilled for the Bourn 10K multi-turn pots, 5-pole rotary switch (to cycle to each tube's cathode circuit) and DVOM test points so it's easier to adjust your bias.

Normally I dont like drilling the top-plate of the chassis for stuff like this and often use the back of the chassis, but I wanted to make it easier to adjust/set bias from the front while on the audio rack (so switching between Triode-Pentode & re-bias could more be easily accomplished). I use a plastic television adjustment tool to reach in between the tubes set the bias.
By the way I've made similar mods to an A250 as well, with equally good results (but with a few minor changes)

If you (or anybody) wanted more detailed information on these mods either post here or PM me
WopOnTour

 

[WopOnTour]

Hey Spaceman, so have you started on the resto for your A260 Chorale yet?
FYI I purchased ANOTHER A260 Chorale today for $50- so it will be getting the same treatment as my last one.
I may just keep this one for the garage :thmbsp:
WOT

 

[spaceman]

Hey, congrats on finding another one, WOT, I bet that made ya pretty happy. :thmbsp: Did you get the later version trannies this time? I haven't started any projects yet, but over the last couple months, I did a few repairs & painted my basement, a bigger job than I anticipated. I basically have a nice little shop area now (though not exactly organized yet), nice & bright with adequate working room. I'm pretty anxious to get going, lots of projects, but I'll be taking my time, & hopefully avoiding any mistakes.

 

[WopOnTour]

Hey, congrats on finding another one, WOT, I bet that made ya pretty happy. :thmbsp: Did you get the later version trannies this time?

Yes, a nice CL score.(I've never had much luck with CL) And it IS the Rev-2 version with the improved power supply transformer and 4400ohm pri-Z ouput trannies(vs 7000 for the Rev-1 "666" OPTs), however not near in as pristine as the last one (as pictured in your 1st post in this thread below).
By comparison it's a total beater and is gonna take some elbow grease.But I need to finish a Citation IV and Fisher 800C first, before I an devote any time to it.

But even with it's perceived short-comings, when I was done with the Rev-1 A260 though I was quite impessed- it sounded amazing.(to the point I enjoyed certain types of music on it, almost as much as my Citation II)
I hadn't really planned to part with it- but got sort of "swindled" out of it in a labor-for-labor bartering deal. Someone had to do the hardwood on our staircase, so it might as well have been someone (a carpenter) from our local audio society!:thmbsp:
I'm not so good with wood projects, if it doesn't have wires going in or out I'm kind of lost...
WOT

 

[spaceman]

Excellent, I'll be interested in your opinion on the differences in the versions, once you get to it. :yes: I don't expect it's a night & day difference, just curious how much better you think they are, after you've heard both. I'd probably go ahead & order parts now, but I'm wrestling the flu, so not sure how well the mind's actually working.

 

[spaceman]

Hey, I "finally" got around to it! I knew coming into this that my chassis was pretty rough, from a liquid spill, but the damage was limited to cosmetics, I think. I took a before & after pic, the after being with 2 good applications of Simi-chrome & lots of rubbing. Actually, my preamp is surprisingly smooth, especially the volume & balance pots. :thmbsp: Sorry it took so long, WOT, but here's that "up the skirt" shot, now that you don't need it.

 

[NYListens]

Good stuff. Are you going to recap it now?

 

[spaceman]

Yep, just gotta re-read WOT's post to see what caps he used. I have a list of the stock ones, & will order from Jim McShane, so I guess he'll know better than I do what stuff's good.

 

[WopOnTour]

Hey spacedude!
My suggestion would be to build the negative bias generator (caps/diodes/resistors) on a couple of solder strips and mount it UNDER the chassis next to the power transformer.(like I did see pics above) That way you can completely eliminate that C3 capacitor on the far side of the chassis (you can just leave it there unconnected for asthetics) and then do your 3 main filter cans in sequence (the 3 cans right next to each other) Here's some diagrams of the original PSU and my suggested mods. These have worked very well on a couple A260 and an A250 I have restored.

So I used 2x820uf low ESR Panasonic in the doubler. Then a JJ 100x2 for the next 2 DC rails and then a 40x3 (all from Jim Mcshane) in sequence starting from the outside of the chassis and working inwards.

My goal with the bias supply was to try to get it a bit more negative (-40V or so) which wont run the tubes as hard and will allow you to better cope with slightly higher 120VAC main supply voltage.However I eventually ended up with more like -46V which required the addition of individual pots to control the bias to each output tube.(see pics above) I also added a pot in the DC heater circuit to the series wired V1/V2/V3 heaters that provided adjustment to bring them down closer to 12.3V drop each.If you want you can then measure the pot and install a fixed resistor.

HTH
WOT

 

[spaceman]

I see now, that's triple the capacitance. :thmbsp: I just emailed Jim a bit ago, & I imagine he'll see this, in case it's useful to him. Hey, I was born in '61, the year this amp was made.

 

[NYListens]

I see now, that's triple the capacitance. :thmbsp: I just emailed Jim a bit ago, & I imagine he'll see this, in case it's useful to him. Hey, I was born in '61, the year this amp was made.

Yes, we are just caretakers of this equipment for the future generations. Everyone of my Fishers has been older than I. As I was born in 1967. Kind of cool when you think about it.

 

[spaceman]

I see now, that's triple the capacitance. :thmbsp:

Ha, I say some dumb stuff sometimes, so one more won't hurt. Jim's on a business trip right now, but that's cool, it'll give me more time to try to figure things out.

 

[sloober]

Yes, we are just caretakers of this equipment for the future generations. Everyone of my Fishers has been older than I. As I was born in 1967. Kind of cool when you think about it.

Hey NYlistens, I too was built in 67. In Bronxville, NY. All my gear is older than I am, by 5 to 10 years I would say. I was fortunate that I was the only one who wanted the old electronic junk the HS was throwing out one year. I got my Altec, A Bogen, Dynaco, a Eico HF-60 (just one:tears and several other odd audio things and tape platers and speakers. It was a big haul.

That HK will come out nice. Kinda itching to do my HK Ballad. :scratch2:
John

 

[WopOnTour]

I see now, that's triple the capacitance. :thmbsp: I just emailed Jim a bit ago, & I imagine he'll see this, in case it's useful to him. Hey, I was born in '61, the year this amp was made.

LOL I'm a '60 model myself (same as my Citation II) :yes:
Good vintage? :scratch2:
WOT

 

[WopOnTour]

ALWAYS up for those LOL.

Here's some shots of my H/K A260 modifications:
-Mcshane'd power supply (revised rectifier with "stacked" 2x 820uf ultra low ESR caps in the doubler, JJ 2x100uf, and CP Manufacturing 3x40uf all mounted top-side)
-Totally rebuilt and reloated bias generator to achieve minimum -40VDC (you can see it on the far left of the under chassis shot)
-Total recap of ALL coupling positions -Russian K40Y PIOs(4), Mcap Supremes(2), Auricaps(2), 716P Orange Drops(2), Hovland Musicaps(4)
-Individual bias pots with 10 ohm cathode resistors
-Top-side bias test points with rotary switch
-Triode<> Pentode Switch (added 200ohm resistor to screen for stability)
-Added new RCAs for AUX1 AUX2 and Mag Phono (after photo obviously)

I basically removed the two stock 5K balance pots, and installed the triode switches in those empty holes, then drilled for the Bourn 10K multi-turn pots, 5-pole rotary switch (to cycle to each tube's cathode circuit) and DVOM test points so it's easier to adjust your bias.

Normally I dont like drilling the top-plate of the chassis for stuff like this and often use the back of the chassis, but I wanted to make it easier to adjust/set bias from the front while on the audio rack (so switching between Triode-Pentode & re-bias could more be easily accomplished). I use a plastic television adjustment tool to reach in between the tubes set the bias.
By the way I've made similar mods to an A250 as well, with equally good results (but with a few minor changes)

If you (or anybody) wanted more detailed information on these mods either post here or PM me
WopOnTour

Holy thread resurrection Batman!
I had to bring this one back to provide an update, in that almost15-years after completing this restoration on the Harman Kardon A260 Chorale, I am STILL listening to it on a regular basis!

Over that period I've rolled in the occasional alternative tube sets into different sections, played around a lot with different bias levels, messed with the triode-pentode modes, done most all signal and distortion analysis on the scope and analyzer, and I will have to reiterate THIS LITTLE HK AMP IS AMAZING!
I have owned the Citations II & V, I still have wonderful the FIsher Model 200s in my main listening space, yet I still find myself being regularly drawn out to the garage where I have my A260 Chorale jacked into a pair of big Altecs (816A + 511 horns) running mostly my PONO thru a Carver C-1 preamp, to listen to some of my shop-day favorites in utter amazement. I quite simply love this thing!

In the meantime, I relish that I had the opportunity to assist a few now departed AK buddies like audiodon and spaceman in getting their A260s to a level that brought them similar satisfaction and wonderment. Will continue to advise anyone that asks for help on this amp. What I'm adding today is the diagram I had drew up for the negative bias generator which I see being the key element that, when combined with the ability to adjust each output tube bias individually paramount in being able to maximize the performance of this great piece of HK history.

Thanks again to this community for helping me to learn so much and gain the confidence to not just restore but to experiment, learn, and refine
WopOnTour