Vintage Asylum

Classic gear from yesteryear; vintage audio standing the test of time.

Return to Vintage Asylum

Message Sort: Post Order or Asylum Reverse Threaded

Harman Kardon FA30XK sounds weak and lifeless

130.76.32.199
Posted on September 12, 2013 at 10:38:41
thadeus
Audiophile

Posts: 2
Location: North West
Joined: September 12, 2013
 My solid state amp blew up, so decided to hook this baby back up. Speakers have 102dB sensitivity, so this thing should really scream, I would think. At one watt on the old amp, it was quite loud. It also just doesn't sound good at all. Not gritty or harsh distortion, but totally lacking definition. The power tubes have Harman Kardon logos on them, and the signal tubes are all different brands. Is this how old tubes sound? Do all the capacitors need to be changed? Can I get away with changing just the big electrolytics? What about those large paper tubes in line with the vacuum tubes that contain multiple capacitors? Do people change all the little ceramic capacitors, too when recapping?

 

Hide full thread outline!
    ...
RE: Harman Kardon FA30XK sounds weak and lifeless, posted on September 12, 2013 at 11:01:06
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 You have the kit version of the FA3000. Poor technique on the part of the assembler may be contributing to your woes.

The power tubes rate to be worn out. Buy a new, correctly matched, set of 6V6s from a reputable dealer, like AA sponsor Jim McShane. The OEM 7408s are the industrial version of the 6V6.

The NOISY OEM SS diodes need upgrading.

The same make/production run of tubes should be used in a given position of both channels. Different brands in different positions is not a problem. Get all the small signal audio tubes tested. We'll worry about the FM tuner section, later.

H/K used a "Cheap Charlie" method for DC phono section heaters. The phono section heaters are used in the single bias network that serves all 4 O/P tubes. Frankly, that sucks! Install 2X (1 for each channel) RC bias networks to service the O/P tube pairs. If you use phono, I'll help build a proper, regulated, DC heater supply.

Your speakers are efficient and 6 WPC will be plenty. Switch the O/P tubes to triode mode by connecting each screen grid to the corresponding anode via a 100 ohm resistor.

More to come, this evening.


Eli D.

 

Come on now Eli., posted on September 12, 2013 at 12:04:07
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 You're just jealous because some SOB at HK out Cheapoed the El Cheapo.Don't worry tho,I submitted your name to the Nobel prize and the Kyoto award so we are bound to strike on one of them.Argh argh argh!
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Harman Kardon FA30XK sounds weak and lifeless, posted on September 12, 2013 at 13:15:10
thadeus
Audiophile

Posts: 2
Location: North West
Joined: September 12, 2013
 Thanks. I have the schematics with it if that will help with descriptions of what to modify.

 

RE: Harman Kardon FA30XK sounds weak and lifeless, posted on September 12, 2013 at 13:55:13
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 You have mail!

The schematic will be of great assistance. Upload a scan so other "inmates" can contribute.

Some modifications are obvious. OTOH, if you are comfortable, we can really tear into the "beast".


Eli D.

 

RE: Come on now Eli., posted on September 12, 2013 at 14:09:28
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 H/K had PLENTY of company in using that damned "Cheap Charlie" DC heater method. Stromberg/Carlson, EICO, Fisher, and "who knows" used it too. That doesn't change the fact that that sort of engineering is guano! Devil take the blasted "Bean Counters".

"El Cheapo" refers to the builders of the project. :>D EC is very economical, but poor engineering practices were not employed. I am fussy about things my name goes on. ;>)


Eli D.

 

RE: Harman Kardon FA30XK sounds weak and lifeless, posted on September 12, 2013 at 18:29:44
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Thad
Here is what you want to do..Take your meter and put it on DC and clip your ground lead on the chassis..Test each side of each cap to ground.One side should have high dc voltage and the other side should read 0vdc..It is easier to disconnect once side of the cap and see if you are passing DC..Check to see which side the higher voltage is on first and then disconnect the opposite side and see if you pass DC..If you have any dc at all,toss out that cap.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Come on now Eli., posted on September 12, 2013 at 18:39:59
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Don't I know they had plenty of company and with Eico,there was absolutely no excuse for it when they had enough current from the the power trafo to run the 12AX7 heater.
Tell them Dafuk barosh
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Harman Kardon FA30XK sounds weak and lifeless, posted on February 22, 2015 at 18:20:48
VFET
Audiophile

Posts: 2
Joined: February 21, 2015
 HI Everyone , I have this same receiver my problem started when I put new coupling caps and the small electrolytic not the big ones what has happened since is that the output tubes replate in just few seconds! the high voltages are preset but there is no 24 bia voltage on the 400uf/50v cap measuring from pin each leg of the twin bias pot measures on side of the pot on 6 volts the other leg has no voltage also no voltage on the ceter tap of the voltage, I don't have the schematics I have one from the A 300 tube amp , can anyone help trouble shoot, it was working fine! before putting new coupling caps, it seems I should have gone with if it runs don't fix it! I was trying to improve on the sound:) thanks. Sikander

 

RE: Harman Kardon FA30XK sounds weak and lifeless, posted on February 22, 2015 at 18:28:45
VFET
Audiophile

Posts: 2
Joined: February 21, 2015
 sorry for some typo in my message should have read that there is no 24v bias voltage when measuring from chassis ground to positive terminal of the 400uf/50v. Measuring again from chasis ground to left leg of each of the twin bias adjust pots measures 6vdc on the right leg of each of this pot there is O volts as is between chassis and center leg of each tap. All tube redplate within a few seconds of powering up and get very hot! there is no sound whatsoever! Before I replaced the old coupling caps with new one and the small voltage electrolytic caps in the pre-amp section this receiver was working well the sound was also ok I decided to improve on the sound quality . Can anyone help me as to what is causing the problem? Also a schematic of this receiver will be appreciated. Thanks for any kind help. With Best Regards! Sikander.

 

Page processed in 0.022 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]