Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on September 24, 2010, 08:34:58 pm

Title: Harmon Kardon / Mono Block
Post by: plexi50 on September 24, 2010, 08:34:58 pm
What should i do with this monoblock setup? Any wild ideas? (2) EL84 (1) 6CG7 (1) 6CA4
I have all the tubes that came with these. Blackplate RCA 6BQ5's as well. I removed them to test them

(http://i356.photobucket.com/albums/oo5/plexijtm45/Pamp.jpg)
(http://i356.photobucket.com/albums/oo5/plexijtm45/Tubes.jpg)
(http://i356.photobucket.com/albums/oo5/plexijtm45/Logo-2.jpg)
(http://i356.photobucket.com/albums/oo5/plexijtm45/Concerto.jpg)
(http://i356.photobucket.com/albums/oo5/plexijtm45/Pair.jpg)
Title: Re: Harmon Kardon / Mono Block
Post by: plexi50 on September 24, 2010, 09:10:29 pm
Thats what i am affraid of. Molesting them to build more 18 watt amps
They sure look nice and yep them transformers are calling me

I need to build some thing unique 
Title: Re: Harmon Kardon / Mono Block
Post by: plexi50 on September 24, 2010, 10:33:22 pm
I would really love to build a true vibrato with one of these blocks
That would be probably the greatest accomplishment for me outside of building another amp itself
Title: Re: Harmon Kardon / Mono Block
Post by: LooseChange on September 25, 2010, 05:53:37 am
How about restore and flip them... They must be worth some cash.
Title: Re: Harmon Kardon / Mono Block
Post by: tubenit on September 25, 2010, 06:55:38 am
Quote
I need to build some thing unique  


I have a 6V6 with reverb version of this amp & like it alot.  

Here's a soundclip: http://www.soundclick.com/player/single_player.cfm?songid=9534655&q=hi&newref=1
If a popup asking if you want to close it comes up, just click "no".

You'd need to punch another hole for a 9 pin socket for a 12A_7  & rewire the 6CG7 for a 5879 pentode.

I've punched numerous holes into steel mono block chassis by tracing a penny on to the chassis. Then using 1/8" drill bit to make holes around the inside perimeter of the traced penny circumference. Punch out the plug and use a grinder drill bit to smooth the hole for the 9 pin socket. Usually takes about 20 min max.

With respect, Tubenit
Title: Re: Harmon Kardon / Mono Block
Post by: mresistor on September 25, 2010, 09:27:52 am
No offense, but I think what LC suggested might be the way to go. There could be a serious audiophile out there looking for one of these HK setups in good condition. You've got both amps and the preamp it appears. It might be worth more to you to clean it up and sell it as is. Then use the cash to buy some transformers and a chassis.
Title: Re: Harmon Kardon / Mono Block
Post by: plexi50 on September 25, 2010, 09:45:55 am
I have many ideas and i really love tubenits amp he built. But i believe this set needs to stay untouched and flipped

PRR would kill me and he would be right
Title: Re: Harmon Kardon / Mono Block
Post by: RicharD on September 25, 2010, 10:05:12 am
+1 on the restore.  Ground the properly, give em a cap job, outfit them with some decent tubes, and sell em for a profit.
Title: Re: Harmon Kardon / Mono Block
Post by: LooseChange on September 25, 2010, 10:09:02 am
Check the serial numbers on them... If they are consecutive, it's a matched pair and worth even more.
Title: Re: Harmon Kardon / Mono Block
Post by: plexi50 on September 25, 2010, 05:22:58 pm
All three serials are different. I like the copper chassis's
Title: Re: Harmon Kardon / Mono Block
Post by: dynaman1 on September 27, 2010, 09:17:43 am
Harmon Kardon = $$$. Good stuff to audiophiles, especially the unmolested lower powered units. Pair of identical monoblocks? What a find!

You'd be facing some serious karma, should you tear 'em up. I'd sell all three units together so's not to be considered a home wrecker.
Title: Re: Harmon Kardon / Mono Block
Post by: stingray_65 on September 27, 2010, 10:56:53 am
Hey LC!

I just contacted my biddy Marc, He's an audiophile with serious GAS and is now lamenting his cash flow when I mentioned your HK Mono blocks.

His suggestion is to NOT restore them and flip them.

Many serious audiophiles he suggests are very particular on how they are restored and what brands of components.

They might end up redoing much of your work to suit it to their tastes.

His other suggestion is that if you do not have much money  tied up in them is to wait for a better market.

That may be years to come, but it is his feeling that it is a buyers market for high end vintage gear, many people needing money and have excessive gear are selling.

It is odd because I read in the paper last week this recession is over. I have more time now to read a newspaper  while I'm unemployed LOL

Ray

Title: Re: Harmon Kardon / Mono Block
Post by: plexi50 on September 27, 2010, 08:02:49 pm
Harmon Kardon = $$$. Good stuff to audiophiles, especially the unmolested lower powered units. Pair of identical monoblocks? What a find!

You'd be facing some serious karma, should you tear 'em up. I'd sell all three units together so's not to be considered a home wrecker.

I dare not alter them. I have not even pluged it in yet. No time. Just too busy and to tired at ther end of everyday. I did test all the tubes but thats as far as i have gone. They will sit until i get some idea of what they might be worth. That ought to modivate
Title: Re: Harmon Kardon / Mono Block
Post by: eleventeen on September 27, 2010, 10:49:46 pm
I dunno about "low money" being an impediment to someone buying them. You only need one customer and they are definitely, definitely worth more in pairs. 
Title: Re: Harmon Kardon / Mono Block
Post by: RicharD on September 28, 2010, 12:01:51 am
>They will sit until i get some idea of what they might be worth.

I looked on fleaBay at completed listings.  A pair of HK-250's sold for $950.00  That's the 4 x 6L6 version.  I think you have the HK-20's.  I'd bet an easy 6 bills as they sit.
Title: Re: Harmon Kardon / Mono Block
Post by: LooseChange on September 28, 2010, 04:59:18 am
There you go.
Title: Re: Harmon Kardon / Mono Block
Post by: plexi50 on September 28, 2010, 08:37:35 am
Sounds good to me. I will take some pic's later today and post it on Egad. If nothing else it will be fun to watch the bidding