My time at Hovland - HP-100 Lore - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th January 2013, 06:04 PM   #21
Mr. dB is offline Mr. dB  United States
diyAudio Member
 
Mr. dB's Avatar
 
Join Date: Dec 2003
Location: Arkansas
Quote:
Originally Posted by elektroj View Post
Thanks, morinix, your story got me rolling on the floor.

Several years back I remotely helped someone to tune-up his HP-100 with better capacitors. Once that tantalum at the output was replaced by some film cap, the person reported that the "Hovland sound" was gone and it sounded just like any other plain vanilla preamp. Needless to say, the amp was quickly sold.
I guess they used tantalum in that location as some sort of a "harmonic synthesizer" - just look at the distortion spectrum in tantalum measurement taken by C.Bateman (below).
In the process I also reverse engineered most of the amp by looking at pictures the owner have sent me. Here's the sketch of a line stage, for those who are interested

P.S. When I saw the PCBs and all the various sorts of resistors used, my first thought was - "they must be shopping cheaply at some surplus store".
Was the tantalum cap a wet slug tantalum, or a tantalum bead?

NAIM Audio still stuff their circuits full of tantalum beads, that seems to be the source of the "rhythm and pace" that English audiophiles enjoy. If you replace the little distortion-generators, they complain that it loses its "tunefulness".
  Reply With Quote
Old 16th January 2013, 06:07 PM   #22
dgta is offline dgta  United States
diyAudio Member
 
Join Date: May 2011
Very funny story. Thanks.
You didn't say if any divining rods were used.
  Reply With Quote
Old 16th January 2013, 06:30 PM   #23
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by Mr. dB View Post
Was the tantalum cap a wet slug tantalum, or a tantalum bead?
<snip>
It was one of the axial variety. Kemet or something similar.
  Reply With Quote
Old 16th January 2013, 06:39 PM   #24
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by Salectric View Post
There is a lot more to audio engineering than what we can measure on a test bench.
No. There's a lot more to audio marketing than what we can measure on the test bench.

jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W S Maugham
Check out Linear Audio!
  Reply With Quote
Old 16th January 2013, 06:45 PM   #25
diyAudio Member
 
kstagger's Avatar
 
Join Date: Dec 2003
Location: Grand Rapids
hmm... tantalum cap, eh? I'm reminded of the venerable B&K ST-140 with it's much loved "tubey" sound. Looking at the PCB, I see a really cheap 47uF electrolytic on the input. I replaced this with a generic film and then suddenly the "tube"/warmth is gone. The amp sounded much more neutral.
  Reply With Quote
Old 16th January 2013, 07:15 PM   #26
diyAudio Member
 
Bob Richards's Avatar
 
Join Date: Feb 2011
Location: Portland Oregon, USA
Quote:
Originally Posted by kstagger View Post
hmm... tantalum cap, eh? I'm reminded of the venerable B&K ST-140 with it's much loved "tubey" sound. Looking at the PCB, I see a really cheap 47uF electrolytic on the input. I replaced this with a generic film and then suddenly the "tube"/warmth is gone. The amp sounded much more neutral.
Second harmonic distortion is the same note as the fundamental, but one octave higher, so it's always an enhancement. It sounds really good. One of the ways to produce this is with an asymetric distortion mechanism, such as a minimalist tube circuit or a non-biased polarized electrolytic in the signal path. The tradeoff is Intermodulation Distortion, which is rarely desirable. In a guitar amp where you want distortion it can be argued that this is desirable. In a hi-fi amp where there will be many sounds mixing (heterodyning), there is a very fine line between enough and way too much. I've done the research. 1dB of symetry offset should be the max limit in hi-fi land. I would never choose to generate 2nd with an electrolytic... Pfffff!!! (Behringer has a non-biased polarized electrolytic in the input signal path of some of their DSP units, which is why I redesigned and rebuilt all their analog circuitry in my DEQ2496 - see my website).

Last edited by Bob Richards; 16th January 2013 at 07:17 PM.
  Reply With Quote
Old 16th January 2013, 07:24 PM   #27
morinix is offline morinix  United States
diyAudio Member
 
Join Date: Jun 2006
I actually have the exact tant. capacitor that Hovland used, I just have to dig it out of my stuff.

Don't get the Voodoo mixed up with hovland marketing. As far as I know the guys at Hovland never let the public know about the dowsing. They kept it under wraps like a drug habbit while I was there.

No divining rods were ever used. If the rods were used in front of me do you think I would have left that out of my story? - No way! THAT would have made a great paragraph!

I have more to post and will do that later.
__________________
Robert
Lounge Audio
  Reply With Quote
Old 16th January 2013, 10:45 PM   #28
AVWERK is offline AVWERK  United States
diyAudio Member
 
Join Date: Jan 2004
Location: OC,Calif.
I remember Hovland reduing a friends Marantz 8b before he became a company. That was around 1985? Could be off a few years.. It sounded excellent and everything was gutted and redone just as well if not better than the original.
I think he was working out of his garage down in Santa Monica at the time?
Havens & Hardesty ( retail hiend store ) used to recommend him for mods on all things tube.
Sad that excellent products need such attention waved over them like that though.
  Reply With Quote
Old 16th January 2013, 11:22 PM   #29
diyAudio Member
 
Bob Richards's Avatar
 
Join Date: Feb 2011
Location: Portland Oregon, USA
My experience with Tantalums is that they are low reliability. If they ever get reverse voltaged, you can just about count on failure.
  Reply With Quote
Old 25th January 2013, 05:19 PM   #30
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by morinix View Post

During the whole time I worked there they never gave me a schematic. Can you believe it! You are employed as a bench tech and you are never given a schematic. Being curious, I kept a PCB and a note pad off to the side of my bench and like and inmate locked away in the Tower I slowly mapped out the topology trace by trace when Mike and the Assembler Lead Lady were not watching. After about a week, low and behold! I had seen this topology before.
You would have fit right in with another amplifier company, where I understand the big guy does all of the design --- by taping up PCB artwork! Then the stuff is thrown over the wall to people who extract the schematic and figure out how to test the product. One of those people contacted me to find out if I could consult there, the principal "decoder" having been on a long leave of absence due to health concerns, but having sent a resume I never heard from the owner. Evidently the person I know is still there.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
help hovland hp200 jonstanza Tubes / Valves 1 2nd May 2013 10:57 AM
Repair help wanted for Realistic HP-100 Electrostatic Headphones HIPCHECK Headphone Systems 6 25th November 2011 04:43 PM
Differences between HP 8903A and HP 8903B cl84 Equipment & Tools 2 16th June 2010 07:34 PM
Peerless 811647 / HDT 100 + P Audio E12-200S or HP-12W noodle_snacks Multi-Way 0 29th March 2006 07:58 AM
hovland best prices ermes Multi-Way 0 18th November 2004 10:19 AM


New To Site? Need Help?

All times are GMT. The time now is 12:19 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2