Yamaha's Hyperbolic Conversion Amplification (HCA) Circuit
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Shinja
diyAudio Member

Join Date: Jul 2008
On the latest "transistor gijutsu(トランジスタ技術)" , a japanese electronics magazine,
an article of HCA circuit written by inventor of it , Masao Noro.

http://toragi.cqpub.co.jp/tabid/587/Default.aspx
related articles
http://toragi.cqpub.co.jp/Portals/0/...circuit/HP.pdf
http://toragi.cqpub.co.jp/tabid/541/Default.aspx

I scanned and summarized it for this forum.
(attached img003)

On 図G(illust. G) obviously Iin = IC1 + IC2
Next , from fundamental characteristics of transistor,
VBE1-VBE3 = Kln(IC1/ID1)
VBE2-VBE4 = Kln(IC2/ID4)
circuitly,
VBE1-VBE3 = -(VBE2-VBE4)
then
Kln(IC1/ID1)+Kln(IC2/ID2) = Kln(IC1・IC2/ID1・ID2) = 0
therefore
IC1・IC2 = ID1・ID2 (fixed)

we can obtain linear Iout with amplifying IC1 and IC2 with power current mirror.

But general power amp's output stage is voltage buffer,
so voltage type HCA circuit is invented .

img005 and img006 explains another non-cutoff circuit : translinear bias circuit.
translinear bias circuit feedbacks output current while HCA is open loop like working.
Attached Images
 img003.jpg (152.8 KB, 644 views) img005.jpg (188.2 KB, 638 views) img006.jpg (167.8 KB, 627 views)

Last edited by Shinja; 7th July 2012 at 07:51 AM.

 7th July 2012, 10:11 PM #92 jony   diyAudio Member   Join Date: Jun 2004 Location: wroclaw Shinja THX for sharing this amazing material with us. Can you tell as what was on the rest of the pages of this appendix about HCA?
 9th July 2012, 12:53 PM #93 Jon Lord   diyAudio Member   Join Date: May 2005 Location: Kaiserslautern That's very cool information !! Regarding who is inventor and to put it into the correct historical context: The HCA version with feedback to the emitter resistors (as used in the MX-10000) was basically invented by Blomley and further studied and published in L'Audiophile (France) by Jean Hiraga and Gerard Perrot (aka Hephaistos of Lavardin) in early 1980ies. I think the MX-10000 HCA design is based on these studies. The ties of Jean Hiraga to the Japanese Audio scene was pretty tight at these days, but finally it is not clear in which direction the information was flowing, but ulimately Blomley was the initiator. Regarding the "voltage version", a very similar approach (with a little HEC in it) was earlier invented and patented by Manfred Schwarz (of Wega Germany, developing for Sony ESPRIT division in the late 70ies). This circuit was commercialized by Sony in their ESPRIT amplifiers TA-N900, N901 and N902. Basically one can say, that most likely the honor of the invention of "HCA" goes to UK, France and Germany, but the honor to transfer it into a series product goes definitely to Japan. A very similar thing happened with Technics Class AA (aka VC-4), which is inspired by Class S (By Sandman) and Current Dumping (by Walker), but realized in a way that it actually does, what Walker only claimed ... __________________ My amplifier is very musical: It accompanies myself on the grand piano, that's not half bad !
 9th July 2012, 01:28 PM #94 Jon Lord   diyAudio Member   Join Date: May 2005 Location: Kaiserslautern The Masao Noro-Patent for HCA can be found here: Patent US4404528 - Output amplifier - Google Patents This was filed after the L'Audiophile articles, so they never got Patent protection outside JP and US. Masao Noro has a huge amount of Patents on his name. I would not expect that he invented all that (In case this is the case he must be a "workaholic" kind of a super genius). Anyhow, it is very common to big Japanese Corporations, that they have only one or a few official inventors (Very often the Engineering Director or the like), so sometimes a person, who is higher in hierarchy gets the honor of being the inventor. So there is a big chance, that another Yamaha employee or a conglomerate of several engineers ist the real "inventor". So the understanding of the term "inventor" is pretty different in Japan ... Japanese members please correct me, if I'm wrong ! __________________ My amplifier is very musical: It accompanies myself on the grand piano, that's not half bad !
tiefbassuebertr
diyAudio Member

Join Date: Jul 2005
Location: D-55629 Schwarzerden
Quote:
 Originally Posted by Shinja On the latest "transistor gijutsu(トランジスタ技術)" , a japanese electronics magazine, an article of HCA circuit written by inventor of it , Masao Noro. 2012?7????????????????????? related articles http://toragi.cqpub.co.jp/Portals/0/...circuit/HP.pdf ???????USB???????????? I scanned and summarized it for this forum. (attached img003) On 図G(illust. G) obviously Iin = IC1 + IC2 Next , from fundamental characteristics of transistor, VBE1-VBE3 = Kln(IC1/ID1) VBE2-VBE4 = Kln(IC2/ID4) circuitly, VBE1-VBE3 = -(VBE2-VBE4) then Kln(IC1/ID1)+Kln(IC2/ID2) = Kln(IC1・IC2/ID1・ID2) = 0 therefore IC1・IC2 = ID1・ID2 (fixed) we can obtain linear Iout with amplifying IC1 and IC2 with power current mirror. 図H is a current type HCA circuit,the output stage of MX-10000 . But general power amp's output stage is voltage buffer, so voltage type HCA circuit is invented . 図I is voltage type HCA circuit of AX-2000 MX-2000 AX-2000a. img005 and img006 explains another non-cutoff circuit : translinear bias circuit. translinear bias circuit feedbacks output current while HCA is open loop like working.
Very interesting report. How difficult it would be a translation from the Japanese language in English or another European language with help by the tools from follow URL?
ICR and OCR technologies intergration - solutions for developers from ABBYY

BTW - for "Class-S" check out this thread/article:
http://www.diyaudio.com/forums/solid...ification.html
"Sandman, A. 'Class-S: A novel approach to amplifier distortion', Wireless World, September 1982, pg. 38" (not online available)
and this terms for google: FFEC (Feed Forward Error Correction)

P.S. At first look the topology of the output stage from the PDF
http://toragi.cqpub.co.jp/Portals/0/...circuit/HP.pdf
looks similar to that one from Linn's power amp model "Klout" - go to the attachment
Attached Files
 C_tmp_Linn Kloud_ckt.pdf (55.4 KB, 184 views)

Last edited by tiefbassuebertr; 9th July 2012 at 02:21 PM.

 9th July 2012, 02:11 PM #96 Shinja   diyAudio Member   Join Date: Jul 2008 thanks. I didn't know such the studies outside of japan. I have heard the name Jean Hiraga at japanese audio scene, but I thought he is mere a man of trading company. I had read a article of Technics's classAA on japanese audio magazine. According to it, technics's engineer explained classAA is based on current dumping and stasis circuit. I have never heard class S by sandman . Last edited by Shinja; 9th July 2012 at 02:22 PM.
 9th July 2012, 02:26 PM #97 Jon Lord   diyAudio Member   Join Date: May 2005 Location: Kaiserslautern I made a mistake: The HCA-Patent from Masao Noro is the following one: Patent US4803441 - Amplifying circuit - Google Patents It describes everything in English language ... The other Patent I quoted earlier is referenced by the Noro application (copy and paste error). __________________ My amplifier is very musical: It accompanies myself on the grand piano, that's not half bad !
Jon Lord
diyAudio Member

Join Date: May 2005
Location: Kaiserslautern
Quote:
 Originally Posted by tiefbassuebertr P.S. At first look the topology of the output stage from the PDF http://toragi.cqpub.co.jp/Portals/0/...circuit/HP.pdf looks similar to that one from Linn's power amp model "Klout" - go to the attachment
Andreas,

the Linn only has fixed current sources in the bases of the CFP output transistors (instead of resistors).
This helps stabilizing the bias currents and improves linearity. If these current sources were driven by the input of the power stage (by feed forward), then you would have something similar to the "voltage HCA" or Manfred Schwarz' error correction scheme.

The Schwarz circuit doesn't have a name anywhere so far so I would define it here as Schwarz Error Correction (SEC).

One of the Schwarz Patents can be found here:

Patent US4439743 - Biasing circuit for power amplifier - Google Patents

That this circuit works very well can be seen on the Sony TA-N902, where the output stage gives 0.005% distortion (at 20kHz, half power) without any global feedback.

Just another question: I once saw the L'Audiophile articles in your literature collection. Are you able to find them again and say us if my comments (based on memory) are correct. (Hiraga, Hephaisthos, early 80ies) ???
__________________
My amplifier is very musical:
It accompanies myself on the grand piano, that's not half bad !

tiefbassuebertr
diyAudio Member

Join Date: Jul 2005
Location: D-55629 Schwarzerden
Quote:
 Originally Posted by Jon Lord Just another question: I once saw the L'Audiophile articles in your literature collection. Are you able to find them again and say us if my comments (based on memory) are correct. (Hiraga, Hephaisthos, early 80ies) ???
L'AUDIOPHILE - French TOC-overview 1977-1988 - found by
Audio bricolos (death in the meantime):

CD1: Première série : 43 numéros, de 1977 à 1988:
ELECTRONIQUE, théorie, recherche

Alimentations
Influence des circuits d'alimentation -1- le cas du préampli Kanéda. (G.Marec)
L'influence des circuits d'alimentation -2- Amélioration d'une alimentation non régulée
L'influence des circuits d'alimentation -3- Amélioration d'une alimentation non régulée
L'influence des circuits d'alimentation -4- Préampli Kanéda: le contrôle de l'extrème grave (G.Marec)
Vieilles recettes ou nouvelle cuisine pour nos alimentations (Héphaïtos)
Vieilles recettes ou nouvelle cuisine pour nos alim -2- expérimentation objective (Héphaïtos)
Vieilles recettes ou nouvelle cuisinne pour nos alimentations -3- Analyse subjective (Héphaïstos)
Vieilles recettes ou nouvelle cuisinne pour nos alimentations -4- réalisations (Héphaïtos)

Amplification
Analyse d'un schéma pas comme les autres : le Quad 405
Aspects de l'électronique (Y.Neveu)
Mesure de la distorsion par intermodulation dynamique (1) (M.Otala)
Analyse comparative des méthodes de mesure de distorsion (2) (M.Otala)
La distorsion dans les amplificateurs (3)
Un avis sur la perfection électronique
L'IIM ou distorsion dans l'interface ampli/enceinte
Réflexions sur la réalisation et l'emploie des égaliseurs graphiques
Le comportement des amplificateurs en régime musical
L'analyse tridimentionnelle et les amplificateurs chez Technics
Evolution des circuits amplificateurs (J.Hiraga)
Performances en bruit d'un préampli associé à une cellule (P.Faugeras)
Les amplis Kanéda classe A, 15W, 30W, 40W, 50W et70W (J.Hiraga)
Distorsion par transitoire -1- définition et origines (P.Faugeras)
Distorsion par transitoire -2- Les solutions (P.Faugeras)
La distorsion dans l'amplificateur de puissance (Héphaïstos)
La distorsion thermique (Héphaïtos)
La distorsion thermique - tube contre transistor (Héphaïtos)
L'étage de sortie de l'ampli -1- réflexions théoriques (Héphaïtos)
L'étage de sortie de l'amplificateur -2- (Héphaïtos)
L'étage de sortie de l'amplificateur -3- (Héphaïtos)
L'étage de sortie de l'ampli -4- solutions moins classiques (Héphaïtos)
L'étage de sortie de l'ampli -5- la classe A quadratique (Héphaïstos)
L'étage d'entrée de l'amplificateur -1- : étude théorique (Héphaïtos)
L'étage d'entrée de l'ampli -2- le différentiel classique (Héphaïstos)
L'étage d'entrée de l'ampli -3- différentiels insolites (Héphaïstos)
L'étage d'entrée de l'ampli -4- expérimentations complémentaires (Héphaïstos)

ebay offers of this magazine:
eBay | Revue L'audiophile Collection

partly online available
L'tage d'entre de l'ampli : -2- le diffrentiel classique (Hphastos)
L'tage de sortie de l'ampli -1- rflexions thoriques (Hphatos)
L'tage de sortie de l'ampli -4- solutions moins classiques (Hphatos)
L'tage de sortie de l'ampli, 5me partie, la classe A quadratique (Hphastos)
http://www.pure-hifi.info/pdf/Le%20m...3%AFtos%29.pdf

Perhaps French members can translate.

Last edited by tiefbassuebertr; 9th July 2012 at 05:23 PM.

tiefbassuebertr
diyAudio Member

Join Date: Jul 2005
Location: D-55629 Schwarzerden
Quote:
 Originally Posted by Jon Lord The Schwarz circuit doesn't have a name anywhere so far so I would define it here as Schwarz Error Correction (SEC). One of the Schwarz Patents can be found here: Patent US4439743 - Biasing circuit for power amplifier - Google Patents That this circuit works very well can be seen on the Sony TA-N902, where the output stage gives 0.005% distortion (at 20kHz, half power) without any global feedback.
a certain similarity you will find by this topology:
http://home.tiscali.nl/data.odyssey/...ml#Harm%20Dist
compare this topology to the output power stage of

Last edited by tiefbassuebertr; 11th July 2012 at 07:39 AM.

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