No - feedback amplifier

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Search for a no-feedback amplifier showed the attached circuit from

TUBEAMP

What about the design? Want's to built a new amplifier.
 

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  • The End mk.II 1302 og 3281 a.JPG
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Local feedback

Well I'm sure it will sound good.
Technically, it isn't a no-feedback design - there's lots of local feedback / degeneration; has to be to get good sound.
But it certainly is a non-GLOBAL-feedback amp.

jan didden

Ok, thanks.

I was told that amplifiers without FB sounds well. So - local FB can not be avoided concluded out from your statement.

Gudmund
 
AX tech editor
Joined 2002
Paid Member
Forgot to ask.....do you prefer a symmetrical solid state design?

Just short....symmetrical or ?

Well, I find it difficult to say that a particular topology is better or not. You can make great symmetrical amps and great non-symmetrical as well.
So much depends on the circuit details and the implementation.
Things like the grounding layout, (remember, not all grounds are created equal!) or power supply decoupling, and supply routing probably have at least the same impact as the topology.
If you are not experienced in those issues, your best bet for a successfull implementation is to selct a design that you like and where the designer gives info about how to put it together, and follow those.
With a circuit like the one you showed, and good implementation practise, your amp will certainly sound very well.
 
Well, I find it difficult to say that a particular topology is better or not. You can make great symmetrical amps and great non-symmetrical as well.
So much depends on the circuit details and the implementation.
Things like the grounding layout, (remember, not all grounds are created equal!) or power supply decoupling, and supply routing probably have at least the same impact as the topology.
If you are not experienced in those issues, your best bet for a successfull implementation is to selct a design that you like and where the designer gives info about how to put it together, and follow those.
With a circuit like the one you showed, and good implementation practise, your amp will certainly sound very well.

Understand....well , I have made some amplifiers, and know that the wire connection from PSU to the PCB might affect the stability of the outputstage...also depending on the ground layout as you mentioned.

I shall stay with the symmetrical design...it looks good... from my point of view.

Thanks
Gudmund
 
I guess LC knew something you don't. LOL!

If LC refers to me I can assure you that I never used TIP type of BJT's anywhere. BF471/472 in my schematics are completely different kind of animals, for pre-drivers only. :D

For drivers I would certainly recommend something like 2SA1930/2SC5171. ;)

And for outputs not a crap as 2SC3281/2SA1302 but something like 2SA2121/2SC5949. ;)
 

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Plenty of feedback, just not the usual type. Looks like current rather than voltage feedback. Why on earth would you choose to use crap like the TIP41/42 as drivers to 2SC3281/2SA1302's...

A little research showed that faster drivers in the mkII version could make the circuit unstable.
It seems that L.H.Clausen changed drivers as well as o/p transistors in the mk3 version, which I found at the same site.

As to your statement concerning 3281/1302, the mentioned powertransistors has been used more than once, and messured linearity of the Toshiba's equals the types that you suggest.
 
A little research showed that faster drivers in the mkII version could make the circuit unstable.
It seems that L.H.Clausen changed drivers as well as o/p transistors in the mk3 version, which I found at the same site.

As to your statement concerning 3281/1302, the mentioned powertransistors has been used more than once, and messured linearity of the Toshiba's equals the types that you suggest.

Sorry ....was suggested by Lacy Cat !
 
check out this thread:
http://www.diyaudio.com/forums/soli...-nfb-negative-feedback-me-wrong-question.html
also this threads and URLs perhaps are of interest:
http://www.diyaudio.com/forums/soli...e-ended-related-solid-state-output-stage.html
http://www.diyaudio.com/forums/solid-state/162142-tip3055-2n3055-based-power-amps.html

Output Buffer Stages
http://www.diyaudio.com/forums/solid-state/155582-help-amp-16.html (Harman's T-Circuit: Post #151)
http://www.diyaudio.com/forums/soli...t-transistors-leach-superamp-help-needed.html
http://www.diyaudio.com/forums/solid-state/25172-baxandall-super-pair.html (CFP, Sziklai-Darlington)
http://www.diyaudio.com/forums/solid-state/165165-edwin-20-watt-elektor-1970-may-3.html
http://www.diyaudio.com/forums/solid-state/113943-quad-303-triple-cascade.html
http://www.diyaudio.com/forums/soli...llower-diamond-buffer-power-output-stage.html
http://www.diyaudio.com/forums/solid-state/174126-best-topology-no-feedback-classab-buffer.html
http://www.diyaudio.com/forums/solid-state/71338-hot-follower-99-a.html
http://www.diyaudio.com/forums/pass-labs/34437-power-follower-99c-vs-zen.html
http://www.diyaudio.com/forums/solid-state/156685-jfet-audio-buffer.html
http://www.diyaudio.com/forums/solid-state/156344-anyone-built-mosfet-follower-similar.html
Buffer Amp
http://www.diyaudio.com/forums/showthread.php?s=&threadid=130130

Quasi complementary concepts
http://www.diyaudio.com/forums/solid-state/162310-how-identify-quasi-complementary-amplifier.html
http://www.diyaudio.com/forums/solid-state/88258-brother-quasi.html
http://www.diyaudio.com/forums/solid-state/53264-another-quasi-complementary-design.html
http://www.diyaudio.com/forums/pass-labs/6810-quasi-complementary-output.html
http://www.diyaudio.com/forums/solid-state/167394-quasi-amplifier-begginers.html
http://www.diyaudio.com/forums/pass...omplementary-mosfet-citation-12-taa-book.html
NMOS Amplifier 900
http://www.diyaudio.com/forums/showthread.php?t=130463
N-Channel mosfet amplifier schematic needed 106759
http://www.diyaudio.com/forums/showthread.php?t=40065
Push-Pull using only N-Channel MOSFETs 5053
http://www.diyaudio.com/forums/showthread.php?t=24744
N-channel only output devices in a power follower. 7511
http://www.diyaudio.com/forums/showthread.php?t=14320
N-channel Problem HELPPPPPP 7542
http://www.diyaudio.com/forums/showthread.php?t=4476
http://www.diyaudio.com/forums/solid-state/110771-improving-linearity-n-ch-mosfet-output-stage.html
http://www.diyaudio.com/forums/soli...nder-development.html?perpage=25&pagenumber=1
http://www.diyaudio.com/forums/soli...better-audio-non-complements-audio-power.html
http://www.diyaudio.com/forums/solid-state/154388-its-cheap-its-n-its-dirty-its-circlomos.html
Black devil #47
http://www.diyaudio.com/forums/solid-state/154493-your-opinion-about-schematics-5.html
http://www.diyaudio.com/forums/solid-state/99967-anybody-have-scan-483b-motorola-2.html (Black devil)
only N-Channel/NPN BjT's
http://www.diyaudio.com/forums/attachment.php?s=&postid=821629&stamp=1137723117
von
http://www.diyaudio.com/forums/showthread.php?s=&threadid=72149
http://www.diyaudio.com/forums/solid-state/162644-siliconix-siemens-nmos-amplifiers.html
Only N-Channel MOSFETs (NMOS); better Audio from non complements by Audio Power? 1102
http://www.diyaudio.com/forums/showthread.php?t=148646
http://www.diyaudio.com/forums/solid-state/174126-best-topology-no-feedback-classab-buffer.html

current-conveyors (CC) Jannemann PAX
http://www.diyaudio.com/forums/parts/163039-current-conveyors.html
LEF Carlos Candeias
http://www.diyaudio.com/forums/solid-state/168185-how-does-lef-load-effect-free-amplifier-work.html

push-pull-push-und-push-pull-pull
http://www.diyaudio.com/forums/solid-state/66334-gamut-d200-clone.html
http://www.diyaudio.com/forums/soli...h-pull-pull-like-gamnut-whats-right-name.html

Parallel connected output devices
http://www.diyaudio.com/forums/soli...s-paralleled-place-one-output-transistor.html
http://www.diyaudio.com/forums/solid-state/140542-how-drive-8-pairs-mjl21193-94-a.html
MOSFET Output
Improving the linearity of an N-ch MOSFET output stage 3524 Starter: X-PRO, Entwickler vom A3i
http://www.diyaudio.com/forums/showthread.php?t=110771
http://www.diyaudio.com/forums/solid-state/23526-best-mosfet-output-stages-11.html (page 11, also circlotron)

Error Correction
http://www.diyaudio.com/forums/showthread.php?s=&threadid=78163&highlight=linxNew error correction amp
http://www.diyaudio.com/forums/solid-state/89023-bob-cordell-interview-error-correction.html
http://www.diyaudio.com/forums/solid-state/41752-re-new-error-correction-amp.html
http://www.diyaudio.com/forums/soli...r-correction-amp.html?perpage=10&pagenumber=1.
http://www.diyaudio.com/forums/soli...awksford-error-correction-nfb-unity-gain.html

MJR
http://www.diyaudio.com/forums/showthread.php?threadid=30819
http://www.diyaudio.com/forums/showthread.php?threadid=125650
http://www.diyaudio.com/forums/showthread.php?s=&threadid=93193&perpage=25&pagenumber=1

NDFL (nested feedback loops)
http://www.diyaudio.com/forums/showthread.php?threadid=40871
http://www.diyaudio.com/forums/solid-state/148066-new-cherry-ndfl-amp.html

CFP gain stage, modifications.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=146346&perpage=25&pagenumber=1
CFP und emittergekoppelte Differenzverstärker
http://www.diyaudio.com/forums/showthread.php?threadid=146346
http://www.diyaudio.com/forums/showthread.php?postid=1862357#post1862357
http://www.diyaudio.com/forums/solid-state/88515-cfp-vas.html

Cascode
http://www.diyaudio.com/forums/solid-state/174542-what-name-topology-2.html (emitter cascode)
http://www.diyaudio.com/forums/pass...ke-stasis-no-longer-used-todays-amps-why.html
http://www.diyaudio.com/forums/solid-state/154670-my-folded-cascode-vas-linearity-investigation.html
http://www.diyaudio.com/forums/attachment.php?s=&postid=1621315&stamp=1222759259 (folded cascode)
http://www.diyaudio.com/forums/showthread.php?threadid=61289 ((Rush Cascode for input)

IC-Amp
http://www.diyaudio.com/forums/solid-state/69782-death-gain-clone.html
http://www.diyaudio.com/forums/chip...ed-topologies-yamaha-mx-10000-quad-405-a.html

Compensation capacitor Cdom
http://www.diyaudio.com/forums/showthread.php?threadid=105453

SuSy
http://www.diyaudio.com/forums/showthread.php?threadid=77568 (SuSy US 5376899 go to TI)
http://focus.ti.com/docs/prod/folders/print/opa1632.html (Nelson Pass SuSy US 5376899)
Four for SuSy? (Sansuis Diamond Transistor)
http://www.diyaudio.com/forums/showthread.php?postid=687745#post687745
http://www.diyaudio.com/forums/showthread.php?s=&threadid=148709&perpage=25&pagenumber=1
http://www.diyaudio.com/forums/attachment.php?s=&postid=1899163&stamp=1249756796

Technics Class-A versions
http://www.diyaudio.com/forums/showthread.php?threadid=23590
http://www.diyaudio.com/forums/attachment.php?s=&postid=275083&stamp=1070435722 Technics SE-A1, AA
http://www.diyaudio.com/forums/attachment.php?s=&postid=275084&stamp=1070435794 Technics SE-A1, AA
http://www.diyaudio.com/forums/attachment.php?s=&postid=275085&stamp=1070435872 Technics SE-A1, AA
http://www.diyaudio.com/forums/showthread.php?s=&threadid=32254&highlight=
http://www.diyaudio.com/forums/showthread.php?threadid=32254 (New Class A)
http://www.geocities.com/technicshifi/SVI2004A.JPG (SVI2004A)
http://www.diyaudio.com/forums/attachment.php?s=&postid=372795&stamp=1082105786 (SVI2004A inside)
http://www.diyaudio.com/forums/attachment.php?s=&postid=1707595&stamp=1231499564 (TechnicsOutput BUF)
http://www.diyaudio.com/forums/solid-state/922-technics-class-bias-circuits.html

Class XD
http://www.diyaudio.com/forums/solid-state/87916-class-xd.html
http://www.diyaudio.com/forums/analog-line-level/91779-class-xd-doug-self-again.html
http://www.diyaudio.com/forums/showthread.php?s=&threadid=87916&highlight= (Diskussion)
http://www.diyaudio.com/forums/showthread.php?threadid=91779 (Diskussion, Quelle für URL)

Class-B w-o-crossover-distortion
http://www.diyaudio.com/forums/solid-state/45249-crossover-distortion-gone.html
http://www.diyaudio.com/forums/solid-state/160285-class-b-w-o-crossover-distortion-1975-a.html (Visch Topology)
http://www.diyaudio.com/forums/solid-state/162559-new-class-super-non-switching-need-revival.html

Class G, H
http://www.diyaudio.com/forums/solid-state/39481-high-power-class-g-amplifier.html
NFB
Looking for Feedback on this No Feedback Amp
http://www.diyaudio.com/forums/showthread.php?s=&threadid=145476
http://www.diyaudio.com/forums/showthread.php?postid=1838160#post1838160
http://www.diyaudio.com/forums/solid-state/94676-bob-cordell-interview-negative-feedback.html
http://www.diyaudio.com/forums/solid-state/42259-zero-feedback-impedance-amplifiers.html
http://www.diyaudio.com/forums/soli...-distortion-cancellation-power-amplifier.html

Auto-Bias, variable Bias
http://www.diyaudio.com/forums/solid-state/145013-variable-operating-biass-output.html
http://www.diyaudio.com/forums/soli...ss-b-thule-audio-topology-also-used-teac.html
http://www.diyaudio.com/forums/showthread.php?postid=1679112#post1679112 (Optobias US4752745)
http://www.diyaudio.com/forums/pass...as-automatic-self-biased-overview-wanted.html
http://www.diyaudio.com/forums/soli...-complementary-power-amplifier-j-diamond.html
http://www.diyaudio.com/forums/soli...-sliding-bias-amps-out-there.html#post2326257
http://www.diyaudio.com/forums/soli...g-schemes-bipolar-transistor-circlotrons.html

Out = GND
Hafner/QSC
http://www.diyaudio.com/forums/solid-state/169988-qsc-topology-but-without-opamp.html

Preamp, Equalizer
Make A Good Pre-amplifier???
http://www.diyaudio.com/forums/showthread.php?s=&threadid=91049
http://www.diyaudio.com/forums/solid-state/153755-baxandall-tone-control-circuit.html

Voltage Regulator
Bipolar discrete shunt regulators
http://www.diyaudio.com/forums/showthread.php?threadid=114070
http://www.diyaudio.com/forums/solid-state/90728-bob-cordell-interview-power-supplies.html
Various
http://www.diyaudio.com/forums/solid-state/165130-curious-extra-knob-trans-amp.html
http://www.diyaudio.com/forums/soli...iency-class-audio-amplifier-aes-preprint.html
http://www.diyaudio.com/forums/solid-state/23526-best-mosfet-output-stages.html
http://www.diyaudio.com/forums/soli...e-current-dumping-circlotron-afterburner.html
http://www.diyaudio.com/forums/pass-labs/166784-pictures-your-diy-pass-amplifier.html
http://www.diyaudio.com/forums/solid-state/130175-old-transistor-data-2.html
http://www.diyaudio.com/forums/soli...opologies-100ma-idle-sound-closest-class.html
http://www.diyaudio.com/forums/solid-state/154493-your-opinion-about-schematics.html (Black devil Nytech couple capacitor to loudspeaker)
http://www.diyaudio.com/forums/solid-state/169282-help-diff-amp-current-balance.html
http://www.diyaudio.com/forums/pass-labs/153832-pass-delite-amp-baf.html
http://www.diyaudio.com/forums/solid-state/168694-could-ever-functionnal.html
http://www.diyaudio.com/forums/solid-state/150024-class-inherent-disadvantages.html
http://www.diyaudio.com/forums/solid-state/23526-best-mosfet-output-stages.html
John Curl's Blowtorch preamplifier part II 1.184.524
http://www.diyaudio.com/forums/showthread.php?t=146693
Crescendo Elektor 63
http://www.diyaudio.com/forums/showthread.php?t=148227
Ebay 15W class-a zero feedback modules? 241
http://www.diyaudio.com/forums/showthread.php?t=147979
First time solid amp 226
http://www.diyaudio.com/forums/solid-state/149025-first-time-solid-amp.html
Beast with a Thousand JFETs 13048
http://www.diyaudio.com/forums/showthread.php?t=150048
Class A push-pull 760
http://www.diyaudio.com/forums/showthread.php?t=148900
http://www.diyaudio.com/forums/solid-state/97551-igbt-amplifiers-5.html#post2317589
http://www.diyaudio.com/forums/solid-state/139924-luxman-l58a-2sk163-2sj44-4.html#post2327172
(Clausen's Millenium Amp "The End")
http://www.diyaudio.com/forums/solid-state/162310-how-identify-quasi-complementary-amplifier.html
http://www.diyaudio.com/forums/solid-state/175866-real-amp.html#post2342144 (what is the best Amp for big that torodial transformer)
http://www.diyaudio.com/forums/soli...do-millennium-offset-problem.html#post2322721
http://www.diyaudio.com/forums/pass-labs/160416-threshold-amps-dc-protected-2.html (post #13 universal DC protect methody)
http://www.diyaudio.com/forums/pass-labs/146310-bf862-preamp.html
VSOP-Amp
http://www.diyaudio.com/forums/showthread.php?s=&threadid=141606
 
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