Den store AKG-tråd

[kvik]

Til fri afbenyttelse om alt AKG-relateret, nyt og gammelt i skøn forening..





Tema-oversigter
Under udarbejdelse

AKG Electret ( K4 - K145 - K340 )
AKG K240 ( Sextett - DF - Monitor - Anniversary - Studio - MkII - Red )
AKG K250-290 ( K250 - K260 - K270S - K270P - K280 - K290 )
AKG K4/5xx ( K400 - K401 - K500 -K501 )
AKG K6/7xx ( K601 - K612 - K701 - Q701 - K702 - K712 )

[Ostebaronen]

Jeg har stadig mine AKG K140 liggende i en skuffe. Tager man alder i betragtning så lyder de altså ganske hæderligt og spiller bedre end mange nye hovedtelefoner. Jeg burde få smækket et mindre stift og tungt kabel på dem så de er mere brugbare. En ting der måske ikke er optimalt på denne model af de stive læder puder. Det kan godt gøre lidt ond efter et stykke tid at have dem på hovedet. Ligeledes bliver de presset sammen over tid og så er det ligepludselig plastik der trykker mod ørene.

[CHIbsen]

Stikord til det der måske engang kan blive til en sammenligning af K400, K401, K500, K501 og K701.

Nedenfor er de musikgenrer jeg bruger som pejling af hvilke model jeg vælger at lytte til:
K400: Blues, Country
K401: Blues, Country
K500: Jazz
K501: Klassisk
K601: Rock
K701: Heavy Rock
Det er en meget generel betragtning, og der er selvfølgelig overlap. Men jeg vil aldrig høre heavy på K500/K501.

Denne artikel fra Headphonia er efter min mening er god beskrivelse af K500/K501
https://www.headfonia.com/akg-k500-k501/
Jeg foretrækker K500/K501 med original puder.

K400/K401 minder mest om K500/K501. Med lidt mindre rumlig fornemmelse og en bas, der fylder lidt mere. Jeg synes K701 puder forbedre dem. Bassen kommer til at fylde lidt mere. K400 eller K401 er min favorit hvis jeg skulle vælge en model til alle musikgenrer.

K601 minder mest om K701, men er lidt mørkere i lyden.

Fra Head-fi: https://www.head-fi.org/articles/a-hope ... ana.12330/
"So the easy or hard to drive a pair of phones is, depends on both parameters, the sensitivity and the impedance. The worst case would be a pair of phones of very low sensitivity and also a very low impedance. Why? because they'll be asking to the source more watts to sound equally loud as a more sensitive pair, and an important part of that power will be asked in the form of current intensity, which is something that most portable players, headphone outs in receivers and players, etc. aren't designed to deliver. This is the case of cans like AKG 701 or Denon D5000."

Jeg har lyttet til en del klassisk med K501 og little dot mk V.
Bruger en Aune X7s med K500 og K601. Begge modificeret til balanceret XLR (den indkøbsansvarlige ved AGK har haft en sær form for humor i forbindelse med K500'erne, for der er to røde ledere i ledningen.).
Og Xcan V2 fungere rigtig godt med dem alle.

[CHIbsen]

Har købt et sæt af disse puder:
https://www.ebay.com/itm/251638845983

Det er fine puder, men vil ikke kalde dem en erstatning for K701 puder. De har formen fra K701, men de måler kun 27mm på den tykkeste del. En ægte K701 pude måler 32 mm -jævnfør min skydelære uden kalibreringscertifikat
I tykkelse minder de mere om K400/K401/K500/K501 puderne.

[CHIbsen]

Denne tråd kan måske også bruges til at spørge Mortenhoe hvilke effekt det have at recable K500? viewtopic.php?f=77&t=5329#p90400

[CHIbsen]

Og hvis der er nogen der kan beskrive forskellen på de forskellige K240 modeller, så læser jeg det meget gerne.

[Mortenhoe]

Denne tråd kan måske også bruges til at spørge Mortenhoe hvilke effekt det have at recable K500? viewtopic.php?f=77&t=5329#p90400

Det kan du snart spørge Kvik om, da jeg lige har foræret ham mine K500. Jeg har lige pakket dem, og de bliver nu sendt til Norge.

[Mortenhoe]

Og hvis der er nogen der kan beskrive forskellen på de forskellige K240 modeller, så læser jeg det meget gerne.

Jeg har kun hørt min Sextett af K240 modellerne. De har lidt AKG huslyden, men med en fantastisk bass.

K500 er til sammenligning meget neutrale. Forestiller mig at de er rigtig gode til klassisk musik. Dette lytter jeg dog aldrig til. - Netop derfor de kommer op til et nyt hjem.

[CHIbsen]

Denne tråd kan måske også bruges til at spørge Mortenhoe hvilke effekt det have at recable K500? viewtopic.php?f=77&t=5329#p90400

Det kan du snart spørge Kvik om, da jeg lige har foræret ham mine K500. Jeg har lige pakket dem, og de bliver nu sendt til Norge.

Dem kan han da ikke blive andet end glad for

Sendt fra min SM-G930F med Tapatalk

[Kolind]

AKG K340 - Jeg holder så meget af dem, at jeg har købt et backup-par
De har en særlig plads hos mig. Konstruktionen er lidt af et freakshow.. men det er vel lidt af charmen!

Det er vel grundlæggende en Sextet med en electret driver foran.

[kvik]

jeg sidder og pusler med en AKG-oversigt, som jeg senere tænkte kunne ligge i åbningsindlægget. Er lidt i tvivl om, hvilke oplysninger der kan være interessante/relevante i sådan en oversigt. Herunder et udkast, forslag og kommentarer hetil modtages gerne.

Kunne egentlig tænke mig også at samle lidt mere udfyldende om hver enkelt model, måske med citater fra diverse tråde/fora, måske med links til relevante tråde. Har ikke helt gjort op med mig selv, hvordan det skal gøres. Har blot siddet og googlet modeller, og der er så meget interessant baggrundsinformation, men spredt over indlæg og tråde.

[CHIbsen]

jeg sidder og pusler med en AKG-oversigt, som jeg senere tænkte kunne ligge i åbningsindlægget. Er lidt i tvivl om, hvilke oplysninger der kan være interessante/relevante i sådan en oversigt. Herunder et udkast, forslag og kommentarer hetil modtages gerne.

Det lyder som en rigtig god ide

Hvis du vil sikre dig at informationen der bliver linket til forbliver tilgængelig, skal den så ikke gemmes "lokalt". For eksempel så sad jeg og ledte efter en beskrivelse af de forskellige K240 modeller. Og den tråd, der linkes til i dette indlæg er væk: https://www.head-fi.org/threads/akg-k24 ... ns.475244/

Hvad med service dokumenter som det man finder nederst på denne side:
http://pro.akg.com/de/p/k401

Hvordan bliver de forskellige modeller kvalificeret til din liste? Hvad med K271, K301, K550/K551 og K1000?

[CHIbsen]

Her er et youtube link til en måde hvorpå man kan fikse elastikken til K400, K401, K500 og K501,
https://www.youtube.com/watch?v=3-HTpw8glHQ
Nogen der kender andre muligheder?

[Burgunder]

Solderdude har en del målinger af forskellige AKG hovedtelefoner her https://diyaudioheaven.wordpress.com/

[kvik]

@CHIbsen:

Jeg fulgte også et link til AKGs arkiv, hvor jeg endte på deres nuværende ‘glossy’ forside på engelsk. Troede de helt havde undsagt sin egen histiore, indtil jeg fulgte dit link til service-siden på tysk. Der er heldigvis lidt tilbage om de gamle modeller (http://pro.akg.com/de/produktarchiv).

Jeg har som sagt endnu ikke besluttet mig for, hvor grundig/gennemgribende oversigten skal være. Der er muligvis også visse copyright-hensyn ift specielt billeder: Ligesom jeg må finde ud af, hvor meget jeg skal lægge vægt på kildeangivelse.

AKG har jo lavet en hulens masse modeller gennem årene. Umiddelbart tænker jeg, at det er mest hensigtsmæssigt at fokuserer på de bedre/bedste/sjældne/specielle. Her kommer jeg sikkert til at læne mig op ad beksrivelser på nettet, når jeg skal udvælge.

Noget mere wiki-agtigt kunne også være en mulighed, men aner arbejdet hermed bliver for omfattende ift min personlige motivation.

Jeg prøver nok først at sidde og rode lidt med billeder og facts de næste uger, og ser så hvor det leder hen indholds- og formmæssigt.

[Mataugust]

Keith Jarret, med eller uden trio, lyder fabelagtigt på K701. Måske ikke helt korrekt, men vanvittig medrivende.


Sendt fra min LON-L29 med Tapatalk

[CHIbsen]

Keith Jarret, med eller uden trio, lyder fabelagtigt på K701. Måske ikke helt korrekt, men vanvittig medrivende.


Sendt fra min LON-L29 med Tapatalk

Det er uden tvivl det, der er det vigtigste for Mr. Jarret -at det er medrivende

Sendt fra min SM-G930F med Tapatalk

[CHIbsen]

AKG K340 - Jeg holder så meget af dem, at jeg har købt et backup-par
De har en særlig plads hos mig. Konstruktionen er lidt af et freakshow.. men det er vel lidt af charmen!

Det er vel grundlæggende en Sextet med en electret driver foran.

Minder deres konstruktion ikke en del om mine in2uit electrostatz?

Sendt fra min SM-G930F med Tapatalk

[CHIbsen]

AKG har jo lavet en hulens masse modeller gennem årene. Umiddelbart tænker jeg, at det er mest hensigtsmæssigt at fokuserer på de bedre/bedste/sjældne/specielle. Her kommer jeg sikkert til at læne mig op ad beksrivelser på nettet, når jeg skal udvælge.

Det lyder som en rigtig god ide.

Og enig i, at man let kan få problemer med copyright. Det bedste ville jo være hvis vi skrev det hele selv Tror du ikke vi i fællesskab kunne mønstre de fleste interessante modeller?
Man kunne eventuelt eventuelt afholde et AKG meet som kunne give input til din indledning.
Eller vi kan lave en tour med forskellige AKG modeller. Jeg sender gerne et par stykker af mine rundt, hvis det har interesse. Du kan da få mine K501 op til sammenligning med dine nyanskaffelse.
Jeg læser hellere 4 linjer fra jer, end 2 sider poleret tekst fra en pro. Jeg er blandt andet ved at se om jeg kan fremskaffe noget Keith Jarret musik. så jeg kan opleve de medrivende K701'er

[kvik]

AKG K240-familien:

Nedenstående er en sammenstilling af oplysniger fra HeadFi. Det bliver for rodet at indsætte kilder overalt, så jeg håber de betrufne HeadFi-medlemmer kan leve med ikke at blive krediteret direkte. Jeg overvejede at fordanske sammenstilingen, men i første omgang får det lov at stå på engelsk. Der bliver muligvis også tilføjet mere henad vejen. Specifikationer for de forskellige modeller findes i trådens første indlæg.


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AKG K240 Sextett

AKG K240 Sextett.jpg (73.44 KiB) Vist 24660 gange

The Sextett is the original version of the K240, first made in 1975. The name "Sextett" refers to the ring of six passive radiators. These are like little driver membranes without voice coil behind them. They give a very precise control over how the acoustic backwave returns to the listener's ear, crucial for spatial presentation and general frequency response.

This construction was used in a few other AKG models of the time as well, most notably the K340. Here only five radiators were used, however, as the sixth spot was occupied by what some refer to as the crossover.

The Sextett can be identified by the color of the metal rings on the earpieces (silver, not gold), by the large round perforations in the headband (also used to identify "Cardan" versions in general), and by the appearance of the inner side of the earpiece, where the passive radiators are visible behind a plastic grill, encircling the driver.

Construction-wise the K240 sextett appears in 4 different versions, based on 2 different drivers and 3 different radiators:
1. Early Production: Driver A, Radiator A
2. Early-Middle Production: Driver A, Radiator B
3. Late-Middle Production: Driver A, Radiator C
4. Late Production: Driver B, Radiator C

However, the 2 drivers are functionally and sonically identical, so sonic differences can be attributed to the baffle plate/passive radiator, leaving only 3 different versions sonically:
1. Early Production - Orange radiators with orange backing
2. Middle Production - White radiators with orange backing
3. Late Production - White radiators with grey or black backing, plus four pinholes in the baffle

Soundwise bass is said to be reduced when moving from EP to MP to LP, and lower midrange is reduced and treeble increased when moving from MP to LP. The four small holes in the LP baffle/radiator let some sound pass through, bypassing the radiators, which would likely account for the sound being slightly tilted away from the bass and towards the treble, and it is possible that the driver change was done to counter-balance some of the effects of the pinholes. So, within the context of K240 Sextett the EP version will be the 'warmer/bassier' one, and the LP version the 'cooler/airier' one, with the MP version somewhere in between.

Because of how much the parts are mixed, it can be difficult to tell the middle and late production versions apart. Some are obvious by using all early or all later parts, but most are mixed up. The earliest one is easy to tell, because it always has the headband with holes (and a better quality one too), the non-flat grille, orange radiators, more glossy plastic, "AKG" is written in silver inside a black box on the badge, and has a different kind of cord. Some of the middle production have these features, but not necessarily all of them together.

Eventually AKG released the K241, a more cost-effective model which used the same baffle as the late production Sextett, but with no passive diaphragm (and the two different densities of filter material front and back), but with what was called variable acoustic resistors (a principle patented by AKG). K240 Monitor then replaced K240, K241 was discontinued, and (in some markets) the Sextett was marketed for a while as K242. After a while the K240 Monitor went from six big patches to a larger number of smaller patches, closer to the driver.


AKG K240 Diffuse-Field

AKG K240 DF.jpg (115.04 KiB) Vist 24660 gange

The K240 DF was produced from early 1980s to mid 2000s, and as with most AKG models there are several versions:
1. The early ones with dual-entry cable and 1/4 plug (early to mid eighties)
2. The single-entry ones with big sound ports (aka K241 baffle)
3. The ones with smaller sound ports covered by paper-like patches
4. The ones with smaller sound ports covered by cloth-like (woven) patches

To identify the version at hand remove the foam insert/disc covering the driver (this is only attached loosly under the earpads). The earlier version will have 6 large baffle vents/sound ports (3 in white and the other 3 in black or light blue/grey).

The late production version came with a 1/8 plug + 1/4 adapter, instead of 1/4 plug only.

The earlier version is said to be a bit warmer sounding and with more emphasis on the mids, where the later production is more linear, detailed and has a larger soundstage. 
The diffuse-field equalization is intended to produce a flat frequency response, thus providing an uncolored sound, which is also how K240 DF seems to be perceived by most listeners. To some this sound signature wil be the right kind of neutral, to others it will be too lean/boring.

There are a number of mods to slightly alter the balance..

A. Pads: The stock pleather pads can be exchanged for velour ones to reduce bass. A thin inlay under the pads will increase bass (careful not to block the baffle vents).

B: Outer foam disc: Sits inside cup between driver and ear. Can be pulled out (and put in again) easily. Without it sound gains clarity.

C. Inner foam ring: Usually disintegrated due to ageing, removing the clutter/gunk might reduce bass/increase clarity. The original foam ring is still available, replacing the disintegrated one will be beneficial also. Basically the foam ring on the inside of a K240 is there to keep the frame parts from banging together. It's nice to have and prevents some mechanical noises.

D. Vent filtering: Check that filter material isn't torn. If paper-like material something like coffee filter paper can be used. If fabric-like material something like upholstery lining ("cambric") can be used.

E. Clamping force: Tighter fit means more bass. The construction doesn't as such cater for clamping force adjustment, though replacing the (often tired or missing) elastics will help in maintaining correct clamping.

F. Balanced cable: Running K240 DF balanced is claimed to musically transform them*. Requires re-wiring, make sure to mark positive and negative wires on both ends to prevent phase inversion.
* )"The phones are incredibly musical with extremely good transient response and micro-dynamics persevered with the macro-dynamics as well now. The bass presentation now is very articulate with the character of each instrument preserved and weighted great within the context of the musical piece. The whole midrange has more presence without the glare or artificial sibilance. The whole presentation opened up."


AKG K240 Monitor

AKG K240 Monitor.jpg (65.24 KiB) Vist 24660 gange

The K240 Monitor was introduced at the same time as the K240 DF, and was manufactured alongside the whole period (early 1980s to mid 2000s). According to AKG tech support the two are identical in the mids and highs.

The early monitors use the sextett baffles (so did the early DF's), then later models used woven fabric with more ports, and then later on a weird type of woven paper, and then just cheap paper ports (closer to what the studio uses on the newest ones), before akg fully discontinued them.

The K240 Monitors are hard-wired, and have 'gold' rings. The earlier monitors are balanced with a 4-core wiring and a silver 1/4'' jack (like the sextetts were), and later models are hard-wired with 3-core wiring (shared ground) and a gold 1/8" jack.

They are said to be fairly consistent sounding across versions, with perhaps the 50th Anniversary Editon to stand out slightly in a positve way (if nothing else then for the looks).


AKG K240 Anniversary Edition

AKG K240 Anniversary Edition.jpg (208.57 KiB) Vist 24660 gange

Manufactured in 1997 (only) for AKG's 50th anniversary. Sometimes refered to as K240 Jubilee, but mostly called K240 Anniversary Edition. This is basically the K240 Monitor with a bit of bling ("Anniversary Edition" insignia on left side, "50 AKG 1947-1957" markings on inside of earpads, Gold AKG lettering on top of leatherette).


AKG K240 Studio

AKG K240 Studio.jpg (97.78 KiB) Vist 24660 gange

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AKG K240 Mk II

AKG K240 MkII.jpg (111.82 KiB) Vist 24660 gange

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AKG K240 Red Edition

AKG K240 Red Edition.jpg (124.15 KiB) Vist 24660 gange

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Upshot

Historical upshot from the AKG-forum (unknown if AKG representative or regular forum member):

"The first K240 was introduced in 1975. From its design it looked similar to the K240 models we know from current production. Only the metal rings over the ear cups were of silver colored polished aluminum and the inner headband was perforated. Like in the recent version K240 Monitor a 32mm driver was used but it was surrounded by 6 passive radiators. Each radiator consisted of a membrane attached to a perforated disc covered with carefully selected acoustical friction material. Conventional circum-aural headphones often have a resonance peak in the upper bass region followed by a more or less significant bass roll off. The result: an unnaturally sounding boomy bass. The resonant frequency of the passive radiators in connection with the relatively high friction of the damping material behind these membranes effectively influences this irregularity in the frequency range.

In the region of the bass boost the membranes become transparent to sound waves and thus reduce the air pressure in the coupling cavity between capsule and ears. In that way the bass boost is leveled out. Below this boost-frequency the membranes block the sound waves and the roll-off is compensated. This acoustic principle was invented by Dr. Goerike, co-founder of AKG.

The first K240's had a four core cable and were available in two connector versions. One had the standard 6,3 mm stereo jack while the other carried a 5 pin connector according to the German DIN standard. This plug was known as Wuerfelstecker (Wuerfel = dice) because the 5 pins were arranged like the dots of a dice. The advantage was that the connector could be plugged into an amp or TV set in two directions. One caused the internal speaker to be turned off, while in a 180-degrees turned position both speaker and headphones were on. For this trick it was necessary to have all four terminals of the headphone drivers connected to the plug.

In France the K240 was named K242 for marketing reasons and during the first years of it's production.

Headphones with the same working principle as the K240 but with individual design were built by AKG for Philips (N6330), Saba (H200) and Uher (W774 and W775).

Although the first series of the K240 were a great success, there were certain discussions among the experts at AKG if the same effect as achieved by the passive radiators could be reached or even surpassed by a different design possibly less critical in production. This brought the introduction of the K241 where instead of the passive radiators only various sound ports covered by acoustically resistive material were used. The dynamic drivers were surrounded by apertures closed by carefully selected friction materials with various values of perviousness related to the acoustic impedances of the outer ear. The K241 was introduced in 1979.

Soon after the introduction of the K241 it's principle of the variable acoustic resistors – patented by AKG – was applied to the K240 as well and replaced the passive membranes.

In 1984 AKG introduced the K240DF, acoustically equalized to the diffuse sound field. The K240DF refers to such a sound field present in a reverberation chamber using third-octave filtered pink noise and measured in the close vicinity of the ear drum with a measuring probe. The work of the IRT - Institut für Rundfunktechnik (Institute for Broadcast Technology) in Munich proposed a standard for headphone-monitoring calling for the diffuse field equalization of monitoring headphones coming closest to loudspeaker monitoring, because there existed no current IEC or CCIR standard for such a system. Especially at times, when program material is exchanged between stations internationally and the monitoring facilities may vary it looks extremely sensible to exclude the varying acoustical parameters of the different monitoring rooms and refer to standardized headphone monitoring when comparing program material.

The K240 Monitor as made from 1984 to 2006 was based on the K240 without passive membranes but with the ear related resistive sound ports. It's earshells were decorated with gold colored metal parts and a three core cable with universal 6,3/3,5 mm (1/4" and 1/8") plug was attached.

In 1997 when AKG celebrated it's 50th anniversary the "K240 Jubilee" in limited edition was made. Acoustically a K240M, it had different nameplates and came with a booklet with a short history of AKG.

In 2002 the 'Studio' Series of headphones was launched. A newly developed capsule with low impedance makes these products especially suitable for portable equipment. The cable is easily detachable. The first series had a minijack connection while from 2003 on a miniXLR-connection between earshell and cable is used. In the same year the closed version of the K240 Studio called K 271 was released. "


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Service / Repair

Service manual for K240 Sextett/DF/Monitor/Studio and K241:




Spare parts for K240 Sextett/DF