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Kenwood L-08C Pre-amplifier Review (Vintage Audio, QuirkAudio restored)

AndreaT

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Cut it out. We had dbx with 110dB dynamic range, Dolby C came out before CD and gave us in the 70dB+ S/N. And open reel.

Preamplifiers are a shadow and I mean a shadow of their former selves. Not even close. Okto, Topping and Benchmark 'preamps' are just linestages with hardly any functionality. Where's the MM stage, the MC stage, the tone controls, the filters, the loudness contours, the multiple inputs, headphone stages and processor loops? Notably absent. They are a tiny sub facet of a real preamplifier.

I have plenty of real preamplifiers- you should try one yourself. And today (because it's pouring rain), just for fun, I'm measuring phono overloads because a bunch of people are interested. Guess what? The worst one so far is a 2015 product. The best one so far is a 1980 product!
And as far as the micro groove LP, great 1940’s source with important limitations:
1) The very variable quality of different pressings.
2) The progressive constant decrease in linear velocity as the stylus would get closer to the center: the first song was reproduced with the best quality, the last on the disc the worst.
3) Way too dependent on the dust in the environment and very difficult to clean the grooves from it
4) Very poor stereo separation between channels, at best 25 dB in the bass and mids, 15 dB in the treble
5) Noisy surface: the 0 signal parts were audible, very audible in the background noise the created from the friction of the diamond stylus over the vinyl.
6) The warps of the vinyl plate (a very, very common occurrence, often not qualifying for a free replacement. I still remember my disappointment when I bought the “Trilogy” LP by ELP and found that a rumble was added to the first song, clearly audible every 2 sec through the ppp of the signal at the beginning. The Empire 298 arm/ Shure V15-III was barely able to track. The quality control was poor and inconsistent.)

So, nope, I do not miss the LPs a bit, nor the MM or the MC inputs of the dinosaur preamplifiers.
 
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617

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Look at this EQ by Cello:
2021-03-1616.29_1800x1640.jpg


Look at how much control the top knobs offer on the signal path and gain staging. Then you have the eq knobs on the bottom which go from 15hz to 25khz.

Have a look at one of the stepped potentiometers:
ImagefromiOS_1274x1280.jpg

Are those..ball bearings?

The preamp is the center of the hifi. The job it has to do is not that technically amazing - it's just line level electronics after all, but it should be a nicely sized and nicely designed unit with really nice switches. It should have a killer MM/MC stage and some defeatable tone controls.

For me, in 2022, hifi is sort of an all or nothing affair. Either I'm streaming direct to powered speakers, or I want a beautiful way to connect a bunch of vintage sources to probably passive speakers.
 

MacCali

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How come they put on all units measured that TIM is unmeasurable? TIM and TID are the same thing?

What is that in regards too in English lol
 

Addicted to music

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Look at this EQ by Cello:
2021-03-1616.29_1800x1640.jpg


Look at how much control the top knobs offer on the signal path and gain staging. Then you have the eq knobs on the bottom which go from 15hz to 25khz.

Have a look at one of the stepped potentiometers:
ImagefromiOS_1274x1280.jpg

Are those..ball bearings?

The preamp is the center of the hifi. The job it has to do is not that technically amazing - it's just line level electronics after all, but it should be a nicely sized and nicely designed unit with really nice switches. It should have a killer MM/MC stage and some defeatable tone controls.

For me, in 2022, hifi is sort of an all or nothing affair. Either I'm streaming direct to powered speakers, or I want a beautiful way to connect a bunch of vintage sources to probably passive speakers.

Yes they are ball bearings, probably not critical in this application but I would use bearings with a seal that isolate it from dust. Today, I doubt if you can buy ball bearings without a cover! However I never tried! All ball bearings that I replace all comes with seals on both sides.
Thanks for sharing that image, 1st time I’ve seen a potentiometer implemented this way. Can you or anyone weigh in if they owned one care to comment on reliability. You can see from the picture where it was most used, it looks like spring leaf contacts too, stand correct if I’m wrong, the intent was good but I doubt it can do better than a normal pot with typical wafer. It looks like 2 contact points, the other is that inner circle trace!!! A normal pot with resistive wafer would use a single contact that is mechanically ganged for reliability, and some would have conductive grease implantations. Alps pots also transitioned into sealed plastic units to isolate it from the exposed environment for reliability, I hoped this is the case for these? Not only that this one also has different materials that the signal must pass through, and no grease to reduced wear. Just sharing my thoughts.
Elector Magazine in the 80s wrote an article on volume pots for studio consoles and identified how unreliable standard mechanical pots were, they published a conversion for volume control pots using contactless OPAMP controls that would support the replacement in certain studio control consoles. Today, I wouldn’t even be seen without using contactless volume control. One of the 1st point of degraded signal is via this contact. But that’s my findings and over sight over the years in this hobby.
 
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Addicted to music

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Back in the early 80s I was trying to purchase a Perraux amp, and went to a dealer that advertised it, only later to find out he no longer carried it. Being a "High-End" dealer, he had moved on to better SS amps. I should not have listened to him, because the amp he sold me twice needed substantial repairs over a 10 yr period. I still have the amp in storage (I paid $1300 back then). He also tried to convince me to buy a tube amp instead, but I didn't like the necessity of changing tubes; however, if I had listened to him at least I could have re-sold those mono amps and not lost too much money, whereas my ss amp (which was well reviewed by Absolute Sound) is basically ballast.

you wouldn’t have missed much, there Preamp was pure class A I believe and most of there power amps were Hitachi Mosfet implementation. I trialled them, the power amp were powerful for its time, the power supplies in them use to dim the lights when it was 1st switched on as they had no soft start and 20yrs later I see on the WWW that the power switch would fail On those units. The Preamp were extremely well made, i doubt if you see built quality like that for through the hole again.
 

Addicted to music

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And as far as the micro groove LP, great 1940’s source with important limitations:
1) The very variable quality of different pressings.
2) The progressive constant decrease in linear velocity as the stylus would get closer to the center: the first song was reproduced with the best quality, the last on the disc the worst.
3) Way too dependent on the dust in the environment and very difficult to clean the grooves from it
4) Very poor stereo separation between channels, at best 25 dB in the bass and mids, 15 dB in the treble
5) Noisy surface: the 0 signal parts were audible, very audible in the background noise the created from the friction of the diamond stylus over the vinyl.
6) The warps of the vinyl plate (a very, very common occurrence, often not qualifying for a free replacement. I still remember my disappointment when I bought the “Trilogy” LP by ELP and found that a rumble was added to the first song, clearly audible every 2 sec through the ppp of the signal at the beginning. The Empire 298 arm/ Shure V15-III was barely able to track. The quality control was poor and inconsistent.)

So, nope, I do not miss the LPs a bit, nor the MM or the MC inputs of the dinosaur preamplifiers.

Most “Vinyl lovers“ put up with all the points you mentioned! What’s worst is amplitude distortion that so audible that one owner I was having a GTG just dismissed! On the same track on digital, you doesn’t even get that audible distortion, no ”snap crackle pop” either. When you use headphones, all this becomes so annoying and really disrupts your listening pleasure. I remember the 1st time using a set of Stax Lambda Pros with CDs in the mid 80s, I never looked back!
 

anmpr1

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Can you or anyone weigh in if they owned one care to comment on reliability.
I can't speak from first hand knowledge about any of that. To me, its history is, however, interesting in its own right. I first came across what I presume to have been a Palette 'prototype' in Audio magazine. Might have been in one of the 'industry overview' blurbs. I'm not sure if it was a one-off, or an actual product. The device was designed by Richard Burwen-- a man who knows more about audio in his deep sleep than I'll ever know in my most lucid moments. Dick also direct marketed what he called a 'low noise preamplifier' advertising it in the back pages of Audio. I believe his circuits were used in the similarly named LNP-2.

LNP-2 was a full featured preamplifier--actually it had more features than any consumer preamp at the time, and was sold as a 'front end addition' to Mark's modified Studer A80 tape deck. Aczel owned one for a while, using it to play some second gen master tapes. I think Mark sold his own open reel 'master' dubs from recordings he had made, too.

As things go, Feature Fashion changed, less became more, and minimalism dictated an abandonment of LNP type of signal manipulation thinking-- all resulting in the ML-6x preamp. For more money than God had in his checkbook, Mark sold you a source selector and volume control (one phono/one aux line--wood sleeve optional), and you needed two (four chassis w/power supplies) for a stereo setup.

After Madrigal and Levinson divorced, Mark decided it was time to shake things up a bit. Working with Tom Colangelo, the two collaborated with Dick on what became the Audio Palette. I read somewhere (I hope I'm not making this up) that Burwen couldn't relate very well to the build detail (re: expense) of the final product, but that was always pretty much Mark's game. Whether he gave you the most or the least, he'd always charge the most.

The idea behind the Palette was that the user would install it next to his listening area, and then make adjustments for each individual recording as needed, keeping track of the settings in a notebook, and do that for each and every recording. It was the only way to be sure they were getting the sound they deserved.

Below was linked before, covering the 'marketing' angle pretty well:

https://audiophilereview.com/amps/the-cello-demo-and-why-it-worked-so-well/
 

anmpr1

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Seriously, this is a piece of beauty.
A dealer in my area featured the C1, plus Yamaha's matching FET amp (with meter bridge). The total package system included the Gale/Sao Win designed Lucite DD turntable, along with chrome Gale loudspeakers. They also had the Yamaha cassette deck shaped like a wedge. Really cool looking system. The price tag was one of, "If you have to ask..." I was able to afford the matching Yamaha headphones. LOL

image-asset.jpg
 

Ismapics

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Bear in mind, The Compact Disc was officially released for sale in October 1982 (Japan) and the L08c/L08m earliest brochure date I can see is July 1981, so we have an approximate 1 year difference. The L08c/m pair also does not appear in any general brochures until 1982. If you are in any doubt, check the date codes on the internal devices or caps that weren't replaced by your tech.

The L05/7 m/c were available in 1977.
Wow, reading your post made me look at my CD rack. I have CD's I purchased in 1983 and 85, still here and working perfectly. Police Zenyatta Mondatta, Dead or Alive Youthquake and Vision Quest. Still there.
 

rwortman

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Where's the MM stage, the MC stage, the tone controls, the filters, the loudness contours, the multiple inputs, headphone stages and processor loops?
My new Mcintosh C49 has 6 digital inputs, 3 unbalanced and 2 balanced analog inputs, MM and MC phono inputs with loading adjustable locally and by remote control, bass, treble, and balance controls, two sets of balanced and unbalanced outputs that can be switched on or off, a fixed output(record out), 3 trigger outs, 2 of which can be programmed to turn on or off with input selection, any input can be designated as home theatre passthrough and HT passthrough mode can be triggered by a 12v trigger input from the AVR. It also has was is purported to be a high quality headphone output. No processor loop or loudness contour though. A pretty full feature set for a modern preamp. Not inexpensive but those preamps from the old days weren’t either.
 
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nebunebu

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Look at this EQ by Cello:
2021-03-1616.29_1800x1640.jpg


Look at how much control the top knobs offer on the signal path and gain staging. Then you have the eq knobs on the bottom which go from 15hz to 25khz.

Have a look at one of the stepped potentiometers:
ImagefromiOS_1274x1280.jpg

Are those..ball bearings?

The preamp is the center of the hifi. The job it has to do is not that technically amazing - it's just line level electronics after all, but it should be a nicely sized and nicely designed unit with really nice switches. It should have a killer MM/MC stage and some defeatable tone controls.

For me, in 2022, hifi is sort of an all or nothing affair. Either I'm streaming direct to powered speakers, or I want a beautiful way to connect a bunch of vintage sources to probably passive speakers.
Stunning unit! - the dials reminds me of the high-quality vaults from the netflix series "Army of Thieves".

Come to think of it, I haven't seen any reviews of passive pre-amplifier where one just attenuate a signal?
 

restorer-john

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My new Mcintosh C49 has 6 digital inputs, 3 unbalanced and 2 balanced analog inputs, MM and MC phono inputs with loading adjustable locally and by remote control, bass, treble, and balance controls, two sets of balanced and unbalanced outputs that can be switched on or off, a fixed output(record out), 3 trigger outs, 2 of which can be programmed to turn on or off with input selection, any input can be designated as home theatre passthrough and HT passthrough mode can be triggered by a 12v trigger input from the AVR. It also has was it purported to be a high quality headphone output. No processor loop or loudness contour though. A pretty full feature set for a modern preamp. Not inexpensive but those preamps from the old days weren’t either.

Congratulations on buying a real preamplifier! :)
 

anmpr1

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Congratulations on buying a real preamplifier! :)
I'm sure the specs on the '49' are good, and it is flexible, however I am not happy with its user ergonomics. This is not exclusive to McIntosh, so I don't want to single them out-- so many products require the user to navigate through a menu tree via a rotary knob or push button. You see that everywhere, nowadays-- from in car dash functions to toaster ovens.

The 'old' preamps were much easier to use, because each function had a button accessible on the front panel. Of course it is no doubt cheaper to run everything through a CPU, but at the prices Mac charges, you'd think they'd be able to offer something more user friendly. Maybe discrete function selectors are not what their user base wants. Maybe they just do it because of cheapness.
 

DSJR

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6) The warps of the vinyl plate (a very, very common occurrence, often not qualifying for a free replacement. I still remember my disappointment when I bought the “Trilogy” LP by ELP and found that a rumble was added to the first song, clearly audible every 2 sec through the ppp of the signal at the beginning. The Empire 298 arm/ Shure V15-III was barely able to track. The quality control was poor and inconsistent.)

So, nope, I do not miss the LPs a bit, nor the MM or the MC inputs of the dinosaur preamplifiers.
Umm - There's bass drum beats at the beginning of Trilogy (The Endless Enigma). I'm sure you don't mean that though ;)
 

rwortman

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I'm sure the specs on the '49' are good, and it is flexible, however I am not happy with its user ergonomics. This is not exclusive to McIntosh, so I don't want to single them out-- so many products require the user to navigate through a menu tree via a rotary knob or push button. You see that everywhere, nowadays-- from in car dash functions to toaster ovens.

The 'old' preamps were much easier to use, because each function had a button accessible on the front panel. Of course it is no doubt cheaper to run everything through a CPU, but at the prices Mac charges, you'd think they'd be able to offer something more user friendly. Maybe discrete function selectors are not what their user base wants. Maybe they just do it because of cheapness.
I think it’s more to with operating the functions from a remote control. When you can adjust almost everything from your chair, rows of buttons and knobs on the front panel aren’t going to get used.
 

Herbert

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US release was March 1st 1983, six months after Japanese home market release. That was the deal Sony/Philips struck when Philips were dragging the chain.

Sony (and the consortium of manufacturers) more or less said "all the Japanese manufacturers are ready and you want to delay the release date because you cannot get your products finished in time??" "Screw you, we'll release in Japan and do a worldwide release when you get your act together next year, in six months." Philips had a lot of trouble getting their players to work, letalone be good enough to sell.
I have a Sony CDP-101 (the first besides the Hitachi-DA1000) bought new in 2014. The HiFi-Shop had it in stock with three other units since 31 years.
In the box was also a Compact Disc catalogue and a clared velvet cloth to clean the CDs. I bet my a.. if some audiophiles blind-tested it against
a modern DAC (without knowing the unit is now 40 years old) they would choose it over the competitor because of the flaws of the DAC.
 
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don'ttrustauthority

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dbx playback had quite a lot of audible artifact - gain pumping, swishing, etc. So did Dolby S and Dolby C. Dolby B is a little better in this regard. Open reel - well, for example a 4 track Revox A77 ( considered one of the best hifi reel to reel machines made, kind of a pro-sumer unit ) has a S/N ratio of 62 dB at 7½ ips. So, yes, 20 dB better than vinyl- but still 40 dB worse than good digital. And at 7½ ips it rolled off by 3 dB at 20 kHz and more like 6 db down at 20 Hz. So, nothing really to brag about. 15 ips is better, but no commercially pre-recorded tapes back then were done at 15 ips.

So sources back then were not really all that transparent.
Yes they were. Maybe it's possible to hear a tone in the tape hiss I missed in hindsight, but I guarantee you I didn't miss any of the music they intended me to hear.

The music recorded in those days was recorded to sound best in small transistor radios, so they pumped the bass and treble. Inaccurate equipment gets you closer to the "intent" of the music producer.

Don't they do the same thing today? Record music so it sounds best with non neutral playback? Pretty sure they do.
 

don'ttrustauthority

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DBX added horrible fake quality to music. Tone controls for treble and bass were often not defeatable and added more problems than they solved. MC and MM amplification was often noisy and the RIAA (or inverse RIAA) input FR commonly with 2-3 db of error. I am happy now and I was not so much until late 1990’s when they finally mastered CDs right and DACs began to perform well enough. There is nothing, xcept my youth, that I miss from those old days.
I had an original Technics 270 something dbx, it might have been the acid, but I could swear I heard it pumping the music. Freaked me the f out.
 
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