KENWOOD L-07C or L-07C II ?

[Locomotive]

Hello everyone. I an having an issue with the L-07C I bought recently. Everything sounds great thru the AUX and TUNER inputs but after buying a Turntable (KENWOOD KD-12RB) and a bunch of records and moving a lot of heavy things around in the garage and hooking everything up with a severely injured back the LEFT CHANNEL INPUT terminal on PHONO 1 does not work at all. The turntable I bought works properly also through both channel output wires the L/H WHITE and R/H RED wires and I also tried both ground wire terminals separately.
My KENWOOD KX-79CW Cassette player sound output is much lower than the AUX and TUNER output sound levels also thru this KENWOOD L-07C PRE-AMP I bought.
I am going to look inside it for any problems and I would like your opinions on what to look for etc. I'm going to take the cover off in a little while to check things out and I will state my findings and maybe take some pics. I did read a lot of the AK pages about these Pre-Amps. I might get stuck with this L-07C so I would also like your opinions on if I should get another L-07C or the L-07C II Pre-Amp and why/what are the differences?
It sounded fantastic thru only the right channel because the Bass really came alive thru my Kenwood L-09M Amps and Kenwood MV-9D and MV-5D speakers which usually sound really bright using my Kenwood CD-324M CD Player or my Kenwood L-07T Tuner. Your help will be greatly appreciated. I can't wait to hear it with both channels working properly playing some of the
awesome old Rock records I scored on CL.

 

[Locomotive]

Left channel on phono 1 works for now

Well after looking it over for a long time (6:45 P.M. to 3:30 A.M.) with a bright light and taking many pictures I could not find anything wrong with it. The only discrepancy I found was someone opened it up at one time and put two button head sheet metal screws on the L/H & R/H lowermost rear fastener positions on the Grey colored outermost sheet metal upper cover where there should have been two tapered/countersunk head sheet metal screws installed. I found the two countersunk head sheet metal screws installed on the lower most Black sheet metal cover front L/H & R/H corner fastener locations where there should have been two button head sheet metal screws installed and just swapped the correct screws upon reinstallation of the sheet metal upper & lower covers.
I checked everything I could but I believe moving all the wires that were wrapped around the metal terminal posts a little bit and unplugging the PHONO 1 & PHONO 2 terminal plugs (picture provided) several times on the CB wiped clean a bit of corrosion that was probably causing the PHONO 1 L/H CHANNEL to not operate at all. I am going to clean and treat All the terminals and switches with the proper DEOXIT products as soon as I find where I put it. I did not think what I did would fix the issue with the PHONO 1 L/H CHANNEL when I put everything back together but I hooked everything back up for the heck of it & wow was I happy I tried it out! It was 3:00 A.M. so I couldn't really turn it up loud but it sounds goods and sounds like it is working properly so far.
The issue with the cassette player I believe seems to be the rotary TAPE DECK A & B switch contacts are dirty and possibly slightly corroded and hopefully will work properly again by cleaning and treating them with the proper DEOXIT products also.
I still would like to know the differences between the KENWOOD L-07C & the L-07C II PRE-AMPS & your opinions on both. I read somewhere that the L-07C II was way better than the L-07C but he did not explain why parts wise/what electrical components are better but said it sounded better and had better BASS than the L-07C PRE-AMP. What say you fellow AKer's?

 

[sixthday]

Differences of 07C and 07CII

http://www.audiokarma.org/forums/showthread.php?t=576181

 

[MudSlideSlim]

Well I have both but they are out of rotation now. The 07C have a ventilation grill ( or a dust entry grill) on its top and its lighter gun metal gray make it look like something that was pulled out of a USN battleship. I like both but the 07C does have a funky look but hey I love funk. If I were to move to Funky Town this would be the Preamp to take. Both have no Opamps in them which, I've read, makes them easier to repair.

The 07CII is an almost black gun metal color and completely sealed. The finish has a slight satin finish as opposed to the 07's very flat finish. My 07CII is in much better shape and had light use then my well used and much older looking 07 so of course it sounds a lot better. I can say that the 07C's are better in sound and construction that any of my Yamaha preamps I've owned.

The 07II certainly looks better and I like the fact its sealed. They both surprise, surprise work well with the 07M amps which are very underrated and well worth owning. EchoWars is the Kenwood expert here and I would follow his advise. Some day I hope to send my L07 collection to him for an overhaul.

 

[Locomotive]

Dirty switch contacts etc.

Thank you MudSlideSlim and sixthday very much. I'm worried about the dust in my Garage also.
I found all my Deoxit products but have not used them yet but after listening for a while at HIGH VOLTAGE/DECIBLE levels with the Turntable and Cassette player I really need to clean all the switches and knobs ASAP.
I heard some loud humming noise at HIGH VOLTAGE levels so I remembered the Owners Manual stated to put a ground wire between the two L-09M Amps if you hear a humming noise so I did. When I turned everything back on the L/H CHANNEL was not working again. So I removed the ground wire and thought it might be an intermittent electrical L-09M input problem though I'm not sure yet until I open it up and look. I'm using some Monster Ultra 600 interconnect cables and on the L-09M Amp I'm using for the R/H CHANNEL the input connector feels more solid and sturdy when connecting that cable than the L-09M Amps input connector I'm using for the L/H CHANNEL. I removed and reinstalled the input cable a couple times and now the L/H CHANNEL works again. I noticed the cassette player on TAPE PLAY A was cutting in and out real bad on the L/H CHANNEL but got better as I turned the knob back and forth several times so it really needs to be cleaned good. I'm hoping the L/H channel problem goes away after a good cleaning with DEOXIT products on the TAPE player knob and the PHONO knobs. They are so dirty I'm worried I might damage something if I JAM OUT without cleaning everything first. I hope the L/H L-09M AMP input is ok also. I did not have any problems when playing CD's through the AUX CHANNEL or the TUNER inputs though for the first few weeks of ownership. Only when I tried the Turntable and cassette player for the first time recently did I realize there were issues when I used them. I'll keep Ya'll
posted but it's very low on the priority list right now. Thanks again and God Bless you and your Family.

 

[Locomotive]

KENWOOD L-07CII PRE-AMP factory options?

Hello everyone I just bought a KENWOOD L-07CII PRE-AMP on EBay today TUESDAY 08/04/2015 and it is described as he stated exactly word for word as
follows below-
"This is a KENWOOD L-07CII preamp. Sounds great and works great. The tone controls make noise when turned. I have had this preamp for some time and never noticed this because I never used the tone controls. The unit has a very good MC phono section. It is very high quality construction. Please examine the photos closely for physical shape. It is my opinion that it is in very good physical shape. This is the Japanese model. Upon checking the service manual and inside the unit I find that this preamp has been factory wired for 120 volt use. So it does not need a step up transformer. I have ran this preamp with a lot of different power amps including Kenwood L-05M's and L-09M's and it worked great with all of them".
I bought my L-09M AMP's from this same person so I have no reason to not believe him because they kick out some major HIGH VOLTAGE ROCK AND ROLL. So I ask you if this was an option? Could it be factory wired for 120 volts? Has anyone ever heard of this or was he taking a big risk of possibly destroying this PRE-AMP? Someone knowledgeable about this please chime in & let me know. I also bought a L-07C recently that the LEFT CHANNEL PHONO 1 INPUT DOES NOT WORK AT ALL. It did temporarily after I looked around inside and took pictures but now the LEFT CHANNEL PHONO 1 INPUT DOES NOT WORK at all anymore even though I did a very good cleaning of every connection, plug, switch, knob, wire post with twisted wire ETC. It did fix the low output of the TAPE PLAYER and the BASS and TREBLE controls. I found both the BASS and TREBLE shafts were not in far enough inside their prospective rotary potentiometers or gain control rotory switches. Not sure of the correct nomenclature right now without looking in the REPAIR MANUAL. But I am also wondering why they were sticking out approx. 1/4 inch when I cleaned them with DEOXIT 5 AND DEOXIT GOLD cleaners. Is there suppossed to be a small circlip or other type of fastener to keep them from coming out of thier places? It looks like someone in the past may have soldered some of the twisted wire posts onto a sliding switch in the past and possibly other terminal wire posts also. i will post some pics of the L-07CII I just bought and the inside of my L-07C PRE-AMP also so you can compare them to your PRE-AMP terminal posts and please let me know if they are different than yours/not stock OEM construction of the L-07C PRE-AMP. For some reason I cannot load more than 1 picture at a time. I am in the garage a good ways away from the wireless internet connection so that might be why. I will post more pictures some other
time in the house hooked up to the router with a hardline. I need to find out about this wired for 120 volts factory option or not deal for now though so please help me someone who might know. Thank you.

 

[Locomotive]

sellers reply

This is the sellers reply below-
" I have had other Japanese market electronics and their plug is round pin. The power cord had never been unsoldered . Checking the service manual the unit has the correct board and transformer for the North American market" .

 

[EchoWars]

If you can post the part number off the power transformer, I can see how that compares to the service manual...

 

[Locomotive]

It works better than the L-07C except the PHONO 1 when it was serviceable

Not necessary, but thank you anyway EchoWars. I posted my findings in my other thread called "Kenwood L-09M AMP special locking RCA input & Remote cord end connectors" a couple days ago and below for you right now.

I guess he was right about being wired for 120 VOLTS. I jammed out for 4 hours straight last night until the local 10pm curfew with the TRIO L-07CII PRE-AMP I just bought and all went well except for 1 thing. The PNONO 1 gives something like feedback using a microphone too close to amps at about 3/4 turn of the main volume knob. It's a humming noise that gets louder the more I turn the volume up past the 3/4 or approx. 3 O'clock position. I tried both grounding terminals separately and not connecting the ground wire at all from the KENWOOD KD-12RB Turntable to no avail. No big deal, but I do like it really loud most of the time and the volume level is satisfactory. The KENWOOD L-07C PRE-AMP did not do this though the short time the PHONO 1 LEFT CHANNEL INPUT was working through it. I did notice the TRIO L-07CII PRE-AMP sounded much better, clearer and louder than my KENWOOD L-07C PRE-AMP using all the inputs except the PHONO 1. The KENWOOD L-07C PRE-AMP PHONO 1 LEFT CHANNEL INPUT when it was working for the short time it was serviceable/working sounded louder and clearer with no feedback or humming noise than the TRIO L-07CII PRE-AMP PHONO 1. The BASS and TREBLE knobs on the L-07CII PRE-AMP are way more adjustable and really help dial in the best sound you want for each type of component and music medium you use to listen to. The BASS was AWESOME last night. I could feel the vibrations through my bones and through the bottled water container I was drinking out of. Those KENWOOD L-09M AMPS were barely even warm after jamming out at ear ringing HIGH VOLTAGE ROCK & ROLL levels for more than 4 hours straight! It sounds awesome also cranked up with the improved BASS and TREBLE adjustments! The KENWOOD L-09M AMPS, MV-9D, MV-5D speakers, and L-07CII PRE-AMP kick major ass here in my man cave/garage! They sound awesome cranked up no matter what medium of music I'm listening to; CD's, Albums, Tuner, or Cassettes! They are all KENWOOD old school components also.
Looking forward to trying out different components and speakers in the future, but for now this system kicks major ass! LOL!!! It's time to rock and party!!! :guitar: