The six-channel MET1

The PV-1 to now...
plurn
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Re: The six-channel MET1

Post by plurn »

scottm_dj wrote: ...
US fuse F1 should be 1/2amp...and is is 1/4. UK spec as I suspected

US fuse F2 should be 1/4 amp...and is is....very interestingly T500 so 500ma which is 1/2 amp. Uk spec is 1/8 amp. This could be an issue.
I would think the fuses for F1 and F2 were placed in the wrong order. If they were swapped with each other they would have the correct values for 120V operation.
scottm_dj wrote:None of the fuses appears blown but i bet F2 is the tube fuse and didnt have a low enough value in it. What do you all think?
Fuses don't work quite like that. If for the moment we assume that there is no fault with the equipment, if you put in a fuse with a higher current rating than specified, the equipment will work quite happily. The circuits only draw as much current as they need and it will be less than the fuse rating. So in a properly working device the fuse does not limit anything. The only issue in that case is if a fault occurs and the fuse has too high a rating, then your equipment is not appropriately protected and may draw too much current and cause further damage.

Now for the other case where you have a properly working device and you install a fuse that has too low a current rating, then the device may draw more current than the fuse can handle and the fuse will blow/break.

So after all that, it is more likely that the F1 fuse that is only rated at 1/4 has blown. As it is protecting a circuit that may draw up to 1/2 an amp.

If none of the fuses has blown, then it may be that you have a more serious issue.

I think you need to properly check the fuses to determine if they are blown or not. A visual check might not be sufficient. If you have a multimeter you could remove the fuses and do a continuity check on them. Or just replace F1 and F2 with new fuses of the correct value.

If they are not blown, and replacing the centre channel tube does not help, then you may need to get the MET1 checked by a technician.

My money is on the F1 fuse being blown.

Anthony
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Re: The six-channel MET1

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scottm_dj wrote:... Sounds fantastic for sure...or did. It was heaven for about 90 min until..boom..all sound ceased immediately. It now just plays about the same volume as a turntable cartridge level--no matter what the volume there is little to no amplification.
...
Just from rereading your old post, are we sure there is a fault? The fact that your are getting some sound makes me think you are hearing crosstalk from another input. CJ controls are quite finicky. My ET5 will occasionally pick up the remote signal from my other remotes and will change volume or change inputs or mute or go into EPL1 mode when I don't want it to. It is not always obvious what has happened and it can take a little while to figure out.

So is there any chance your input has changed, or the EPL or theatre mode has engaged? Looking at the picture you posted, EPL does not seem to be engaged. You seem the be using the second multichannel input MC2. Is that the intended one?

I know this is unlikely - just thought I would mention it just in case.

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Re: The six-channel MET1

Post by scottm_dj »

It most certainly looks to be a bad fuse now (even though appears OK), but even with schematic file i can't tell which fuse is for the tube control. I don't have a multimeter, but i swapped fuses and lo and behold then the unit wouldn't even turn on (cause I realized now the bad fuse would be in the "control" portion so no buttons). A promising find. Hopefully the bad one is the easier to find 1/2 amp version--Radio Shack may have that in-store...IF I can still find a store itself :)

I hope that's it cause it's tough to go back to the McCormack now after being spoiled by the CJ sound for a little while!

Does anyone know if F1 or F2 is for tube control?
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Re: The six-channel MET1

Post by scottm_dj »

UPDATE: I finally found the 2 replacement fuses...the 1/4 amp one was much more difficult to track down but i found it yesterday.

Soo...good news and bad news. The good news is that the tubes came back with the replaced fuses (see pic...we have glow again!). The bad news is i now have an extremely distorted rear left channel. At first i thought it was the CJ (maybe a tube)...then the speaker itself...but the acid test of switching speaker lines showed it was in fact the AMP. Yikes.

Sooo...whatever took out the original fuse in the CJ also appears to have hit the amp as well-even though it was doubly protected w conditioner and sine wave power. At least i think that would definitively show its the amp...brain frazzled from too much going on at once (incl some house issues). Ill do the "ultra" acid test today by running directly from my Oppo into the amp, which will show for sure.

Of course i would have multiple preamps but only ONE amp... Its only 5ch but i can always use the center channel and revert it to work as the rear im thinking... I should've left well enough alone i'm gonna no doubt hear from my friends, as the McCormack setup was working beautifully and I just had to tinker :)

Quite ironically i need to clear my floors for replacement hardwood in about 3 weeks...so probably will dismantle all and figure it all out when thats done...

In the meantime I'll keep my eyes out for the matching MET150 amp--i think even harder to find now than the MET1 preamp though...

One more thing: I took the plate cover off and checked out the tubes. What is the replacement procedure for the MET1 as there's not much room to work in that tight space. Do they pull right off with a little wiggling? Do you need cotton gloves to properly handle the replacement tubes? Jeffrey..any insight? :)
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Re: The six-channel MET1

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Wow...a double fuse failure...one for the MET1 and one for the amp. The amp was just badly distorting a channel but Steve McCormack himself said it's 90% one of the two fuses per channel that's causing it(he's got to be the nicest guy in the industry). Anyway, all is good now...save for an abnormally loud rushing noise coming from the center channel. Regardless of system volume level it stays the same--could that be a bad tube? Speaking of....what are the signs of a tube going bad either music or noise-wise in a channel? How do you know when to replace?

Thx all for your advice. So relieved that's all it was for both units as it could've been even a bad speaker itself distorting--i guess that's why the fuses are there!
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Re: The six-channel MET1

Post by jeffreybehr »

scottm_dj wrote:Wow...a double fuse failure...one for the MET1 and one for the amp. The amp was just badly distorting a channel but Steve McCormack himself said it's 90% one of the two fuses per channel that's causing it(he's got to be the nicest guy in the industry). Anyway, all is good now...save for an abnormally loud rushing noise coming from the center channel. Regardless of system volume level it stays the same--could that be a bad tube? Speaking of....what are the signs of a tube going bad either music or noise-wise in a channel? How do you know when to replace?

Thx all for your advice. So relieved that's all it was for both units as it could've been even a bad speaker itself distorting--i guess that's why the fuses are there!
Great news, Scott.

On the center-channel 'tube' noise, have you switched that tube to another position? Removing the layers of plexiglass 'shelves' with their stacks of spacers from around the tubes...
Image
...makes tube swapping MUCH easier. In this pic, one can see one of the M8080s in the front-three channels and two of the three other tubes. All wear extra c-j damping rings while the three front also wear Herbies' dampers.
http://herbiesaudiolab.net/preamp.htm

BTW, the MET150 also uses a pair of fuses on each channel's DC-rails, but for the extra grand or two one has to pay for an MET150, these are located on the back panel and not under the bottom cover.
Image
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Re: The six-channel MET1

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No swapping yet...funny you should that pic of the plexy completely stripped...i was a bit shocked to see the manual mentioning only to remove ONE layer. Then you can "barely" get to them--and its a pretty intricate procedure to extradite them straight up. I would think i could take all 3 covers off, make sure all the tubes are good (have 3 brand new ones from Watford i'll replace the front 3 channels with), then replace it once it's good to go with all tubes.

Question is...how do the middle shelves come off? There's a hex nut at the top...but what is needed for the 2 shelves?
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Re: The six-channel MET1

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scottm_dj wrote:No swapping yet...funny you should that pic of the plexy completely stripped...i was a bit shocked to see the manual mentioning only to remove ONE layer. Then you can "barely" get to them--and its a pretty intricate procedure to extradite them straight up. I would think i could take all 3 covers off, make sure all the tubes are good (have 3 brand new ones from Watford i'll replace the front 3 channels with), then replace it once it's good to go with all tubes.

Question is...how do the middle shelves come off? There's a hex nut at the top...but what is needed for the 2 shelves?
1. I removed all of the plexiglass plates (from my MET150 AND MET250, too) and left them off. Why would you put them back on? They don't do anything but collect dust.
2. Grab each spacer with thumb and finger and unscrew.
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Re: The six-channel MET1

Post by scottm_dj »

Ill do that...remove them and install the three new Mullards in L R C and then experiment with the originals to find the two best for the remaining rear channels. Sounds like that rushing noise in the Center just may be the tube...

I think those tube guards are to keep kids (and pets) away from their workings...but most homes (or rooms) a unit like this will be in that won't be an issue.

There's actually a MET 250 amp as well as a 150?

What about gloves for these smaller tubes..needed?

Thx for the advice!
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Re: The six-channel MET1

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[quote="scottm_dj"]Ill do that...remove them and install the three new Mullards in L R C and then experiment with the originals to find the two best for the remaining rear channels. Sounds like that rushing noise in the Center just may be the tube...

I think those tube guards are to keep kids (and pets) away from their workings...but most homes (or rooms) a unit like this will be in that won't be an issue.

There's actually a MET 250 amp as well as a 150? Yes; 250 Watts per channel into 8 and 400 per channel into 4 and with lots of those excellent-sounding Teflon-film caps. See http://conradjohnson.com/vintage-conrad ... -products/
Sounds excellent with my less-efficient speakers

What about gloves for these smaller tubes...needed? IMO, no; I use an OvGlove with output tubes but not Voltage-gain tubes.

Thx for the advice! You're very welcome.
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Re: The six-channel MET1

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Ah..the 250 is only 2ch...the MET150 is the only multichannel amp they have...

One more quick question regarding the unfamiliar phase inversion the CJ does. I reversed all my main speakers and it's definitely "correct" with them now...but my sub now sounds a little "off" in timing. Would that need to be set on a control for it as well to compensate? Would it be the 0-180 adjust control?
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Re: The six-channel MET1

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scottm_dj wrote: One more quick question regarding the unfamiliar phase inversion the CJ does. I reversed all my main speakers and it's definitely "correct" with them now...but my sub now sounds a little "off" in timing. Would that need to be set on a control for it as well to compensate? Would it be the 0-180 adjust control?
If you're driving the SW from the preamp, yes, it too need to be reversed.
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Re: The six-channel MET1

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The only question is...how to adjust the sub :) I don't have "high level" speaker connections...just the low level RCA input as typical HT...so obviously not "reversible". I think the "phase" control is just for whether the sub is in front or behind the listening position. My sub (attached) is the Innovative audio subtable (anyone remember that company?) along with their cabinet speakers. By far my best audio purchase ever--15 yrs old and still going strong--gorgeous looks and sound but less than accessible sub controls. I think I'll call the seemingly friendly folks at CJ tomorrow and ask a few questions--including that.
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Re: The six-channel MET1

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One 'reverses' the SW connection by turning the phase knob to '180' if it was on '0'.
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Re: The six-channel MET1

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scottm_dj wrote:The only question is...how to adjust the sub :) I don't have "high level" speaker connections...just the low level RCA input as typical HT...so obviously not "reversible". Think I'll call the seemingly friendly folks at CJ tomorrow and ask a few questions--including that.
Does your sub not have a phase inverter switch? It's usually labeled "phase" or "0 / 180"?
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Re: The six-channel MET1

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I edited post showing how i thought that switch was used...and why its not easy to get to :)

have to tip that 150lb monster on its side...and i think it's already at 180 cause it's behind me...
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Re: The six-channel MET1

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If the controls are underneath, maybe a mirror and a flashlight? Otherwise you probably will have to get somebody to help you tip it on its side a little,... you don't want to hurt yourself. My sub weights about 100 lbs and it was a 2 person job to get unpacked and placed in position.
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Re: The six-channel MET1

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I internally adjusted the output of the sub from my exa e28 DSD DAC control panel (highly recommended-will do a system summary pic soon) and it sounds much better now. DSD by its nature is full range with no system level tweaking "allowed". Speaking of DSD...want a disc to show off how lush the MET1 sounds? Track down by any means posible James Taylor Hourglass SACD--the whole disc has an amazing organic sound, especially the absolutely gorgeous Gaia. Midway through that multichannel track is an explosive drum crash out of nowhere that will test the mettle of any system! :)
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Re: The six-channel MET1

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Wow...the "sleeping giant" just awoke. No doubt didn't get much use over in its old UK home, I let it "burn in" a couple nights on low volume and all the sudden... Just wow. I've never heard such a rich, lush sound from recordings I'm extremely familiar with--I have sensitive ears for terrible, brittle sound (very bothersome) and this is so refreshingly non-fatiguing on them. The two standouts so far are of course...certain tracks on Beck Sea Change...but the big surprise is the SACD tracks of Doobie Brothers "Long Train Runnin' and Without You". The kick-drum intro on the former was like nothing i've heard before with this song. So THIS is what the tube sounds delivers :)

I think i'm done---I'll keep my McCormack amp cause i like to leave it on constantly for best warmed up sound, and I couldn't do that with the CJ amp version due to the tubes. Happy camper.
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Re: The six-channel MET1

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Quick question: Center channel definitely needs a new tube as it's getting more and more static-y now and launching with a metallic 'ting' sound. Now i know which location is which channel which is very helpful--but i have one more burning question...can tubes be changed with the unit in standby mode, or do you need to turn off system (unplug) completely and lose the config settings? I think someone said rail and plate voltage is OFF in standby (standby is not off fully though)...but is that enough to change out the tubes safely?

I definitely wanted to inquire before i start to meddle :)
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