Just purchased a Marantz 7t

[rab32chevell]

OK! Since joing Audio Karma recenntly, I'v heard all the buzz about the 7t. It's strange, in all my years in Hi-Fi, I never heard a single person ever talk about the 7t. Personally, I'v owned about a dozen 7Cs, so I am familiar with much of the 7t. All but the sound of the transistor version. After thinking about it, it seemed to me that since Sid Smith designed it (I think), it just has to have tremendous potential since Sid was a master transformer designer which is why the power amps He designed are still fantistic today. The guy I bought it from off E-bay yesterday said it has a problem. He says when you turn the balance control all the way to the left, both channels turn off. Any ideas of what can be causing that? I know, from reading all the threads about the 7t, that replacing the caps may be necessay. It has a 12400 serial number so it may be one of the earlier ones. Jstang said he heard the earlier ones may sound different than the later ones. Has anyone looked into that aspect further? No matter what, the Marantz 7t just has to be the best buy in the world today in a pre-amp considering that for $500 today, all you get is a little box with a cheapo phono pre-amp in it. One of the reasons I wanted the 7t is because it has TWO main outputs and I run two Marantz 500s. One on each channel. Having an output for each channel/amp will make things much better. Any and all information you can share about the 7t will be much appreciated. Thanks for listening.

 

[jstang]

I now have a very early and very late 7t.....

I have not listen much to the late one....

12400 would be more towards the early side.

Post a pic of the insides.

Are the transistors black and round? If so, it has the early transistors....

Sounds like maybe a bad balance pot.... Almost every electrolytic caps in an early 7t will need replacement.

jk

 

[rab32chevell]

I now have a very early and very late 7t.....

I have not listen much to the late one....

12400 would be more towards the early side.

Post a pic of the insides.

Are the transistors black and round? If so, it has the early transistors....

Sounds like maybe a bad balance pot.... Almost every electrolytic caps in an early 7t will need replacement.

jk

I had a chance to look inside and it does have small round-black transistors. Also, it has the large black cap in the tone control with the yellow ring instead of the red lettering like the later ones I've seen. I was hoping the balance control may just need cleaning since the balance control is rarely used. One other thing I noticed is the board on the left next to the input jacks appears to have some sort of white residue at the top by the top transitor. It looks like a light coat of baby powder. I'm wondering if that is a sign of overheating. It comes off easily. Close examination reveals that the solder joint for that transistor appears to be cold. I'm wondering if that cold solder joint could be causing an excess resistance or maybe the joint looks like that due to a failed resistor. What I mean is, can a solder joint be damaged from heat due to failed parts? I know a cold joint is bad. Also, there is a very slight burnt order but I'm not really sure if it smells burnt or if is just a normal oder. I just talked to Steve Mantz at Zed Audio about his modifications but forgot to ask him what brand of caps he uses. I'm just guessing that the board on the left rear that has the white residue is the phono board. Has anyone built up the power supply? It looks surprisingly small for such a High end pre-amp. Steve Mantz suggests building up the power supply as part of his modifications. Anyone have any thoghts or suggestions?

 

[jstang]

Hmmmmm.... The 7t uses 7 watts of ac power including the pilot lamp.....so over heating does not seem likely. But something could have "out gassed".... That's an overly technical term for going puff....

Can you post a pic? Or pm it.....

The supply can be improved... His mods are nice.


Jk

 

[PB_Audio]

WOW, ... 'a dozen 7Cs'.
I love my refurbed 7T.
Nevertheless, I hope you kept at least one of your 7Cs.
The only Marantz I'd like to add to my collection one day is the 7C and either an 8B or a pair of Model 9 amps.
It will probably never happen.
I'm already suffering from 'too much audio-itis'.

 

[rab32chevell]

WOW, ... 'a dozen 7Cs'.
I love my refurbed 7T.
Nevertheless, I hope you kept at least one of your 7Cs.
The only Marantz I'd like to add to my collection one day is the 7C and either an 8B or a pair of Model 9 amps.
It will probably never happen.
I'm already suffering from 'too much audio-itis'.

Unfortunately, I no longer have a 7c. I do have a pair of Model 1s. During the 1970s, HI-FI really took off. In 1974, I thought I reached the pinacle with a McIntosh c28 and a 2100 with a pair of Ohm fs. Someone said I should have gotten a C22 and a 275 which I actually got within about 2-3 months. I never came across another one of either of them again. But, I met these two guys who I was competing with for used equipment and we are friends to this day. They turned me on to Marantz tubes. The Marant tubes were honestly in another league from the Mac stuff. I boiught every 7c and 8b I coujld get my hands on. The going price was only $400 for both the 7c and the 8b. The Matantz tube power amps were the real prize. I would take an 8b or another 9 over anything made to this day. They just sound right. They are very open and airy with really good bass. Tip for you 8b owners out there. Put your connectors on the "test" output jacks. The normal jacks have a low frequecy filter below 20hz. Sid wanted the filter buy Saul didn't so they compromised by putting both outputs jacks. Sid Smith"s designs were so stable that they didn't need the filter. We took our 7cs to a guy in Detroit who could really make the 7c sing. He only charged $90 with a new set of Telefunken tubes. Them Marantz 7 series of pre-amps are just to beautifull. I just can't afford the tube 7c anymore. They aren't $400 anymore. I'd love to get this 7t to sound really good and I'm confident it can.

 

[PB_Audio]

No doubt about it, a properly restored 7T is hard to beat.
The only preamp that I prefer is the Mark Levinson ML-1.
I'm sure there are others; but I'm very satisfied with the 7T, ML-1, 3300 and the Soundcraftsmen PE-2217. Handy, if you need an equalizer in a room with acoustics issues.
PS - I still have both the MC-2100 and C-28. I'm not really a fan of either.
I did like the MR-74 tuner; but replaced it with a Marantz Model 20 and eventually a 20B.
The MC-2205, though, makes a suitable back-up for the Model 500.
No doubt, Mac makes a fine product ... it's just not up to the performance of Marantz.
The Marantz 7C and 7T are superior to any MAC Preamp ...easily.

 

[rab32chevell]

No doubt about it, a properly restored 7T is hard to beat.
The only preamp that I prefer is the Mark Levinson ML-1.
I'm sure there are others; but I'm very satisfied with the 7T, ML-1, 3300 and the Soundcraftsmen PE-2217. Handy, if you need an equalizer in a room with acoustics issues.
PS - I still have both the MC-2100 and C-28. I'm not really a fan of either.
I did like the MR-74 tuner; but replaced it with a Marantz Model 20 and eventually a 20B. The MC-2205, though, makes a suitable back-up for the Model 500.
No doubt, Mac makes a fine product ... it's just not up to the performance of Marantz.
The Marantz 7C and 7T are superior to any MAC Preamp ...easily.

I think we have a lot in common. In my opinion, the c28 is the most beautiful pre-amps ever. They still had the solid silver knobs rather than the later black center knobs. The c28 and 2100 were great with my ohm Fs back then. I was hopping the 7t would better the Levinson since that is my solid state reference. Is there anywhere the 7t betters the ML1? The Levinsons didn't have much dimensionaity which was their main shortcoming. It's still hard to match their definition, even today. In any event, the 7t is so versatile that I had to have one, especially since the are not expensive, yet!

 

[jstang]

Well if you had the 7t properly refurbed... maybe it would de-thrown the ML....

No doubt about it, a properly restored 7T is hard to beat.
The only preamp that I prefer is the Mark Levinson ML-1.
I'm sure there are others; but I'm very satisfied with the 7T, ML-1, 3300 and the Soundcraftsmen PE-2217. Handy, if you need an equalizer in a room with acoustics issues.
PS - I still have both the MC-2100 and C-28. I'm not really a fan of either.
I did like the MR-74 tuner; but replaced it with a Marantz Model 20 and eventually a 20B.
The MC-2205, though, makes a suitable back-up for the Model 500.
No doubt, Mac makes a fine product ... it's just not up to the performance of Marantz.
The Marantz 7C and 7T are superior to any MAC Preamp ...easily.

 

[PB_Audio]

I think we have a lot in common. In my opinion, the c28 is the most beautiful pre-amps ever. They still had the solid silver knobs rather than the later black center knobs. The c28 and 2100 were great with my ohm Fs back then. I was hopping the 7t would better the Levinson since that is my solid state reference. Is there anywhere the 7t betters the ML1? The Levinsons didn't have much dimensionaity which was their main shortcoming. It's still hard to match their definition, even today. In any event, the 7t is so versatile that I had to have one, especially since the are not expensive, yet!

Trust me on this, any lack you found when listening to your ML-1 came from your other equipment, the acoustics, wiring or the source.
A properly refurbisned Marantz 7T, on the other hand, is very much on par with the ML-1.
Any differences you may experience will likely come from the synergy, or lack there of, among the other items in your system. They are both among the very best... ever.

 

[PB_Audio]

Well if you had the 7t properly refurbed... maybe it would de-thrown the ML....

Seriously... I'm going out on a limb here, and say it's too close to call.
Until I had my 7T souped-up (by virtue of a great restoration) I never would have imagined just how good they could be.
Both preamps just get out of the way of the sound. Then it's up to your Power Amp and speakers...
What more can be asked of a preamp?:yes:

 

[rab32chevell]

Seriously... I'm going out on a limb here, and say it's too close to call.
Until I had my 7T souped-up (by virtue of a great restoration) I never would have imagined just how good they could be.
Both preamps just get out of the way of the sound. Then it's up to your Power Amp and speakers...
What more can be asked of a preamp?:yes:

I can't wait to hear mine when it is done. It seems Jstang took his 7t further than what Steve Mantz did by his comment on the DIY review of Steve's modifications. I wish I knew electronics so I could modify mine the way Jstang and others do to their equipment. I haven't sent mine out yet but I did get the prices for the various updates.

 

[PB_Audio]

... attention to detail...

 

[jstang]

The T was said by Saul to be a work of genius by Syd.

The use of steel plates with Teflon insulated posts has a something to do with it. They create ground planes to prevent noise , cross talk, stray capacitance/inductance. And of course the stepped tone controls...

The manufacturing cost of doing this makes the choice very deliberate... Meaning they though hard and long about it before they placed the POs for the inventory. Besides the ground planes, they used the best components at that time, most( not all) are still world class.

There were cheaper techniques, but they used the steel plates and Teflon post...an exspensive design that I have never seen repeated in audio. In my opinion superior to pc boards for an audio preamp.

I personally think the performance numbers are much better than documented by test gear they had at the time...the test gear of that time was analog meter based. Being able to measure extreme low distortion levels was very very difficult back then. And spectrum analzsers were exotic pieces of test gear found only in the mil labs..today better test gear is found on eBay cheaply. The unit is insanely quiet, flat and wide.... It's power supply is a bit under designed for today's noisy AC. But a few mods and a good AC power conditioner takes care of that.

Perhaps newer transistors would be nice.... But I have a hard time removing the stockers after reading that sticker on the inside.

I would love to hot rod a C, but cannot bring myself to do it. The re-issue C might be a choice.

johnk

 

[rab32chevell]

Seriously... I'm going out on a limb here, and say it's too close to call.
Until I had my 7T souped-up (by virtue of a great restoration) I never would have imagined just how good they could be.
Both preamps just get out of the way of the sound. Then it's up to your Power Amp and speakers...
What more can be asked of a preamp?:yes:

If you don't mind me asking; who did your restoration and what did they do? I know different caps make a difference too. I don't know what brand of caps Steve Mantz will use. What kind do you guys have in yours? The fact is, I haven't fired up my system since about 1995 or 96. I just shut it off one day and never turned it back on, not realizing what damage I may be doing by not turning anything on for so long. I am now very afraid to turn anything on, especially my 500s. I don't know if it makes any difference or not, but neither of my 500s has ever had much use and the parts had never been stressed by high power use. About 3 months ago I told my wife that I must bring music back into my life so I have the fire back in me.

 

[jstang]

Silmic IIs with bypasses and lots and lots of other tweaks and mods.


Jk

 

[PB_Audio]

If you don't mind me asking; who did your restoration and what did they do? I know different caps make a difference too. I don't know what brand of caps Steve Mantz will use. What kind do you guys have in yours? The fact is, I haven't fired up my system since about 1995 or 96. I just shut it off one day and never turned it back on, not realizing what damage I may be doing by not turning anything on for so long. I am now very afraid to turn anything on, especially my 500s. I don't know if it makes any difference or not, but neither of my 500s has ever had much use and the parts had never been stressed by high power use. About 3 months ago I told my wife that I must bring music back into my life so I have the fire back in me.

Funny you should ask..."If you don't mind me asking; who did your restoration and what did they do?"
Check out the posts on either side of your question...
Yep... He's The MAN!
"What did he do?"
Everything. Naturally...

 

[jstang]

Are the 500s and 7t back in the groove?