7T & 3300 audition

[jstang]

Yours and mine have most of those mods outlined by MOER plus some others.....but most of the goals/intentions/benefits have been met....or exceeded.

The biggest most time consuming mod? Replacement of every resistor with 1% mil films has not been done... The time to do that correctly and cleanly would be days on the 7t. Plus Marantz had already used 1% metal films in some locations.

But a few correctly placed 30$ bulk foil resistors might really do wonders....:scratch2:

At some point I will post my thoughts of my C vs stock T vs modified T.

Jk

 

[ChrisMarantz]

I didn't know that there are different versions of the 7T based on the production age.

I guess that I'll have to pull mine down of the shelf this weekend and check it out. Maybe snap a few pictures while I'm at it.

 

[jstang]

Yes different.... I have a very early one # 10430 and very late # 18649. If I remember the serial numbers. One made in '66 and the other in '69.

The transistors are different.
Some of the caps.
Slight difference in the internal shielding.
More Wiring insulation on the later.
The finish on the face.

And slight differences in the schematics by serial number.

I have not done a long term listen to the newer one. Just dioxit it and made sure it played correctly on the test bench.

I now have 7c too. So some day there will be comparison of my three 7s. The very late stock C, the very late stock T and my modified very early T. As far as solid state Marantz and otther brands, the 7t is by far my favorite, especially when appropriately modded.

Maybe we can get pb-audio to do a side by side of his Mark Levinson and his modded 7T.

I doubt very much I will ever modify a C, other then pure stock repairs. But a studying of the C indicates a few areas that can be improved.... But why?

Jk

 

[PB_Audio]

Yes different.... I have a very early one # 10430 and very late # 18649. If I remember the serial numbers. One made in '66 and the other in '69.

The transistors are different.
Some of the caps.
Slight difference in the internal shielding.
More Wiring insulation on the later.
The finish on the face.

And slight differences in the schematics by serial number.

I have not done a long term listen to the newer one. Just dioxit it and made sure it played correctly on the test bench.

I now have 7c too. So some day there will be comparison of my three 7s. The very late stock C, the very late stock T and my modified very early T. As far as solid state Marantz and otther brands, the 7t is by far my favorite, especially when appropriately modded.

Maybe we can get pb-audio to do a side by side of his Mark Levinson and his modded 7T.

I doubt very much I will ever modify a C, other then pure stock repairs. But a studying of the C indicates a few areas that can be improved.... But why?

Jk

Indeed, the 7C, being a tube preamp of the highest sonic quality will be virtually impossible to surpass in the mid-range with a solid state preamp. It absolutely excels in the reproduction of vocals and most band or orchestrial instruments.
Those of us who are getting up in years will likely not miss the higher order harmonic info lost in the higher frequencies.
On the other hand, for those who have a power amp and speakers capable of 'High Fidelity' in the lower frequencies, the 7T will be the champ vs the 7C.

Regarding the Mark Levinson ML-1... with its outboard power supply, it is the quieter unit, no doubt. The detail, accuracy and sound stage are to die for.
The real test is musicality. Again the Levinson excels. Finally, the phono pre was the reason the Levinson was produced in the first place. At the time it was unsurpassed. But, then... that was decades ago.
Regarding the 'Modern High-end'...
I've lost interest.
To fairly compair the modded Marantz 7T to the Mark Levinson ML-1 Preamp would require the very best DAC and CD transport OR pulling a turntable out of mothballs and buying a new, SOTA phono cartridge.
I haven't had a turntable set up for over 20 years, since I last moved.
That will have to wait until I retire in another 10 years.
I'm now more interested in my tuners, being lucky enough to have a good FM station 'locally'.

 

[jstang]

Let's prove it... Bring it with you the next time.....

We can compare the 7c, stock 7t, modded 7t and the ML1.

Promise I wouldn't mod it.....at least without you watching....

Regarding the Mark Levinson ML-1... with its outboard power supply, it is the quieter unit, no doubt. The detail, accuracy and sound stage are to die for.
The real test is musicality. Again the Levinson excels. Finally, the phono pre was the reason the Levinson was produced in the first place. At the time it was unsurpassed. But, then... that was decades ago.
Regarding the 'Modern High-end'...
I've lost interest.
To fairly compair the modded Marantz 7T to the Mark Levinson ML-1 Preamp would require the very best DAC and CD transport OR pulling a turntable out of mothballs and buying a new, SOTA phono cartridge.
I haven't had a turntable set up for over 20 years, since I last moved.
That will have to wait until I retire in another 10 years.
I'm now more interested in my tuners, being lucky enough to have a good FM station 'locally'.

 

[PB_Audio]

Deal!
I'd love to hear the Mark Levinson ML-1 vs the Marantz 7T vs the Marantz 7C with the Ohm F speakers and the SOTA DAC and transport.
Maybe we can spin some vinyl too.
I'm not currently using the ML-1... so, you may as well play it for awhile.
Oh, and mod away... The ML-1 is getting old and may very well benefit from some TLC.
I'd be interested in hearing your evaluation of the design.
Gee, I wonder if there's any Panasonic caps in the ML-1???

LOL!

Meanwhile, the 7T is so good, that which one may emerge the winner hardly matters.
... diminishing returns...
In the end, the Marantz 7T for $750~$900 is clearly the better value vs the 7C for $3K~4K, or the Levinson ML-1 for $1500~2000.
Then again, a carefully restored and modded Marantz 3300 for $400~$500... PLUS the cost of the RESTORATION, certainly represents good value, AND is a very good sounding preamp when properly restored.
Marantz always made a very good preamp. These three are the best.

 

[ChrisMarantz]

I tool my 7T off the shelf last night to give it a closer look. It's serial number 12681.

This afternoon I'll be pairing it up with my model 15 amplifier and a pair of Pioneer HPM100's.

I haven't used these in a long while and it will be interesting to see how they compare to the model 33 pre-amp and model 16b I have been listening to for the past nine months.

 

[jstang]

You have a relatively early model. Early transistors. You really should recap the unit. My early unit and another one I have seen really needed new caps. My late 7t from 1969 is all stock did not need any new caps, they tested fine. Not to say the new ones have better caps.

Also the newer ones have different transistors.

I can only tell you I love my early one that is recapped and modded. I have not really used the later one and that will remain stock, but does need further cleaning.

My current 7t has a huge 3d sound stage and wide flat response. The tone controls are at flat for bass and one click boost for treble. I could live with treble controls flat. The rest of system has a lot to do with that, but the 7t is only pre-amp that I have that I really like set that flat.

Ok love my 7t....enough said.

Jk

 

[ChrisMarantz]

You have a relatively early model. Early transistors. You really should recap the unit. My early unit and another one I have seen really needed new caps. My late 7t from 1969 is all stock did not need any new caps, they tested fine. Not to say the new ones have better caps.

Also the newer ones have different transistors.

I can only tell you I love my early one that is recapped and modded. I have not really used the later one and that will remain stock, but does need further cleaning.

My current 7t has a huge 3d sound stage and wide flat response. The tone controls are at flat for bass and one click boost for treble. I could live with treble controls flat. The rest of system has a lot to do with that, but the 7t is only pre-amp that I have that I really like set that flat.

Ok love my 7t....enough said.

Jk

I'm sure your right about the recap. I really haven't used it much since I bought it. I guess I'll have to add it to the queue for winter projects

 

[nelsress]

Great thread! I'm anxious to hear about the "shootout" between the 7C, 7T and ML-1. I recently purchased a 7T and was wondering if one of you could educate me as to what the two main outputs are for? I mean, I know they're to go to the amp but the wording on the back says "Use Either" or something to that effect yet there is no switch anywhere I noticed where one could connect two amps and use the 7T on both, which was what I was hoping to do.
My plan was to use the 7T with my vintage Marantz amps (32 and 15) and a 300B tube amp project I'm about to finish in the next couple weeks with the Marantz amps driving my ADS L-880's and the 300B driving either my A-25's or Rectilinear XII's, if they're efficient enough to use with that amp.
Originally the plan was to use the 300B amp with EV Aristocrats I spent a year or so getting together but the listening room is also the living room and not everyone loved the Aristo's, in fact one person hated the blonde finish completely so I guess they're moving on.
Anyway, any advice concerning any of this is always welcome, as is suggestions on how I can best improve my 7T either myself, or the best, most reasonable person to send it to. Thanks, I appreciate the always freely exchanged information/opinions here on AK.

 

[ChrisMarantz]

You will like the 7T with the Model 15 amplifier. Together they make a great pair and the sound is truly awesome.

I don't remember why the 7T has 2 sets of output connections, I'll have to look in the owners manual to see what the recommended use is.

 

[Brian]

A number of preamps had dual outputs in that period for use with remote or bi-amp systems. The 15 should be gone through if it has not been as when in production it could become unstable and self-destruct. If not gone through, the chances are it has even more of a chance to destruct. The 16 solved the problem pretty much and the 16b got it cured. Of the 3, I liked the 15 best though it was the smallest power wise. Next was the 16 and I never particularly loved the 16b. I'd not throw any of them out the door, though. The 7T in spec is my favorite Marantz SS preamp and they go so well together. Now you need a 20 or 20b tuner to complete the set and the SLT.

 

[nelsress]

Thanks Chris and Brian. In fact I planned to have the model 15 gone over. Actually it's a necessity as it's a project I got a month or so ago that someone had pilfered the transistors out of the one side. Not being able to pass up a "deal" and with the thought that if I didn't buy it that it would end up in a landfill, I paid $50 for it and lugged it home. Not having a stereo preamp in my basement shop I performed testing on it one channel at a time using my mono Fisher 50-C preamp and Fisher FM-80 tuner, which is when I discovered nothing on the right side leading to finding the transistors on that side missing.

That's when I hit the net to see if anyone offered overhauls of these. Are you guys familiar with John at Marantz Services Instrument Resources? The web search yielded his company name and a link to his website. I've been in communication with him and he seems very knowledgeable and straight forward as well as a very nice guy.

As for the 7T cap upgrades and mods-do you think they're good and would they be something I could do-I'm fairly good with a soldering iron.

And one more thing-I've heard that too many people just slosh up pots and switches with Deoxit and it's not always a good thing to do, particularly to some vintage high end equipment like the Marantz 7T. Do I need to have a professional clean and lube the switches and controls on my preamp or are there important steps to include/exclude while attempting this procedure? I noticed some noise/scratchiness last night while adjusting the volume.

Sorry for going on and on, I do that sometimes. Thanks guys.
Nelson

 

[Brian]

I can not help with your questions as I'm not a techie type. I've used Terry DeWickt, Echowars and, Warren Bendler for repairs and highly recommend them. I have no problem asking if the tech has done restoration of the 15 and 7T and ask for the person's contact information and followup with them to see how the experience went including communication, turnaround times, budget to actual cost variance and overall satisfaction.

Key to the units is ability to cross reference parts, especially in your case and depending on the why the parts were stripped, things like board repairs if needed. Many parts using manufacturers part numbers present a headache to techs without experience.

 

[nelsress]

Thanks Brian, perhaps I'll "knock" on Terry, Warren and Echowars door and see what they think. I appreciate the leads.

The guy I referenced was apparently a Marantz tech for many years and now does this as a hobby. He told me that it was good that I bought the 15 and that there wasn't anything inside it that couldn't be remedied. He said he'd replace all the transistors with modern matched sets with equal or better specs as well as go over the whole thing, sounded good to me! As for turnaround time he was talking 10 business days! Pretty quick!


John said he has more than one 7T in use and that he's worked on them, along with virtually every other Marantz piece produced. In fact it was after talking to him a couple times on the phone that I made the decision to seek out and purchase my 7T. He told me if there were any issues with the 7T when I got it that he's sure it wouldn't take much and that he could do it.

 

[ChrisMarantz]

That's when I hit the net to see if anyone offered overhauls of these. Are you guys familiar with John at Marantz Services Instrument Resources?

And one more thing-I've heard that too many people just slosh up pots and switches with Deoxit and it's not always a good thing to do, particularly to some vintage high end equipment like the Marantz 7T.
Nelson

I have gotten help from John in the past and I have found him to be knowledgeable and straight forward to deal with. He seems to have a lot of experience with the 2 digit models. His help solved a problem with a 16B that I was working on.

When I use Deoxit, I use as little as possible to clean the control. I don't demand that every switch be absolutely perfect with every use. I keep in mind that these are vintage controls and with some of them being 35-40 years they should be treated carefully.

 

[jstang]

John who?

Modified 7t vs stock 7c? I am staying with the moded T.......for now.

The c has The edge in midrange warmth & detailing.... But the modified T is wide, flat and very detailed through out the range. With ZERO noise at max volume.

Stock worn 7Ts would lose out to my stock 7c. My later 7t is very nice, it's caps tested fine. Order of my rating....

First the modified 7t ( caps and other mods )
Second the stock 7c ( only the caps tested and are fine ...pots cleaned and nothing more)
Third the very low use 7t ( caps tested fine...)
Fourth would be older stock 7Ts....most of which need caps.

With that said my 7c has only had the pots and switches cleaned. I need to pull all the tubes and test them and give the sockets a cleaning. I have ESR tested the caps. They seemed fine. It is a very late unit. So at some point I will get a chance to go through it and give it some more listening time... But it will never get modified.

The T is a great preamp that is over looked because in pure stock form they are usually worn....but very repairable.

Johnk

 

[jstang]

The 7t can directly drive a 600 ohm head phone load. So two amps at the same time is not an issue.

However, think twice about how those amps are grounded or if they are chassis tied to the AC load circuit. You can end up with a ground loop.

Jk

I recently purchased a 7T and was wondering if one of you could educate me as to what the two main outputs are for? I mean, I know they're to go to the amp but the wording on the back says "Use Either" or something to that effect yet there is no switch anywhere I noticed where one could connect two amps and use the 7T on both, which was what I was hoping to do.
.

 

[BeerLegs]

I have met John and he would be a good choice for a 15, 16 or 16B. (No offense to the others mentioned here, they seem like a pretty good choice too.) He also told me he worked for Marantz for many years and as mentioned before, seems to be very knowledgeable about the two digit Marantz's. He rebuilt my buddy's mint 16 and 7T and my buddy is just thrilled with them. I have a 1150, 3250B and a few other items that I'm going to have him restore soon. He normally deals mostly with the two digit models, but since I'm local, he made an exception.

 

[nelsress]

Thanks for all the input guys, you've reaffirmed my initial opinion/assessment and I'll be shipping my 15 to him this week. It's wrapped in two cardboard boxes flattened out to soften the corners and then a few inches of bubble wrap as of this afternoon. I think I'll send him my 7T to go over too, just to be sure it's ready for a long new life. Thanks again, I appreciate all the assitance.
Nels