Marantz 8B Questions

[Pio1980]

If I'm reading it right, 6.8 ohm, and the bias rectifier.
This model 8 amp doesn't fully conform with the schematic I have, apparently some running changes in the model 8.
I'll have to check it against some others.
The main striper caps I'd worry over are two in the output end if presebt, unless you plan to use the hi pass front end filter input as a DC blocker. The amp is better in "test" direct input.
I'd use the best metallized polypropylene caps to replace the others if I replace the Goodalls in mine.

 

[USMC Spike]

Hi Pio,

Yes, for the rectifier, I figured when I did this to make the minimal change, removed one
end from Selenium and add the Silicone diode.

That 6.8 ohm wasn't replaced at least by me.
If I recall, it goes to the pots. I'll have to check my
schematic.

My bad, it is a Model 8, it says so on the back. Later model 8 I presume.
Does anyone know if they had consecutive serial numbers for the
whole 8 line? That is 8 and 8B just kept getting incremental serial numbers?

 

[Pio1980]

Not sure if the numbers run consecutively thru the entire series thru the B.
Here's mine, #1217;

 

[Pio1980]

Checking a couple more 8B sn;
9764;


7687


5095

 

[Pio1980]

 

[Pio1980]

And this;
http://www.amkproducts.com/marantz_production.htm

 

[USMC Spike]

Oh, now you got me looking through my paperwork. I got my Marantz8 about 1995 or so.
A few things I forgot about, I found with my schematics...I'll post as I scan them.

 

[Pio1980]

According to the listing, the op 8B is close to the end of production, and I don't think the numbers for the 8B are consecutive from the 8.

 

[USMC Spike]

Pio, What was the OPs SN? I found a High Number listed, shown here:

This was serial number 20300 as listed on the back sticker F020300 if I recall.
I think the later 8Bs had the diode board on the front of the amp. What was that
supposed to do? Keep way word I/Es from messing with the pot settings?

 

[Pio1980]

Ink stamp # on the OP#s amp is 10392, I can't find an ink stamp # on the other amp.
The added board on the 8B carries the four 1.5 pF feedback caps added from the output section to the splitter grids.

 

[USMC Spike]

Check out the F020300 image that I just loaded up.
Also, what would we use for the 7.7mA current sources discussed in the
Audio Dimensions Upgrade Kit.

 

[Pio1980]

View attachment 1328571 View attachment 1328566 View attachment 1328571 View attachment 1328566 View attachment 1328566 View attachment 1328572 View attachment 1328573 Pio, What was the OPs SN? I found a High Number listed, shown here:

This was serial number 20300 as listed on the back sticker F020300 if I recall.
I think the later 8Bs had the diode board on the front of the amp. What was that
supposed to do? Keep way word I/Es from messing with the pot settings?

Adding production of both versions gives 20141 total, I can't explain 20300 from that.

 

[USMC Spike]

Pio, Unless Marantz had a FO for foreign office and they started at 20000, so this could have
been the 300 Marantz 8b for overseas production.

So I'm guessing we could upgrade this baby with some MUR860s, Polypro film caps,
some nice Paper in oil caps, a few hybrid caps, along with the Silver Mica caps.

I'm not sure I'd add the tant caps in there. if any, I would use the low leakage UKL
bi polar Nichicons. 50uf or more, 6v or more. Can do.

 

[Pio1980]

An active current source module may include a transistor, resistors, and perhaps a zener diode.
Probably an Audio Dimentions supplied item.

 

[USMC Spike]

Pio, Yes, that is what I was thinking too. This listing is their kit, they sell or install.
I also saw a few amps in various conditions where there were no serial numnbers.
That is always a red flag in my book. Have a good evening, thanks for the bandwidth.

And these aren't the mods I was thinking of either. I have the list of Paoli mods for
the Marantz8, 8b. I just can find it at the moment. This other stuff was filed in my binders
for easy access.

 

[Pio1980]

Pio, Unless Marantz had a FO for foreign office and they started at 20000, so this could have
been the 300 Marantz 8b for overseas production.

So I'm guessing we could upgrade this baby with some MUR860s, Polypro film caps,
some nice Paper in oil caps, a few hybrid caps, along with the Silver Mica caps.

I'm not sure I'd add the tant caps in there. if any, I would use the low leakage UKL
bi polar Nichicons. 50uf or more, 6v or more. Can do.

Could be. The PIO caps may give or preserve a vintage tube sound. A matter of taste I suppose.
I've never seen this mod, apparently before the prices shot up on the amps.
I admit I don't use mine as much as I should, perhaps I find aspects of vintage tube SQ too "vague" in some respects without the mods. I have been using a MOSFET amp instead that sounds like a great tube amp should in many respects. I hesitate to mod my 8 due to it's relative originality tho being refurbed.

 

[USMC Spike]

So now that were talking amps...What are the better PreAmp, PreAmp Tuner or receivers to be on the look out for.
My little girl is now five and I want to get a some thing nice for her room in the future. She can hear the difference
between the TV speakers, the tv enhances system of Carver PremapTuner and Yamaha 2202 Amp, with ADC Image shaper speakers.

Then to Daddys rig a marantz pre and 170DC wired into the Cornwalls.

A nice med powered received that I can restore for her that she'll have for
the rest of her life, I hope. That is my goal.


I hear you on modding these 8s. Unless we save the part and put it back together again.
and age the new connections That is why I only removed on wire form the rectifier and
spliced in the 1N4007 UF. Never had to change a resisor for the bias because it was
hitting it rigght in the middle of the Pot range! Also no issues with Balance either.
Last time I play it was 10 - 15 years ago, I should bring her up slowly, she'll be fine.

I would trade her for the Sansui AU-111. I grew up with an AU-111 and always loved it.
Then my sisters boyfriend and sis parted ways and his Sansui system went with him.
The memories of it remain.

 

[Pio1980]

Pio, Yes, that is what I was thinking too. This listing is their kit, they sell or install.
I also saw a few amps in various conditions where there were no serial numnbers.
That is always a red flag in my book. Have a good evening, thanks for the bandwidth.

And these aren't the mods I was thinking of either. I have the list of Paoli mods for
the Marantz8, 8b. I just can find it at the moment. This other stuff was filed in my binders
for easy access.

I'd like to see them.

 

[Pio1980]

So now that were talking amps...What are the better PreAmp, PreAmp Tuner or receivers to be on the look out for.
My little girl is now five and I want to get a some thing nice for her room in the future. She can hear the difference
between the TV speakers, the tv enhances system of Carver PremapTuner and Yamaha 2202 Amp, with ADC Image shaper speakers.

Then to Daddys rig a marantz pre and 170DC wired into the Cornwalls.

A nice med powered received that I can restore for her that she'll have for
the rest of her life, I hope. That is my goal.

You could get a gazillion recommendations starting a thread on that.
After lightning got my modest good sounding Technics AV receiver, I bought a more modern bpc looking Pioneer of similar class cheap that sounded unpleasantly harsh at first, but slowly settled into a remarkably nice listenable musically pleasing component. The point is that there are some decent otherwise undistinguished candidates out there.

 

[Pio1980]

Bedtime here, check in later.