Marantz 2325 experts please

[Echoplex]

The resistor under the board must be someones fix for not having the correct value.

Yes, I was afraid of that. It'll definitely be on the list for P800 updates.

Keep the 150 ohm ceramic up off the board for dissipating heat.
I suggest checking to see if any other resistors were replaced and to keep things accurate with the schematic.
R816 should be one 390K ohm 5% 1/4watt.

Ok, will do! Yes, will definitely be checking each resistor carefully.

Well....found something else on PE01 that needs replaced. RE11 resistor that sits right behind BA312 looks like it's been repaired from the top; right where the lead joint bend is, there's a dab of solder on it that looks like someone cut it, then repaired it. Strange...

Guess this is what I get for being curious huh? No good deed goes unpunished! What started out as a simple repair has now turned into a full blown overhaul!

The bypass caps on the filters could be fine as is, but i have read somewhere that placing them right where the power comes into the amp board is better.
Lots of mixed opinions on stuff like that, so sometimes you have to go by your own ears.

Makes sense, especially with all the power up/power down cycles..maybe at the front is better? Hmmm....Looks like I've got some reading and researching to do.
For now, they'll stay as is.

As far as films go, try to go polypropylene if you can find correct sizes that fit.

Yes, will be updating PE01 with lots of Wimas for sure! They seem to have quite the repuation here, and it has my attention.

Thanks much for all the helpful advice!

 

[Echoplex]

My P800 board didn't have that resistor underneath but I don't know what's been done to your board previously. Here's what I did to mine. I can also post a labeled photo of PE01 if you like?

Excellent! Love reference photos and diagrams....really speeds up the learning process!
Sure thing....keep'em coming! Thanks much

 

[wurlyman]

Here's my PE01 board as it is now. I will soon be replacing the BA312 op-amps (IC chips) with a new modification that I've just purchased.

 

[Echoplex]

Here's my PE01 board as it is now. I will soon be replacing the BA312 op-amps (IC chips) with a new modification that I've just purchased.

Yes, I've been checking these out as well.

Looks like it will be a nice upgrade; lower noise floor and flatter frequency response from the plots posted on Sparko Labs website. Definitely convenient...smaller module boards for essentially a drop-in replacement.

I’ll be interested to hear your review on the results. Please keep us posted.

 

[wurlyman]

Yes, I've been checking these out as well.

Looks like it will be a nice upgrade; lower noise floor and flatter frequency response from the plots posted on Sparko Labs website. Definitely convenient...smaller module boards for essentially a drop-in replacement.

I’ll be interested to hear your review on the results. Please keep us posted.

Yes, it is simple. Requires removing 8 resistors, 2 caps and replacing 4 caps and 1 resistor and of course the Op Amps. I'll post it after it's done.

 

[Echoplex]

Well, got my parts in for the P700 boards yesterday.

Time for R719/R720 to get some new resistors. Also, going to be replacing the zener diodes w/3W versions.

Was thinking that it might be a good idea to use ceramic tube insulators this time around because the heat shrink was pretty cooked on the originals. Or, is it even necessary since the new ones are rated higher?

Also, after swapping the new ones in, will I need to make any adjustments to P700 before powering up? Thx!

 

[wurlyman]

Well, got my parts in for the P700 boards yesterday.

Time for R719/R720 to get some new resistors. Also, going to be replacing the zener diodes w/3W versions.

Was thinking that it might be a good idea to use ceramic tube insulators this time around because the heat shrink was pretty cooked on the originals. Or, is it even necessary since the new ones are rated higher?

Also, after swapping the new ones in, will I need to make any adjustments to P700 before powering up? Thx!

Here's how I did mine. You might re-check bias as per service manual.

 

[Echoplex]

Will do. Thx!

 

[catrafter]

20V 3W zeners
1N5932BRLG
Thanks to Echoplex for mentioning these.

Tom

 

[wurlyman]

20V 3W zeners
1N5932BRLG
Thanks to Echoplex for mentioning these.

Tom

Tom, I didn't replace those. What is the purpose? it wasn't brought up when I was doing my rebuild.
Thanks,
Stu

 

[catrafter]

I am always learning and trying to 'up' my game.
I have only seen the original zeners fail under the conditions in this post. It is interesting that some Marantz documents reference H716 and H717 as BZ parts and others reference them as CZ, which has a higher power rating.

Tom

 

[Echoplex]

Progress! Got the new resistors and zeners put in on both amp modules tonight.
Thanks to Tom (catrafter) for the advice.

Pansonic Metal Oxide Resistors
1.2k Ohm 3W
Mouser Part # 667-ERG-3SJ122
P700 locations R719/R720

On-Semiconductor Zener Diodes
20V 3W
Mouser Part # 863-1N5932BRLG
P700 locations H716/H717

Check out the old resistors from R719 locations @ bottom of photo...pretty cooked!

 

[Leestereo]

I am always learning and trying to 'up' my game...

We're all in that boat, I think...

 

[Echoplex]

Made lots of progress over the weekend...

First, I got started rebuilding P800 by desoldering most of the old components, then cleaning up the board with acetone and cotton swabs. Next, installed all new Nichicon PW series electrolytics, On-Semi voltage regulators & rectifiers, and all new Ohmite carbon comp resistors. The resistor @R801 is a wirewound type from TT Electronics and was mounted up high off the board with heatshrink used on the leads. The metal oxides and ceramic resistors I left alone as they measured good. For the ON-SEMI voltage regulators, I used mica insulators (TO-220 types) and Dow Corning 340 heat sink compound. The diodes, polyester and ceramics were also left alone as they tested good.

Next, I got started on PE01 pre amp / tone board. Here, I used the following: Sparkos Labs BA312-M modules, Nichicon KT, Muse and PW series electrolytics & Wima films throughout. I did lots of research and found a variety of opinions and builds, and ended up using a combo of several to help inspire my own. One other thing that can’t be understated here...many of the components on PE01 required bending leads in what seemed like extreme ways in order for them to fit properly. At first, it kind of concerned me a little, but it came out great!

Regarding the BA312-M modules...
It's a nice, good quality module, and a worthwhile replacement for those who can't find an original BA312 to keep their Marantz units running.

My initial impression upon first listen was that it had an accentuated mid-range boost. I know frequency talk can get esoteric for some folks, but when I say mid-range boost...I mean vocals will be forward in the mix, with a slight glassy-sounding top end overall. The trade off compared to the original? Some of the more nuanced instrumentation like percussion, background vocals will either be slightly buried or brought more forward that will have a noticeable effect on the soundstage. But again, these are only initial impressions, so take them with a grain of salt.

I want to put my 2325 through it's paces and experiment more with the gain settings on my separate phono pre-amp before I put too harsh a tag on the BA312-M prematurely. It is brand new afterall, and I changed a bunch of caps at once, so more time is going to be needed to break things in and let the amp settle a bit more.

I have to thank several fine folks here for the tips, advice and suggestions: Leestereo, catrafter, wurlyman, KutzlerTrans, Steven Tate.

 

[Echoplex]

I didn’t encounter any problems making final adjustments per the SM for idle current 15mV, setting bias 0-3mV per right /left channels, and I got the power supply adjusted right @ 35V.

I forgot to mention earlier that at first listen, I had the gain on my Pro-Ject Tube Box DS set @ 50db fed into the Aux. Before the upgrades were done, that was the sweet spot, but I’m going to try 40db gain setting tonight when I get home and see how that sounds - which I suspect will be much better. Right now, with the new modules, the gain @ 50db is a little hot, and I can’t crank the amp past 12 o’clock without it sounding too harsh. I mean, it’s really loud!!! LOL

This has been a fun project to do and I enjoy experimenting around with different caps etc. It amazes me how an 80 cent cap can change the character of an amp pretty drastically.

At the end of the day, If I end up not being able to get the sound I want, then I’ll put everything back like it was. I may end up doing a few changes a little at a time, starting by putting those Panasonic films back in at the inputs on PE01 just to compare them to the Wimas etc.

Till then a little eye candy...

 

[wurlyman]

With my Volti/Klipsch KHorns I can't push the volume above 10 O'clock. 9 is my general setting.

 

[Echoplex]

That’s a pretty moderate volume for me Stu.

 

[wurlyman]

That’s a pretty moderate volume for me Stu.

KHorns are very efficient. You can run them with 10 watts.

 

[Echoplex]

Update...

I changed the phono preamp gain settings to 40db this time, and that made all the difference! Straight away I notice a few things... the mid frequencies are not as accentuated as before on the 50db setting.
Everything sounds nice and balanced, and all of the EQ settings are flat @ the 12 o'clock positions. I don't have to boost or take anything away... it's just perfect as-is. The bass frequencies have improved as well....much tighter, less boomy/muddy.

I gotta say, I'm impressed. The new BA312-M modules have improved the overall sound/frequency range. I've gained about 10db just by way of the module design, and the noise floor is considerably lower....backgrounds much quieter, less grainy sounding. This is awesome!

Don't just take my word for it, try them out for yourself and see what you think!

 

[wurlyman]

Can you explain how you change the gain settings please?