Help w/ NAD 3020e

Hi all,

I'm going to preface my questions and potential stupidity by saying that I'm relatively new to Hi-Fi separates and therefore am fairly green in terms of technical issues. So apologies in advance and sincere thanks for any help.

I've recently picked up an NAD 3020e off eBay that's in lovely condition and was hoping to use it as a pre-amp for my Technics 1210 running into my Pioneer amp.

I'd (foolishly it seems) been under the impression that all 3020's had a separate pre-amp stage but it looks like I've got and bought the only one that removed that feature.

So my question is this: is there any way that I can use the 3020e as I intended without blowing the whole setup to hell?

It's been suggested that I could run the Tape Out from the NAD into the Line input of my Pioneer but I'm slightly concerned that the signal coming from the NAD won't have any of the warmth or tone that I bought it for. Would that be correct?

Any help would be greatly appreciated!!!
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
To use the preamp alone, the connection to an external outlet socket etc. must be after the preamp and before the main amplifier so that you retain the volume, tone, balance and muting controls. The tape connections simply re-route the input sockets to the tape- out sockets and you have no preamp or controls at all, when using them.

As you find, there are no external connector(s) for pre. out. on the 3020E as the schematic shows: nad 3020e 3220pe integrated amplifier schematic Download page :: Schematics Unlimited
What you can do as a DIYer, is locate the pre/main connections inside the amplifier and the points are clearly identified as A and B on the schematic and corresponding to R and L channel pre. out/main in. Then run shielded wire leads from here to a pair of new, insulated RCA sockets mounted on the rear panel. The shield wire must also be connected to the closest ground of the respective preamp/amplifier and the RCA socket ground tags.

Obviously, this means a bit of work in soldering a few minor parts and taking care with some small dia. shielded wire plus doing a bit of drilling with care to prevent a mess of metal particles everywhere. I also recommend a 1 - 4.7k resistor be wired in series with each A & B connecting lead to its socket, to limit any accidental damage that comes with unforseen (ab)use.
 

mightygrey

Member
2021-08-10 6:23 am
Hi there, do you mean these 'A' and 'B' points on the circuit diagram on the attached screenshot?

If so, I'll need to open up the hood next and try and identify where these are.

The reason I ask is that I have a NAD 3020e, and I'm keen to add some pre-outs to it.

Thanks!
 

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Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
That thread was abandoned more than 5 years ago, probably because the OP was looking for an easy answer way, rather than having to add connector sockets etc.
Points marked A&B are the inputs to the power amplifiers and these also connect to points X&Y at the outputs of the preamps. Those points are perhaps easiest to identify and access at the left and right side pins of the balance control.

Essentially, if you want to use the NAD as a control preamp, the output must be taken from those points located just before their power amps but after all the preamp controls, including the volume, tone, muting and balance controls. The input sockets may also have tape-out connectors grouped with them but these are at fixed line level, so they're unsuitable for a direct connection to an amplifier.
 
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mightygrey

Member
2021-08-10 6:23 am
I appreciate the prompt response (despite being an ancient thread!).

I'm comfortable soldering as well as panel-mounting some new RCA outputs, now I just need to figure out how to locate the points on the schematic under the hood visually.

Can you by any chance link me to a picture that shows where I ought to be connecting the new wiring to? I presume that I'll need to link L/R to the 'hot' terminals on the RCAs, and ground to a common ground point.

Cheers!
 
Following the preamp schematic it is not advisable to separate the preamp and the power section of the NAD. A balance pot is right at the output of the preamp, which means relatively high output impedance. And the tone control network sits right at the output of the preamp stages and is not buffered.
All in all: No to separation. Not a good idea, sorry. Leave the amp as it is and probably upgrade the aging capacitors, etc.
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
NAD 3020 preout.PNG
The NAD 3020B, for example, has much the same schematic and connections as the 3020A,i,E etc. but already incorporates "pre out" sockets with heavy wire bridges to the internal amplifiers as often described. Presumably, you just switch the speakers off or remove the connections to use the external power amplifier(s) alone. It's all a bit basic but that's the NAD way of doing things and it assumes a moderately high impedance input to the amplifier(s).
 
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Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
I should also have mentioned that the "pre out" and "main in" sockets are located adjacent to each other at a standard centre spacing of (I think) 3/4" or 19mm so that a "U" bent heavy gauge wire bridge could be inserted to each pair of out-in sockets on the rear connector panel. By heavy gauge, I mean the size of an RCA plug pin. Unless you have some workshop skills and a clean, short length of 3.2 mm galvanised wire, I think very short RCA leads may be the easier way to go.

If you look at the rear panel of most larger Japanese integrated amplifiers from the 70's - 80's, you'll find the same wire links fitted, though they were seldom used then, other than to facilitate testing or repairs. NAD originally incorporated as many features of the popular Japanese products as they could in their effort to break into the huge audio market but when few owners or reviewers ever claimed to use the feature, it seems NAD simply deleted it in later models.