1983 NAD 2125 Amp / VS 3150

[Fomoco69]

Hello music Lovers….I have a chance to buy these two amplifiers in excellent condition for my sons vintage JBL speakers…which amplifiers would sound better?

 

[ski2xblack]

I'd be wary of 40+ year old amps. Have they been serviced? Any sort of guarantee of function by the seller? (You didn't mention if the seller is a commercial outfit or an individual--the electronics repair shop in my neck of the woods warrants the used kit they sell--but if you're buying "as-is" from some rando, you should pass.)

The amps themselves were innovative enough for their day. They were affordable, conservatively rated, and performed well. Under the hood, they sported a class G supply, which they exploited quite tirelessly for marketing purposes, touting their rather prodigious peak power via IHF headroom specs. The 3150 was rated 50 watts continuous, but with >6db dynamic headroom, or 200+ watts or so. They really could do that, too, and for far longer than just a few cycles. And they could drive low impedance loads.

That was the good. Now for the reality. At their age, they almost certainly need re-capping of the supply, definitely need re-biasing, and probably a whole host of other repairs and maintenance. Dated parts in need of replacement may be unobtanium. While serviceable, they are a real rat's nest in there, too. And the cost for all that makes the whole idea a poor value proposition in this cheapskates opinion.

If you must go vintage, your son would be better off with something a bit less vintage than those ancient NADs. Maybe a early 2000's Yamaha instead? Or just get new kit, depending on how he plans to use it (e.g. streaming as a source, or bt, etc). The JBLs are probably sensitive enough that Yamaha's least expensive two channel networking integrated would suffice. Just make sure it's one with that retro-cool (and genuinely useful) variable loudness control!

 

[TLS Guy]

I'd be wary of 40+ year old amps. Have they been serviced? Any sort of gurantee of function by the seller? (You didn't mention if the seller is a commercial outfit or an individual--the electronics repair shop in my neck of the woods warrants the used kit they sell--but if you're buying "as-is" from some rando, you should pass.)

The amps themselves were innovative enough for their day. They were affordable, conservatively rated, and performed well. Under the hood, they sported a class G supply, which they exploited quite tirelessly for marketing purposes, touting their rather prodigious peak power via IHF headroom specs. The 3150 was rated 50 watts continuous, but with >6db dynamic headroom, or 200+ watts or so. They really could do that, too, and for far longer than just a few cycles. And they could drive low impedance loads.

That was the good. Now for the reality. At their age, they almost certainly need re-capping of the supply, definitely need re-biasing, and probably a whole host of other repairs and maintenance. Dated parts in need of replacement may be unobtanium. While serviceable, they are a real rat's nest in there, too. And the cost for all that makes the whole idea a poor value proposition in this cheapskates opinion.

If you must go vintage, your son would be better off with something a bit less vintage than those ancient NADs. Maybe a early 2000's Yamaha instead? Or just get new kit, depending on how he plans to use it (e.g. streaming as a source, or bt, etc). The JBLs are probably sensitive enough that Yamaha's least expensive two channel networking integrated would suffice. Just make sure it's one with that retro-cool (and genuinely useful) variable loudness control!

In addition NAD stands for "Not Always Dependable". I have never liked their gear, and have worked on it in times past. In terms of build quality I rated them close to junk actually. I would absolutely never want to own one.
Why do you want to go vintage? As far as I am concerned if you want to go vintage there is only one brand to consider and that is Quad. Highly reliable and many sites offer service.

 

[lovinthehd]

I doubt they sound differently driven within their limitations. As I mentioned in your other thread, why change for lesser rated amps?

 

[Fomoco69]

I'd be wary of 40+ year old amps. Have they been serviced? Any sort of guarantee of function by the seller? (You didn't mention if the seller is a commercial outfit or an individual--the electronics repair shop in my neck of the woods warrants the used kit they sell--but if you're buying "as-is" from some rando, you should pass.)

The amps themselves were innovative enough for their day. They were affordable, conservatively rated, and performed well. Under the hood, they sported a class G supply, which they exploited quite tirelessly for marketing purposes, touting their rather prodigious peak power via IHF headroom specs. The 3150 was rated 50 watts continuous, but with >6db dynamic headroom, or 200+ watts or so. They really could do that, too, and for far longer than just a few cycles. And they could drive low impedance loads.

That was the good. Now for the reality. At their age, they almost certainly need re-capping of the supply, definitely need re-biasing, and probably a whole host of other repairs and maintenance. Dated parts in need of replacement may be unobtanium. While serviceable, they are a real rat's nest in there, too. And the cost for all that makes the whole idea a poor value proposition in this cheapskates opinion.

If you must go vintage, your son would be better off with something a bit less vintage than those ancient NADs. Maybe a early 2000's Yamaha instead? Or just get new kit, depending on how he plans to use it (e.g. streaming as a source, or bt, etc). The JBLs are probably sensitive enough that Yamaha's least expensive two channel networking integrated would suffice. Just make sure it's one with that retro-cool (and genuinely useful) variable loudness control!

Ok, thanks for your detailed response….I received the 3125 yesterday off E bay & its super clean inside & out…I opened it up & gave it a lite cote of Deoxit, let dry & it sounds very good for a 1984 Amp rated @ 25 WPC…it’s got good weight to it & is small, I like that….I will receive the 3150 next week… one owner original & super clean too….I can return them both if I want but will probably just keep one?…I was just curious how they compared to my 1984 Yamaha A700 & my Denon PMA757…which is a keeper

 

[ski2xblack]

Assuming they all work properly, and you're not pushing them into the red, I'd say it's a wash.

I don't know if the 3125 has the dual rail trickery of the 3150, I suspect it doesn't, it's probably the least powerful of the lot. So the 3150 may be the most powerful of the lot in spite of the conservative 50w rating, but the difference may be too marginal to matter in practice. They're all similarly linear, low distortion, and low output impedance, so they should be audibly indistinguishable. (Again, assuming they are in spec and fully functional.)

Beyond operational fitness, maybe one or the other has features that you like or would actually use. The 3150 is the only one with pre-outs/main amp inputs (got a sub? Split the outputs, send one to the sub and use a hpf on the other for the main amp inputs-voila, crude bass management in your retro rig).The Yamaha is the only one that has variable loudness eq, the others don't (I, personally, find that quite useful). I can't think of much else features-wise, they're all pretty standard issue integrated amps. And they may not be in comparable cosmetic condition at their age, so there's that, or maybe you're just a sucker for the utilitarian battleship grey aesthetics of the NADs.

Don't overthink this, or expect any sort of revelations. Pick the one(s) that work, and get back to the music.