Vintage amplifiers that could challenge or approach current state of the art amplifiers

[DSJR]

looks like the backside of a D-150 to me...

Here's the frontside.
Mine were dump finds (which I've certainly mentioned before). Predictably working fine as found.

I have two IC150's plus a wreck for parts, but after replacing the four signal tantalums as suggested by Crown, they're still remarkably transparent (only a chip a channel). Both getting crabby with age (switch-on-delay doesn't work on one and hf filter only works on one channel on t'other). That D-150 front panel with 'ears' looks nice though............

 

[Vintage. Dude]

There's also a M-90/C-90 pre/power pair sitting gathering dust over at my Dad's place. M-90 is a lovely amplifier.
(not my pic)

Yup i have pioneer elite c90/m90a combo and its great stuff, top of the Line. 125 db SNR its impressive even back then in the 80s. Today its remarkable result

 

[Sal1950]

I have a thing for FETs and MOSFETs, as you can see:
Adcom GFA-535
Adcom GFA-555

Those Adcoms are bipolars IIRC.
Nelson's redesign to the GFA-5300 and 5500 used MOSFET

 

[DavidMcRoy]

Those Adcoms are bipolars IIRC.
Nelson's redesign to the GFA-5300 and 5500 used MOSFET

Yeah, they are, and so are the Rowlands. I tend to have a preference for MOSFETs, though. I think I could pick them out in a double-blind test, but I've never tried it. And I seldom feel confident about doing well in a DBT.

 

[Doodski]

Yeah, they are, and so are the Rowlands. I tend to have a preference for MOSFETs, though. I think I could pick them out in a double-blind test, but I've never tried it. And I seldom feel confident about doing well in a DBT.

I've listened to and serviced a ton of MOSFET amps and I can't say I ever heard a difference but I can say they can sometimes be a major pain in the butt to service when they blow. To have them sound different would mean the transconductance(gm) curve/load line has not been configured for the best amp input to output linearity.

 

[DavidMcRoy]

I've listened to and serviced a ton of MOSFET amps and I can't say I ever heard a difference but I can say they can sometimes be a major pain in the butt to service when they blow. To have them sound different would mean the transconductance(gm) curve/load line has not been configured for the best amp input to output linearity.
View attachment 246016

The "real or imaginary" tell tail sound of MOSFETs to me is a pleasantly "airy, detailed" high end. Bipolars have a "hard" midrange for lack of a better descriptor, it seems to me. Again, it wouldn't surprise me if it turned out that I'm just dreaming. I'd actually like to be tested!

 

[Doodski]

The "real or imaginary" tell tail sound of MOSFETs to me is a pleasantly "airy, detailed" high end. Bipolars have a "hard" midrange for lack of a better descriptor, it seems to me. Again, it wouldn't surprise me if it turned out that I'm just dreaming. I'd actually like to be tested!

Well, there's a ton of peeps that say MOSFETs sound tube'ishy and MOSFETS have advantages over bipolar junction transistors so they may well be different/better. I have not blind tested them but I would love to see if there is something to this MOSFET urban rumor. I don't have access to a steady daily supply of gear anymore so I doubt I'll be blind testing MOSFET amps soon.

 

[Sal1950]

The "real or imaginary" tell tail sound of MOSFETs to me is a pleasantly "airy, detailed" high end. Bipolars have a "hard" midrange for lack of a better descriptor, it seems to me. Again, it wouldn't surprise me if it turned out that I'm just dreaming. I'd actually like to be tested!

For me that's an Audiophile Myth right up there with the sound of DSD vs PCM
I've got a bipolar Adcom GFA-545 II driving my L & R front channels and a MOSFET GFA-5400 driving my center channel.
OH the shame of it. LOL

 

[Ken Tajalli]

Well, there's a ton of peeps that say MOSFETs sound tube'ishy and MOSFETS have advantages over bipolar junction transistors so they may well be different/better. I have not blind tested them but I would love to see if there is something to this MOSFET urban rumor. I don't have access to a steady daily supply of gear anymore so I doubt I'll be blind testing MOSFET amps soon.

I think the urban myth originated from the fact that Mosfets operate similar to the way Tubes do.
But sound different? That's the myth part.

 

[SirPaulGerman]

I got a Yamamah MX-55, and the owner replaced all the caps, here are some measurements
@restorer-john
are those numbers any good ?

 

[Vear]

My Kenwood/Trio L-05M mono-blocks would get my second vote for this thread. I won't risk shipping my AU-X1 to @amirm but I would probably be willing to send him the L-05M's sometime later this year.

The L-05M are high speed/bandwidth and are basically the 100W versions of the L-07MII (which were 150W). The specs of the original L-07M were not as aggressive as the later L-05M or L-07MII.

I offered these up to Amir for testing a few weeks ago via PM. I haven't heard back from him so I'm waiting to see if there is any interest.

 

[Ken Tajalli]

I offered these up to Amir for testing a few weeks ago via PM. I haven't heard back from him so I'm waiting to see if there is any interest.

persevere ! he was renovating his house I believe.

 

[Sokho7]

SINAD comes through..

 

[SirPaulGerman]

Got very lucky, was able to get a Nec A-10II integrated amp for $200 in mint condition, I was doing some research and found a Japanese video about the amp

you can see the numbers, so it looks like a dual mono amp but is not ? I dont get the reserve power ?

@restorer-john
what do you think ?

 

[Scytales]

A very good Youtube channel, indeed !

 

[Videopac]

Yamaha MX-10000:

 

[DSJR]

The "real or imaginary" tell tail sound of MOSFETs to me is a pleasantly "airy, detailed" high end. Bipolars have a "hard" midrange for lack of a better descriptor, it seems to me. Again, it wouldn't surprise me if it turned out that I'm just dreaming. I'd actually like to be tested!

Late reply so apologies for drifting back a bit - My HH VX300 doesn't have much of a 'sound' really. The sub 20hz filter can make the low bass appear more 'clipped off' perhaps (I don't *think* it's imagined), the mids are as 'musical or not' as the recording allows and now the offsets are fixed and set (one channel had a open circuit bias resistor giving half a volt DC on the speaker outputs and the other channel had barely drifted at all from service sheet settings, but now they're the same), the highs are again more as the recording allows* - basic specs are printed on the top cover too so don't think the company hid anything for a pro user. The thing runs rather warm after a couple of hours in it's not too well ventilated cupboard and the D-150 perched on top barely feels as if it's been on after the same period, so for me a no brainer to use the latter mostly.

* Another vibe for how easily our minds can be fooled - I thought the HH amp a little 'crisper' sounding than the Crown. I suspect it was extra dissssstortion on the bad channel as now with both channels behaving and output terminal offsets at around 5mV as the service details suggest, it 'sounds' pretty nuch exactly the same as the Crown and just gets on with it as it should. I'm sure a domesticated version could be simplified in wiring looms and so on, but there's no hum using the single ended 1/4" TS input (there's a ground-lift switch on the back) or noise that I can hear. A shame the original Noble attenuators can't be got any more as this sample was heavily used in a TV company editing suite and the controls are getting 'crabby.'

 

[Videopac]

Kenwood Basic M2(a):

 

[pseudoid]

Those Adcoms are bipolars IIRC.

Adcoms are soooo 1980s
You have to learn to let go, @Sal1950 !
My bipolar Adcom GFA555 almost gave me separation anxiety when I finally sent it to another retirement home.

 

[Herbert]

What about the Nakamichi IA-3?
It replaced a Musical Fidelity B-1
in my setup after 15 years and remember to have tested some
2-Channel amps around 2005.
Ears deceive you but the IA-3(s)
sounds great but has some weaknesses: Weak transformer that
runs hotter than the trannies. Heavy crosstalk between inputs / channels cause lines are unshielded. Replaced both