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

[Doodski]

Those pictures are from someone else, I am working on a list for parts, the amp is from 1987, is working fine but is going to need a recap and is a best, super heavy

Oh yeah, I can tell from looking at the construction that it is a beast. The pre-amp is going to be hefty too. Really nice gear.

 

[SirPaulGerman]

I used to have a Sony TA-N330ES, it was a nice amp but restorer-john called a pretender, so I upgraded to the Yamaha set

 

[Doodski]

I used to have a Sony TA-N330ES, it was a nice amp but restorer-john called a pretender, so I upgraded to the Yamaha set

Hehe.. Just look at the difference in construction and layout. It uses a STK IC for a voltage amp section from the looks of it. The thin silver and black colored thing sticking out of the PCB at the left side of the pic.

 

[GXAlan]

Nice setup! The Marantz PM-90 is an example of vintage Japanese audio and I would expect the Yamaha to be even better.

I have sent a Amir a vintage solid state integrated amp from the 1960s to test. It was “restored” as much as possible instead of “resto modded” particularly in the use of some NOS transistors from the era and keeping the old potentiometers, etc. It will give us a nice baseline for what should be the absolute lowest performance would be and I expect it todo certain things as well as modern gear…

 

[Doodski]

@SirPaulGerman I looked at the B-2X amp's service manual and found no voltage specs for the power supply but I did find that the power supplies use 22,000 micro farad 80VDC capacitors. So... be careful when working on it because <~80VDC at high current will give you a very strong shock. I've endured this sort of shock before and I can tell you it's not pleasant and can break bones if not electrocute you. Imagine a person being defibrillated and that is ~what you can expect basically if you electrocute a major muscle. So make sure you discharge the power supplies before doing anything inside. No mistakes, be sure to discharge.

 

[Chrispy]

So tuning back in after a while, do we have an actual agreed-upon ranking of this supposed amp quality ranking? At least a speaker-limited version?

 

[DanielT]

Those pictures are from someone else, I am working on a list for parts, the amp is from 1987, is working fine but is going to need a recap and is a best, super heavy

If you want tips and advice, I suspect that there is an active ASR member, with a name suitable for the context, who can give it to you. See who posted the brochure on Hifiengin:

Yamaha B-2X Natural Sound Stereo Power Amplifier Manual | HiFi Engine

www.hifiengine.com

Edit:
By the way. Doodski also seems to be in tipping mode.

 

[Doodski]

If you want tips and advice, I suspect that there is an active ASR member, with a name suitable for the context, who can give it to you. See who posted the brochure on Hifiengin:

Yamaha B-2X Natural Sound Stereo Power Amplifier Manual | HiFi Engine

www.hifiengine.com

Edit:
By the way. Doodski also seems to be in tipping mode.

Yeah sure we can all help if necessary. It's fully operational at this time so it's seems to be a routine capacitor remove and replace if the owner really wants to do that. The mechanical disassembly and reassembly should be straightforward being a Yamaha.

 

[restorer-john]

You need to be very careful with the B-2X if you go in for a full blown recap. Personally, I would fully inspect all the caps and test the unit thoroughly before doing a thing. You need a baseline of what is in spec and what is out of spec (if anything). Measuring distortion on the amplifier will be almost impossible without an AP as it is so low at any power level.

Heat and dried glue damage will be your main issues. Be very careful around hot/charred/discoloured PCB tracks as they will delaminate if you aren't familiar with vintage Yamaha PCBs.

 

[Doodski]

You need to be very careful with the B-2X if you go in for a full blown recap. Personally, I would fully inspect all the caps and test the unit thoroughly before doing a thing. You need a baseline of what is in spec and what is out of spec (if anything). Measuring distortion on the amplifier will be almost impossible without an AP as it is so low at any power level.

Heat and dried glue damage will be your main issues. Be very careful around hot/charred/discoloured PCB tracks as they will delaminate if you aren't familiar with vintage Yamaha PCBs.

I checked a bit on those 22,000 micro farad 80VDC caps quantity 4 and the lead time with some reputable suppliers is up to 41 weeks. TTI in the USA has some various caps although the size needs to be matched so no telling what their inventory will be like after sizing.

 

[restorer-john]

I checked a bit on those 22,000 micro farad 80VDC caps quantity 4 and the lead time with some reputable suppliers is up to 41 weeks.

Personally, I wouldn't be touching them until they have been tested for value and ESR and tested the amp up to full power in both channels to see if there's any difference between channels (separate power supplies). Unless they are showing signs of distress, I'd likely leave them alone. It's the small value electros, tantalums and even films where the problems occur. The big caps rarely ever fail, go out of spec or give trouble. When they do, it's obvious.

Put it this way, I'd prefer an untouched B-2X than a re-capped unit. But that's me.

 

[Doodski]

Personally, I wouldn't be touching them until they have been tested for value and ESR and tested the amp up to full power in both channels to see if there's any difference between channels (separate power supplies). Unless they are showing signs of distress, I'd likely leave them alone. It's the small value electros, tantalums and even films where the problems occur. The big caps rarely ever fail, go out of spec or give trouble. When they do, it's obvious.

Put it this way, I'd prefer an untouched B-2X than a re-capped unit. But that's me.

I was thinking similar on the big caps. They can also be fairly expensive from the prices that I saw.

 

[ZolaIII]

Be very careful around hot/charred/discoloured PCB tracks as they will delaminate if you aren't familiar with vintage Yamaha PCBs.

How do you propose handling those (cleaning and renewing joints) if not fried to much (dark brown - burned up entirely so you get a hole removing a component you wish to renew)?
And you would tuch it a lot so let's hear it.
I even have a friend nearby who can root, print and cut me new PCB's but it wouldn't be cheap even I would only pay him for material and printing and of course that's me.

 

[DSJR]

I had my Quad 405-2 recapped last year and to be honest to my ears it's comparable to most of my more recently purchased amps and betters a fair few, It just sounds right in my setup.

Both 405 versions are pretty poor on the bench these days, but 'good enough' for purpose. THD was in the lower 70's according to tests and they hated anything les than 4 ohms with a passion.. main power issue was the small case they used (I believe it's the same as a 303 or II sideways) and the under-heatsinking meant heavy current limiting to save the circuit from cooking too much.

The 606mk2 onwards on the other hand, is I believe a very good amp even today with proper 4 ohm drive and the current Artera Stereo version has been very lightly tweaked to update it further (still cheap in audiophool terms ignoring the better class D offerings which no self respecting audiophool would touch with a bargepole)

 

[Lionheart-UK]

I would be fascinated to see how arguably the first Class-A amp available in the UK the Sugden A21 (wooden case) would perform under modern testing techniques. I love the sound the 50+ year old Sugden produces with my old mkII Klipsch Fortes whereas most of the pricier modern kit does not cut the mustard and I have always wondered how it would test.

 

[sergeauckland]

Both 405 versions are pretty poor on the bench these days, but 'good enough' for purpose. THD was in the lower 70's according to tests and they hated anything les than 4 ohms with a passion.. main power issue was the small case they used (I believe it's the same as a 303 or II sideways) and the under-heatsinking meant heavy current limiting to save the circuit from cooking too much.

The 606mk2 onwards on the other hand, is I believe a very good amp even today with proper 4 ohm drive and the current Artera Stereo version has been very lightly tweaked to update it further (still cheap in audiophool terms ignoring the better class D offerings which no self respecting audiophool would touch with a bargepole)

The 405 had perfectly adequate heat-sinking when used as an amplifier for reproducing speech or music. Even with full-power testing, the heat-sinks would run hot, but not excessively so. The amplifier consists of a 3W Class A amplifier for each channel, augmented by the current dampers, so even at idle the heatsinks would dissipate some 20 Watts so would be warm (50% theoretical efficiency of each Class A plus the dumpers' standing current). I have measured quite a few 405s, and never found them under-cooled.

As to the performance into 4 ohms, that was a limitation of the original 405, but largely solved with the 405.2, albeit it never liked nominally 4 ohm loudspeakers that in practice dropped to 2 ohms or below, but then nor did many other amplifiers of the era. It worked superbly with KEF 104.2 and 107s which were purely resistive 4 ohm loads. It was very well protected such that it would survive pretty much any abuse. For use with difficult loudspeakers, (particularly successful with Mission Argonauts), putting the two channels in parallel worked a treat, Quad making a conversion kit available.

S.

 

[Lionheart-UK]

Both 405 versions are pretty poor on the bench these days, but 'good enough' for purpose. THD was in the lower 70's according to tests and they hated anything les than 4 ohms with a passion.. main power issue was the small case they used (I believe it's the same as a 303 or II sideways) and the under-heatsinking meant heavy current limiting to save the circuit from cooking too much.

The 606mk2 onwards on the other hand, is I believe a very good amp even today with proper 4 ohm drive and the current Artera Stereo version has been very lightly tweaked to update it further (still cheap in audiophool terms ignoring the better class D offerings which no self respecting audiophool would touch with a bargepole)

The 405 had perfectly adequate heat-sinking when used as an amplifier for reproducing speech or music. Even with full-power testing, the heat-sinks would run hot, but not excessively so. The amplifier consists of a 3W Class A amplifier for each channel, augmented by the current dampers, so even at idle the heatsinks would dissipate some 20 Watts so would be warm (50% theoretical efficiency of each Class A plus the dumpers' standing current). I have measured quite a few 405s, and never found them under-cooled.

As to the performance into 4 ohms, that was a limitation of the original 405, but largely solved with the 405.2, albeit it never liked nominally 4 ohm loudspeakers that in practice dropped to 2 ohms or below, but then nor did many other amplifiers of the era. It worked superbly with KEF 104.2 and 107s which were purely resistive 4 ohm loads. It was very well protected such that it would survive pretty much any abuse. For use with difficult loudspeakers, (particularly successful with Mission Argonauts), putting the two channels in parallel worked a treat, Quad making a conversion kit available.

S.

I've been using my 405-II with a pair of Klipsch Fortes in a vintage system and I guess not needing so much juice to power them the Quad is in its element, I sometimes swap the Klipsch around with a pair of less sensitive Dynaco A25-II with equally acceptable results though, it might be a synergy thing going on with older kit but the 405-II just sounds right to my aging ears.

 

[makinao]

A friend gave this monster to me last month. It was lying in her brother's garage for a few years. I immediately sent it over for a checkup and overhaul by a local amp specialist. If it comes back in good shape, I might look for a pair of good used 4311's for it.

 

[Hipocrates]

I might look for a pair of good used 4311's for it.

That's a superb piece of equipment when properly reconditioned... The 4311's will come up short.
They are tricky to work on, the schematic have errors... once working, is a delight, my favorite receiver ever.

 

[makinao]

That's a superb piece of equipment when properly reconditioned... The 4311's will come up short.
They are tricky to work on, the schematic have errors... once working, is a delight, my favorite receiver ever.

What speakers do you recommend? I don't have a lot of space for anything bigger than bookshelves or thin floor standers, or budget for brand new.