Older PURE CLASS-A Amplifiers

Anyone compare all these vintage amps to the PASS .5 and now .8 series.
Are the newest .8 pass amps truly in a whole different league than the older amps mentioned?

Luxman M-05. 105 watts per channel of the absolute most beautiful Class A power that can be found anywhere.

Bedini 25/25. If you can find one, buy a lottery ticket the same day. The 25/25 continues to astonish me!

Krell KSA-100MKII - one of the best balanced and mid ranged voiced amplifiers of all time. Caveat- You must send it in to be serviced every 15 or 20 years! Power supply caps need to be changed as they dry out - degrading sound & bass performance. Highly recommended - if you can find one.

I second the Classe DR-3B. A friend of mine had one for a short while and I told him to never sell it. It was one of THE best amps I have ever heard IMO. His speakers were relatively ineffiecient so he sold it. I couldn't swing owning it at the time.

Look for the rare Pass Labs Aleph 0s (40W pure Class A)stereo power amplifier. This was one of the most natural sounding power amps I have ever heard. I am always looking for one ever since I heard the Pass Aleph 0s years ago. By the way the Pass Aleph 0s is one of Nelson Pass's favorite amp of all time. I talked with him for about an hour one day and he told me if you can find a Aleph 0s make sure you grab it.

Is it necessary to change the caps after many years of intensive use on a Classe Audio DR3B?

Is it necessary? No, unless you're having audible problems (muddy, veiled, undetailed sound).

Electrolytic caps deteriorate with time & heat & other factors -- a major factor being non-usage. You have used your amp, so deterioration is less than in other cases.

Replace with caps of same value -- or even adding coupling caps... BUT leave this stuff to a qualified tech.

hi. another thing to add is anything made by nelson pass. the guy is really cool. I called pass labs once to talk to someone about my older threshold amp and pass himself took the call, I told him upfront that I did not have the funds for one of his newer amps, but he still talked to me for over a half hour about his older threshold and aleph amps. he gave me lots of good advise. good luck, chris

threshold sa3, or any ot the pass aleph amps, if they have enough can power for you. one of the biggest secrets in hifi is that some of these older amps not only compete with the new stuff, they are actually much better than what is out there today. goodluck chris

Hello,

Is it necessary to change the caps after many years of intensive use on a Classe Audio DR3B? What kind of caps am I supposed to buy?

Regards
Vesaas96

Here's to keeping the thread alive. Good for the search engine and anyone looking for good old class A amps.

The smaller Bedini's like the 45/45 and 25/25 are underated. I have a 45 that puts out sweet music to my Maggie 3.6's.

Jimmyblues, my 45/45 has a less than 100 ser #. When I spoke to John about it and mentioned I liked SET amps, he said mine was single ended and no wonder I liked it so much. Is this what you meant by the "real Bedini"?

best Class A , don't forget krell ksa 80b and threshold s200/e

A shortlist of the amplifiers you are looking for:

Classe DR-3B or DR-3 VHC (very high current)
Bedini 25/25 under serial number 100 -- these were the real 25's -- not the later and cheaper Japanese version, as John likes to call them.

Levinson ML-2's
Electro Research A75 John Iverson's first real amplifier
Krell KSA-50
Threshold SA-3

You can also try Pass labs Aleph series of amps. I used to have an Aleph 5 which was very nice, if your speakers are efficient they are excellent.

Aloia or a sugden

Did somebody say STAX? I got a DA 300. A littal harsh on dynamic speakers. oh so sweet on ribbons & electrostatics. However I don't have anymore:( Anybody looking for some sweet class A amp?

Well, actually the 8008BB is not really class A, but it shares the same platform that its big brother the Palladium is based on and it's available used for under 1k.

Aragon 8008BB.

Don't think you can get the Threshold SA-1 mono blocks for $1000, I've looked.
SA-3 would do, the Forte #4 is a good amp and you would have enough left over to get it upgraded be Jon Soderbreg.
You could even get 2 Forte #4 and biamp for your price.

There are a lot of Class A tube amps too- any reason they are not on this thread?

Threshold SA/4e is one of the greatest ever pure class A amps.

The Levinson ML3 is definitely not a Class amp.
It's a AB with only enough biascurrent for approx. 6 Watts @ 8 Ohms Class A. The ML2 has 25 - 40 (European model) Watts Class A and consumes 400 Watts at idle.
You can bridge two ML2 monos to get 100 Watts Class @ 8 ohm.
The Krells with forced cooling were not my favorites with their flimsy covers and coolernoise. I had the KMA 200 Mk II and the consumed 2300 Watts just minding their own business.
Krell made real good amplifiers starting with their plateau biasing models (KSA 300 and forth)
Threshold SA/1 is a classic. Nice sound beautiful crafted but lamps for meter-illumination have to be replaced now and then. If you don't need the slamming power of a Krell this would be one of my favorites although I wonder if they are hard enough biased to deliver 160 Watts Class A @ 8 ohms. I turned down the biaspot anyway to thermally distress the amp.
Class A is not an indication of good sound anyway.
In most cases it's a waste of energy.
I had the Krell KSA 100 & the KMA 200 Mk II and found them both musically inferior compared to the Rowlands 7 (series II and IV) and 8T which are Class AB designs.
For power and musicallity I found the Rowlands 7 a real "bargain".

These Clayton aren't too old, but here's any interesting review:

http://iar-80.com/page6.html

Krell KSA-100 MK11 gets my vote.

I have the chance to get the levinson ML3, is it still a good amp considering its age or should i consider a later model, if i do purchase it what pre amp should i match with it.

Currently using an older modified Adcom 535-II to drive new Paradigm Studio 100 v3. I find the sound to have a hard top end which is almost hurtful (my previous speakers did not have as much treble extension).

Wondering if a better power amp is required. Would it be possible to use a Pass Aleph 3? Specs seem to indicate the Paradigm 100's are not super easy to drive.

Thx.

Miguel

Hi,
I have two of the Lazarus highbird mark III amps and the Cascade Classic MKII pre amp.
The system sounds awesome. It is a work horse. I have it since 1993.

As for Greg. His last name is miller.
The last I heard about him was back in the nineties that he was planning to go to Japan.
Apparently, the high-end audio market over there liked his products.

I am looking as well for copies of the circuit for the above.

Thanks,
Jonathan

Threshold SA -1 mono block power amps are my choice for great pure class a sound. Also the SA-2 mono blocks and even the stereo SA-3 amp. All of these amps are timeless and have incredible sound.

- A good old CLASSE DR3 VHC this amp is a small power house and deliver 45 WPC of pure classe A and it is reliable and sweet souding, weighting in at nearly 90 pounds....

Classe DR3. Hands Down!! (Having owned many pedigree amps (McCormack DNA2, Jadis Defy 7 among others)

Pass labs Aleph series have to be in there with a shout. As David 99 says, the Aleph 3 has to be one of the great power amps out there, not the most dynamic, but such a sweet, detailed sound. I have been using it into my Living Voice Avatars for 3 years. You need 50 watts, then there is the 5, I believe at 60 watts, or the 4 that comes in at 100, something for everyone

Elinor: You should try your Threshold with some Goertz MI-2 Veracity cabling. Just make sure to use proper impedance compensation i.e. Zobel networks and see what you think. The results are extremely complimentary and natural sounding for a staggeringly low price. Sean
>

I own a Threshold T200 and I would not consider selling it. Poweful beyond its 100W/channel rating and still one of the sweetest sounding SS amps I've heard. Put a pair of MIT Oracle Cables on it or Transparent Ultras or Refs and you will stop searching for power Nirvana.

Threshold SA/1's & SA/2's set the standard in Pure Class A sound.

Don't forget about the Sugden A21ap, excellent 25wpc pure Class A. They show up here occassionally for well under $1,000.

The older Threshold S and SA series amps can still hold their own against the newer equipment. I am quite familiar with them and have heard many of them over the years at a local dealer that used to sell Threshold. I currently have the S350e Class A/AB model. As someone else had mentioned, I think I would shy away from the T-50 model because I also have heard that the IGBT ouput devices used by the T series are no longer available. All of the older Threshold amps that I have heard, including my own have delivered a relatively neutral presentation, depending on what other components were also in the chain. IMO they have a similar sound to the Pass X series amps. If you happen to see one of the class A SA series for sale GRAB IT!

What is your experience of intensive wear that pure Class A designs impose to output transistors? Does Class A amps were at a faster rate than a/AB?, which are the sonic implications of such "wear" in older Class A designs?

The Platinum Reference I is the biggest chanllenge to power amps. I have yet to find anything that make it sound acceptable to my ears.
I have matched it with about a dozen amps 5 years ago (from $$$$ SS amps to tube amps )and gave up at the end. No matter what you feed through it, it never sound as open and relax as some other better monitor speakers. I ended up ATC SCM10s as it sound much more realistic, relax and open ( very dynamic without the constrain I felt from the Platinums.)

The Aleph-3 is the best amp I have ever owned.
Too bad I bought some Thiels and had to go to a bigger amp.I wish I would kept the amp and bought different speakers (for power only as I love my Thiels) Although this thread asks for CLASS A bias amps only.I would like to add,my Threshold A/B S/300 is a killer amp!
It drives my Thiels with ease,and then some.

nobody's mentioned the Pass Aleph series amps, amongst the most famous of all class a solid state amps...are they not considered to be in the same league as the above mentioned amplifiers??

How come nobody mentioned Plinius? Older SA-50 amp is extremely good for the money.

I owned a pair of Mark Levinson ML3 - similar to ML2's but double mono in one chassis which I loved. Very few for sale though...

The other class A amp that I really enjoyed was my Musical Fidelity A100, a higher power version of their well respected A1 with a rich warm, fluid sound. They later introduced an even larger version A200 and mono-blocks A50 which occasionally become available on the market but I have never heard them. However the best of the A series was definately the A1000 (not A1001) - this was awesome ( a Tim e Paravicini of EAR design I believe) if you can find one.

Ecclectique, None, if I ever see them first. Its the only SS amp I've ever heard w/Quad 63's that I have enjoyed as much as tubes. It really is great.

Why not go with a pair of Monarchy SE-100 Delux's. They are an improvement over the Sm70's and they fit in your budget. Also, they run cooler than the SM70's. There's a pair for sale here for $989. Why not make an offer.

Later,

I second Ramy here (Gryphon DM100), the only caveat would be the intensive wear that class-a design brings to output transistors, Is there any technical trad-off in that?

Regards,

Fernando

Hi Gang. I see a couple of posts on the original Mark Levinson ML-2 mono's. Indeed they were amazing amplifiers, however....Your chances at finding a working pair for a $1000 are "Slim and none". cheers

I am looking to drive Platinum Reference 1 monitors, similar to the Solos. They are very power hungy, so I guess I would need at minimum 50 watts. I liked the Monarchy cause it looks like they double down with each increasing ohms load.

Tpk- I had the 50 w Class A model. A very sweet Class A.

The SM70 has been discontinued. The SM70Pro is still a current product. The SM100's were replaced by the Se100's. Monarchy is very slow to update their webpage. I was trying to purchase a second SM70 about two months ago. I called Monarchy and they informed me that it had been discountinued.