- excellent build quality - unfatigueing, soft, easygoing, essentially neutral sound - more than enough power for most people - excellent reputation of reliability

- probably not the most transparant amp on the market.

I connect this power amp to a Quad 44 pre amp and JBL speakers. It is one of those devices that you''ll eventually forget. It is small and featureless, and just reproduces music neutrally and without listening fatigue. It has more than enough power for most people. While everyt detail seems to be "there", it can be that it''s not the most transparant amp. Some people change the entry opamps in the device because of this perception, but I never bothered. I am happy with the 405.

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I had a Harman Kardon integrated amp before. Very nice, but the Quads sound definitely softer.

Perhaps the best 2 speaker studio monitor amp??????? Clarity and Bass

May need minor adjustments because of age, but definetly worth getting repaired. So I say none.

What can I say that hasn''t already been said about Quad 405, answers to the noise feedback I had the same trouble but undone a screw fixed some earthing wirer and done it up attached it too the earth on the mixer and hey presto, clean as a whistle. My Quad 405 is attached to BBC industy standard HHB Circle 5s Passives and the clarity is v.good. This little amp was once attached to a pair of Tannoy Westminister 2s and did a great job but were perhaps too big to run for a 100w RMS amp.

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Rotel

Built to last, great sound after some mods, deep and wide soundstage, not sounding "as behind a two-ft.-wall (as many other items do in comparison), small and easy to handle

before modifying this amp it sounded a little dull and dreary, reproducing voices as if they came from behind a courtain

Meanwhile I've head (nearly) all of them! When I was a lad of 23 or so, I picked up a 22/II-set at a dealer who didn't know the value of this "old" stuff. After some days of adoring the glooming valves (and listening to them coupled to a consumer-class Philips preamp being at least a little better than the 22) I had to sell them when I found myself in financial trouble (have mercey on me!). So after some years of Japanese and American hi-fi (even a McIntosh 2500 joined my line-up briefly!) I got a Quad 33/303/Tuner set for a friend lbeing in lack of any good stereo components. I was stunned when I recognized the quality of sound reproduction and wanted to remember... Then I found a 303 in a free ad paper ad and decided to buy it. It outscored my Sansui completely! And this not only at newer CDs, especially old stuff as e.g. some live-recordings by Jimi Hendrix became vital and realistic, the musicians "swapped" over an invisible wall and joined my listening-room. I added two RCA-input connectors, but that was a step back, so I removed them and replaced the original DIN-feature by a high-quality one.
Now being courious again I looked into the papers and found a 405 and got it, but at home I had to realize hum coming from the right channel. And I was completely disappointed when I noticed the poor sound quality
As no one could stop me now I bought a second one (!), immediately undergoing it several acts and steps of modification. The lousy op-amp was replaced by some newer ones (meanwhile Burr-Brown OPA 627 is my first choice here!), and the power output connectors were cut off and replaced by some solid 16A ones (don't under-estimate the effect on the clean sound reproduction!). Additional capacitors (crossing the original 10.000 mF Capacitors) added some quickness to the sound reproduction, only when the amp is turned off it shows some kind of bad behaviour, after a few seconds it will intimidate the listener with a squeaky noise. But we will work hard on this!
Summing up I can recommend this amp strongly to everybody who is looking for a no-nonsense quality amp being affordable yet. But keep in mind that it will live up to its true potential only if you modify it at least in the way I did. And, don't forget to have a slight glance at , but don't get hooked as I did! (Four stars for talent of the original item, but 5 after modification!)

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Quad 303, Sansui BA-F1, - various amps came and went

Have owned this unit for almost 20 years, without a failure or breakdown.
Have used various other makes but always come back to using this amp.
I find it provides excellent detail on Blues and Jazz movements and the teenagers in the house go wild when allowed to play the latest rap or hip-hop using Quad.

Weight - heavy

If anyone is looking for some thump in their sound system this little ditty will do the trick.

Would caution users to watch the power output have had to repair the walls several times due to plaster cracking.

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Sansui. Kenwood and Nad

Sound, build

I'm sorry?

The fact that this is a reference amp in recording studios all over the world, says it all. 100W of pure clarity, this is one of the greatest Power Amps ever made. If you want faithful reproduction (as any audio enthusiast should), this is the one for you. The only criminal thing is that these days you can pick them up for only £150!

My only gripe - buy the £50 and upgrade to the 405-II, it's a massive improvement on the original circuitry which had a design fault.

It really kick's you down with it´s power!!!

???

I bougt a complete PA to have in my knew basement. This was a PA that we've used in band rehersal about 10 years ago. No one been using it since then, mostly because the speaker (homebulit) is so big.
When I took it home I discovered that it included 2(two) Quad 405! And they are just the best!!!
I'm going to try them out as much that I can, in PA for guitar, bass, etc.
Is it a good idea to try one of them to hi-fi music in my home?

reliable and look like they are so powerful - which they are
Beautiful sound

basically nothing- maybe the speaker connectors - but hey big deal

Basically i bought these from a guy to use in my home studio. They were a little buzzy but a few new Caps soon fixed that. The monitor audio speakers that came with the amps suited them perfectly.

The quads never distort in normal use and produce a very natural and faithful sound. I just loive the look of them - The one red light - so cool

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2xquad 303a (frequency splitting versions)
leak stereo 30 plus
prophet 5 synth

Everything- I Suppose sound and versatility are the key.

Heavy due to fairly old style of power transformers.

I love the power amp, i use primarily for my guitar. I know it may sound like a waste of such clarity but when it is hooked up with a decent pre-anmp it allows for great tone. I have also used this for music on occasions, when i need to fill a large hall for example!
I love this amp.
I received it from my uncle it part build mode and finshed it with some help. I then built it into a rack unit case so it would fit into my guitar rack. Pretty good huh?
The only changes from the original that i have are it is bridged into a single mono output (switchable), and that it has 1/4 inch jack plug inputs, i also think my heatsink is larger but im not completely sure.
Anyway its a great amp.
P.s. The fifty pounds is only for parts which were missing e.g. a couple of Tantalum Capaciters, but these are fairly easy to acquire.

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None- Nothing i have owned can touch this
Have a Sony amp but is not in same league in power.

Clarity, power, reliability, lack of anything other than the music, can drive my Speakers brilliantly (Celestion A3).

I have had if for over twenty years and not found any yet. perhaps its' styling is no longer modern...

The first in a line of Quad CD amps, and one that I have never felt the need to upgrade from. I never dreamed when I bought it I would still love it and use it daily 22 years later.

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Home built Blomley 30W and John Linsley-Hood 10W class A amps.

Overall sound, construction

Age?

I was in my uncle house when I saw it...how ugly, I said. Then he told me somebody was selling it. I listened it with my uncle´s VTL tube preamp and a pair of NEAR 15M, and got surprised by its good sound. I took this cinder block and go to my place, connected to my preamp and compared to my Parasound HCA 1000A in my HT system...my jaws just dropped down! How a 20 years old gear could sound as powerfull and clean as a modern high current amp? And not just that...it appeard to sound more sweet and warmth than the Parasound. Got much more surprised when I go to Internet and downloaded full info about it (there is a page exclusively for this amp!) where the reviews from those days said that this amp was one of the best in all the world...and, again, amazed when I saw that QUAD offers full service for it, including original new parts (transistors and power transformer). I will never sale my Parasound (I love it) but now I will keep this little wonder for my bedroom only-music hi-fi system.
Oh! Did I mention how much I paid for it? Well...that is another surprise...just 90 dollars!

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Parasound HCA 1000A