Cyrus 3 VS Cyrus 7

Here is an interesting little comparison for you. During my work today I needed to take some measurements of known good amp performance.

Here is the Cyrus 3 in Purple and the Cyrus 7 in Red. Input is 0.1V and output is set at 1V into 5R.

I'm pleased to note exactly what my ears suggested to me after owning both amps for years. The Cyrus 3 has fewer high order harmonics. On balance though, I can see in the measurements that the Cyrus 7 has better PSU noise rejection and the harmonics of 50Hz mains hum are lower for that.



The main reason for this difference is a change in designer from the Cyrus 3 to the Cyrus 3i and then 7 (onwards). From the 3i onwards most Cyrus amps claim the same THD figures on their website, and while I am not sure how much that means I think it suggests pretty much the same traits from amps after the 3i.

 

very interesting ...

an observation ..the noise of the 7 from 7000hz upwards is about 3-4db higher


speculating that if you look at the toal noise of both amps across the frequency spectrum the 7 could actially be noiser ?

I've not heard the 7 but have heard the 3 several times in various systems and always thought it a tad hard and bright ....but pretty respectable at its price point.

is the central purple spike anomalous?

 

Very much not - that's the test tone.

 

Yes, it looks like they have the decoupling capacitors feeding back to the input of the amp somehow by non-ideal grounding configuration.

Maybe my Cyrus 7 is in need of a service though!

I'd never call the Cyrus 3 hard sounding, but it certainly isn't warm like a valve amp can be. I'll do some IMD measurements and stick those up to complete the picture.

 

IMD results. I do wonder if my Cyrus 7 is a little broken as I didn't expect such bad results, although they are not actually BAD, just not as good as the Cyrus 3.

Anybody loan a new Cyrus amp for testing?

 

Cyrus 3 is just about the perfect amp IMO, if the power rating is adequate. With a PSXR and external MC stage there is really no need to look further unless you need more power.
The distortions are all well below audibility, as are those on the 7 in all probability.

People put up with quite shocking levels of distortion from vinyl (and enjoy it) so 0.05% or so of THD shouldn't be cause for concern IMO - no matter what the distortion spectrum feeding the headline figures.

 

i agree with you rob, the cyrus 3 not i was to me the better of all, that has always been my opinion,

 

Having just heard my friend's cyrus 8, I was quite shocked by how good it was.

here's the GULP bit..

I thought it was as better than his valve amp, and in some ways, better than mine (that is DIFFICULT to type).

It made me re-evaluate modern amplification, and I went through a trial process of having about 5 alternative amps over.

Now, well, now my valve amp is gone, and I have a solid state power amplifier.

Do I need to change my name to solid-state-neck? - doesn't quite have a ring to it.

 

Distortion figures, important but have been of interest to me.

My 300B (now sadly departed) showed a clean pair of heels to a highly regarded Belcanto Evo 2 amplifier - despite distortion levels approximately 1,000 times better!

My latest buy, has distortion figures WORSE than a Bel Canto, which in turn is WORSE in distortion terms than a Cyrus, but I thought sounded the best match for my speakers.

'What type of distortion' ? is a question I hear a lot, and, unless you reach a point (I blatantly haven't ) where you understand harmonic ringing, different ''orders'' of distortion and their magnitude of ''nastiness'' on the human ear.. then all you can rely on is your personal preference in your own system.

 

Depends what you want an amplifier to do.

If you want fidelity, nothing added except gain and nothing taken away, then low distortion is mandatory.

If you don't mind having what passes through the amplifier altered, then of course distortion is fine.

The problems arise when amplifiers with quite obvious problems are described as superior. They aren't - the owner simply likes the distortion.
Even worse is when high price tags are associated with this apparent superiority when in fact it is simply distortion.
Distortion can harden the sound, often heard as better clarity, it can alter timbre, often heard as greater transparency, and it can alter dynamics.

I'm not against signal manipulation but I like to do it in a controlled way.

 

Well done for being open minded enough to go against your own usual wisdom and get what you actually thought sounded best Chris. I know it is sometimes difficult to do if you have held an opinion for a long time!

So what did you actually get?

 

You own a "7" Simon?

Is it as good as the reviews suggest it is?

I'd sort of set the pecking order thus..

the 1.....ok for a starter amp (I have one btw)
2 .......stonkingly better
3 and 3i what ever it was lost the plot abit
7 ......extremely good

I have considered trying a 2 in place of my valve amp as the valve relacement is a bill I don't need.

 

The Cyrus 2 and 3 are closely related, and so are the 3i and 7, despite the names.

So I'd say the 3 is best as an amp, better than the 7 going by the above results. The 3 is a somewhat similar amp design as the 2 but with refinements at the input stage and a few other places. However Rob tells me the 2 has a superior phono stage.

I suppose I'd rank them

3
2
7
3i

 

The C2 was around at the peak of the vinyl period and so I think the phono section reflects this. Unlike the otherwise very similar C1, the 2 has a real MC stage with a low noise head amplifier sitting in front of the MM and RIAA stage. The C1 just bumps up the gain on the MM stage.

The C3 has a simpler MM only circuit built around a pair of op amps.
It works well enough but they set the LF to roll at 40Hz which is too high IMO. It could usefully be lowered (not difficult) and then it will likely match the C2 on MM.

Simon and I were surprised at just how well the C2 performed in terms of distortion from a cold start. Roughly were the C3 performs.
Very good amp if you want a clean and powerful (physically) small amp and like vinyl.

 

Interesting Simon - kinda confirms my prejudices.

About 4 years ago CodaII of this Parish (Robert) hosted a great day to ostensibly try some larger speakers at home (Vandersteen 2.5s IIRC) , and Rob_Cyrus and a couple of others provided enough amps between them we could try almost all variants of Mission / Cyrus 1, 2, 3,6,7,8, and the ultra monoblocks, with or without PSUs, back to back(!) Also had a Unison S6 valve amp on hand. I took my Nait 2, just because it fits in a rucksack and it's a good leveller - not the greatest, just something else. Sources spanned various digital and Robert's fine NA vinyl setup.

Much hilarity, and good chat and food, ensued.

The 2 and the Nait were very, very similar - just different flavours of small amps, but totally liveable-with if both sounded slightly soft-centred. I liked the Cyrus 6 best - punchy, clear but smooth, enjoyable. Everything later, howsover it was configured, was just increasingly harsh in comparison. By the time we got to the monos it was a kind of 'cinema sound ' - an artificial boost obvious in the presence range, lots of apparent bass through being not so well controlled, relentless/hard overall. IOW a clearly tailored sound, not a 'low distortion at any cost' approach. I thought the Unison was baggy and indistinct by comparison with all the SS candidates, and the Cyrus 2 and 6 my best of the day. Make of that what you will!

 

I blame Denis Morecroft
The 3i onwards leaned on DNM thinking and were no longer Henry Azima/Martin Colloms designs.

They even started producing Cyrus badged DNM thin solid core cabling.

 

I've added the service manual for the Cyrus 2 and 3 to the reference library. I'd be interested in your thoughts on the differences in the amp sections Martin. I can see a clear difference at the input (phase splitter?).

I wish I had a service manual for the Cyrus 7, it would be nice to check mine is working correctly.

 

Ah yes, I remember it well. Must do it again some time!

I'd actually been meaning to look for the thread relating to this, and find that it is still there in the cyrusunnofficial archive. Looking back, it set in motion much of what I have been exploring since.
On the pre amp front, other than a Cyrus pre X we also had a Musical Fidelity passive to play with which I rather liked at the time and subsequently had both TVC and LDR passives before finally (four years later) returning to an active now.

The earliest Cyrus was in fact a 1 not a 2, so that must have been the one you liked Martin and yes, similar to the Nait is my memory.
Sadly the 3 was DOA - unhealthy cracking noises were all we got and it went back to Huntingdon shortly thereafter.

I fully expected the 7 to sound better than the 6 and was rather surprised

1. that it didn't
and
2. that all present agreed. (Given the varying audio tastes represented on the day.)

It should also be remembered that, in theory at least, the 6 is to the 8 as the 5 is to the 7, ie the lower powered sibling. You don't often hear the 5 mentioned though.

In addition to the mono Xs, I also had a Smartpower at the time, the Cyrus switchable stereo/mono amp and I think that was most likely the tipping point into 'cinema sound' - paired with a pre X I think there was only one of the assembled who expressed a liking for the results.

Getting back to the 6, I still have it and still use it - it runs the kitchen speakers.
I think that the pairing with the Vandersteens was probably the best it ever sounded in that room though. I never did get to a properly efficient speaker (though I did get to hear some, thanks Martin) and things like the big old Kefs that were one of the options at the time really didn't do it any favours.

The smartpower did go, the Cyrus CD6 stayed and has recently been back for a new laser. Again, on the day, it was blamed for the harshness that started to become apparent (at which point we switched to a CD player with valves in, make of that what you will.) It actually sounded best with the C6 which isn't particularly surprising and at the present time I think it still sounds rather good - though everything else around it has changed.

I also spent a number of years thinking I might like a valve amp and auditioned a fair few - the Unison wasn't particularly to my taste either, others I found better.

There was also an EAR 834P there on the day which I'd always assumed I'd move to as and when I changed phono stage.

And so to the present day, I never did buy an EAR but the phono stage of my pre is valve based and though the power amp does have a single valve the power is from MOSFETs. I caused some surprise at home the other day when I said that the current amps were likely to stay for a long time; I do think that may well be the case though.

 

My Cyrus 7 is broken now! I thought I'll replace all the electrolytic caps so I opened it up, wrote down what they all are, then went over a few of the solder joins on regulators, connects etc to make sure they were good. Put it back together and when I try to take it out of standby it just flashes a red light. The manual says it means 'internal error'. Oh poo!!

I've looked carefully for solder blobs shorting stuff and the correct voltages seem to be provided.

Perhaps one of the output devices has given up? How should I best check this? I guess it can't be something that problematic or the thing would just not work, but it knows it isn't working and flashes the red light.

 

Robert - thanks for the extra detail. Yes, nothing wrong with the CD6 at all!

You must drop by if/when next in Bath, your comments on hearing the H2s actually prompted me to properly sort-out a compensation issue on couple of experimental voltage regulators in play at the time, after which everything got a lot better (esp when the re-decs got finished and I moved back upstairs!)


Simon - I bet it is something like a blob of solder bridging two tracks. If you can identify the transistor pinouts, you can use the didode-test function between either pin and the Base to check for blown transistors (P-N direction is forward-biased, so should register about 0.65-0.7v; blown transistors will register open or, more rarely, short on any P-N direction)- but since you haven't apparantly touched any, and they arent static-sensitive, I doubt you've actually killed anything.