cyrus 1 amp later version

[whats gan on]

ok mate i will try them

[richie00boy]

The pot is not easy to replace because it has the balance function in it. I really doubt different diodes are going to give you a big improvement. There are none in the power amp circuit bar output spike protection diodes, changing those will make zero difference. Go with the PSX and see from there.

[AndrewT]

Hi,
there is not much room inside that case, so it limits what can be done (neatly).

I prefer to put a lot of muscle into the PSU (some disagree).
That's why the Two uses a PSX, seems Cyrus agree with me.

Modern capacitors seem to have more capacitance inside the same case size.
So my first suggestion is to double the PSU smoothing capacitance (or more if you can squeeze it in).

This raises the RC time constant of the PSU and allows a more extended bass to be produced with less sag in the supply rails.

Alternatively, put in a separate PSU for each channel with their own rectifier and smoothing from the single transformer.

Once this has been done, go and study the schematic and identify the other time constants that limit the bass response.
Then change the electrolytics for new, possibly bigger, but definitely better electros ( the High frequency, High Temperature, High Ripple, caps are decidedly better than what was available 25years ago).

[richie00boy]

The Cyrus is only 10 or so years old. They use good (Elna) caps as standard and 'big' upgrades may not be a realistic expectation IMO. On the other hand, if it has had a hard life and/or been left on a lot it could be worth blanket replacing the caps.

[AndrewT]

How old is this Cyrus?

[whats gan on]

Originally posted by richie00boy
The pot is not easy to replace because it has the balance function in it. I really doubt different diodes are going to give you a big improvement. There are none in the power amp circuit bar output spike protection diodes, changing those will make zero difference. Go with the PSX and see from there.

Originally posted by AndrewT
Hi,
there is not much room inside that case, so it limits what can be done (neatly).

I prefer to put a lot of muscle into the PSU (some disagree).
That's why the Two uses a PSX, seems Cyrus agree with me.

Modern capacitors seem to have more capacitance inside the same case size.
So my first suggestion is to double the PSU smoothing capacitance (or more if you can squeeze it in).

This raises the RC time constant of the PSU and allows a more extended bass to be produced with less sag in the supply rails.

Alternatively, put in a separate PSU for each channel with their own rectifier and smoothing from the single transformer.

Once this has been done, go and study the schematic and identify the other time constants that limit the bass response.
Then change the electrolytics for new, possibly bigger, but definitely better electros ( the High frequency, High Temperature, High Ripple, caps are decidedly better than what was available 25years ago).

hi andrew that sounds good i am in newcastle so your not far from me thanks for your advice

[poynton]

I would hold off replacing the power caps. In my Cyrus they were slit foil caps...nice quality.

Bypass by all means and replace local caps with Pana FC / Black Gate or whatever is flavour of the month.

Andy

[hacknet]

i noticed the slit foil too but after replacing them all the dynamics came out. details and vocal clairty was much better too.

[Sonusthree]

I managed to put an alps blue velvet in my Cyrus 2 (identical fitting to Cyrus one and a late model like yours) and the improvement was not subtle. I didn't use a daughterboard but simply bent the pins slightly to fit. Tricky but definitely worth it. I also replaced the balance control with two metal film resistors.

I'm in the process of recapping my Cyrus and it is surely overdue. 10 years may be Okay but 16 (or more years old is surely starting to get risky even with quality components. I have seem some horror stories with caps failing in these amps and am getting a little nervous about mine.

The biggest question as mentioned above would be whether to go to the expense of replacing the large power caps. They are quality parts but are they still OK?
I recently contacted Cyrus about replacing the four 15000uF slit foil caps in my PSX and they told me that they don't normally replace them because they are very stable! I'll have to take their word for it but maybe that means that your large power caps will be fine too? Mundorf are doing some reasonably priced large electrolytics now. Hmm........I wonder if they might be a good choice here?

Whats Gan On,
We have strangely similar systems;
CD4se, Tannoy 611, Cyrus2 + PSX. I also own some cyrus Ones and have recently owned Tannoy 611Mk11 like yours but preferred the compromises of the MK1.

In my experience with cyrus (Ones an Twos) and these Tannoys I find it hard to get enough bass from them. It's definitely all there but seemingly hidden by the upper frequencies.
In normal use they sound bass light but with reggae or drum n' bass they suddenly sound quite balanced again and have no trouble with finding the lower octaves in adundance.

I'm taking some pics of my amp tomorrow, anyway, so PM me if you would like copies by Email.
Cheers.

[richie00boy]

You can just remove the balance control, no need to replace it with resistors. Adding resistors merely adjusts the level slightly to as it was before at the expense of slightly more loading on the source. It depends on your preference I guess.

The pot I used was a Vishay one from RS, which would no way fit into the original board, hence the need for a daughter board.