K5881 Stereo Power Amp

[JohnG]

I have a Stereo K5881 mki Power Amp, is it possible to use this as a monoblock if another K5881 mki Stereo Power Amp is paired with it ?
Would any mods to the amps be required ?
My amp has delivered a performance I never thought was available from it, as a result of driving it with a Slagle AVC.
This has got me thinking about getting more from the set up and the monoblock come to mind.

[bob orbell]

If you get another, you can bi amp your speakers , but as for turning each into mono amp's, it's possible, but will require a major redesign. BOB

[A Stuart]

The 5881PSE came with specific instruction how to wire it as a monoblock, something involving the 15ohm lead from the output transformers (for 8ohm speaker). Would have to dig it out and think if this would be less simple with a push-pull.
Alastair

[JohnG]

I completely forgot about Bi Amp set up.
I like the idea of Option 1, one amp driving one KLS 3, with as short a speaker cable possible. This may mean I have a slightly different build spec driving each speaker as both amps are built by different individuals.
The other option 2, is to have one amp driving one set of drivers on each speaker, using longer speaker cables.
Option 3, have both amps checked out by a engineer and if both are matched use Option 1.

[JohnG]

The amp I was looking at that got my Monoblock idea kick started vanished from the auction finished.

The good news for me is that the Electronics Engineer building the 845 Monoblocks, has informed me that the end of May is a realistic date to finish the build, as his work load has become more manageable.

Having thoroughly convinced myself the Slagle AVC is a device to drive my K5881. As a result I am thinking about tweaking my power amp.
Is there any suggestions available, that would uplift the performance of a K5881 MKI, for a affordable cost for the modifications,
all thoughts are welcome ?

[Richard]

Hi John, are you using the AVC now? How do you find the quality and volume, does it feel as though there is enough drive? I've only heard one AVC pre which was very smooth and sweet but lacked a little ooomph.

Passive pres generally need a sensitive power amp so an obvious mod to try for your K5881 might be to convert it to MkII design which was done for sound improvement but also increases sensitivity to 75mV.

The MkII changes are detailed in Nov 1996 supplement article and MkII component tweaks are in Feb 1997 article on the Platinum disc http://www.world-designs.co.uk/cd%20rom.htm

[JohnG]

I am using the AVC at present and can see it being in use regular.
It has got my attention and I am at present discussing with the Electronics Engineer on another idea for it in relation to my 845 Monoblocks.
As for how the AVC works with the K5881 and compares to other devices I've used, it has shown itself as the go to device.
The KLP1/K5881, has a effect that degrades the performance, there is a muddiness and lack of detail.
The Stepped Attenuator/ K5881, has a more detailed performance and does not seem to be lacking in presenting a clean sound. It is IMO a decent method of adjusting volume levels.
The Slagle AVC/K5881, has a effect on the performance that is more like a upgrade, the Power Amp delivers at a different level to how I am familiar with it. Bass is deeper and controlled and there is more headroom, to the point I was comparing it to the 845. Another plus point and one I am not familiar with, is there was not a volume level that you felt was enough, it played at all levels with what seems to be a equal performance and not needing to make changes to levels to feel a little more is to be extracted from a performance.
The KLS3's were delivering at a new level of performance and these will be used with OTA ESL 57's as a comparison.
I will update on this, when I have the session completed.
I have thought of the K5881 MK11 but I have not seen any clear descriptions that confirm it is a major upgrade to K5881 MK1. I have seen that MK1 owners have tweaked their circuits and have been more than content, remaining with the MK1 version.
If there is anybody in the East Anglia region who has a MK11 that would like to compare it to a MK1 with a Slagle AVC, I will be happy to take part.

[Richard]

Yes a comparison with a MkII in your own system would be ideal.

[Ali Tait]

Originally Posted by Richard

Hi John, are you using the AVC now? How do you find the quality and volume, does it feel as though there is enough drive? I've only heard one AVC pre which was very smooth and sweet but lacked a little ooomph.

Passive pres generally need a sensitive power amp so an obvious mod to try for your K5881 might be to convert it to MkII design which was done for sound improvement but also increases sensitivity to 75mV.

The MkII changes are detailed in Nov 1996 supplement article and MkII component tweaks are in Feb 1997 article on the Platinum disc http://www.world-designs.co.uk/cd%20rom.htm

I built an AVC with the Slagle transformers a while back Richard, best pre I’ve had in my system by a country mile. One of the best bargains in Audio I reckon, given you can pick up a pair of the transformers for only 200 dollars.

Sold mine on as I now have a set of Tribute AVC’s to try, have yet to wire them up though.

[JohnG]

Thank you Ali, as you are one of the members who pointed me toward the Slagle AVC. I am very impressed with it, It has been used with the
OTA ESL 57's all morning, these have really sang, but showed the k5881 has a few weaknesses at rare times, so still a win win for me. As I can really live with this system. The K5881+KLS3 is to become my wifes HiFi set up for listening to streamed music and CD.
I have spoke with the Engineer about stripping the AVC's out of their box and placing then inside the finished 845's as replacement for the inbuilt balance controls, I use the balance control at present as a volume control, allowing a pre amp to be bypassed feeding the Power amp direct from the source. A type of minimalism in relation to circuitry and cables.
I will need a second pre for the wifes system, as she worries about my HiFi components, so I will be looking at a further AVC/TVC to be placed in the cannibalised AVC box.
I would be keen to hear your overview of the Tribute Volume Control.
The Slagle AVC I have is the Dual Mono. This version requires less DIY wiring when producing a finished model.