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Hi I have one of these and my left side speaker is not working done cable amd speaker swap to check amd seems Left bank gone down .. is it an easy fix ? Thx

I think I could now rebuild a rotary engine after watching this

Wonderfull piece of audiogear, good that it was repaired!

Thank you, very interesting! I have had mine from new in 1989 and it is all original, except for the crumbling phono sockets that I repaired. I am curious about the bias and cooling - it gets warm but not excessively so. It is not run very hard as the room is small.

Thank you. Very helpful!!

Just wonder if you still offered Karin repairs as I have one which is in need of some expert advice.

Very detailed and careful stepwise build. I'm an old fogey and have been using valve amps for my audio fix for almost 40 years now. My one comment regarding vacuum tubes is that they are extremely robust in terms of over and under voltages and filament voltages. whereas, in solid state devices, over and undervoltage/currents will usually fry them it is not such a big deal for a tube. But I am trying to move into the 20th century by learning how to integrate more solid state into valve amps where appropriate. Your video is very helpful in this regard.

Thanks for this! Where do I buy the replacement power supply for the a7? Thank you

Measure its RMAA

nice informative video... please tell me which Linn preamp you like best… 1. Linn Karin or 2. Linn Klimax Kontrol without upgraded dynamic ps/dual mono boards 3. Linn Klimax Kontrol with upgrded dynamic ps/ dual mono boards ❓

Bought one used today and i'm afraid of the amount of power he is delievering to my speakers (With vintage high-End transparent cables). By now i'm not putting the volume higher than the second led. Is it possible that an integrated amp can be considered with an issue with what i have described ( I mean - more power then the specs described on the specification papers) ? I know it's a 150 W, but holly! My Paradigm Studio 20 V3 speakers are 89 Db and maybe the problem is they are sensitives for this guy.. I will try with the EPOS M15.2 wich are 86 db and hope i can push the volume to the third led at least without being so afraid. I also have the Musical Fidelity Power+Pre A3.2 and also the combo Nakamichi PA-5 + CA-5, and never felt so afraid as i am with this beast. Can you give me your opinion?

Thanks for the excellent video. Is the 12V zener diode used to bias Vgs of the MOSFET to turn it on? So does this mean that there is 12V drop between the drain and source of the MOSFET? And you would use this to calculate the power dissipation of the MOSFET, and the heatsink required, correct? What is your thought on putting a LR8 voltage regulator from the node between R524 & C503 to the node below R1? Thanks again. I'm having a difficult time finding LTSPICE model for LR8 so I don't know how to simulate it.

I'm guessing based in Scotland somewhere?

The bias voltage measured was actually -17mV not +12mV so that's one topic. Another is that this should not depend on whether the cover is in place or not. That the bias drops by 300uV suggests that there is either a leakage path caused by some blown power supply decoupling cap, a problem wth the earthing or tha the amplifier is oscillating (above the audio band - prob several 100s of MHz). IMHO.

Nice work. Good looking unit there. I'm sure it will last forever now that you've serviced it up nicely.

These Krell labelled outputs look like Motorola MJEs, don't you think? The whole unit looks well made, but not devoid of compromises, pretty much like a castrated version of their usual works of art.

I don't like push button volume controls personally. You cannot beat a standard pot.

The components of the 8000A are of high quality and I have never had to change any since the late 80's, except for the RCA connectors. Still, I had to touch up some cold solder spots, which is common on large PCBs. One of those spots was in the output stage protection circuit, which caused intermittent disconnections. I once caused an inadvertent short and the protection worked, but if this circuit fails the output shorts can be fatal.

Very useful video. Thanks

Just found your site as I'm trying to build an ESP based Graphic Equaliser with automatic setup for each band so was looking for a digital volume control to set ref level. This was really informative and well described and a great help. Are you able to post the Arduino code you used as this would save me such a lot of time as I am very new to coding? Thanks again ether way for publishing the video.

its two clips in there mate

Great stuff. I'm a new subscriber and working my way through all your videos. Enjoying them all and getting a lot from the troubleshooting process. Cheers.

Thanks for this, I had an A5 to fix and you saved me time showing how to take it apart.

Neat.

Very nice video, thanks

I used to own Cyrus components but I don't like the Class D gear at all. IMHO the Class AB sounded better.

This is my first vid of yours I've seen, enjoying the in-depth look and scope views, thank!👍

Great analyst and video the more Cyrus I see the less I like them.

What caused the diode to fail, do you think ?

Mine failed as well and took out a b&w 805d4 tweeter. Well done Cyrus !

Excellent as always, keep up the great work👍👍

Nice to see how its built, for an expensive brand i'm surprised how basic the output stage is, they retail at 3000€ apparently where i live 😱😂

Are you satisfied with the final design you showed? Would you be willing to share the schematic?

Hi there, Do you have a full list of the parts your removed? So easier for me to order in one go. Thanks.

Just found your site after pulling out my Cyrus collection after 5 years in storage. I had a nasty addiction with about 15 units. Bi/mono amped in a surround sound system. Mainly older stuff. Apa7.5 etc. Anyway now no space for it. I’ve learned so much from your posts.

Found your channel this week, and have watched over a dozen videos of yours 😊 Needless to say, I love the content, and subscribed. Watching you work makes me realise just how much my own channel is “hobby” level 😊 Thank you. Regards from Madeira.

Nice, I have bought a kit based on that IC, it was in 'Silicon Chip' (Australia) so that solves PCB problems (offloaded it to someone else), However I do like your phone app idea, what are you using there, or did you write that yourself? One Idea I had was a circuit to monitor the amp and if something like a overload, or excessive clipping occurs it would automatically wind back the volume.

It's a really fascinating product you've made. However, you might consider removing U1 for two reasons. Firstly, a balanced output from any source will typically have its own driver, so there's no need to worry about its output impedance. Adding an extra op-amp not only increases the BOM cost but also introduces a bit of noise. Secondly, I'm not a fan of directly connecting an op-amp's input pin to the external world without any current-limiting series resistor. In today's environment, where numerous gadgets with switching power supplies can cause sudden spikes on the wiring lines, this might damage the op-amp. While this op-amp does have back-to-back diodes, they are only between the input lines.

I ajusted recently the bias current on my Audiolab 8000A (version of 1988, issue 3). May be my particular personal experience doing this can be useful to someone. The amplifier runned very hot. So I'm sharing this experience. Myalbatech showed this in his beautiful video "Repair of a trio of audiolabs" and the following is my particular personal experience. This version has not presets and bias current is set by the pair of SOT resistors R809//R811 on L channel, and R810//R812 on R channel. In each channel, the pairs of resistors are connected in paralel (//). In my amplifier, R809 was 6k8 and R811 was 43k. Also, R810 was 6k8 and R812 was 43k. Please note the pairs above are also in parallel with another resistor (placed on component side) of 1k5 , labelled as R807 on L channel and R 808 on channel R. Then (considering the 1k5 resistor) changes on the 43k resistor have very very small effect in the bias current. After some tests, performed as stated in the service manual, I set at 7k5 for R809 (L) and 7k15 for R810 (R), both preferred values, the first on E24 series and the second on E48 series). The 43k resistors were not changed. SOT resistors were selected with the amplifier cover and baseplate mounted, but without screws fitted (as specified on the service manual). There is (by construction) a "heat chamber" inside the amplifier and this temperature rise inside controls the bias current in such a way it reduces slowly the bias, taking about 30 minutes to stabilize. As a curious test, taking the cover off the "heat chamber" lowers its temperature and the bias increases (ambient temperature was 26 ⁰C). So, a bias setting with cover off is not valid. And gives place to a too low bias when the amplifier is working with its cover in place.

Very nice, can you share building details please?

Great, I'll keep it as a reference. When using DB9 connectors, is the communication TTL or CMOS as is? RS232? Have you thought about using RS485? With a 120 ohm twisted pair shielded cable and many meters without problems. Something I would put is a rotary encoder and some push buttons. Using a wifi app to control it is very good.

Are these for sale?

Brilliant work, I really like the bias monitoring and the app. One of the best attenuator implementations I've seen.

Very nice sir 👌

Hello sir, if for example i want to connect it to a computer or a digital device, which channel should I choose? for example to connect it to a laptop.

hello. i have 6vs2. it sometime auto turn on by itself. i can not control it. do you have any suggestion on the issue?

Good morning, When adjusting bias in the Audiolab 8000a amplifier, we need (or do not) have 8 ohms loads connected at the amplifier outputs? Could we adjust bias with output binding posts not connected to speakers or suitable resistive loads?

linkfor power supply ?

Hi, I suceeded obtaining the 2 pages in fault on the service data manual for the Audiolab 8000a (drawings CST207-036). The famous pages with the pcb drawings as seen from the component side and also for the copper side. Someone interested please send me a private e-mail. Measuring the voltage across each one of the reservoir power supply ELNA capacitors (10000uF/50V), with a high impedance digital multimeter as a voltmeter, about 45V is a regular value? In each one (diagram says +44V and -44V). The big problem is my 8000A is labeled at rear as 220V but in my country ( Portugal, Europe) I measure normally a mains AC voltage in the range 231V-233V. By the local standard it is nominally 230 V, with extreme possible limits at -11% and +6%. I'm worried if this may overload the amplifier, stress components by heat... And also a voltage dangerously near the 50V capacitor range.

Excellent video. Could you put the spice files on line for the amp please? You do have some envious test equipment. what was your distortion analyser? Have you any idea where I may find a full circuit diagram? I have a problem on the preamp and I cannot find a schematic on the internet anywhere. Thanks Peter Thomas