Zaphod Beeblebrox

1,000 hours @ 85 degrees C is not a good figure. In fact, it's pitiful. Personally I suggest that ONLY 5,000 + hours @ 105 degree C caps should be used. Fortunately, it's a preamp, so you should be OK for a few years, but be prepared to replace the lot in a few years. More critically I see no reference to leakage current. There are several capacitors in the ME15 that MUST be low leakage. If you examine the old capacitors (branded ME), you will note the letters: 'LL' on the cover. This indicates that they were specifically designed and built to be low leakage. For these reasons, I always recommend that ME products should only be serviced by techs with experience in the product. Even better is the fact that the right capacitors to do the job will invariably cost less than over-priced, so-called 'audiophile' ones. Take your ME products to Ron Berger next time. He knows what he is doing.

The power switch turns the power light on and off, along with a connected ME power amp. The preamp is designed to be permanently powered on, as warm-up times are extremely long. This is all spelled out in the instruction manual. Yes, the jumper has been standard since the late 1980s. What types (brand and model) of electrolytic capacitors were replaced in your ME15?

So, there is no fault with the preamp? What are you trying to rectify? The operation you described is exactly how it was designed to be. Due to the lack of Global NFB, the ME15 should be left powered continuously. And yes, the jumper allows for the phono stage to be continuously powered as well. I do not advise willy-nilly replacement of electrolytic caps, unless it is performed by someone who knows ME products intimately. Some of the electrolytic caps are VERY carefully chosen for very specific performance parameters. Price and alleged reputation of capacitor manufacturers is not necessarily an appropriate guide either. Peter Stein went to very significant investigation in order to source the right capacitors for his products. Again, Ron Berger is your man to advise and properly service your ME15. He knows and has worked with ME products for more than 20 years.

No schematic is available, but one is not required. I've been servicing ME products for more than 40 years and have never required a schematic for an ME preamp. What is the fault with the ME15? I may be able to advise, or service the preamp for you. I note that you are in Melbourne, so Ron Berger at Winovate can service your preamp for you. He does not need a schematic either.

Not a typo. The ME850 employs a progressively more aggressive sensitivity to high frequencies, beginning at approximately 10kHz. So, at around 10kHz, the amplifier can deliver approximately 15VRMS, whilst at 20kHz, it will deliver approximately 2VRMS before shutting down. The shut-down is not instant, since some music contains significant LF and/or HF information. Improper earthing will cause an instant shut-down. The LF side begins at around 20Hz and is progressively more aggressive as the frequency descends, reaching maximum sensitivity at DC. The HF protection system protects HF drivers, whilst the LF protection system protects bass drivers. Damage to HF drivers when using an ME amplifier are extremely rare. Some, rare, ME models (ME500, ME1000, ME1200, et al) employ less aggressive protection systems and auto-reset capability in order to satisfy professional users. Rest assured: Your ME850 is doing it's job perfectly.

Preamp fault. The ME850 is doing exactly what it was designed to do. Balanced connections are a waste of time in a domestic environment.

No other amplifier, that I am aware of, uses the comprehensive protection system used by the ME850. Ultrasonic oscillation can only be detected by an oscilloscope. BTW: Are you saying that you have disconnected everything from the preamp, except the power amp and the fault remains? If so, then the preamp requires repair. FWIW: I use an Audio-gd DAC with al my ME amplifiers with no issue.

The ME850 is designed to shut down, in order to protect your speakers, under any one of the following fault conditions: * Excessive DC at the speaker terminals. (approximately 2 VDC will cause an amplifier shut down). * Excessive low frequency information below 20Hz. * Excessive high frequency information above 10kHz. An ultrasonic oscillation of (say) 30kHz will cause an instant shut down. * Improper earthing of any connected product, regardless of how remote. IE: An antenna amplifier, connected to a TV, which is, in turn, connected to any ME power can cause a shut down. Antenna amplifiers are frequently responsible for inserting dodgy signals into audio systems. * Overheating. If heat sink temperatures reach 90 degrees C, the ME850 will shut down completely. It seems clear that you have a problem with an item which is connected to your system. Unplug everything, then try one item at a time to see which product is causing the ME850 to shut down.

I would suggest that you are wasting your time replacing the resistor, as that type of resistor can sustain temperatures of 150 degrees C all day long. They are capable of much higher temperatures in short bursts. Never forget the tech's adage: 'If it ain't broke, don't fix it.' If the speakers are working well, then leave them alone. If there is a problem, them determine what that problem is and fix it. Don't just replace stuff, without first determining what the problem is.

I'm not sure about the crossovers. They could be original. If so, then they should work fine for the next couple of hundred years. Amplification is important for the big Duntechs. I would suggest a big old Krell. The heavier, the better.

A 47uF film capacitor will be HUGE and expensive. Since the 47uF is likely used in a shunt configuration, then it's impact on sound quality will be minimal. If it's faulty (unlikely) then replace it with a good quality bi-polar electro. However, before you do anything, I suggest you measure. It is incredibly unlikely that the Solen caps are faulty. Ditto the ME caps. Both are reliable, long lasting components. I would suspect faulty tweeters first. I don't know the particular model, but, if it uses ferro-fluid in the design, then it may have dried out, thus reducing efficiency. Have you measured the frequency response to determine if the speaker is faulty? Brad Serhan may be able to shed light on the speakers. I'll ask him. I do know that he in the process of examining some/all of the old Orpheus models and issuing upgrades for them. One last point: Brad Serhan (the designer of your Orpheus speakers) is a brilliant and highly talented speaker designer. If someone imagines that they can make Orpheus speakers sound better, without Brad's knowledge, experience, test equipment, CAD software and fine ear, then I suggest that they are in for a rude shock. Although the CS18 was a relatively low cost speaker, Brad would have issued the same care and attention to detail that he does on all his designs. IOW: Be VERY careful about making significant changes to the CS18.

First suggestion: Don't sell them. Update and service them, as you won't replace them for any sane amount of money. If you want to sell them, then the price is difficult to accurately gauge. However, I will offer some ideas: ME25. I'd estimate that manufacture date of your ME25 is around 1990. It appears to be absolutely original. That is a good thing. And a bad thing. Good, because no idiots have introduced extra problems, which I hate. Bad, because it really deserves a complete overhaul and update. After all, those electrolytic caps are now well over 30 years old. AFTER a full overhaul and update, I'd suggest that a retail value of approximately $1,000.00 would be fair. Figure on spending around $400.00 ~$450.00 to overhaul and update your ME25. You can do the maths. ME200. Yours appears to a later ME200 variant. I'd guess that it was built sometime around 1999 ~ 2000. It has been repaired (new fan support foam fitted) at some in the past few years. The fan support foam is the new type and is expected to last many decades. It could use an update to the DC servo system, but that is not compulsory. However, it will give a lift in sound quality. After a full overhaul and update, I'd suggest that a retail price of around $800.00 is fair. Figure on a full overhaul and update to be around $400.00. You do the maths.

Very possibly. That is still not a brand I am familiar with, but looking at the logo, it does make sense.

Dunno about the logo, but I very much doubt that ASIC would allow registration of a name that is so similar to ME Sound P/L. It's likely a backyarder cashing in on the ME name. I can't answer the question about XLR or RCA, as I am unfamiliar with the topology inside the unit. In general terms, XLR connections make no difference in a typical domestic situation. As for cables, the fewer the number of contacts, the better, so a XLR - RCA cable would be best.

This is not a product of ME Sound P/L. It may be made by someone attempting to cash in on the ME Sound name. It was certainly not designed and built by Peter Stein. I've never seen this brand nor product. It may be unique.

I can supply a third party remote that works a treat. $20.00 + postage.

Not quite. Single ended (SS or valve) do exhibit such a characteristic. Push pull is different, though pentode valve amps tend to deliver approximately the same output power, regardless of load impedance. Triodes, OTOH, operate more like SS amps, in that they deliver more power into successively lower impedances. Within limits. A SS Class A amp, like a Class A/B amp, may deliver higher powers into successively lower impedances. NB: There is no amplifier in this universe that can deliver a perfect doubling of maximum power into half the output impedance. What happens is that, manufacturers will typically build a (say) 100 Watt amplifier, but rate it at (say) 50 Watts. Krell did it with the original KSA50 amplifier. The KSA 50 was actually a 75 Watt @ 8 Ohms amplifier. Then, as internal losses of the output stages increased, due to higher current requirements, the amplifier appeared to double it's output with each successive impedance drop.

Great idea. My tip is that there will be no audible difference. For several reasons.

Logically, you'd think so. However, there are several problems with that system: Contacts: Every mechanical contact creates some distortion. Number of steps: I don't know how many steps the switch you mention possesses, but if it's significantly less than 128 steps, it's ultimate ability to correctly resolve a particular volume setting will be very much hit and miss.

Not a great idea, on several levels: 1) Constant volume control changes will be required depending on source selected. Mistakes WILL occur and this will risk speaker damage. 2) The volume pot used in the ME25 is the best available. It introduces no audible distortion.

Set the DAC output for full volume and use the ME25 to adjust the volume.

Me too, but I note that most of the ME25 has been untouched. All electros are originals (which were carefully designed and chosen by Peter Stein) and not some over-priced, over-rated and under-performing 'audiophile grade' components. This suggests that the mods have been restricted to wiring only.

IF the preamp works, then I think all should be fine. The internal wiring has been changed to a solid core, PTFE insulated type (I am familiar with this type of wire). Since this wire is fragile, then the point where the wires have been soldered to the connectors has been reinforced with what appears to be silicone glue. Provided the wiring is not unduly disturbed, all should be fine. The upper ribbon cable has been hard wired (it should have a plug-in connector) rather untidily. Again: If it works, then don't disturb it. I don't see that any of the changes will have caused a performance drop.

Winovate are the best guys to take your ME product/s to for service/upgrades/inspections. The pictured crate is a power amp crate. Likely an ME750 or ME850. It is not a preamp crate. I would estimate that your preamp dates to around 1996. It is a newer style, with the latest power supply. If it has not been upgraded since manufacture, I would encourage you to take it to Winovate for a full service/upgrade. This is not essential, but will result in a significant improvement in sound quality. The second pair of outputs can be used with a subwoofer. Ensure that the sub inputs are not parallelled. They must be isolated from each other. A simple multimeter check can verify.

All good. What would you like to know?