Does anyone care to ask an amplifier designer a technical question? My door is open.

Roger
this is related to a question you raised in past post on subs and remote controls.

ramtubes - The amp is any old SS 100+ watt amplifier. Currently a nothing special Denon. The woofer level control is on the crossover.

This solves a lot of problems with powered subs. Unless they have a remote (do they now?) it is difficult to adjust the level for different CDs,

Firstly I Agree, especially if someones subs are setup in typical fashion across the room with the main speakers.

My solution
I am using for the last two years, two Dynaudio BM12s studio subs in Room B with my Wayne Picquet restored Quad 57's. They (BM12s) are one example of a solution with a credit card sized remote control that handles db and crossover levels, phase, and allows you to save 4 settings. Classical is typically a higher DB setting then compressed popular music.
The BM12s are handling 60 hz and down and the RM10 has full control of the 57's. The subs come with their own Class A/B amps and on the boxes are heat sinks. Mine are now positioned on either side of the listening couch. This allows for the db levels to be set the lowest, phase 180. The sub amps heat sinks don't even get warm. Very little vibration from the boxes.

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We last conversed about a year ago when I inquired about slope cards for an RM3 that I own. I was thinking about a project to bi-amp my Matrix 800's at the time.

btw - A nice surprise coming back here for winter conversations to find you have the most popular thread on Audiogon. 8^)

Cheers Chris

@ct0517 - nice set up. I sometimes use my RM-10 with my ESL 57s in biamp set up. The Class AB amp I use for the bottom is a Luxman M-02. I use the Beveridge RM-3 (no remote) to crossover at 100 Hz, 4th order crossovers for both high and low pass. Rather than two woofers I use four in an asymmetrical array. I am curious how you settled on the 60 Hz cutoff and what other levels you may have experimented with.

I have an amp maintenance question, if I may.

I favour amplifiers that are either Class A or at least have very rugged power supply capacity (I use several Classe DR3 VHC, a Belles A, a Rowland 5).  What are the symptoms of the supply caps being on the way out and at what general age do they become seriously at risk?  The Classe amps, for instance, are hitting 30 years old now.



Got into these way back to be able to drive 1 ohm speakers but stuck with them after speaker changes as I love the sound.

What are the symptoms of the supply caps being on the way out and at what general age do they become seriously at risk?

Sometimes caps can last a very long time, depending how hot they got how close to the limit the voltage was ect ect.
Look for bulging.
http://embedonix.com/wp-content/uploads/2015/09/good_bad_ugly_capacitors.jpg
Top Leakage
http://www.southseascave.com/wp-content/uploads/2014/12/IMG_1820sml.jpg
Base leakage
http://protectyourpower.com.au/wp-content/uploads/2016/05/Brisbane-Airport-UPS-Call-1.jpg

Cheers George

What is the role and importance of significantly upgraded power cords in component design? It seems to me that the PC is a fundamental part of the electronic device and that the manufacturer should optimize the cord for the device in building it. What are your thoughts on the matter as someone who actually builds electronics?

There is a voltage drop across any power cord that can influence the output power of the amplifier. What is less well understood is that it can affect distortion too. Much depends on the amplifier design of course, but these effects are measurable and no surprise in some cases that they can be heard too.

Question about the effects of different impedance settings and phono cartridges.

The loading is there for the preamp, not the cartridge! I know this sounds counterintuitive but here's how it works:
The cartridge has an inductance and the tone arm cable has a capacitance (along with the input capacitance at the preamp). Together they form a tuned circuit. With a Low Output Moving Coil cartridge, this resonance can be at several MHz. If the preamp is unhappy about Radio Frequency Interference (RFI) at its input, it will affect the sound- the additional distortion will likely make it bright. The loading resistor detunes the resonant circuit and thus prevents the RFI. Problem solved?
The downside is usually two things: 1st, by loading the cartridge in this manner you are causing it to do more work. The energy has to come from somewhere and that means the cantilever will be more stiff- less able to track higher frequencies! The second problem is that (generally speaking) a preamp that requires loading to sound right probably also has stability issues, usually because the designer hasn't sorted out the facts in the 2nd paragraph below your quote. This instability often results in excess ticks and pops that **actually would not be audible were the preamp actually stable**!

This latter fact comes as a surprise to many people, but when you are exposed to a stable phono circuit, it is very relaxing to not be hearing so many ticks and pops. This has nothing to do with bandwidth BTW. For more on this seehttp://www.hagtech.com/loading.htmlandhttps://www.whatsbestforum.com/threads/cartridge-loading-a-misnomer.15077/