Why don't amplifier Companies use high end fuses?

I think we are all forgetting a major contributor to audio products -- logistics. It really depends on how critical this specific area is to an audio manufacturer. If we are talking about somebody like ARC (Audio Research) who is so critical about these things that they have to use a specific brand/type of solder, then the selection of fuse can also be a major contributor.

Wyred 4 Sound used to advertise "upgraded Furutech rhodium fuse" in their DAC 2 SE level, so the boutique manufacturers that use specialty fuses are out there. However, Wyred now only indicates "upgraded fuse" without specifying type/brand.

When an audio manufacturer needs to have a board manufacturer build xx number of boards for them to use when assembling/integrating their audio equipment, they don’t want to worry about sourcing a specific fuse type. I have talked to a boutique amp manufacturer who never knows what kind of capacitors will be available for his main power supply when he gets ready to do a manufacturing run on his amp.

When the sub $10 fuses are readily available at industrial manufacturing houses (such as Little Fuse or Buss), it becomes very easy for them to just assembly and ship. These fuses are most likely sub $2 at this point and time is money. Even at the price point of Krell or Parasound, an additional $50-100 for a fuse will affect bottom line, especially in amplifiers or devices that have multiple fuses. I know the Parasound amps have a total of 5 fuses (that’s $250-500 dollars that affect the bottom line, which is typically 50-60% or retail).  The additional time to order/unpack/insert custom specific fuses may also be a major contributor to a manufacturer who just wants to "get the amps out the door".

Possibly. It depends on how many fuses the fuse maker is able to produce. To further the logistics/sourcing issue, I ordered ONE specific size Isoclean fuse from a reseller. He did not have it in stock and had to go to his distributor who responded with "we have no idea when we are going to get another shipment from Isoclean". He then offered me the option to wait (could be 2 weeks, could be 6 weeks...?) or to get a Hi-Fi Tuning fuse at the same price.

Another time, I had tried to order 8 Synergistic fuses of a specific size and the reseller just did not carry that many at a time in stock. I had to wait for Synergistic to finish their production run before I got the order shipped.

Now try ordering 50 fuses of a certain type? 100 fuses? You could be stuck waiting 2-3 months for a production run to get your amps out the door. The Little Fuse / Buss are available anywhere/everywhere right now (or just order from Digikey’s stock of 2,000+). The alternative is to try to mass order a huge number of fuses from the fuse maker. This could overload them as they may not have the tooling to put out that many and still provide all current distributors/resellers their supply. Then the fuse maker can be burned when the audio manufacturer doesn’t order more within a certain time frame. (i.e. does anyone remember when Patron stopped supplying their tequila for a long time?) Then the audio manufacturer has another logistics point to make sure they have enough fuses in house to supply 4-6 months (or whatever) of production runs.

Of the consumers that buy stuff at the Krell/Parasound level, I bet that over 80% of them use the stock fuse. Heck, I bet over 50% still use the stock power cord (I mean, it’s just a power cord, right?!?!) lol

+1 @nonoise - completely agree.

I just had a fuse blow in my Krell and had to re-order another Furutech.  While I was waiting, I decided to put back in the stock fuse.  After 15 minutes, I literally could not listen anymore.  It was completely unlistenable!  I put in a spare Isoclean I had lying around.  While it did not have the resolution of the Furutech, it was so much better (significantly) than the stock fuse!!

Wow, this thread went to a black hole in a hurry!

Several things we need to be aware of:

- If you have looked inside a fuse (like the glass fuses), you will see a VERY thin wire. Say a 1 amp fuse. The internal wire is extremely small, something like 26awg or 28awg (not entirely sure). If this is for a preamp, would you ever put on a power cable smaller than 18awg? (that’s stock, and I don’t think they make them smaller). No, you would upgrade to something like 14awg or even 12awg -- so that there is less current restriction. All A/C has to go through this tiny wire, even if it’s less than 1" long.

- The wire in the fuse has electrical resonance as well. Different upgraded fuses will sometimes do things to combat this resonance. The same thing happens inside electrolytic capacitors (during charge/discharge). The material/filler used in capacitors has a definite affect on electrical resonance and sound quality. Poor resistance to electrical resonance in caps will result is harsh sound that lacks solidness.

- People who say that the fuse and power cords are not in the signal path are not entirely correct. The actual waveform signal that starts at the source is never the actual signal that makes it to the amp. For anyone who doesn’t realize this, the basic idea of a transistor or op amp circuit is to "regenerate" the incoming signal. It never truly "passes through". There is always a resistor that the signal passes through and then a opamp/transistor gain circuit. Well, the gain circuit uses voltage/current from the A/C power supply to re-create or "add to" the output voltage for the signal. The power cord and fuse has a definite impact to the quality of this power supply voltage/current.

- Since A/C power is used to create/add-to this signal, the type of power cord or fuse will definitely affect the "flavor" of the sound. Just like comparing gold-plated connector to rhodium plated. Comparing silver wire to copper wire, etc.

- There are things that our ears are hearing which we cannot measure for at our current level of technology. Granted, electrical engineers will "nay say" this, but ask yourself this: What can we measure today that we couldn’t measure 10 years ago? 20 years? 35 years? (when they were making tube based electronics).

Thank you @almarg.  I was going to comment as I can accept disagreements, but I cannot accept false statement about what I say.

That being said, I also have experienced the 2-3db effect when changing fuses or power cords or op amps.  I'm going out on a theory here and I'm sure there will be a lot of conjecture to this, but I believe this all has to do with how a particular circuit "slews" in response to the input waveform.  This also has mostly to do with digital sources (if we played from an analog tape, we probably wouldn't have this scenario). 

Waveforms from a DAC chip are always created by the DAC chip sending out flat-line DC at different voltage levels.  With a 16-bit CD, we have the ability to define 65,536 different possible voltage levels between the lowest point on a waveform and the highest point.  However, the output from the DAC chip is always DC (essentially a square-stepped waveform).  If we put a tap on the output of the DAC chip and look at the total waveform, it looks like a true analog waveform to us.  However, once you zoom into the waveform very closely, you will still see that it's just square-stepped DC at different levels.  You might have to zoom 1000% or more to actually see this.

The fight we have with any audio chain based on a DAC is to smooth out this square-stepped waveform so that it resembles a true analog waveform (with no steps).  This can be done by applying several/many op amp circuits.  The negative feedback capacitor value can affect how this adjusts the waveform as well.  Class A circuits are excellent for waveform "smoothing" as they have a very gradual response to the initial input and have more "decay" on the back side of the waveform.

When an op amp (or discrete circuit) responds to the square-stepped wave, it will try to "slew" up to proper voltage to generate this on the output.  As soon as it starts "slewing" it will draw voltage from the capacitors in a power supply.  Because the capacitor are "temporary" storage, the available voltage starts going down.  This is where A/C will start to flow in and restore any voltage in the caps.

Now, if a circuit responds too fast to the incoming "square-stepped" waveform, then it will try to reproduce that "square-stepped" effect as accurately as possible.  Slowing down the "response" to a change in input voltage is where want to go.

Different fuses can adjust things one way or the other.  For example, using a silver-based fuse can allow very fast and very high conductivity when the op amp circuit tries to draw from the power supply.  It will do as least amount of "waveform smoothing " as possible because it can respond and slew very quickly.  However, putting in a gold-plated Isoclean fuse can slow down the "initial draw" of current from A/C.  It's not the total amount of current we are limiting.  It is the "response of the initial draw" (like a water faucet slowly turning on until it get to full output).  The Furutech rhodium fuses behave in a different way.  They are quicker responding than the gold-plated Isocleans, but not as quick responding as the HI-Fi Tuning silver.  This slower response of "initial draw" can cause a more smoothing of the waveforms, causing us to get "louder noise".

It's all based on speaker drivers as well.  The square stepped waveform (when measure by a scope) can seem to be correct size, but when most of this is very fast slews to the next point where we have an area of straight DC, you won't get the volume that you expect.  Since what we hear as based on the speaker moving (i.e. response to "changes" in voltage), if there is any DC in the waveform, we will not hear it.

This also can explain why silver elements or op amps with extremely fast slew rates will tend to translate waveforms to be faster than what they really should be.

This is all theory based on what I have learned over the years, but I believe it can explain why one fuse will "sound louder" than a different fuse.

Couple extra comments:

My description of how the power supply works is not 100% completely correct. However, it was meant to give a "general idea" to those who don’t know.

Any sort of DC in a waveform is not good. The preamp and amplifier will still use "power/watts" to raise the voltage to the correct level and KEEP that voltage level. However, any sort of DC in the waveform means the speaker is NOT moving! Speakers only react to "changes in voltage". So, if there is DC in the waveform (even if it’s in tiny chunks and only makes up 50% of the waveform), then we will NOT hear it.

If there is still 50% DC in the waveforms, then the sound will indeed be about 3 db quieter. (essentially, half the power is being used to move the speaker - the other half of the power is used to keep DC at a particular voltage).

Also, changing the direction of the fuse could affect how the power supply does the "initial response to draw" from the A/C.

Yes, it's signed.  That means the values don't actually represent 0 to 65,536.  The values represent -32768 to +32767.  This represents the waveform on both the positive side as well as the negative side the waveform (mid point representing 0 volts).  When the 16-bit word is read, DAC knows to output 0 volts DC when the 16-bit data word represents the mid point.  However, it is still 65,536 different actual points of voltage.  It is not 8 bits positive and 8 bits negative.  An 8 bit word would only represent about 256 different steps and that is not nearly enough for audio.

I also never said it was not a "A/C" waveform (A/C meaning alternating current).  I only said it was not a true "analog waveform".  As opposed to a digital waveform, which is usually interpreted to be "square stepped" or "on/off" in most cases.

I'm going to politely state the above as known facts for everyone who doesn't know and not respond from a post that I see only as a troll intending to start a flame war.

@kosst_amojan

@geoffkait

The more I read posts, the more I see that you both like to flame discussions. If that is what you both want to do, there’s nobody here that will prevent you (unless forum administrators jump in).

However, please keep in mind that while you have the large number of posts you submit attacking each other, you are also attacking the OP by swamping their mailbox with posts that they probably don’t want. It is also frustrating to other users reading these discussions when the subject matter diverts into a flame war. You’re not just hurting each other, you’re hurting the OP and many other readers. If this is what you really want to do, I can’t stop you, but I hope you are aware of the impacts, especially to newer users who don't understand who you guys are.