@tomic601
......so these A/B
can describe some of the switch gear involved as a DIY project
In essence one takes one or more relays and switches a single speaker (or pair) from one amplifier to the other. That is simple. However the output levels, using pink noise, must be closely matched within 1/4 dB or better. It is well known that if one amp plays louder than the other the louder one will be preferred. Its a well known trick on how to sell the inferior product, just play it a little louder, but not enough to make the volume difference audible.
To match levels you need a pot that switches also, or the pot need not switch if the amps are ok playing unloaded, which most are.
What is hard to deal with is all the wires and little things like the long wire to the button, matching levels, checking and double checking everythings.
However this is how I evaluate my amp, my mods and other amps. I am starting to mod some popular amps that I feel I can improve. This is a new area of interest for me and I want to make sure I am not going backward. Therefore I leave one channel (or one mono) stock and compare it to my mod.
One has to know what one is looking for and what kind of music at what level will expose the differences. I try as wide a range of music as any listener might himself. Only 1 of 10 CDs I find to be useful. Some are horribly compressed, some already muddy, some dont have the right kind of instruments. For instance a harpsichord is not going to reveal distortion, Its already full of harmonics.
Perhaps here is a good place to modify my statement about the difficulty in designing amps vs preamps. Its not about the difficulty and I wonder who started that. Probably some self serving designer who doesnt know how to design a power amp. There are companies like that where their power amps do not exist or are just horrible. I simply find power amps more interesting to design so my work has focused there.
I think the RM-5 is one of the best full function 3 tube preamps out there. If I did it today, 37 years later, I would do it the same way. The RM-1 is lower distortion, wider bandwidth but a lot more complicated. I did not want to make 1,000 of something so complex, support it and deal with the people who buy the really expensive stuff. I wanted to make something that sounds good, works forever, is affordable and brings joy to the user.
I have had the opportunity to work on many higher end preamps and they are difficult, they go through tubes at an alarming rate, cause the owners much frustration and cost in keeping them going. Sadly they often don't sound that great either. If the phono EQ is fudged thats a no no.
can describe some of the switch gear involved as a DIY project
In essence one takes one or more relays and switches a single speaker (or pair) from one amplifier to the other. That is simple. However the output levels, using pink noise, must be closely matched within 1/4 dB or better. It is well known that if one amp plays louder than the other the louder one will be preferred. Its a well known trick on how to sell the inferior product, just play it a little louder, but not enough to make the volume difference audible.
To match levels you need a pot that switches also, or the pot need not switch if the amps are ok playing unloaded, which most are.
What is hard to deal with is all the wires and little things like the long wire to the button, matching levels, checking and double checking everythings.
However this is how I evaluate my amp, my mods and other amps. I am starting to mod some popular amps that I feel I can improve. This is a new area of interest for me and I want to make sure I am not going backward. Therefore I leave one channel (or one mono) stock and compare it to my mod.
One has to know what one is looking for and what kind of music at what level will expose the differences. I try as wide a range of music as any listener might himself. Only 1 of 10 CDs I find to be useful. Some are horribly compressed, some already muddy, some dont have the right kind of instruments. For instance a harpsichord is not going to reveal distortion, Its already full of harmonics.
Perhaps here is a good place to modify my statement about the difficulty in designing amps vs preamps. Its not about the difficulty and I wonder who started that. Probably some self serving designer who doesnt know how to design a power amp. There are companies like that where their power amps do not exist or are just horrible. I simply find power amps more interesting to design so my work has focused there.
I think the RM-5 is one of the best full function 3 tube preamps out there. If I did it today, 37 years later, I would do it the same way. The RM-1 is lower distortion, wider bandwidth but a lot more complicated. I did not want to make 1,000 of something so complex, support it and deal with the people who buy the really expensive stuff. I wanted to make something that sounds good, works forever, is affordable and brings joy to the user.
I have had the opportunity to work on many higher end preamps and they are difficult, they go through tubes at an alarming rate, cause the owners much frustration and cost in keeping them going. Sadly they often don't sound that great either. If the phono EQ is fudged thats a no no.