damacman
Resident Psycho
Mine has these.
MAC 1500 Owners Thread
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Mine had those. One was getting weak after 50 years of service. I looked around for a while and found a matching quad set of Westinghouse made tubes that tested as new.
Boy, the improvement in sound was startling!
My mighty MAC bench tested at 39/40 wpc.
That's pretty impressive. When HF reviewed a brand new MAC1500, they came up at 33/34 wpc from 22-20k cps while meeting THD spec. Mc specs rates it at 30 wpc @ 0.5% THD 30-20k in their conservative tradition. Personally, I never found tube brands to make much audible difference in Mc.Mine had those. One was getting weak after 50 years of service. I looked around for a while and found a matching quad set of Westinghouse made tubes that tested as new.
Boy, the improvement in sound was startling!
My mighty MAC bench tested at 39/40 wpc.
Keep in mind that mine has the Modafferi mods. One of the things he does is improve the power supply.
I believe the vintage 7591 tube can make 28 watts.
So, 39/40 wpc is still under the tubes capability.
damacman
Resident Psycho
Nice!!Mine had those. One was getting weak after 50 years of service. I looked around for a while and found a matching quad set of Westinghouse made tubes that tested as new.
Boy, the improvement in sound was startling!
My mighty MAC bench tested at 39/40 wpc.
Apparently this is a very low hours unit and all tested very strong. Unfortunately, I have no way to test them myself.
I've seen a lot of 7591s, never a matched quad of these.
I shortened my coax to 75 ohm input by a few inches. It made a difference on a few stations: MPX light is brighter, stations locking into stereo better.
Spent most of the time yesterday listening to vinyl.
McIntosh did a great job designing the phono input on this MAC.
Spent most of the time yesterday listening to vinyl.
McIntosh did a great job designing the phono input on this MAC.
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Pulled the SL-1100A out of mothballs! It’s got an NOS Denon DL-160 on it. Great combination.
That’s hooked up to the phono 2 input. My MMF-7.3 is hooked up to the phono 1. Both sound great.
The MAC phono design is plus/minus .5 db of the RIAA curve from 20hz to 20k hz.
That was incredibly back then. A lot of equipment back then was 2 to 2.5 db plus/minus off the curve.
That’s hooked up to the phono 2 input. My MMF-7.3 is hooked up to the phono 1. Both sound great.
The MAC phono design is plus/minus .5 db of the RIAA curve from 20hz to 20k hz.
That was incredibly back then. A lot of equipment back then was 2 to 2.5 db plus/minus off the curve.
Scored some AR Pro Series II 12 gauge speaker wire. The positive and negative is separated by 3/8 for less capacitance. That’s important to me because of the 25 feet run to the speakers.
Found spade lugs that fit too! I biwired the Vandersteen 2Ce Signature II speakers. Yes, all the ends have gold spades that are correctly crimped using a Klein crimper.
Found spade lugs that fit too! I biwired the Vandersteen 2Ce Signature II speakers. Yes, all the ends have gold spades that are correctly crimped using a Klein crimper.
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I gained in the damping factor by going 12 gauge from 16 because of the required 25 feet!!!!!
The MAC1500 has about a 13 damping factor. A long run of 16 gauge drops that to 6. Supposedly I’m around 10.5 with the 12 gauge.
I can hear improvement in the bass, but realistically that’s about it. I might do critical listening to certain LPs that I have, or better yet, just enjoy the heck out of it!!!!!!!!
I’m really curious to see the math behind this.
I now see why you feel that you’re decreasing your damping factor, you’re adding wire resistance into the denominator (source) where it is part of the numerator (load).
The damping factor of the MAC1500 (advertised at 10 or “greater than 10”), is not decreased by lowering the load resistance. DF of an amplifier is calculated at the rated impedance (in most cases 8 Ohm) load and is a ratio thereof. As the load impedance decreases, the calculated damping factor of the amplifier would also decrease, therefore lower resistance speaker wire would lower the damping factor of the amplifier by a small amount. It is either way a very low damping factor by most standards other than SET amps. Fortunately, your speakers (I don’t have an impedance curve in front of me but, …) probably don’t dip down below 8 ohms in the bass region, more likely at the crossover point.
I suspect that if you’re truly hearing a difference, it is due to the change that you made from the 8 Ohm output taps to the 4 Ohm output taps. If you like the difference then nothing else really matters.
I’m also curious, seeing “12 GAUGE” on the jacket, whether this is different from 12AWG or not regulated the same. Probably more clear to audio types who might not understand AWG and doesn’t need to meet any electrical code.
The damping factor of the MAC1500 (advertised at 10 or “greater than 10”), is not decreased by lowering the load resistance. DF of an amplifier is calculated at the rated impedance (in most cases 8 Ohm) load and is a ratio thereof. As the load impedance decreases, the calculated damping factor of the amplifier would also decrease, therefore lower resistance speaker wire would lower the damping factor of the amplifier by a small amount. It is either way a very low damping factor by most standards other than SET amps. Fortunately, your speakers (I don’t have an impedance curve in front of me but, …) probably don’t dip down below 8 ohms in the bass region, more likely at the crossover point.
I suspect that if you’re truly hearing a difference, it is due to the change that you made from the 8 Ohm output taps to the 4 Ohm output taps. If you like the difference then nothing else really matters.
I’m also curious, seeing “12 GAUGE” on the jacket, whether this is different from 12AWG or not regulated the same. Probably more clear to audio types who might not understand AWG and doesn’t need to meet any electrical code.
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You need a wood case to spend your cash flow on.
