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Post by leonski on Jan 23, 2021 17:00:02 GMT -5
The 2 XPA-DR1 mono blocks are amazing. Glad I went with them. They sound brighter than the two Adcom 555's I was using as mono blocks. Much greater dynamic range, the bass is tighter and more prevalent. The Adcoms would heat up when loaded up where the DR1's stay cool at the high volumes. Glad I decided to go with the DR1's and not spend the money to upgrade the Adcoms. Of course the Adcom 555 heated up when working into 4 ohms. I doubt it was intended for such a load. And I'm also not surprised that you noted better results with a dedicated amp per channel and I'm not certain it was due to simply 'more power'. I've hardly ever heard anyone say a bridged amp sounded better than the UNbridged version. www.stereophile.com/content/adcom-gfa-555-power-amplifier-1989-measurementsStereophile measurments from 1989. 600 into 8 ohms 'bridged' would be about what it should do....... and note the tester had fuse failures when attempting 2 ohm loads at high power. The same as 4ohm bridged. |
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Post by routlaw on Jan 23, 2021 17:12:58 GMT -5
The 2 XPA-DR1 mono blocks are amazing. Glad I went with them. They sound brighter than the two Adcom 555's I was using as mono blocks. Much greater dynamic range, the bass is tighter and more prevalent. The Adcoms would heat up when loaded up where the DR1's stay cool at the high volumes. Glad I decided to go with the DR1's and not spend the money to upgrade the Adcoms. I've had my DR-1's and DR-3 for just over a year and continue to still be impressed with them. Normally when someone makes a comment about a piece of gear sounding brighter I take this as a derogatory remark about the components performance. Perhaps you didn't mean it this way, but I would like to address this concern for anyone else reading. Effectively I don't think these amps are brighter sounding, however they do have the ability to amplify any and all signals with the greatest amount of effortlessness I've ever experienced and this includes those octaves at the top end of the scale. From my experience a great many amps fall short in this regard, running out of steam with higher frequencies where congestion and compression become all too obvious. In many ways the DR series of amps seem to be almost chameleon like effortlessly amplifying anything that is thrown at them be it grandiose, good, bad or ugly. With really good recordings digital or analog these amps are very smooth and sweet at the top end, but with less than stellar recordings listeners will hear those issues within the recording. Other amps might congest these signals rendering them a tad less "bright" and and perhaps more rolled off instead. The DR series of amps convey a very lively and alive presentation with incredible dynamics, more than any amps I've ever owned and its been quite a few from some of the most venerable names in audio. However if there is something wrong upstream with the rest of your system these amps will let you know about it quickly. I love their light weight, efficiency and coolness working under the most demanding of loads. They never get warm to the touch while either my XPS-1 and XMC-1 will run hotter than all 3 of these amps put together. No small feat IMO. Thanks |
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Post by tomcheeser on Jan 23, 2021 20:31:03 GMT -5
I meant the DR-1's "sound brighter" in a good way. The Adcoms were 30 years old. I bought them in 1990. I'm sure the capacitors were tired and needed replaced, which made them sound dull.
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Post by leonski on Jan 23, 2021 20:45:05 GMT -5
I meant the DR-1's "sound brighter" in a good way. The Adcoms were 30 years old. I bought them in 1990. I'm sure the capacitors were tired and needed replaced, which made them sound dull. The caps which probably needed a 'rest' would be the big PS caps. Some even number of 'cans', at least 4 and maybe as many as 8 ..... For example? I'm bringing an ancient (maybe late 70s?) Kenwood KA7100 back to life. The 'big' PS caps are from ELNA, a top-tier manufacturer. They are 50v, 6800uf and STILL available. However? For test purposes, and after an inspection, it fired right up. No leakage or bulging of those caps or it woudn't have gotten that far. Now? Noisy switches and that sort of thing....but the amp and preamp are FINE. Nelson Pass, the designer of the original 555 claims such big PS caps should go 30 years. And yours? Unless abused and since they are used regularly, should go at least that long. The couple Photos I found show 4 large caps connected by bus bars. BE CAREFUL if you open to replace or inspect. This is something a reasonable amateur can do. In your case? But 105 c rated IF POSSIBLE since you are a power user and clearly run the amp to the edge of its specs / abilities. |
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Post by tomcheeser on Jan 23, 2021 20:57:56 GMT -5
I was going to have John Hillig at Musical Concepts upgrade the 555's. After a lot of research, i decided to go with the DR1's. Was also looking at Big Sky Audio.
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Post by leonski on Jan 23, 2021 21:57:57 GMT -5
I was going to have John Hillig at Musical Concepts upgrade the 555's. After a lot of research, i decided to go with the DR1's. Was also looking at Big Sky Audio. Just get the 4 PS caps replaced. From the pics? Can't take more than an hour....and the parts are commodity cheap. Big problem will be finding a near-exact replacment. Capacitance and voltage? should be no problem....dimensions may be a little different today. And the connections? The pics look like 'screw in' connectors......Also not rocket science. If you want some help finding the part? Write me a PM with exact value / voltage / temp rating and I'll see what I can dig up. A pic would be nice, too as well as aprox size....height and diameter. |
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