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Audio Research LS7 - Recapping ????

kash

kash

pfm Member
Just received this ARC LS7 pre amp and taken a look inside. The person that recapped it was definetly on a mission.....why so many, what are they doing, big cluster of caps to the left???? Looks like it's had a new power lead as well. So many questions!

It will be a few weeks before I can fire it up and hear what it sounds like. Are the Brimar valves any good? not really after warm, more detail and punch would be my preference. Picture of a stock LS7 included.

https://live.staticflickr.com/65535/53501461307_79e55acfb1_h.jpg
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Only thing I can presume is that they've replaced all (or as many as they can) of the electrolytic caps with Polypropylene ones. Polyprop are supposed to sound better.
 
Brimars are great sounding. Their ECC81 beat out Telefunken and Mullard in my SE EL84 unit.

Perhaps consider doubling up on the O-ring dampers.
 
gez said:
Only thing I can presume is that they've replaced all (or as many as they can) of the electrolytic caps with Polypropylene ones. Polyprop are supposed to sound better.
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They are different though. A capacitor is never just a capacitor, never just a theoretical ideal. It impacts the circuit in other ways other than capacitance. Things like that always fill me with dread as 99.876% of the time they have been added by someone who is not an amp designer, will never be an amp designer, and purely because they are expensive and some hype on the internet said they were “better”.

If it was mine I would restore it to as close to factory spec as I possibly could. That is the way I approach any vintage audio these days. I’ve heard enough bad 3rd-party modifications and made a few myself to know it is just not a good direction unless you *really* know what you are doing. A lot of people who claim to know what they are doing really don’t IMHO.
 
The original coupling and decoupling capacitors used by ARC have been replaced with coupling caps made by Hovland, obviously, and because the Hovlands are much bigger, who ever did it, had to find room to fit the larger caps. Also I suspect they bypassed the coupling caps, hence why there are several caps stuck/glued/cable tied together. The two banks of caps stuck to the left side of the chassis I suspect are wired to bypass the two power supply electrolitics. Bypassing was a fad many years ago to improve the high frequency performance of larger value capacitors. With a revealing system you can hear this actually degrades the sound as the frequencies are altered as they pass through each capacitor. In the realm of coupling capacitors, Hovland are not that good, well certainly not by todays standards.

As Tony said, its probably best to put it back to how it was. At least that way it will have more value when you come to sell it and it will be as the original designer/maker intended it to sound.
 
I’ve done a fair bit of recapping valve amps. My concern with that unit would be the flying leads on those Hovlands which are very long. They tend to act like antenna and can cause problems with hum and even instability. A few years ago a built an EL84 amp point to point wiring and did a lot of cap changes. Anything with flying leads induced problems. It’s not a dead cert in every amp though but best avoided. If the two big electrolytic caps are original I’d definitely change those. Anyway hopefully all is well with the unit. Brimar as are nice but might be useful to have them checked.
 
Tony L said:
They are different though. A capacitor is never just a capacitor, never just a theoretical ideal. It impacts the circuit in other ways other than capacitance. Things like that always fill me with dread as 99.876% of the time they have been added by someone who is not an amp designer, will never be an amp designer, and purely because they are expensive and some hype on the internet said they were “better”.

If it was mine I would restore it to as close to factory spec as I possibly could. That is the way I approach any vintage audio these days. I’ve heard enough bad 3rd-party modifications and made a few myself to know it is just not a good direction unless you *really* know what you are doing. A lot of people who claim to know what they are doing really don’t IMHO.
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Yeah exactly. Thus the "supposedly". I would be doing the same too, putting the amp back to stock. I mean it's not like AR have a rep for sounding bad is it? (I mean if you're in to Valve of course).
 
You may or may not like the ARC sound but they bypass all coupling and PSU caps IME. They don't use flying leads tho....
 
Juancho said:
You may or may not like the ARC sound but they bypass all coupling and PSU caps IME. They don't use flying leads tho....
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I agree. It's a standard practice for ARC to bypass PSU and coupling caps in all their designs. As far as I know the new Gold coupling caps in reference line are not bypassed. Hovlands are not everyone's cup. They were in "vogue " 20 + years ago touted as the best. I had Hovland tube preamp and it was very good. It was designed around those caps. I have a set of Audio Matiere Paraphrase pre and Equlibre amp and they use Wima MKP bypasses on PSU and Wima couplers bypassed by Hovlands.They are OK together but not that great separately. They are now in " collectible " category so it would be unwise to alter the design but every time I'm listening to the Equilibre amp I have desire to yank out those Hovlands and put some less " high resolution " types. I really like Electrocube caps like those used in Lamm amps but they are not available for hobbyists.
 
Pirx said:
I agree. It's a standard practice for ARC to bypass PSU and coupling caps in all their designs. As far as I know the new Gold coupling caps in reference line are not bypassed. Hovlands are not everyone's cup. They were in "vogue " 20 + years ago touted as the best. I had Hovland tube preamp and it was very good. It was designed around those caps. I have a set of Audio Matiere Paraphrase pre and Equlibre amp and they use Wima MKP bypasses on PSU and Wima couplers bypassed by Hovlands.They are OK together but not that great separately. They are now in " collectible " category so it would be unwise to alter the design but every time I'm listening to the Equilibre amp I have desire to yank out those Hovlands and put some less " high resolution " types. I really like Electrocube caps like those used in Lamm amps but they are not available for hobbyists.
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Many years ago, when I was having the DBL PAXO redesigned, I decided to try out the Hovland caps in the midrange section...which requires 30uF per side. So I got six 10uF Hovland caps, priced around $75 each and had them put into my large prototype x/o, just next to some 30uF Solens, and arranged it so I could swap between the Solens (at maybe $25 per side) and the Hovlands (at maybe $200 per side) with a simple flip of a high quality toggle switch.

And there were no meaningful differences between the Solen and the Hovlands. But there was a very wide chasm between the Solens and the Cardas caps, that I experimented with in the HF network.

So the Hovlands are the same level of crapability as the Solens; and the Solens seem subjectively to have a peak at around 1-2k, making mids sound nasal and unpleasantly forward.

The Wima caps I have tried have always given a mushy sound.

The Mundorf Supremes were better than either the Solens or Hovlands, but still not as good as the Cardas.
 
Trust you have seen this:

ARCDB

The Audio Research Database (ARCDB) provides information about past and present products from ARC (Audio Research Corporation)
www.arcdb.ws www.arcdb.ws
 
Just reporting back on the heavily recapped AR LS7 pre amp. It’s taken me a while to finally fire it up after moving house. All I can say is it sounds pretty amazing paired with the AR D130 into Sounus Faber Sigmnus. The joke is that I’m using my Astel & Kern as a digital source….it shouldn’t sound this good! I’m looking at the Eversolo as source and DAC as a proper replacement. Anyone used one?
 
I use both Eversolo A6 and A8. The A8 replaced a Lumin U2mini and Soekris 2541 dac and I am very happy with it. I still have the Soekris, but I like keeping the system simple. The Eversolo connects wirelessly to the net, the app is very easy to use, I stream Qobuz and play my files from the internal storage.
 
Salamander said:
I use both Eversolo A6 and A8. The A8 replaced a Lumin U2mini and Soekris 2541 dac and I am very happy with it. I still have the Soekris, but I like keeping the system simple. The Eversolo connects wirelessly to the net, the app is very easy to use, I stream Qobuz and play my files from the internal storage.
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Thanks for the reply. Any real difference with the sound quality of the A6 DAC compared with the DAC in the A8?
 
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