audio research sp6/8--better than sp9?

[croft]

HI Audiophiles worldwide.Please help
I have noticed many reveiwers commenting about eraly arc desighns having a far better sound than the later"stripped down"hybrids like the sp9(which i own).
Anybody outthere have one of the early arc pre amps
The valve majick seems to be missing in these hybrids
Any thoughts much appreciated

[fdegrove]

Hi Croft,

Still battling in disbelief?

ARC SP10 was a good,probably the best they produced.
The SP6 and 8 were blown up versions along the theme of the Dynaco PAS3 IMO.

If you want to better that look at the Counterpoint SA 9 and if you want Glenn's answer to that you got this Mega-Micro which was the Britt answer.

Honestly:
do you know of a phone preamp sporting 4 dedicated xformers+rectification+valve regulation+dual mono built somewhere?
Does it sound like a pig's ear to you?
Does it hum?Is it unreliable?
Ever heard the dynamics this can pervey given the right source?

Can it be improved?
Probably.

Sell the ARC's,stop worrying and listen to music.

I'l ltell you straight:not many studios have such a good preamp.

Ciao,

[croft]

Many Thanks Frank for the reply to my post.

Thanks for the imfo about the counterpoint unit.
I have an arc sp9 unit and had niticed the adds on ebay usa for the sp8 and 6 which go for good prices.

The croft unit is very special,and is very good.
The only thing i noticed was that the arc gear has higher grade caps,the soundtage cannot compete with the croft but the caps can certainly be heard.

I was looking to sell the sp9 and go for an all valve sp?as i also have arc dac-1 and oracle delphi which are all brushed alliminium.

Thanks for the imfo on the croft sometimes i dont realize how lucky i am to have this item.
In the long run i will probably end up completely stripping an arc unit just for the case which i really like,then have the mega micros top box fully upgraded and placed in its new home.
I could always get hold of a cheap case to re house the arc unit.
I like the concept of hybrid desighns,the arc sp9 gear does seem to have many shortcomings,the bass is very tight and fast but there is a hard edge to the sound and very"mechanical"
The counterpoint sounds cool
The arc unit has one valve and this is shared and then solid state components are implemented for output,

Will still keep the croft as like you say Frank,its amazing.
Cheers,
Ian.

[Peter Daniel]

You can improve the sound of the preamp by paying attention to arranging proper placement. Use good support, solid shelves and racks, you can substitude original feet with better ones (I like acrylic recently) and put some damping sheets on top panel. You might also try spikes. Check my thread here dealing with those issues.http://www.diyaudio.com/forums/showt...&threadid=5903

[croft]

Many Thanks peter for the exellent imfo and cool pics.

I am a keen hi fi modder and like to try many tweeks,
I have tried spikes underneath the arc sp9 and it did make a huge improvement,arc standard supports are really rubbish and hinder there desighns.

I once heard that sorbethane was a good product to absorb vibration.I also have an earth spike in the garden which is run to the mains.
Youre concept of the spike looks really intersting,i tried some concrete blocks for my valve power amps(leek 20 x 2)and this worked a treat,at the expense of a nearly broken back when i tried to lift them.

Thanks for the imfo
much appreciated,
Ian.

[fdegrove]

Hello,

In the long run i will probably end up completely stripping an arc unit just for the case which i really like,then have the mega micros top box fully upgraded and placed in its new home.

If you allow me to give some advise:

By gutting the SP9 it will loose any resale value and fitting the two chassis Croft Mega Micro in there will require major surgery and it will still show the ARC inscriptions on the frontpanel.

Here is what you could do : ask Mike to return your Croft preamp to Glenn so he can then do component upgrades and transplant the unit into the new (and much nicer looking) units he's currently using.
It will then add new value to it and if ever you want to sell it you will still be presenting an original Croft unit.

As for the glare you notice on the ARC,I notice it too and it may come from the Sovtek 6922 they probably use.
If you can replace it with an NOS E188CC you will find that most of it will vanish.
It benefits from a good isolation scheme as Peter Daniel has suggested.

Just my thoughts,

[slydwz]

The topologies between the SP6/8/dyna PAS were basically the same with the addition of a cathode follower to the ARCs. This is in no way trivializing the ARC, as all manufacturers do follow similar paths (in solid state land you see the same basic layout
in most amplifiers). The SP8 was about the same as the last iteration of the SP6(I believe it was the "E" version), with an op amp based low impedance power supply and a few other minor revisions (note the SP8 uses a tube rectifier). I have never auditioned an SP9, however the 6 and 8 are excellent preamps.
I have an SP8, and a 30 year old D76A which is quite wonderful.

[slydwz]

Oops! Must be getting senile (yeah, I'm getting up there). The
SP8 does not use a tube rectifier, the PAS does. The SP8 uses
"glass" as the initial regulation. Sorry for the miscue.

[croft]

HI Slydwz and Frank,
Many Thanks for the great imfo.
Thanks Frank for the options on the croft pre I was originaly just going to have the top box of the mega micro converted into the new casework as this shouldnt be to bad,as for the front panel they are reversable or i could get the ink of that arc put on,also i like this front beacuse arc already has the holes and switches that would match the megas perfectly,good point though about the resale value etc I think that in the long run i cannot forsee myself selling the croft unit.

Thanks Slydwz for the greta imfo,i serached everywhere for imfo and couldnt find it untill i read your post.Interesting technology concepts,if you never tried an arc sp9 my advice would be to expect a "middle of the road"pre amp.
I noticed that when arc brought the unit out it was described as a more affordable arc pre,my question would be what does arc consider affordable? In uk this pre was £1800 new,hardly budget.Me and the the gentleman who posted me the brilliant imfo before on this site own a croft mega micro which for the money would possotively eat many pre amps out there for breakfast and retailed at roughly the same figure.
I do like the arc construction and component layout,however i am continuassly drawn to the notion that arc gear tends to be best if it was madebefore the sp9 surfaced.In stereophile review of 1987 the reviewr really disliked the sp9 and contacted arc themselves about the unit.
I have yet to hear there earlier desighns which on the surface seem to relate to the valve majick which is neither hear or there in the hybrid desighns,the bass is fast yes but everything else is far from the total freedom that one would expect for £1800
Thanks for the brilliant imfo,it is very usefull and learn something new yet again from this brilliant website and its members ,
Cheers,
Ian.