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Old 24th May 2010, 06:16 AM   #11
UV101 is offline UV101  England
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Ok sorry :-(
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Old 24th May 2010, 07:36 AM   #12
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That's you told Ian LOL.

But you have found large gains from these upgrades which proves there were issues with the original design and you have sorted them out. I think thats the point to upgrading, you can start with something cheap or not as good as it possibly should be and make it much better.

Brent
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Old 24th May 2010, 08:16 AM   #13
SimontY is offline SimontY  United Kingdom
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This guy thinks Arcam make good amps, hmmm. Arcam CD players are good, but their amps were the worst I heard when I last bought one new a few years ago. They sounded dull and shut-in compared to offerings from MF, Rotel and Roksan.

The point made is maybe why we don't see many Resteks.

But that's beside the point really, yours is totally un-standard now and clearly loads better for it!!!
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Old 24th May 2010, 02:51 PM   #14
UV101 is offline UV101  England
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Quote:
Originally Posted by HornTube View Post
It is frustrating to see Brits fumbling with a nasty music-killer-rip-off-amp like Restek. You have Arcam, Creek, MF, Mission, Sugden etc. Offense is not intended here but Restek is one of the worst manufacturers I know - it sounds even worse than Burmester!

Regards
So, I have an amp that cost approximately £2000 which sounded pretty good to my clearly untrained ear when new. I have now changed all the caps and effectively rebuilt what was admittedly a poor pre-amp stage. I have shared my proud achievement with the rest of the DIY community.

My Thanks are
Quote:
Originally Posted by HornTube View Post
It is frustrating to see Brits fumbling with a nasty music-killer-rip-off-amp like Restek. You have Arcam, Creek, MF, Mission, Sugden etc. Offense is not intended here but Restek is one of the worst manufacturers I know - it sounds even worse than Burmester!

Regards
1 I am not fumbling
2 nasty music-killer-rip-off-amp (your very offensive opinion)
3 Arcam, Creek, MF, Mission,Sugden - in the most part the later amps are very poor. (note I said in the most part)
4 Offense is not intended here but Restek is one of the worst manufacturers I know - it sounds even worse than Burmester!
How the f*ck can that not be offensive when i'm proudly displaying my achievement.

Regards to you too
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Last edited by UV101; 24th May 2010 at 03:04 PM.
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Old 24th May 2010, 07:15 PM   #15
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Just tried to say that it would be more effective to mod a better amp, sorry if I'm sounded too aggressive. I apologize.

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Old 24th May 2010, 10:10 PM   #16
UV101 is offline UV101  England
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Hi Horn Tube,

I guess something is lost in translation.

I do have to say, I'm not really finding a problem with this amp. Its really quite good now its modified, and the build quality is very good too! (typical German engineering) :-)

Ian
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Old 26th May 2010, 02:06 AM   #17
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Well, the parts are squeezed together a tad too much. The input sockets are nasty cheap. The cabling looks chaotic and an Alps pot at that price range...

Restek generally has a tendency to sound 2D and sharp - quiet unbritish. I would strongly recommend to use Nichicon Fine Gold and/or other Nichicon & Elna caps. Rubycon is too open and bright for this amp. I guess Panasonic FC or FM is not enough to tame this amp. Please use british caps for the large ones maybe Nichicon or Epcos will do too. More bias for the output stage! Panasonic pot instead of the nasty muddy dirty & nervous sounding Alps. Cardas Silver/Rhodium RCA sockets will bring back some body & authority if you want it darker than you can use WBT (speed loss). I would be careful with doubling the cap values, this has a tendency to sound slow and shut-in. Even technically seen - this can be a disadvantage.
Good luck.

Last edited by HornTube; 26th May 2010 at 02:29 AM.
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Old 26th May 2010, 02:23 AM   #18
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Just forgot, the big white ceramic resistors are really nasty. They are in the 0.1 - 1.0 Ohms range I guess.

At this price range... Sorry but even the cheapest british amps do have better parts - fact. German HiFi does have a strong tendency towards rip-off. Please don't get upset, I'm just trying to be realistic.

I would change the ceramic resistors to MPC or Rosenthal or Isabellenhütte or the big black US resistors with silicone coating - forgot the name.

Last edited by HornTube; 26th May 2010 at 02:33 AM.
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Old 26th May 2010, 07:39 AM   #19
UV101 is offline UV101  England
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Quote:
Originally Posted by HornTube View Post
Just forgot, the big white ceramic resistors are really nasty. They are in the 0.1 - 1.0 Ohms range I guess.

At this price range... Sorry but even the cheapest british amps do have better parts - fact. German HiFi does have a strong tendency towards rip-off. Please don't get upset, I'm just trying to be realistic.

I would change the ceramic resistors to MPC or Rosenthal or Isabellenhütte or the big black US resistors with silicone coating - forgot the name.
I will take a look at those resistors for sure.

All of the internal power stage caps have been changed to FM (were BC) and the results are very good. The opamp on the power stage (I'm unsure of its function without a diagram) has been changed from BB604 to LME47910HA and this has been decoupled with Nichicon. I also repalced the elco's for DC blocking with Wima MKS2.

The main smoothers are replaced with F&T SI and been changed from 10,000uF per rail to 20,000uF per rail. I beleive this has been responsible for the huge leap in dynamics!!!

The origianal preamp consisted of a Buffer (BB2604) and gain stage (BB2604) the Blue Alps pot and a final gain stage (BB2604).

I have bypassed the 1st buffer stage and replaced the remaining 2 BB2604's with Burson discrete opamps. The result is that the entire preamp stage is now discrete. The Bursons are decoupled with a mixture of Black Gate and ZA. I have to say I'm very happy with the results so far.

It is indeed on my list to replace the horrid input phono sockets with something like CMC silver over copper for the 1st 2 inputs at least

You seem to be very well informed on this amp. Do you have a schematic in particular of the power stage? You also say that I should raise the bias. Can you provide details of how I can do this.

All in all, I really like to look and feel of this amp.

Many thanks

Ian
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Old 26th May 2010, 08:23 AM   #20
SimontY is offline SimontY  United Kingdom
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Interesting ideas coming out I see. I had no idea anyone disliked the Alps Blue pot. I use one in my preamp and I'd often wondered if there were gains to be had from upgrading - but I only see very expensive options.

Any pot recommendations from Mr HornTube? And don't say Moroccan Black or White Widow
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