Tim F

Who modifies hifi on here?

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Modifications are a nightmare as one man says one thing and another says something else.   I would only consider modification as an option if I was resurrecting an amp that had blown up.  My only close experience of a modified amp compared to the bog standard was when a guy brought in his Ear 509s that he had rewired with silver wire internally.   It sounded worse than the bog standard dem ones we had.  Now whether it was his rewiring or if he had changed some of the tubes and not rebiased buggered if I know .. but it did worry me that an amateur would take a Paravicini designed and built amp and think they could improve on it.  I have to smile when people challenge Rabski in here on his views when he has built and repaired valve amps for a long time.

I think you have to be careful of mods - my analogy would be people with cars making modifications that add nothing to performance, could make it dangerous and in some cases a set of 4 alloys on the car that are worth more than the car itself with boots on it that are substandard.

If it floats your boat then fine but it is something perhaps that needs a thread in DIY and not in here?

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Super Wammer

I have two modified Quad 405 amps . They have been completed by Fidelio strongly based on the Netgear Mods . They sound in my view much better than a standard 405 . As they are used as the active amplifiers in an active speaker that I suppose with a strong prevaling wind i could say i modified myself they are also identical units which means they save lots of faffing about trying to balance them for any issues. I use them one per channel (one for the left speaker treble and bass and one fr the right speaker treble and bass) they make great music .

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The few 'modifcations' that I have carried out on hi-fi for people have mainly been to turn them back to standard when some clueless bodger has put in some pointless and usually badly installed "upgrade" that has then damaged the equipment!

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On 12/09/2019 at 18:09, rabski said:

Not only noise I agree (resistors), but that certainly counts. I've never seen anything published and life's too short to even think about experimenting here, but like caps, I wonder if there is a frequency-related factor.

Actually, all types of resistors drift, though it's only generally carbon composites that do so substantially.

It's never worried me to be honest. The best thing about DIY is that it's financially feasible (most of the time) to use good components.

The sound of components is a mystery to me. I've taken ESR measurments at various frequencies with polyprop caps and they all measure the same and yet sound very different. I should try frequency response measurements really...

When you say all ressitors drift are you talking about temperature coefficient?

Yes, I like the fact that I can spend whatever I like on components, i've just learnt over the years that price and sound quality don't go hand-in-hand (I'd never waste my money on Mundorf silver/gold/oil caps again)

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5 minutes ago, Fatmarley said:

The sound of components is a mystery to me. I've taken ESR measurments at various frequencies with polyprop caps and they all measure the same and yet sound very different. I should try frequency response measurements really...

When you say all ressitors drift are you talking about temperature coefficient?

Yes, I like the fact that I can spend whatever I like on components, i've just learnt over the years that price and sound quality don't go hand-in-hand (I'd never waste my money on Mundorf silver/gold/oil caps again)

Circuits matter more than anything. Ironically, my cheap phono stage sounds significantly better in terms of treble extension and bass definition with Mundorf silver/gold/oil than with some other comparatively costly caps.

For resistors, age as well, though I agree that it's relatively minor. Vishay publish it for the SMD metal films, but it's only a percent or so over a long time (8000 hours) so no greater than the original tolerance. I'd always allow for 5% in calculations even when using 1% components, but it rarely matters. The only place I would be concerned about it is in RIAA circuits, where closest possible match is ideal.

Price and quality absolutely don't accord, at least not always. I can recall an extremely costly 'foo' resistor in a pal's amp build that turned out to be the cause of serious noise problems. One £56 resistor swapped for a £5 Mills wirewound and problem solved...

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I have just done a mod to my quad iis, I think it sounds better, but it might be expectation bias..........

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Deco Audio in Aylesbury are excellent on modding valve and transistor gear. They have done work for me and a friend. 

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