I've just replaced the BAF wadding in a pair of my speakers with acoustic grade fibreglass (fiberglass in the USA), just for the sheer joy of it.
I think they sound better, but my wife has just said she can't make out the voices on the radio. Perhaps she's just being mischievous?
Fiberglass for speakers, but glass fiber for PCBs. English is a funny language.😉
Maybe it's your wife's subtle way of saying "Stop messing around with that audio stuff(ing)".😡
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I guess I've been lucky with the few pieces of NAD gear I've had since they seemed to be well made. Same for NAD pieces I've seen, pieces others I know own...
Amazing how a company with such slipshod quality has been able to hide it from us over the last forty years.
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Maybe some well-meaning but ignorant previous owner went around 're-flowing' all the solder joints, as recommended on some forums? 'Re-flowing' is a bad way to improve a bad joint, but can be quite a good way to damage a good joint - if that is your aim.
Just reflowing them is a waste of time as the flux is already burnt off.
Either reflow using extra solder or suck off the old solder then apply new solder.
I find components with large pins tend to go dry or break loose first. I have lost count of the number of TV scart sockets I have had to fix due to bad joints.
Until now I repaired all cold joints by adding new solder over the cracked joint solder so I did not sucked the old joint solder.
Also there is a risk of damaging the small diodes or those small tiny resistors because of heat generated by soldering re-soldering process ?
Also there is a risk of damaging the small diodes or those small tiny resistors because of heat generated by soldering re-soldering process ?
That can merely hide the bad joint.robert2017 said:
Yes. It all depends on your soldering skill and tools. You may damage the PCB too.
That's very serious
So should I suck the old joint and re-solder with new solder which also have 3% resin flux ?
I already heated some small resistors and diodes so maybe I should replace those small ones if I will repeat the melting process .
If the NAD is working properly, leave it alone. The more you do to it, the greater the chances of creating problems. True for you, me and everybody.
The 306 is a good unit, but like any piece (regardless of price), there comes a point where one needs to be content with the mods and starts a new project.
Many preamps from the late '70 to late '80s could benefit from new and upgraded components, mainly caps.
Here are some your style of modding could improve:
Adcom GFP-1/ 1A
Kenwood Basic C-1/ C-2
NAD 1020
The Adcom GFP-1 is right up your alley. Good discrete circuits and plenty of space on the board. They really cheaped out on caps. Not just quality, but the values are low for the supply. Replacing the electrolytic along with the ceramic and film caps makes a big difference in sound along with increasing the resale value.
The 306 is a good unit, but like any piece (regardless of price), there comes a point where one needs to be content with the mods and starts a new project.
Many preamps from the late '70 to late '80s could benefit from new and upgraded components, mainly caps.
Here are some your style of modding could improve:
Adcom GFP-1/ 1A
Kenwood Basic C-1/ C-2
NAD 1020
The Adcom GFP-1 is right up your alley. Good discrete circuits and plenty of space on the board. They really cheaped out on caps. Not just quality, but the values are low for the supply. Replacing the electrolytic along with the ceramic and film caps makes a big difference in sound along with increasing the resale value.
Some very constructive comments there PK.
Unfortunately, I haven't encountered the Adcom pre-amp. There's one currently up for sale via on-line auction in the UK, but it's to come from the United States.
Good advice, perhaps someone can suggest a UK friendly alternative for Robert to get stuck into?
P.S. The NAD 1020 is more easily obtainable and up for auction now.
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Have just realised that I may be talking rubbish (as usual!), as I've no idea where robert2017 is based! 😕
Thanks, Galu
I mentioned the Adcom because I know the unit and there is one area where replacing caps makes a noticeable difference and has a basis in electronic theory.
The output coupling caps for the line and phono stage.
Stock, there are 2 10uF polar electros wired in series with their terminals reversed.
+10uF--10uF+, cheap and dirty 5.0uF non-polar.
A Wima MKS-2 4.7uF fits nicely on the board and if anyone here is going to argue going from series electros to a single film can't make a difference...
I mentioned the Adcom because I know the unit and there is one area where replacing caps makes a noticeable difference and has a basis in electronic theory.
The output coupling caps for the line and phono stage.
Stock, there are 2 10uF polar electros wired in series with their terminals reversed.
+10uF--10uF+, cheap and dirty 5.0uF non-polar.
A Wima MKS-2 4.7uF fits nicely on the board and if anyone here is going to argue going from series electros to a single film can't make a difference...
I appreciate why you made that choice. You've made a positive input that would appear to be in line with the OP's modus operandi.
I thought he was in the US. Brash, arrogant, like all us Yanks!
There are always pieces of British kit on eBay US, but in my real world travels, I find very little. A few Arcam, couple of Cambridge and maybe a Musical Fidelity (Rega on a rare occasion.).
High end UK, Roksan for example, pretty much never. I do read a copy of What Hi-Fi and some of the others when I can find them. I do like the ideas and designs, only wish I could try more of it in my system or hear it in other's.
British speakers, well that's another story. I don't know what you do across the pond, but I've never heard a UK speaker I didn't like. Celestion, KEF, Mission, and of course Quad.
Found a pair of Mission 707s at a thrift store for $10. The woofs needed new foam, but everything else was in good shape. The 2-way 8" mid size bookshelf was such a common design during the mid 70s-mid 90s. I can't count the number of these from different companies I've heard.
It's the perfect size for starter systems or small rooms. I've placed a number of them with many people in the area. Those Missions aren't going anywhere. I need them like another hole in the head, but those are some of the best sounding basic speakers (and they have that mid '80s British look, like a Lotus Esprit.)😎
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Lots of arrogance to be found on both sides of the Atlantic no doubt!
Would you agree with the opinion that British speakers have more midrange emphasis than American ones? Or is it a case of them having a 'warmer' sound?
I understand that, with the American continent being so large, there are regional variations in loudspeaker sound that are not found in little old Britain.
I too, like the 80's look - my Mordaunt Short MS100 speakers for example - mine are in black ash, real wood veneer.
Would you agree with the opinion that British speakers have more midrange emphasis than American ones? Or is it a case of them having a 'warmer' sound?
I understand that, with the American continent being so large, there are regional variations in loudspeaker sound that are not found in little old Britain.
I too, like the 80's look - my Mordaunt Short MS100 speakers for example - mine are in black ash, real wood veneer.
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British speakers (to my ears) have a nice, even sound across the frequency range. When Celestion started using titanium tweeters, they weren't overly bright or harsh. Very clean and detailed, but smooth unlike many others employing metal dome tweeters.
I believe the "midrange emphasis" critique is the result of people generally wanting too much emphasis in the bass and treble. So much of it is due to the room interactions and going from a speaker with reduced middles to one more balanced...
Just look at the JBL L-series. They could be considered "shouters" rather than speakers. While still being clean, they're "in your face" even at lower levels. What works in a studio is not always best at home.The only (decent quality) speaker I've ever heard that immediately smacked of excessive midrange, Yamaha NS-10s.
I believe the "midrange emphasis" critique is the result of people generally wanting too much emphasis in the bass and treble. So much of it is due to the room interactions and going from a speaker with reduced middles to one more balanced...
Just look at the JBL L-series. They could be considered "shouters" rather than speakers. While still being clean, they're "in your face" even at lower levels. What works in a studio is not always best at home.The only (decent quality) speaker I've ever heard that immediately smacked of excessive midrange, Yamaha NS-10s.
Whay about the Russia continent being so large. Maybe they have a small chance against US ?
Yes - British manufacturers tend to design for a flat frequency response - unlike the 'boom and tizz' which can be encountered elsewhere.
It was during the 70s that the major British speaker manufacturers played safe with an audience friendly, 'warm' sound - a tactic which guaranteed massive sales during hi-fi's heyday.
It was during the 70s that the major British speaker manufacturers played safe with an audience friendly, 'warm' sound - a tactic which guaranteed massive sales during hi-fi's heyday.
A huge market for loudspeakers perhaps, but Russia is not a continent! 🙂
On the original topic, low voltage caps, say under 16 VDC, will have worse dissipation factor. Every data sheet shows this. I also have a test that drives the cap (through a resistor) with a square wave. It will charge up and down, producing a triangle wave. When you look at the triangle wave, it basically answers the question, "how good an integrator does the cap make?" Low voltage caps often do poorly in this test when examined at audio frequencies and a very low amplitude. There was some old Sprague literature where they looked at cap life. Alas, I can't find it again, but the essence was that the low voltage caps failed first. They pretty much blew it off as expected and immediately went to talking about the higher voltage parts. So, based on performance, you don't want low voltage electrolytics. As for the cap oxide layer degrading without a good polarizing voltage, I think it's real, but was more of a problem with older recipes, or maybe just decades of sitting around. I don't even worry about it with a rebuild. The poster-boy would be the 220 uF or more electrolytic that's often found in a feedback divider. It sees near zero voltage its entire life, yet there's no amazing failure rate. So, many good reasons to stick with 25 VDC or greater caps if they'll fit, and no real downside I've been able to find. That said, I'd stay under 63 VDC or so, because there's no increasing benefit above that, unless you need the voltage capability.
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