Printable View
Hi
As the volume potentiometers has a substantial influence on the sound I wonder if it is a good idea to replace these old 20kohm potentiometers with new ones on an Altec 9440A power amp?
Any recommendations for replacement. The same type, Alphs (may not fit) or stepped attenuator ?
Anyone done it ? Any idea for good replacement ?
Not any good idea ! The originals are good enough !
Any input appreciated
If it ain't broke don't fix it. Altec had some of the best brains available, I seriously doubt cut and try is gonna gain much. And likely will make it worse.
Keeping physical construction quality aside (which affects the longivity & immunity to being scratchy early), a volume control replacements will affect the sound quality only when one changes the value, otherwise not. Changing the value changes the impedance loading pattern inside, and hence a possibility of FR changes.
But as OG has already suggested, why change it unless it is really damaged ?
Well, many says that for example a stepped attenuator sound s much better than an film potentiometer and Blue Alps potentiometer sounds better than most of the other brands.
Accordingly they recommend to replace with the above to get better sound.
I have not yet put the Altec 9440A into the hifi system, but read that the high frequencies are not as good as the lower frequencies and thought that replacing these could enhance the performance.
A widely held view may be incorrect.
Many once thought the world was flat.Quote:
Originally Posted by mah
Quote:
Originally Posted by Old Guy
They must not have lived in San Fransisco or Seattle.
Define many.Quote:
Originally Posted by Old Guy
The Flat Earth Society
No, i am not a member or subscriber of the notion.
:D:D:D:D:D:D:D:D:D:D
Quote:
Originally Posted by bowtie427ss
Bowtie the operative word is ONCE. At ONE time VIRTUALLY ALL the authorities agreed the world was flat.
Flat Earth - Wikipedia, the free encyclopedia
Now, just crackpots.
Quote:
Originally Posted by MerlinVSM
A good pot can improve over a horrible one. But not much over a good one. The Altec does not have horrible pots unless they are bad. You are thinking of spending money and a lot of work to gain "not much."
Check improving your source signal, clean mains power, and caps in the amp first. Your priorities are off IMHO. Lots of work for small gain, especially if any other issues. Speaker placement will make more difference than the pots will. But the way you are talking your mind was made up before you posted.
Quote:
Originally Posted by Old Guy
This post right here Merlin is good advice, no great advice ! I too am from the school of "If It ain't broke DON'T fix it" I could have kicked myself in the A** more times than I care to admit on this.. Messing with something for no other reason than to just mess with it... My thinking well if I replace this it has got to be better.. And 9 times out of 10 I would scramble to try and fix the changes I had done.So now if it has blown up into a million pieces ? It's staying ! :Big smile:
I'm exaggerating a bit, but you can understand my point I hope... I mean in Crossovers,amps,etc... that are 30-40 years old and have original capacitors and such should be replaced.No question you can make an improvement there but on the inductors,L-pads,potentiometers,etc,etc.... Most of the time a good cleaning of the pots will suffice..
Well, as the amplifier at the moment is in bits and pieces when replacing the electrolytics (the 9800uF power cans and others) the thought came up why not replace the volume pots also.
If it to be done the time is now.
By the way one electrolytic was found not working. All replaced with ELNA Silmic II.
There are some 0,47uF /100V capacitors on the driver board which I believe are metalized film capacitors (very colorfull ones) with no name/brand.
Any recommendation also to replace these with higher quality ones as film and foil which also regarded to sound better ?
?
You have to get one idea out of your head. It is not that simple. In an amp, caps are part of a circuit. How they interact is paramount. So putting in caps "regarded to sound better' can actually DEGRADE an amp. Just use good quality parts. Beyond that if you want to spend years experimenting to get the last tenth of one percent be my guest. Not many here have worked on that amp. I have, but the same components are not available today.I would suggest searching the net for amp forums if you are that worried.
Or try and contact Iratec . He works on a lot of the Altec electronics..He may have some suggestions or the parts you need..
[email protected]
Ira Tec Pro Audio's Homepage
Thanks for info. The replacement will be limited to the electrolytics after reading the posts.Quote:
Originally Posted by Old Guy
Next step will be to check the transistors and set the bias. Hope I can find out how.
Any information how this amp sound ? Is it actualy worth spending time and money on it ?
The 9440 is one of the best amps of the day. Sounds better than say, a Crown DC300A.
i left my lungs in san fransisco.Quote:
Originally Posted by Audio_by_Goodwill
on taylor or powell st.
some of the sidewalks have/are steps ...
http://ts3.mm.bing.net/images/thumbn...324940ff643b02
I agree with OG.. These were excellent sounding amps.One amp in your system is enough and will sound great.They were typically rack mounted back in the day for live sound..Could you imagine 4 of these in a rack powering a stack of speakers.. Or some 210's ? Droolsville.... :emot134: It is money well spent IMHO.Quote:
Originally Posted by MerlinVSM
wow, rough crowd here sometimes.
@OP: Old amps can benefit from some refurb work, and while you want to be choosy about how far you want to go in replacing components, you can get a big lift in sonic quality or operational dependability if you fix up the right stuff. Here is a link that might help you:
9440 literature
I've not used the 9440, but I've read about it on some of the diy amp sites I visit... it is well-respected by many. Just do some searching around and you can find some help from people who have refurb'd these and put them to work in home hi-fi applications. And let us know how it works out for you. I'd like to hear one sometime.
Yup that be the ones Tom ! :Thumbs up: I could wake up a few neighbors with those.. :Big smile:Quote:
Originally Posted by tomt
I own and use a 9440 for live stuff, they are dynamite amps, way better IMO than the all worshiped DC300. However, they can be tricky to find today, as many installed altec system used the 159x family of amps and live rigs used the DC300 more than anything else. Even those amps that were toured with would be beat to hell and scrapped at the end of the tour. And on top of that, most people that own them aren't willing to part, funnily enough! I got mine for 150 from an auction guy that bought a load of surplus electronic equipment from the government, and really had no idea what he was looking at. He thought it was some kind of industrial power supply.
Cosmetically, they are not unlike several power supplies made by HP in their 6200 series.Quote:
He thought it was some kind of industrial power supply.
http://www.tennesseequipment.com/Eas...220VAC-pix.jpg
These amps can be found on ebay without having to wait too long, but they do sell high...... even the non-functional ones. I've never liked the look. I guess becasue whatever plating Altec used seems to corrode, and the faceplates are always scratched.