I use a maximum of 70 w/ch in my living room. That is for 50 msec during the cannon shot in 1812 Overture. I would put this amp back together and enjoy it for another 5 years. Or until it starts sounding polite - no volume peaks.
wg_ski, I went back and checked again. 360mVrms is correct, I made the measurement while the amp was driven into clipping. I only held it there for a about 30 seconds, but it was stable during that time.
Being about to refurb my 4330, I would say a Creek is always worth it! As far as the caps, have you measured the ripple on the supply? Hear any hum right next to the speakers? Do you have an IO box so you can do a loopback and see the noise floor?
Have you thought about a relay stepped volume? Or is just a good rotary switch enough.? That's what I am putting in mine along with an output muting relay.
I take all that back. It is a piece of junk and you need to send it to me for scrap immediately. 🙂
The whole cap deterioration thing is something I have been looking into. Age by itself does not cause caps to deteriorate a lot. Having a voltage across them doesn't either. Heat and the the effects of heat are what causes cap failures. I have several conservatively designed amps (Hewlett Packard and Optimation) made in the 1960's and 1970's that have seen some use but the caps at 50 years are still meeting spec. I have checked some NOS 30 year old caps that are still meeting spec.
Replacing caps can be easy or hard and definitely removing them from a PC board has risks. On older units like I mentioned above the board materials are not as sturdy as current materials increasing the risk of damage in pulling caps.
The best way to spot degraded caps is to measure the ESR. If the caps have been cooking and the electrolyte has been evaporating then the ESR will go up and the cap won't perform per spec.
I do not understand how a full power test will show degraded caps. Maybe at or past clipping you can see ripple at the output but below that on an amp with working feedback you won't see much. Power supply ripple can be an indicator IF you know what to expect. Otherwise it can be misleading. A well designed amp could have significant ripple at high current. The designer opted to use the power transformer more efficiently with a larger conduction angle.
The ripple numbers I saw above seem reasonable. I would also just check to see if any caps are getting warm and not from being near other hot stuff. That would indicate significant ripple current which would degrade caps over time.
Replacing caps can be easy or hard and definitely removing them from a PC board has risks. On older units like I mentioned above the board materials are not as sturdy as current materials increasing the risk of damage in pulling caps.
The best way to spot degraded caps is to measure the ESR. If the caps have been cooking and the electrolyte has been evaporating then the ESR will go up and the cap won't perform per spec.
I do not understand how a full power test will show degraded caps. Maybe at or past clipping you can see ripple at the output but below that on an amp with working feedback you won't see much. Power supply ripple can be an indicator IF you know what to expect. Otherwise it can be misleading. A well designed amp could have significant ripple at high current. The designer opted to use the power transformer more efficiently with a larger conduction angle.
The ripple numbers I saw above seem reasonable. I would also just check to see if any caps are getting warm and not from being near other hot stuff. That would indicate significant ripple current which would degrade caps over time.
Yup. A few months of a box of new caps stored on the top of a high-bay in a Colorado warehouse was enough to kill them!
Not sure how to test a cap in-circuit. ESR but C, DF, and TC change. Truth is in the sound. If you hear no hum, you most likely don't have a problem.
If it ain't broke, then start fixing it untilit is, then fix it and brag how you fixed it 😈
Not sure how to test a cap in-circuit. ESR but C, DF, and TC change. Truth is in the sound. If you hear no hum, you most likely don't have a problem.
If it ain't broke, then start fixing it untilit is, then fix it and brag how you fixed it 😈
Well put, Indianajo! Indeed, at least here in Germany you sadly just aren't allowed to pull gear from the dumpsters. Depending on the staff there, I managed to haul some in the past, though. But that's a political theme, so back to topic:
Recently, there's been a thread on the lifetime of capacitors. I've written there about my ~71 year old Hammond C-2 organ whose original PSU filter caps I surprisingly found to be fully intact. Anyway, 71 years ago noone spoke of capacitor lifetime. This just didn't matter in datasheets. I suspect it became important due to miniaturization of these components.
Best regards!
Hello,
Recently i told a good friend to try new caps in his 30 year old Hiraga power amp.
Technology has made big leaps so replacing it with decent caps from Mouser would be an improvement.
In the end it turns out that the old caps sounded better than the new ones.
Maybe try it one more time with the highest grade cap available now? Dont mean audiophile caps but the ones used by companies that focus on reliability.
The ones in the original design were considered high grade back then.
Greetings, eduard
Recently i told a good friend to try new caps in his 30 year old Hiraga power amp.
Technology has made big leaps so replacing it with decent caps from Mouser would be an improvement.
In the end it turns out that the old caps sounded better than the new ones.
Maybe try it one more time with the highest grade cap available now? Dont mean audiophile caps but the ones used by companies that focus on reliability.
The ones in the original design were considered high grade back then.
Greetings, eduard
They may be old paper caps that do not age. Older caps had thicker paper and foil layers so would be a little less sensitive. In that old organ, I am sure it was tubes, so they were much higher voltage. The issue is electrolytics with oil that evaporates over time. We did know about it back then, just no audiophile blogs. It is most severe in the big cans.
"new " "old", "sounded". That does not mean anything. What caps in the circuit, and what specifications? It is very easy to measure power supply filtering before and after. If a DC blocking cap, that is much harder. New cap may have been higher inductance, or higher ESR, though in most audio paths, they are in series with significant resistance so the ESR is irrelevant. Point is, caps are a complex device and one needs to understand the specific parameters for the application.
Perhaps you might want to read my posting in that thread. I've been writing about the PSU filter 'lytics that I had desoldered, measured, including ESR's, and found to be good. Never would I have thought that!
Best regards!
Best regards!
It looks like there is some life left for this amplifier, so I’ll get to work on fixing / replacing the input selector switch.
Thanks to everyone that offered info and suggestions!
Cheers
ceulrich
Thanks to everyone that offered info and suggestions!
Cheers
ceulrich
Ah, gee. I guess I'll have to fix MY old Creek 🙂
Boards came today to do a cap bank for my Mosfet. I'll do the creek next. I have a stepped attenuator I never used. Might add a delay mute relay I pulled out of an old NAD if the relay contacts are still clean. Just had a thought. I have a JDS Subjective I can add in for tone controls. I It has relay bypass for those screaming I would be messing with the Creek simplicity.
Boards came today to do a cap bank for my Mosfet. I'll do the creek next. I have a stepped attenuator I never used. Might add a delay mute relay I pulled out of an old NAD if the relay contacts are still clean. Just had a thought. I have a JDS Subjective I can add in for tone controls. I It has relay bypass for those screaming I would be messing with the Creek simplicity.