Actually I might just be able to listen to my friend's amp in my system. This could help me make my decision. He has a heavily modifed Marantz PM66ki.
It has Black Gates and silver wiring all over, a second toroid in parallel and MASSIVE Elna Silmic psu caps. If this amp doesn't impress me I think my speakers must be to blame, right?
I've attached a recent pic of my hi-fi. I REALLY must get to bed now, phew!
It has Black Gates and silver wiring all over, a second toroid in parallel and MASSIVE Elna Silmic psu caps. If this amp doesn't impress me I think my speakers must be to blame, right?
I've attached a recent pic of my hi-fi. I REALLY must get to bed now, phew!
Attachments
All reasonable comments.
The fact that you've already done some AB comparisons is good.
That's the point about listening rooms ... even with crap ones you can spot the differences ... they're often poor for anything but differential listening comparisons, bearing in mind that some rooms will accentuate some differences you might not notice etc. You sure can't say that any particular speaker or amp is "best" in any listening room but your own!
Well, by all means though, invest in good power supplies including the wiring. A good amp can be rotted by bad power wiring from feedback through the power rails. A friend of mine once developed a supply which cross regulated such that droops on the positive rail would result in a drop on the negative rail so as to improve cross rail modulation. (That was years ago, so I have no details any more, and at the time I was in first year uni and he was a PhD ... so I was left behind
)
The fact that you've already done some AB comparisons is good.
That's the point about listening rooms ... even with crap ones you can spot the differences ... they're often poor for anything but differential listening comparisons, bearing in mind that some rooms will accentuate some differences you might not notice etc. You sure can't say that any particular speaker or amp is "best" in any listening room but your own!
Well, by all means though, invest in good power supplies including the wiring. A good amp can be rotted by bad power wiring from feedback through the power rails. A friend of mine once developed a supply which cross regulated such that droops on the positive rail would result in a drop on the negative rail so as to improve cross rail modulation. (That was years ago, so I have no details any more, and at the time I was in first year uni and he was a PhD ... so I was left behind
)
Well guys, I've gone off on various tangents and tried to explain the status of my listening setup. Bearing all of this in mind, or as much as you could bear reading.... Should I just be building another LM3886 or should I try a discrete amp?
Right at this moment I really could happily follow either path. Ultimately though I'd feel more proud owning a discrete amp, and it would go a bit louder too, which can be fun.
If discrete, then which one? People have suggested several designs, all widely acknowledged as being excellent-sounding and not overly complicated or stupidly expensive. Indeed, with all but the Aspen kits, the main cost is in the transformer and chassis it would seem.
Simon
Right at this moment I really could happily follow either path. Ultimately though I'd feel more proud owning a discrete amp, and it would go a bit louder too, which can be fun.
If discrete, then which one? People have suggested several designs, all widely acknowledged as being excellent-sounding and not overly complicated or stupidly expensive. Indeed, with all but the Aspen kits, the main cost is in the transformer and chassis it would seem.
Simon
Thank you for looking at the tangents though ... I have worked many, many years supporting customers in technical and industrial computing and it has always been essential to first take a step back and examine the whole system when making recommendations for upgrading and I've found that is always a worthwhile step. I tend to apply it to nearly all parts of life now, because sometimes the answer isn't the one that seems logical.
I would certainly go with a discrete amp. You certainly have some control over what goes on, unlike a chip.
I would certainly go with a discrete amp. You certainly have some control over what goes on, unlike a chip.
Nordic said:
I don't want to dismantle the current amp! It will go to work at my office or in another room! Or even as a second amp for the system in the future.
But for curiosity's sake it uses 2 x 100va @ 25vac. The 'sinks are maybe 10cm x 8cm x 2cm deep. I have some more of those. They might be too small for anything with big power output. In fact I'm fairly certain they are. But for normal listening with an efficient chip amp they're ok.
Simon
These look interesting:
Ebay Marantz monoblocks
Could easily be bought and heavily modified on my budget. And perfect for relegating to bass-only duties in the future. 180w RMS into 4ohms - plenty of guts! Also (for a sub) they could be bridged into nearly 400w RMS for an 8ohm load.
Any thoughts?
Simon
Ebay Marantz monoblocks
Could easily be bought and heavily modified on my budget. And perfect for relegating to bass-only duties in the future. 180w RMS into 4ohms - plenty of guts! Also (for a sub) they could be bridged into nearly 400w RMS for an 8ohm load.
Any thoughts?
Simon
richie00boy said:You can't bridge them without internally linking the grounds.
Look nice buy they aren't DIY
Very good point, the second one. Not DIY... But if very modded they'll fit well with my overall "style" lol.
I already have some large schottky diodes. And I could put in some Mundorf M-lytic caps to take care of that end. And maybe increase the bias current, which seems like a nice thing to do. They could be rather good for little money! Being monos they can potentially sit next to the speakers with next to no speaker cable. This could be a winner for best sound.
And I could still ultimately build a proper DIY amp to cover the upper ranges. This sure is tempting!
richie00boy said:
Indeed. I bought the diodes in anticipation of building an amp. I haven't bought those caps though. It's just a thought that springs to mind, knowing they're typically undersized (and possibly badly aged) in a budget commercial amp of a good few years. Also the review said they were fairly small. Let's hope it's that ideal scenario of small caps in big spaces
not if they are already optimally biassed for ClassAB.
Look at that spec: 125W into 8r0 and 180W into 4r0.
That loss of -1.4db into the lower load tells everyone that these amps probably do not perform well into 4ohm loads. Bridging (if that were possible) them is asking them to do exactly that.
Look again.
180W into 4r0, connected to a pair of subs (or dual driver subs) you will get a total power of 360W into 4+4ohm speakers, or for better performance 250W into 8+8ohm speakers.
AndrewT said:
Sorry, I don't understand the finer points of amplifier design... All I can see is a typically undersized transformer causing the inability for power to double into half the impedance. Typical for a budget amp. 30w is "enough" power for my speakers. Amps with up to 180 available will find them a doddle for sure. I like the idea of having headroom.
Do you think they could be a good buy, Mr. T?
richie00boy said:
I can't find where I made a note. They are, I think, 8-amp schottky type in T0220 packages.
Simon
I think Andrew's point could be that if you oversize the PSU 'back to what it should be' then you will simply blow the output stage on 4 ohm loads because it's now trying to push out more power than it was intended for. Personally I think you will be fine as I don't believe you will be expecting to use any of the seemingly-available capacity if you do upgrade the PSU.
You need to find what diodes they are. I suspect they will not be any use in a discrete power amp project, or anything more powerful than a Gainclone.
You need to find what diodes they are. I suspect they will not be any use in a discrete power amp project, or anything more powerful than a Gainclone.
richie00boy said:
Ok, cheers Richie! I'll see what they are and report back here. I'll log-in to my account and view the order history, that'll do it. I think they're suitable for plenty of juice. They're very large.
As for those mono amp. A thought that springs to mind is my future addition of twin 7" bass drivers. They're actually 4ohms nominal each and in series would provide a perfect match for the amp. Very loud it could be.
Oh and I see Andrew's point now. I'd not need the full output, it's more a matter of headroom and playing the music with ease. So no worries about that.
Here we go:
http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=9907270
They seem substantial to me. 8amps is a lot of current. But tbh I'm not sure how one is supposed to over-rate power supply diodes.
http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=9907270
They seem substantial to me. 8amps is a lot of current. But tbh I'm not sure how one is supposed to over-rate power supply diodes.
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