Hi everyone
I'm trying to find the best quality assembled board, most boards seem to have low quality components and many even fakes, is there anyway to skip the hassle of replacing parts and get a high quality assembled board that will cost more obviously, but still represent value for dollar? Honestly I wouldn't mind spending $300 just to get the best components and a separate power supply. I would prefer a high power board, tas5630b, tda7498e, irs2092, ta3020, etc etc. But if there is any high quality lower power boards I'm still interested to check them out.
Thanks!
I'm trying to find the best quality assembled board, most boards seem to have low quality components and many even fakes, is there anyway to skip the hassle of replacing parts and get a high quality assembled board that will cost more obviously, but still represent value for dollar? Honestly I wouldn't mind spending $300 just to get the best components and a separate power supply. I would prefer a high power board, tas5630b, tda7498e, irs2092, ta3020, etc etc. But if there is any high quality lower power boards I'm still interested to check them out.
Thanks!
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SMSL 7498E
I have one of these http://www.amazon.com/SMSL-SA-98E-silver-Digital-Amplifier/dp/B00NBGECXG/ and it sounds comparable to the UcD HG 400 at decent listening volume say 15-20 watts. I removed the board from inside, it has nice quality parts. I know it isn't a board, it's a whole amp including 36V 5A power supply but it sounds great.
I have one of these http://www.amazon.com/SMSL-SA-98E-silver-Digital-Amplifier/dp/B00NBGECXG/ and it sounds comparable to the UcD HG 400 at decent listening volume say 15-20 watts. I removed the board from inside, it has nice quality parts. I know it isn't a board, it's a whole amp including 36V 5A power supply but it sounds great.
Thank you for your suggestion, I've seen that amp, it is good quality for the price, for tda7498e this one also seems pretty good: New 2014 Indeed Class D TDA7498E 160WX2 Stereo Amplifier Silver 36V5A Adapter | eBay
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B O Icepower 300ASC 300W Power Amplifier Module 200ASC Replacement | eBay was selling these in the swap meet as well.Satisfied customer.No need to worry about bad parts .Ships all over.
Just be aware those irs2092 boards have an input impedance of 3300 Ohms.Gonna be limited with what you can drive them with.
Those latest Icepower boards I linked to have an input impedance of 47k .Older Icepower boards were around 8k which is why many manufacturers who used them(P.S. Audio,Jeff Rowland,etc.) used input buffers or transformers to drive them.Driving the pair I have with a tube preamp with no issues at all.
Just figured I'd give you a heads up.
Those latest Icepower boards I linked to have an input impedance of 47k .Older Icepower boards were around 8k which is why many manufacturers who used them(P.S. Audio,Jeff Rowland,etc.) used input buffers or transformers to drive them.Driving the pair I have with a tube preamp with no issues at all.
Just figured I'd give you a heads up.
I have on hand a couple LJM L15D single channel boards and a couple SURE dual channel (all IRS2092 "reference design" although the layout varies). Build quality is excellent, and there's nothing to be gained by "substituting" components on either.
As with all of the IRS "reference" amps their high end response is load sensitive . . . you need to pay some attention to how your speaker impedance behaves. It's easily compensated for (if needed) . . . and it's not an issue at all with "active" designs. The input impedance is also relatively low . . . but not so low as to pose a problem with any competently designed modern source, be it pre-amp or active crossover.
Even poorly designed (or antique) tube pre-amps (designed to drive equally antique tube amplifiers with high input impedance) are easily accommodated, since such contraptions typically deliver a higher output voltage than modern hardware needs, and will have to be padded down to be used with 2092 based (and in fact most modern) amps. The padding network usually raises the input impedance sufficiently that no "input buffer" is needed to make the old gear work properly.
As with all of the IRS "reference" amps their high end response is load sensitive . . . you need to pay some attention to how your speaker impedance behaves. It's easily compensated for (if needed) . . . and it's not an issue at all with "active" designs. The input impedance is also relatively low . . . but not so low as to pose a problem with any competently designed modern source, be it pre-amp or active crossover.
Even poorly designed (or antique) tube pre-amps (designed to drive equally antique tube amplifiers with high input impedance) are easily accommodated, since such contraptions typically deliver a higher output voltage than modern hardware needs, and will have to be padded down to be used with 2092 based (and in fact most modern) amps. The padding network usually raises the input impedance sufficiently that no "input buffer" is needed to make the old gear work properly.
With a 3k3ohm input impedance you need a source impedance of 330 ohm or less to drive it correctly .(Ten to one rule is the usual guideline) .Adding a padding network is like adding a volume pot ,but at a fixed setting. Volume pots add up to 25 percent of their value to the source impedance .So a 50kohm pot(or padding network) could increase your source impedance by up to 12.5k ohm. So add 12.5 kohm to whatever your preamps output source impedance is.Makes it worse.
The 3.3k resistor after the 10uf input cap sets the input impedance.Adding anything (volume pot,padding network,tuna sandwich) before it doesn't effect that resistor at all.Its still 3.3k input impedance.Also didn't realize that tube preamps are incompatible with modern amps .I guess Conrad Johnson,Audio Research,Rouge,Lamn,VTL,Jadis,etc. didn't get the memo.None of them or any amp i've ever seen has a padding network.
For a dual icepower 300 setup is there any audible advantage in having dual switching power supplies or is it better to save money + space and buy a 300AC to run off the power supply of the 300ASC? Even the top of the line dual 700w icepower 700ASC2 runs from a single power supply, so probably no need for dual.
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That's correct, more or less, and leads to the obvious "solution" . . . if you've got a "source" with a source impedance of more than a couple hundred ohms then rubbish it and get something decent. Or . . . do what I said . . .
You've managed to find a schematic and miss the point. The amplifier doesn't care what the source impedance is . . . it simply amplifies the voltage at its input. It is the pre-amp that cares (if it cannot handle a low impedance load). You might want to reconsider that . . . take your time, you've got all year . . .
In any case it's not an issue with any reasonably well designed source . . .
Was replying to your quote.The padding network doesn't increase the input impedance of the amp at all. It's still 3k3 ohms.
You might want to reconsider that.
And source impedance is irrelevant to the amp?Really?
Drive a common irf610 mosfet with 140pf input capacitance with a 100k source impedance and tell me what your bandwidth is .
Nevermind,I'LL tell you....3db down at 11,368 hz.Irrelevant?
You might want to reconsider that.
For a dual icepower 300 setup is there any audible advantage in having dual switching power supplies or is it better to save money + space and buy a 300AC to run off the power supply of the 300ASC? Even the top of the line dual 700w icepower 700ASC2 runs from a single power supply, so probably no need for dual.Found this ,hope it helps.Shows that 300asc can supply 300 watts from its bus supply.Should be full power from both then.Dont think it would be audibly worse.Sorry bout your thread meandering.
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Originally Posted by brik View Post
With a 3k3ohm input impedance you need a source impedance of 330 ohm or less to drive it correctly .(Ten to one rule is the usual guideline)
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You agree that the source impedance needs to be 330 ohms or less to drive the amp correctly,so your solution is to add a padding network which raises the source impedance (into the kilo ohm range)?
Which IS what you said.
Or people should throw out their tube preamps so they can drive a $20.00 amp from China.
Brilliant.
Just making sure im not reading this stuff wrong.
With a 3k3ohm input impedance you need a source impedance of 330 ohm or less to drive it correctly .(Ten to one rule is the usual guideline)
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You agree that the source impedance needs to be 330 ohms or less to drive the amp correctly,so your solution is to add a padding network which raises the source impedance (into the kilo ohm range)?
Which IS what you said.
Or people should throw out their tube preamps so they can drive a $20.00 amp from China.
Brilliant.
Just making sure im not reading this stuff wrong.
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Yes. That "$20.00 amp from China" almost certainly has lower overall distortion than their old "tube preamp" does. And it's probably time to retire the '36 Dodge, too . . . even if it was a great car for it's time. But if you're really committed to keeping your PAS-2 then you might as well keep your Stereo 70 along with it and avoid the "problem" altogether . . .
The IRS2092 "reference" circuit can be driven without issue by any competently designed modern signal source.
Its not a PAS,Its a Morgan Jones designed Beta Follower with a 6sn7 that I built ,or a 6sn7 preamp loaded with Dn2450 cascoded constant current source that I built that I use also.
I even built a preamp with a 37 tube from the 1920's(oh the horror)
I like them all,Alot.
There have been advances in tube designs over the past 60 years.
But I imagine you'd be happy with an 741 opamp with a 1 ohm output impedance.
To each his own.
To help with Z matching maybe one of those Edcor 4.1:1 or 5:1 step down trans would do the trick. Those who don't want a transformer could rig up a 10M90 CCS as a high buffer that'll work with the modules rail voltage.
Adding another 10-15 bucks to the implementation.
Adding another 10-15 bucks to the implementation.
But dewardh says you should just throw your preamp in the garbage if it cant drive an 3k3 input impedence,so if I try this I can keep my preamp?Man ,I hope so.
Either solution would be fine.
Be carefull,a logical post like yours is what derailed this thread.
My latest preamp.I'm so grateful for your guidance, support,and inspiration that I'm naming it "The Big Dewardh".Or "The Big D" for short.
No need to thank me.
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