Dumbloid  [traced]

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Re: Dumbloid

Postby johnk » 08 Mar 2014, 21:02

thanks. it's called a Fresnel lens. it just requires a 1/4" hole and it holds any standard 5mm led in it.
I get mine from mouser.
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Re: Dumbloid

Postby LaceSensor » 09 Mar 2014, 09:02

johnk wrote:I built one using IvIark's rev2 layout. I didn't care for the OPA2134's fizzy decay , especially noticeable at the brighter settings, so I tried 30 different dual opamps in it and the MC33172N sounded great in it so I went with that.
I also added the Jazz/Rock switch to it so it's now a 'special'.
here's a couple of pics of mine in 1590B:

[ Image ]

[ Image ]


That's badass man, nice polish on the top part of the box.
Now to sell for $300 on TGP, right?
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Re: Dumbloid

Postby Jack Deville » 09 Mar 2014, 09:24

mmolteratx wrote:Did up a PCB since a buddy wants one. Once it's verified, I could do a small run. Price would be $5 plus shipping.

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Re: Dumbloid

Postby Manfred » 09 Mar 2014, 11:28

johnk wrote:I built one using IvIark's rev2 layout. I didn't care for the OPA2134's fizzy decay , especially noticeable at the brighter settings, so I tried 30 different dual opamps in it and the MC33172N sounded great in it so I went with that.


The slewrate of the MC33172N is 2V/MicroSecond, the slewrate of the OPA2134 is 20V/MicroSecond.
I guess, that is the whole secret.
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Re: Dumbloid

Postby astrobass » 09 Mar 2014, 16:52

Manfred wrote:
johnk wrote:I built one using IvIark's rev2 layout. I didn't care for the OPA2134's fizzy decay , especially noticeable at the brighter settings, so I tried 30 different dual opamps in it and the MC33172N sounded great in it so I went with that.


The slewrate of the MC33172N is 2V/MicroSecond, the slewrate of the OPA2134 is 20V/MicroSecond.
I guess, that is the whole secret.

Unlikely. I believe 2V/microsecond is still high enough to not affect frequency response in the audible range.

In this application the op amp is rail clipping on one side. Most op amps don't sound good when they're forced to clip in this fashion. There's really no specific datasheet value that will identify an op amp that will sound good or not when used this way.
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Re: Dumbloid

Postby johnk » 09 Mar 2014, 17:21

astrobass wrote:
Manfred wrote:
johnk wrote:I built one using IvIark's rev2 layout. I didn't care for the OPA2134's fizzy decay , especially noticeable at the brighter settings, so I tried 30 different dual opamps in it and the MC33172N sounded great in it so I went with that.


The slewrate of the MC33172N is 2V/MicroSecond, the slewrate of the OPA2134 is 20V/MicroSecond.
I guess, that is the whole secret.

Unlikely. I believe 2V/microsecond is still high enough to not affect frequency response in the audible range.

In this application the op amp is rail clipping on one side. Most op amps don't sound good when they're forced to clip in this fashion. There's really no specific datasheet value that will identify an op amp that will sound good or not when used this way.


I agree completely. out of the others that tried (and even a few stacked ones), their spec of faster or slower slew rate didn't seem to be what made one sound better than the other when clipping.
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Re: Dumbloid

Postby Cannibal » 09 Mar 2014, 17:22

TLC2262 to my ears clips more gracefully than most of the other opamps. Dunno it's because it's a MOS opamp or because of it's abysmal slew rate (0.35 to 0.55 Volt per millisecond, according to the datasheet).
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Re: Dumbloid

Postby astrobass » 09 Mar 2014, 18:03

Cannibal wrote:TLC2262 to my ears clips more gracefully than most of the other opamps. Dunno it's because it's a MOS opamp or because of it's abysmal slew rate (0.35 to 0.55 Volt per millisecond, according to the datasheet).

Having a really low slew, in that range, will limit the amount of high frequency sound getting clipped and this can help eliminate some of the fizz/harshness. It's got to be a LOT lower than 2 V before that makes an audible difference.

That said, I find the LM741 to sound awesome on its own, and I've read on here that the 4558 also works really good for this and I don't believe either have slew rates that audibly affect frequency response.

So I guess if you were guessing op amps that might sound good, going with something under 0.6V slew rate might improve your odds of grabbing a winner or at least, something that doesn't sound as bad as some of the alternatives. It seems like most of the op amps that sound better in this application seem to be older, noisier designs. It could be that the things more modern designs are doing to achieve lower noise, higher slew, lower heat, etc are counterproductive to this purpose.
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Re: Dumbloid

Postby johnk » 10 Mar 2014, 06:04

well, i'm really happy with the MC33172N and I tried a couple of 4458's (RC4458P, JRC4558D) and they had fizzy decays too. a JRC4562D sounded a bit better than the OPA2134 to me but still was a bit fizzy.
the TLC2262 is one that I didn't happen to try since the MC33172 sounded so good, but I might try that one too just for fun.
I know do that TL062's, TL072's, TL082's, 4459's, 4580's, OPA2604, LM1458, HA17458, LM258, LM348N, LM358N, NE5532, LF442 and LM883's didn't work very well in it.

I've read that the MC33172 is basically a dual 741 so that's probably why it works so well in this circuit.

For this message the author johnk has received thanks:
atreidesheir (10 Mar 2014, 08:56)
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Re: Dumbloid

Postby roseblood11 » 10 Mar 2014, 09:33

a LM1458 is "basically a dual 741" as well...

Did you try any rail-to-rail opamps, like TLC2272?
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Re: Dumbloid

Postby Manfred » 10 Mar 2014, 09:53

astrobass wrote:
Manfred wrote:
johnk wrote:I built one using IvIark's rev2 layout. I didn't care for the OPA2134's fizzy decay , especially noticeable at the brighter settings, so I tried 30 different dual opamps in it and the MC33172N sounded great in it so I went with that.


The slewrate of the MC33172N is 2V/MicroSecond, the slewrate of the OPA2134 is 20V/MicroSecond.
I guess, that is the whole secret.

Unlikely. I believe 2V/microsecond is still high enough to not affect frequency response in the audible range.

In this application the op amp is rail clipping on one side. Most op amps don't sound good when they're forced to clip in this fashion. There's really no specific datasheet value that will identify an op amp that will sound good or not when used this way.


You are right, I had a shift of one decimal power while calculating, the frequency response will not affected up to 70 Kilohertz.
What the reason for the audible for the audible sound differences depend on the op amp type?
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Re: Dumbloid

Postby deltafred » 10 Mar 2014, 10:48

Manfred wrote:What the reason for the audible for the audible sound differences depend on the op amp type?

How they operate outside their design spec. They were never designed to reach clipping so how they react when they do can vary dramatically.

Some ring or generate a spike before they settle to their "clipped state". It is most probably this that determines whether they sound good or not.
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Re: Dumbloid

Postby Manfred » 10 Mar 2014, 14:31

deltafred wrote:
Manfred wrote:What the reason for the audible for the audible sound differences depend on the op amp type?

How they operate outside their design spec. They were never designed to reach clipping so how they react when they do can vary dramatically.

Some ring or generate a spike before they settle to their "clipped state". It is most probably this that determines whether they sound good or not.


It would be in interest to have some oscillograph curves in which the clipping signal for different op amps are shown.
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Re: Dumbloid

Postby MoonWatcher » 10 Mar 2014, 15:09

Manfred wrote:It would be in interest to have some oscillograph curves in which the clipping signal for different op amps are shown.

Yes, especially if there were ones that were somewhat considered to sound 'not bad' when they clip.

We may not see a visual pattern, but there still might be something of use. Maybe something typically present, or something typically missing.
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Re: Dumbloid

Postby johnk » 10 Mar 2014, 18:51

i just tried a 2262 in it, and while it's better than the OPA2134, to me the MC33172 sounds the best (i.e. has the best sounding opamp distortion).
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Re: Dumbloid

Postby deltafred » 10 Mar 2014, 19:57

Manfred wrote:It would be in interest to have some oscillograph curves in which the clipping signal for different op amps are shown.

I have seen a website somewhere with a load of scope traces. I will have look and see if I can find it.
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Re: Dumbloid

Postby andregarcia57 » 11 Mar 2014, 01:29

johnk wrote:well, i'm really happy with the MC33172N and I tried a couple of 4458's (RC4458P, JRC4558D) and they had fizzy decays too. a JRC4562D sounded a bit better than the OPA2134 to me but still was a bit fizzy.
the TLC2262 is one that I didn't happen to try since the MC33172 sounded so good, but I might try that one too just for fun.
I know do that TL062's, TL072's, TL082's, 4459's, 4580's, OPA2604, LM1458, HA17458, LM258, LM348N, LM358N, NE5532, LF442 and LM883's didn't work very well in it.

I've read that the MC33172 is basically a dual 741 so that's probably why it works so well in this circuit.




hello ... where can I find MC33172N with good price and original.

no difference MC33172N and MC33172P, MC33172PG ?
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Re: Dumbloid

Postby johnk » 11 Mar 2014, 04:43

I got mine from mouser.
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Re: Dumbloid

Postby box » 11 Mar 2014, 06:33

andregarcia57 wrote:
johnk wrote:well, i'm really happy with the MC33172N and I tried a couple of 4458's (RC4458P, JRC4558D) and they had fizzy decays too. a JRC4562D sounded a bit better than the OPA2134 to me but still was a bit fizzy.
the TLC2262 is one that I didn't happen to try since the MC33172 sounded so good, but I might try that one too just for fun.
I know do that TL062's, TL072's, TL082's, 4459's, 4580's, OPA2604, LM1458, HA17458, LM258, LM348N, LM358N, NE5532, LF442 and LM883's didn't work very well in it.

I've read that the MC33172 is basically a dual 741 so that's probably why it works so well in this circuit.




hello ... where can I find MC33172N with good price and original.

no difference MC33172N and MC33172P, MC33172PG ?

Hi,
Please check here:
http://www.ebay.com/itm/MC33172N-Dual-B ... _56wt_1105

Rgds,
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Re: Dumbloid

Postby andregarcia57 » 11 Mar 2014, 14:03

box wrote:
andregarcia57 wrote:
johnk wrote:well, i'm really happy with the MC33172N and I tried a couple of 4458's (RC4458P, JRC4558D) and they had fizzy decays too. a JRC4562D sounded a bit better than the OPA2134 to me but still was a bit fizzy.
the TLC2262 is one that I didn't happen to try since the MC33172 sounded so good, but I might try that one too just for fun.
I know do that TL062's, TL072's, TL082's, 4459's, 4580's, OPA2604, LM1458, HA17458, LM258, LM348N, LM358N, NE5532, LF442 and LM883's didn't work very well in it.

I've read that the MC33172 is basically a dual 741 so that's probably why it works so well in this circuit.




hello ... where can I find MC33172N with good price and original.

no difference MC33172N and MC33172P, MC33172PG ?

Hi,
Please check here:
http://www.ebay.com/itm/MC33172N-Dual-B ... _56wt_1105

Rgds,
box



Does not ship to Brazil!
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exists between different ICs?
MC33172N and MC33172P, MC33172PG
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