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Old 1st September 2016, 07:53 PM   #11
brucetassin is offline brucetassin  United States
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Here is a very good place to start.
I built the RIAA pre-amp and am very happy with it.
With very little mods it could do you a good job.

Transistor tutorial Audio Amplifiers, Part 5
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Old 1st September 2016, 07:59 PM   #12
Mark Johnson is offline Mark Johnson  United States
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James Bongiorno is the designer of Ampzilla and other famous products.

Here is an article he wrote for the June 1972 issue of Popular Electronics, with the modest title

Build a Distortionless Preamplifier

Oops since it is bigger than the max filesize for .pdf here on DIYA, I have extracted each page of the article individually. There are 5 pages and 5 .pdf files attached. Sorry for the annoyance.
Attached Files
File Type: pdf Bongiorno 1.pdf (381.4 KB, 620 views)
File Type: pdf Bongiorno 2.pdf (522.8 KB, 534 views)
File Type: pdf Bongiorno 3.pdf (540.1 KB, 382 views)
File Type: pdf Bongiorno 4.pdf (381.0 KB, 329 views)
File Type: pdf Bongiorno 5.pdf (377.3 KB, 322 views)
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Old 2nd September 2016, 01:46 AM   #13
Jrp27 is offline Jrp27  India
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Quote:
Originally Posted by Mark Johnson View Post
James Bongiorno is the designer of Ampzilla and other famous products.

Here is an article he wrote for the June 1972 issue of Popular Electronics, with the modest title

Build a Distortionless Preamplifier

Oops since it is bigger than the max filesize for .pdf here on DIYA, I have extracted each page of the article individually. There are 5 pages and 5 .pdf files attached. Sorry for the annoyance.
Thanks mark. I am unable to open the pdfs can you upload the full article on rapidshare and paste the link here.
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Old 2nd September 2016, 03:11 AM   #14
Richidoo is offline Richidoo  United States
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Originally Posted by Mark Johnson View Post
Build a Distortionless Preamplifier
Thanks very much Mark, for taking the time to split the PDFs and post the old article here. I look forward to studying it. James was a great innovator in our hobby... RIP.

JRP27, I had no problem downloading all 5 pdfs. Try right click, save as..
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Old 2nd September 2016, 03:14 AM   #15
Jrp27 is offline Jrp27  India
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Got it. Since 2n4250 and 2n5089 transistors are no longer available, which transistors can be used instead?
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Old 2nd September 2016, 03:25 AM   #16
ammel68 is offline ammel68  United States
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Quote:
Originally Posted by Mark Johnson View Post
James Bongiorno is the designer of Ampzilla and other famous products.

Here is an article he wrote for the June 1972 issue of Popular Electronics, with the modest title

Build a Distortionless Preamplifier
No doubt Mr. Bongiorno was a talented designer, but I can't believe that a 44 year old design can't be matched or surpassed with today's transistors and/or op-amps.

Also, why would you need all the gain of a phono preamp for an iPod?
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Old 2nd September 2016, 03:28 AM   #17
ammel68 is offline ammel68  United States
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Originally Posted by Jrp27 View Post
Got it. Since 2n4250 and 2n5089 transistors are no longer available, which transistors can be used instead?
There are several sellers on eBay who have some 2N4250 and 5089s. Just do a search.
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Old 2nd September 2016, 03:37 AM   #18
JMFahey is offline JMFahey  Argentina
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Keep it simple, Rod Elliotīs single dual Op Amp (TL072 or similar) is already better than what you need.
Agree to adding a capacitor to ground so it has minimal offset.
And even a non polarized electrolytic will do fine.

One important question: what DC Voltage supplies does your ready built amp have?
Because we can probably supply your preamp from them with little effort.
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Old 2nd September 2016, 05:41 AM   #19
Jrp27 is offline Jrp27  India
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Originally Posted by JMFahey View Post
Keep it simple, Rod Elliotīs single dual Op Amp (TL072 or similar) is already better than what you need.
Agree to adding a capacitor to ground so it has minimal offset.
And even a non polarized electrolytic will do fine.

One important question: what DC Voltage supplies does your ready built amp have?
Because we can probably supply your preamp from them with little effort.
Thanks I will try that but I really want a transistor based preamp. I just like the warm fuzzy sound. Chips sound shrill imho.

My power amp is powered by 45 v dc dual supply
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Old 2nd September 2016, 03:00 PM   #20
Mark Johnson is offline Mark Johnson  United States
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Octopart.com was able to find current production devices for the Bongiorno design, see figures below.

Its gain is set by feedback resistors R16, R17, R8 whose values you, the year_2016 circuit designer, can set however you like. Since this isn't a RIAA phono amp you would naturally omit switch S1 and omit the entire "G" signal path (R13, R14, R15, C7, C8).

It is interesting that Bongiorno feels his regulated DC power supply is more elaborate than the power supply designs in other 1972-vintage preamps, AND he feels this is crucial to the ultimate performance of his design. Maybe you could add your own year_2016 innovations and improvements to this portion of the circuit, and get something even better than Bongiorno did, 44 years ago.

_
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