Fjd Posted July 12, 2014 Share Posted July 12, 2014 With summer in full swing you may not of given the op-amp decision much thought lately, but I figured I would give the thread a bump to see if there are any new readers with ideas. I finished up my Creek OBH-11 op-amp modification and posted it in the amp porn thread. https://community.klipsch.com/index.php?/topic/93736-amp-porn/page-7#entry1752196 1 Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 12, 2014 Share Posted July 12, 2014 My how time flies....I haven't had a chance to look at this yet. Just so you know, you can set up an account and get free samples from Texas Instruments with not much more than an email address. That sure beats paying Digikey prices. At least that's how it was back in college. Is there a quad version of the OPA209? Would that be an OPA4209? The OPA1664 might be a decent fit too. What package do you need? Is there already a socket on the board? Quote Link to comment Share on other sites More sharing options...
djk Posted July 12, 2014 Share Posted July 12, 2014 " Is there already a socket on the board?" No. "What package do you need?" 14 pin DIP For playing with newer opamps, buy a machined contact socket (Augat) a Brown dog adaptor board (or two or three) and use surface mount duals. Quote Link to comment Share on other sites More sharing options...
The Dude Posted July 12, 2014 Author Share Posted July 12, 2014 What package do you need? Is there already a socket on the board? What DJK said. My how time flies... Tell me about it, between kids stuff and rebuilding a MC2100. I haven't had much time to play with this. I have been using it on my EV horns for now, but would like to try it on my Heresies, and Drifts. Either which way it has seemed to be a great sounding amp for the price. Once I get my MC2100 up and running I plan to tackle this project in the fall. Quote Link to comment Share on other sites More sharing options...
The Dude Posted July 12, 2014 Author Share Posted July 12, 2014 For playing with newer opamps, buy a machined contact socket (Augat) a Brown dog adaptor board (or two or three) and use surface mount duals. So solder the (Augat) 14 pin dip socket where it needs to go, then get a Brown dog adapter which I would solder the surface mount duals to. So I wold then be able to widen my horizons. Quote Link to comment Share on other sites More sharing options...
djk Posted July 15, 2014 Share Posted July 15, 2014 (edited) Correct! http://www.ebay.com/itm/LOT-of-5-Augat-14-pin-DIP-Sockets-Gold-Machine-Screw-Contacts-USA-Shipped-/151337426754?pt=LH_DefaultDomain_0&hash=item233c69df42#ht_371wt_684 http://www.ebay.com/itm/Mill-Max-IC-Socket-DIP-14-Pins-Machined-Gold-Contact-5pcs-/251010428615?pt=LH_DefaultDomain_0&hash=item3a71632ec7#ht_781wt_882 http://browndog-adapters.com/ For people with the 4136 (Carver, Audio Control, etc): http://browndog-adapters.com/ Edited July 15, 2014 by djk Quote Link to comment Share on other sites More sharing options...
The Dude Posted July 15, 2014 Author Share Posted July 15, 2014 http://browndog-adapters.com/ Would that be p/n 070401the din pin sockets are ordered. Quote Link to comment Share on other sites More sharing options...
babadono Posted July 15, 2014 Share Posted July 15, 2014 p/n 070401 check, that's the one Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 16, 2014 Share Posted July 16, 2014 Is this the part you ordered? http://cimarrontechnology.com/2xdual-to-quadop-ampadapter.aspx Btw, the OPA209 is a dual opamp that I modeled in your circuit and looks to be a generally good fit here. They sound good too. I would recommend adding some ceramic caps across the power supply pins on the adaptor board. 1uF ceramic would be a good start - maybe you can find a leaded one that will work from Digikey. Make sure the voltage rating is above 35V. Quote Link to comment Share on other sites More sharing options...
Fjd Posted July 16, 2014 Share Posted July 16, 2014 Is this the part you ordered? http://cimarrontechnology.com/2xdual-to-quadop-ampadapter.aspx Btw, the OPA209 is a dual opamp that I modeled in your circuit and looks to be a generally good fit here. They sound good too. I noticed that the adaptor can be purchased with pre-mounted op-amps too. Do you have any thoughts regarding the choices of OPA2134, OPA2604, AD8620 or the LM4562MA? I have a LME49720 in my Creek OBH-11 headphone amp (part of a upgrade kit that included certain capacitors and resistors) that I believe is similar to the LM4562 with good success. Quote Link to comment Share on other sites More sharing options...
djk Posted July 16, 2014 Share Posted July 16, 2014 " the OPA209 is a dual opamp" The OPA209 is a single, the 2209 is the dual. Quote Link to comment Share on other sites More sharing options...
The Dude Posted July 16, 2014 Author Share Posted July 16, 2014 Is this the part you ordered Not yet but was going to. I have ordered a lot of parts lately and need to restock my funds as I would like to order a couple of them. I would recommend adding some ceramic caps across the power supply pins on the adaptor board Someone told be ceramic caps aren't good for audio, does that not matter when adding to power supplies. Quote Link to comment Share on other sites More sharing options...
The Dude Posted July 16, 2014 Author Share Posted July 16, 2014 across the power supply pins Would this be across 11 and 4 pin. Brown dog QUAD OP-AMP DIP PACKAGE.pdf Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 16, 2014 Share Posted July 16, 2014 There is no such thing as any cap being "not good".....it all depends on the application, and ceramic wins for power supply decoupling. I'd have to get into a boring dissertation on capacitor parasitics to explain why, but it is all right there in the datasheets if you read carefully. Btw, I'm talking about across the V+ and V- pins for each opamp....you're trying to minimize the inductance of the return currents because there can be some intense high frequency currents. 1 Quote Link to comment Share on other sites More sharing options...
djk Posted July 16, 2014 Share Posted July 16, 2014 Most amplifiers have their loads referred to ground, therefore the main bypasses needs to be to ground, not rail-to-rail. 1 Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 16, 2014 Share Posted July 16, 2014 Most loads don't present an impedance lower than ~600 ohms - and in this circuit it is much much higher. The resultant inductance from increased loop area does not have a significant effect at audio frequencies - nevermind the high impedance of 1uF in the audio band. The high real impedance (resistor) also keeps the Q low, so you usually don't see ringing in that loop. The cap across the supply is more to counteract the inductance presented by the adapter leads and improve high frequency stability. Things can get a bit spitty if your supply rails find it easy to ring - even if it's ringing at frequencies way above the audible band. Quote Link to comment Share on other sites More sharing options...
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