[WGH]

The DIY opamp kit arrived today - 4 Burr Brown 627's for my Insight DAC and Insight EC Pre-amp.

Replacing the AD817's in the DAC was easy and straight forward, the digital board has plenty of room around it. The opamps in the Insight pre-amp are on a vertical board with a lot of wires in the way. Very steady hands with a lot of patience is required to replace the IC's without bending the legs. If you have not worked with parts this small and delicate in tight spaces I suggest you let Frank do it.

I took some photos to show the IC locations and what the opamps look like:

Insight DAC+ with Burr Brown OPA627AP



Insight EC Preamp with opamp locations circled


The sound with the new IC's installed is fantastic. As Frank mentioned there is less sold state dryness, a nicer sound stage, and even better transparency and real detail. The combination of the Burr Brown chips in both the DAC and pre-amp is greater than the individual parts, it really elevates the quality of digital sound, CD's are quite listenable now and catching up to vinyl.

I notice more inner detail with vinyl, all around the music is easier to listen to. I use a separate phono pre-amp so I installed just 2 chips, those who have the internal phono stage can expect great things with this upgrade.

My thoughts while listening is that Frank could bolt on a 1/2" thick milled faceplate and sell these units for $10,000 each and people would think they were a bargain.

Wayne

[martyo]

The result is lower noise, removal of the last trace of sold state dryness, a nicer sound stage, and even better transparency and real detail.

I received and installed the chips in my Ultra DAC yesterday. There is certainly more transparency and detail and a more focused sound stage. Every upgrade Frank does seems to extend the frequency extremes, and here too. Probably the increased detail, but the low end is better again too.
Nice Frank

[pardales]

The DIY opamp kit arrived today - 4 Burr Brown 627's for my Insight DAC and Insight EC Pre-amp.

Replacing the AD817's in the DAC was easy and straight forward, the digital board has plenty of room around it. The opamps in the Insight pre-amp are on a vertical board with a lot of wires in the way. Very steady hands with a lot of patience is required to replace the IC's without bending the legs. If you have not worked with parts this small and delicate in tight spaces I suggest you let Frank do it.

I took some photos to show the IC locations and what the opamps look like:

Wayne

Thanks for the pictures! I await the new chips for my Insight DAC and this will help a lot.

[avahifi]

I am glad the chip replacement projects are going smoothly and that you people are happy with the results.

The most common reason for it to not work is that you folded over a chip pin while trying to insert it and did not get the pin into its socket.  Look very closely for this before you fire it up.  It is possible to kill the chip if this happens.

Because we have pre-tested the chips we are sending you, the pins have already been formed inward slightly for an easier fit in the sockets.

Regards,

Frank Van Alstine

[G E]

We have made the Insight preamplifiers and DACs better than ever simply by a change in the basic op-amp used in some of our circuit configurations.

The change is to replace the AD817 op-amps to Burr Brown OPA627AP op-amps where applicable.  The affected circuits are the line and phono stages in the Insight preamplifiers (2 chips each), and the current to voltage amplifier section in the Insight, T8, and Ultra DACs, (and in some older OmegaStar DACs too) again two chips each.

....

Frank,

Can this Op amp upgrade be applied to any of your Legacy preamps?  of particular interest is my Fetvalve Preamp in a PAT 5 chassis circa Summer 1993.  BTW, I replaced its original tubes last year with the set I got from you and noted a nice sonic improvement.

ge

[WGH]

An easy way to slightly re-form the pins is to bend all four pins at once with small needle nose pliers. A very bright task light for final inspection is also a must have.


Not dead, just sleeping.


I set the EC preamp on it's rear so the board is horizontal and the IC's could be dropped in, it can easily fall over so brace it well or recruit an extra set of hands. Leave the beer in the fridge and celebrate only after the chips are installed and everything works.

Wayne

[Tom Alverson]

We have made the Insight preamplifiers and DACs better than ever simply by a change in the basic op-amp used in some of our circuit configurations.

The change is to replace the AD817 op-amps to Burr Brown OPA627AP op-amps where applicable.  The affected circuits are the line and phono stages in the Insight preamplifiers (2 chips each), and the current to voltage amplifier section in the Insight, T8, and Ultra DACs, (and in some older OmegaStar DACs too) again two chips each.

....

Frank,

Can this Op amp upgrade be applied to any of your Legacy preamps?  of particular interest is my Fetvalve Preamp in a PAT 5 chassis circa Summer 1993.  BTW, I replaced its original tubes last year with the set I got from you and noted a nice sonic improvement.

ge

I have that same FetValve preamp and it does not use any opamps, so this upgrade is not applicable.  There is a possiblity that it might work in an Omegastar preamp, but Frank would have to comment on that.

If your FetValve uses 12AX7 tubes in both phono and High-level stages, it might be possible to have it modified for 12AT7 tubes in the high level stages but I don't know if that can be done in the PAT-5 chassis model.
Tom

[avahifi]

A very early Fet Valve preamp using four 12AX7 tubes (or without a phono section, two 12AX7 tubes) can indeed have its line stage upgraded to use 12AT7 tubes, which have lots more current drive and nicer overall musicality and dynamics.

I would have to see one to figure out the right price for it, but I would keep it reasonable.  If someone wants to send in one to be the "Guinea pig" I would do that one free (except for the cost of the tubes, $35 plus $30 return shipping) if it can be done economically.

Best regards,

Frank Van Alstine

[robinje]

My new chips came in the mail today.  The swap in my Ultra DAC probably took less than 10 minutes total.  The most cumbersome part was removing and reinstalling the 16 chassis cover screws!  The new chips fit right into the sockets with no coaxing or bending of pins required.  It is very obvious how the chips align into the sockets, so no confusion is to be expected.  For anyone on the fence about whether or not to send in your Ultra DAC or to do the job yourself, I highly recommend doing it yourself.  If I can do it, anyone can (assuming you have eyesight, two hands, and not too much caffiene in your system)!  I recommend using a magnifying glass to verify that all the pins are in the sockets after inserting the chips.  The pins do indeed appear easy to bend, so be careful.  Doing the job yourself has the added benefit of being able to see up close the superb craftsmanship of your AVA gear.  I took a few minutes to admire the neat assembly and nicely routed wiring in my DAC.  I could certainly tell just by looking that a lot of careful and thoughtful work went into the design and construction of this unit, way more than would typically be expected considering the reasonable cost of AVA gear in general.  I'll leave any detailed descriptions of sound quality up to others, but I will say that I am extremely happy with my AVA components in terms of sound, function, build quality, customer service, etc., etc... 

[Tom Alverson]

A very early Fet Valve preamp using four 12AX7 tubes (or without a phono section, two 12AX7 tubes) can indeed have its line stage upgraded to use 12AT7 tubes, which have lots more current drive and nicer overall musicality and dynamics.

I would have to see one to figure out the right price for it, but I would keep it reasonable.  If someone wants to send in one to be the "Guinea pig" I would do that one free (except for the cost of the tubes, $35 plus $30 return shipping) if it can be done economically.

Best regards,

Frank Van Alstine

I would gladly be the guinea pig for that upgrade.  I have an original FetValve with all 12ax7 tubes in the PAT5 chassis (with black faceplate).  I have an old Omega-II in my system right now as my tubes in the FetValve are in need of replacement anyway.   I know my preamp is holding me back right now as I have the Insight DAC and ortohbiz's "OLD" 550-Ultra amp. 

Tom

[rlee8394]

From the looks of that Insight DAC board, there are two unpopulated 8 pin DIP sockets. Maybe this board is used for another function as well such as a preamp or bridge? Also, it looks like the 10 pin DIP sockets are gone as well. I assume these were for the current buffers. Since the entire board is not shown, it's hard to tell if there are current buffers on Insight products? Since we're talking chip rolling here to some degree, has anyone tried these op-amps from Burson?

http://www.partsconnexion.com/t/catalog/semiconductors.html

Talk about pricey! Burson site here:

http://www.bursonaudio.com/burson_opamp.htm

Ron

[avahifi]

First of all, Tom, thanks for volunteering your old T7 preamp in a Dyna Pat-5 chassis for the project.

Go ahead and send it to us.

Regarding the blank space on the DAC board, there is more to it than meets the eye.     I would not recommend experimenting with other "non-AVA approved" op-amps as they may cause the unit to oscillate at ultrasonic frequencies, possibly damaging other components downstream without you being able to hear what is happening, until your tweeters melt.

Of course if you have some pet ICs you want us to try (must be unity gain stable and have a standard industry pin-out) go ahead and send us a couple and we will play with them and post the results herein.

Regards,

Frank Van Alstine

[rlee8394]

Frank,

Would the work you would do to Tom's PAT-5 Fet-Valve also apply to the Fet-Valve in the original AVA first generation SL chassis circa 1993? I have one of those if you need to evaluate it. Also, wouldn't that be the same as an update to the prior T7 series? Did the T7 have the Exicon TO-220 mos-fets instead of the Hitachis? Are you only looking to change from the 12AX7 to 12AT7 tube in these older Fet-Valve units along with proper RC components?

Ron

[rlee8394]

Regarding the blank space on the DAC board, there is more to it than meets the eye. 

Hmmm... Maybe SMD's on the backside of the board???? aa

[Wayner]

Only slightly high-jacking this thread, my Insight 170ex showed up today. Now I am totally state of the art AVA in both systems. You know how we've discussed in the past few months, power cord tweaks, interconnect tweaks, and even the dreaded speaker wire gauge thread. You all probably thought I was looking for Frank's wrath. Well, when we've changed cables we kind of hee-haw around abit and go...well maybe? Well the new Insight, in combination with my newly re-modded Dynaco A25XLs and the new chip upgrade in the Insight EC preamp caused an immediate....hell ya!

There is instant, oh, my. What a nice little amp. It has big muscles for a little guy. Sooooo musical. Soooo commanding. Sooooo open....oops 

Now we have a mess. I have to pack up boxes and put the U70 on a shelf for awhile.

Wayner  aa

[Jon L]

First of all, Tom, thanks for volunteering your old T7 preamp in a Dyna Pat-5 chassis for the project.

I would not recommend experimenting with other "non-AVA approved" op-amps as they may cause the unit to oscillate at ultrasonic frequencies, possibly damaging other components downstream without you being able to hear what is happening, until your tweeters melt.


Frank Van Alstine

Have you already tried OPA637 instead of OPA627?

[BradJudy]

Have you already tried OPA637 instead of OPA627?

Frank noted that it must be unity gain stable.  The 637 is not.

[mark funk]

Can these chips be used in my Transcendence-R DAC? If so I well have to give them a try.

[G E]

I would have to see one to figure out the right price for it, but I would keep it reasonable.  If someone wants to send in one to be the "Guinea pig" I would do that one free (except for the cost of the tubes, $35 plus $30 return shipping) if it can be done economically.

If you need a second guinea pig or have a second idea you wish to try, I can send in my unit.  Can provide serial number if that helps.

Greg

[avahifi]

The 627 chips can only be used safely in our most modern solid state units.  They are used in combination with other new devices and they probably would not have any significant benefit in older solid state DACs or preamps (OmegaStar or earlier) and might even be unstable in those applications.  Of course those units can be upgraded to Insight status, and the new chips will just raise those prices $50 if done at the same time.

A Transcendence DAC in the small (12" wide) chassis can be upgraded with everything except the 6N1P tubes and that will make a lovely improvement to these older designs.  The cost would be in the $400 to $500 range depending upon the vintage.  The full Ultra upgrade for earlier hybrid DACs will remain the same price as shown in our 11/08 price sheet, with the new chips included at no additional cost.  Note that the full Ultra upgrade price for a hybrid DAC in the 12" chassis includes moving the guts to the new big chassis to get the job done.  These prices are still a lot less than a brand new unit.

We never used Exicon TO-220 devices in the hybrid preamps, always Hitachi J79 types.

One older all 12AX7 preamp is all I need for testing and Tom's is it.  This exercise is just to upgrade it to 12AT7 line operation, nothing more.  That will make a nice improvement possible in any of our older FV preamps that used 12AX7 line tubes.

Wayne, thanks for your kind comments about the Insight 170 amp.  That old Dyna St-120 chassis makes a really nice package, kind of like a turbocharged VW with a F1 suspension.    All we save from the original St-120 is the case and cover (after my tech cleans them up as much as possible), the external fuseholder, the black and red speaker jacks, and two of the bare heat sinks.

Note that since we are in-circuit testing all the 627 chips we are sending out, the leads are already pre-bent for an easy fit in the sockets.

Regards,

Frank Van Alstine