Vintage HiFi Audio Forum

Audio Discussion => CARVER => Topic started by: wkhanna on January 31, 2015, 11:26:03 AM

Title: C-19 OP Amps
Post by: wkhanna on January 31, 2015, 11:26:03 AM
(http://i2.photobucket.com/albums/y33/wkhanna/DSCF8967_zps6d96cb4e.jpg) (http://s2.photobucket.com/user/wkhanna/media/DSCF8967_zps6d96cb4e.jpg.html)


(http://i2.photobucket.com/albums/y33/wkhanna/DSCF8969_zps7c42d187.jpg) (http://s2.photobucket.com/user/wkhanna/media/DSCF8969_zps7c42d187.jpg.html)


After years of pure joy with my Tom/Anders modified C-19 I have begun further pursuit of end-game performance from this marvel of audio equipment.

First was my installation of musician-grade Portuguese cork between the chassis & transformer.
Next was encapsulating the transformer in mu-metal http://en.wikipedia.org/wiki/Mu-metal (http://en.wikipedia.org/wiki/Mu-metal) along with the installation of PEARL tube coolers.

The next step is taking advantage of the sockets Tom installed to try some new op amps .
After some time investigating available options I have decided to give the Burson Discrete http://www.partsconnexion.com/opamp_burson.html (http://www.partsconnexion.com/opamp_burson.html) units a try.

My question (hello Tom) is which op amps to replace for the pre section?
Are they single or dual?

Title: Re: C-19 OP Amps
Post by: schwarcw on January 31, 2015, 12:59:33 PM
Hey Bill!

Tell us about those tube dampers!
Title: Re: C-19 OP Amps
Post by: Kingman on January 31, 2015, 01:12:32 PM
I've never seen shit like that...hell, I've never even HEARD of shit like that!  :o  :o  :o
Title: Re: C-19 OP Amps
Post by: bearjew on January 31, 2015, 01:40:04 PM
I've never seen shit like that...hell, I've never even HEARD of shit like that!  :o  :o  :o

Kingman, you really are living proof that ignorance is bliss :P
Title: Re: C-19 OP Amps
Post by: Kingman on January 31, 2015, 02:01:48 PM
I've never seen shit like that...hell, I've never even HEARD of shit like that!  :o  :o  :o

Kingman, you really are living proof that ignorance is bliss :P
I bet 1 in 500 have heard of that metal stuff around the tubes...I got tube dampeners like the rubbers on there so I have an idea of their purpose...
Title: Re: C-19 OP Amps
Post by: MacGeek on January 31, 2015, 03:00:14 PM
Well, what kind of difference did it make?  Tell us how it sounds.
Title: Re: C-19 OP Amps
Post by: Sir Thrift-a-Lot on January 31, 2015, 03:00:59 PM
The tube coolers are common fare, but what exactly makes a piece of cork "musician-grade" (he asked hesitantly, awaiting the pummeling that is sure to follow).
Title: Re: C-19 OP Amps
Post by: OldiesButGoodies on January 31, 2015, 03:33:12 PM
the c19 uses dual op amps, I think.  better check w tom or someone in the carveraudio forum.  those burson supremes look awesome.  no idea if they sound better but they sure look badass.
Title: Re: C-19 OP Amps
Post by: wkhanna on January 31, 2015, 04:43:13 PM
The PEARL tube coolers are excellent heat sinks. Now the pre-section tubes are low power & the C-19 uses 'soft-start' so there is not as great an issue with heat degradation, but these are OS Mulards (from Tom) that I want to last as long as possible.
Interesting reading on tubes & the effects of heat here, for those interested. http://www.partsconnexion.com/PDF/pearl_tc.pdf (http://www.partsconnexion.com/PDF/pearl_tc.pdf)

The PEARL's also act as dampers, which affects vibration & 'micro-dynamics' which low-power signal-level tubes demonstrate. Minimizing any vibration is a good thing in audio. More so for signal-level.

My friend Dan & I both noticed increased detail, imaging and a sense that the instruments had a more three dimensional quality. They were slightly, but noticeably more focused & yet removed from the speaker, more established in their own place in the air. Also, there was a V slight roll-off in the very upper end of the frequency, which worked well for my system.

Regarding the cork: Portuguese cork is the best in world (due to its climate).
Musician-grade is simply a grade rating for natural cork. It is the same stuff used for musical instruments like clarinets, saxes & other woodwind instruments.

Again, the reason for using cork is vibration control.
I have used it in all my gear for transformers & IC boards.
Dan & I have found it increases blackness (it makes passages with no sound quieter) & adds detail to subtitle elements like the shimmer of top-hats & cymbals & increases decay. You will notice it on well recorded piano immediately.

The mu-metal is amazing.
By far the most cost effective upgrade I have yet come across.
I put it on all my gear, digital, amps pre, everything.

Many super hi-end units use it to isolate nasty stuff coming off of high-power elements that contaminate sensitive components like chips, caps & resistors.
Nothing new, but seldom implemented on mid-level gear.
Other companies will totally isolate the high-power sections in separate chassis.
Put in the mu-metal yourself gets you a little closer to the last 2% of what is achievable.

Dan & found it gives much tighter, musical sounding bass, better detail, imaging & separation.
One of the first things you will notice is how the sound stage goes way back behind the speaker.

(http://i2.photobucket.com/albums/y33/wkhanna/aa/DSCF8935_zpsa840cf1c.jpg) (http://s2.photobucket.com/user/wkhanna/media/aa/DSCF8935_zpsa840cf1c.jpg.html)

(http://i2.photobucket.com/albums/y33/wkhanna/aa/DSCF8938_zps0f4c2b8f.jpg) (http://s2.photobucket.com/user/wkhanna/media/aa/DSCF8938_zps0f4c2b8f.jpg.html)

(http://i2.photobucket.com/albums/y33/wkhanna/aa/DSCF8941_zps8f8cecb3.jpg) (http://s2.photobucket.com/user/wkhanna/media/aa/DSCF8941_zps8f8cecb3.jpg.html)

(http://i2.photobucket.com/albums/y33/wkhanna/aa/DSCF8873_zpsdfb38851.jpg) (http://s2.photobucket.com/user/wkhanna/media/aa/DSCF8873_zpsdfb38851.jpg.html)

(http://i2.photobucket.com/albums/y33/wkhanna/aa/DSCF8888_zpse0f0e360.jpg) (http://s2.photobucket.com/user/wkhanna/media/aa/DSCF8888_zpse0f0e360.jpg.html)

(http://i2.photobucket.com/albums/y33/wkhanna/aa/DSCF8902_zpsd7817e47.jpg) (http://s2.photobucket.com/user/wkhanna/media/aa/DSCF8902_zpsd7817e47.jpg.html)

Title: Re: C-19 OP Amps
Post by: Sir Thrift-a-Lot on January 31, 2015, 07:29:32 PM

Regarding the cork: Portuguese cork is the best in world (due to its climate).
Musician-grade is simply a grade rating for natural cork. It is the same stuff used for musical instruments like clarinets, saxes & other woodwind instruments.


Thank you, that makes sense to me.
Title: Re: C-19 OP Amps
Post by: schwarcw on January 31, 2015, 11:53:07 PM
Bill,

Great write up and interesting information.  I have never heard of the mu metal before.  I've used the tube dampers and have definitely heard the impact.  A very inexpensive tweak.  I think the best results that I have heard have been on the dampers on the signal or preamp tubes.  I have not tried dampers on power tubes, but I may give that a shot on my small EL84 integrated amps.
Title: Re: C-19 OP Amps
Post by: Rockman Rock on February 15, 2015, 11:16:11 PM
IIRC the LME49720 is a great op amp that can be used in there. Is that what you had in there?

The Bursons are great. I used the Bursons in a Music Hall 25.3 DAC I modded.

Carl, you have the LME49720 in the Twisted Pear Legato v3.1 I/V output in your DAC, specifically the SE and headphone out. Your balanced out is discrete output, no op amps there.
Title: Re: C-19 OP Amps
Post by: Rockman Rock on February 15, 2015, 11:27:25 PM


The Bursons are great. I used the discrete Burson op amps in a Music Hall 25.3 DAC I extensively modded. Your power supply needs to be up to the Bursons. IIRC the Bursons imposed a 700% increase in mA over the stock op amps. I upgraded the op amp supply with Belleson Super regulator with larger heat sinks. It is based on the Jung regulator and was a drop in swap for TO-220 regs. Burson has a new design discrete op amp now so unsure of mA specs.

(http://i417.photobucket.com/albums/pp260/scompracer/Music%20Hall%20253%20DAC/fini.jpg) (http://s417.photobucket.com/user/scompracer/media/Music%20Hall%20253%20DAC/fini.jpg.html)

Title: Re: C-19 OP Amps
Post by: schwarcw on February 16, 2015, 07:15:43 PM
Rockman, you do some great work!

I know that Music Hall DAC.  IIRC somebody put the opamps in backwards with not so good results.  I'm just glad it wasn't me.

Title: Re: C-19 OP Amps
Post by: Rockman Rock on February 17, 2015, 06:39:19 PM
Rockman, you do some great work!

I know that Music Hall DAC.  IIRC somebody put the opamps in backwards with not so good results.  I'm just glad it wasn't me.

Thanks Carl! I didn't either. The fellow I sold it to let somoene borrow it. He got it back and stuck one in backwards. I had them puppies marked for proper orientation too.

Fortunately the DAC still works. The new owner purchased the new design Burson op amps. I have one of the Burson survivors to try in my Legato I/V board.
Title: Re: C-19 OP Amps
Post by: Anders on February 17, 2015, 08:11:54 PM
Pearl tube coolers are great for making power tubes last longer but when I tried them on my preamp tubes I didn't notice much of an improvement so I left them off.
There are other areas that will make more of an improvement like replacing the quad op-amp in the output stage of the C-19. The Brown Dog RC4136 Upgrade Adapter will let you use a standard quad op-amp like the AD823. The 8 pin op-amps are TLO-72 which is a dual op-amp.The Burr Brown 2604 is a drop-in replacement for the TL072 but I used to use the Analog Devices AD-712.
Title: Re: C-19 OP Amps
Post by: Meles on March 09, 2015, 03:30:27 PM
Pearl tube coolers are great for making power tubes last longer but when I tried them on my preamp tubes I didn't notice much of an improvement so I left them off.
There are other areas that will make more of an improvement like replacing the quad op-amp in the output stage of the C-19. The Brown Dog RC4136 Upgrade Adapter will let you use a standard quad op-amp like the AD823. The 8 pin op-amps are TLO-72 which is a dual op-amp.The Burr Brown 2604 is a drop-in replacement for the TL072 but I used to use the Analog Devices AD-712.
I am new to the site and I must say this is pretty hard core. Never heard of a C-19 and I am amazed you guys are modding them. This looks almost dead, but hopefully you'll update on your progress. Am I correct that Anders added the IC sockets for the TLO-72? I saw something on another site that scared me if you upgraded all of those: "The big problem, as I understand can also be the unexpected current draw - especially with TL072 upgrades.  These draw less 3ma or so but up an "upgrade" of say an OPA2604 is 12ma.  That adds up pretty fast to your power supply giving up it's soul. It could also sound worse or nasty things." I was looking at the C-19 schematic online and call me crazy, but it looks like it uses seperate 6DJ8 for MM and MC? This thing is half solid state, but you might be able to yank the phono tube not in use and perhaps some ICs around it. Looks like the unit runs the 6DJ8 at very low voltage and they all run off the same transformer taps, so this might be something that would take the load off of the power supply.

If you get the Burson I'd love to hear what you think of it as i have solid state crossover for which this might take the upgrade to another level. Hopefully Anders has directed you to the key ICs to replace in your situation as I see a lot of them. If you go Burson crazy the expense would be pretty high. Tube rolling and IC rolling all in one, yikes.

You might get a lot of mileage upgrading the bridge rectifiers in the unit. Those in design often claim they can use more mundane diodes to accomplish what hexfred's or stealth diodes do, but I have my doubts having experienced diode upgrades which are pretty cheap.

You might be surprised what you might find in the blackgate FK, C series, and PK at low voltages. I recently upgraded a solid state amp with these and was quite pleased with the result. High voltage black gates are insanely priced these days.