Klipsch Promedia 2.1: fixing a broken channel

After years of living with only a single channel, I attempted a repair and it has been successful so far. Though there is a turn on thump (perhaps because the output devices are not as matched), it seems to work ok. 

In one HF channel, the fuse had blown and kept blowing. This was the initial symptom. I suspect the culprit was the original goop used to hold things together. It became conducting and shorted out one output device (TIP41C). The blackening of the board is suggestive of this.

Thanks to the excellent work by the folk listed in the references below, I had an idea of what to do. In the end, I replaced both Q9, Q10 (TIP41C and TIP42C respectively), and Q6 2N3904. TIP41C had all terminals shorted; TIP42C measured ok. I also changed out a couple of resistors that seemed very charred, though they measured ok (They fell apart when removed from the board). There were mica insulators between the output devices and the heatsink. I cleaned the old heatsink compound and applied new compound. The main clue was to compare measurements between the working and non-working channels.

There is an initial offset of about 60mV in the channel I repaired. This is about 20mV in the other channel. They both settle to about 5mV higher in a few minutes. There was some discoloration in the LF amp board but I did not change anything since it works.

References:

http://christopherbradshaw.net/The_Project_Bin/klipsch%20promedia%20subwoofer%20repair%20-%20page%201.html

http://www.thompdale.com/bash_amplifier/2-1/2-1_bash_amp.htm

http://diyaudioprojects.com/Forum/viewtopic.php?t=4892

Review of Burson Audio Classic V6 op amp in a DIY WHAMMY headphone amplfier

 Thanks to Burson for providing V6 Classic Duals.

Summary? I like V6 Classic over V6 Vivid, in this application.

I changed my testing slightly from my earlier review of V6 Vivid. A couple of different songs. Source volume from the phone is full.

These stayed the same:
Input: Samsung Galaxy S9 plus
Headphones: Sony MDR-7506
No changes to WHAMMY (18V transformer, naked 15V regulators)

The goal is to pick between V6 Classic and the earlier samples of V6 Vivid. Again, I listened to both the op-amps back to back. No instrumentation.

Songs:
(1) Track 1 Unaccompanied Cello Suite No. 1 in G Major, BWV 1007: I. Prélude from Six Evolutions - Bach: Cello Suites, Yo-Yo Ma (2018)
(2) Track 4 The Four Seasons, Violin Concerto in F Minor, Op. 8 No. 4, RV 297 "Winter": II. Largo from Appassionato, Yo-Yo Ma (2007)
(3) and (4) Fragile and Be Still My Beating Heart, Tracks 9 and 6 from Fields of Gold: The Best of Sting 1984–1994 (1993-1994)
(5) Sugar, Track 6 from Free Life, Dan Wilson (2007)
(6) Lies, Track 6 from After Forever, Kasper Bjørke (2014)
(7) You're Getting to Be a Habit with Me, Track 8 from Love Scenes, Diana Krall (1997)
(8) and (9) Breakable and The Way I Am, Tracks 3 and 5 from Girls and Boys, Ingrid Michaelson (2006)

Vivid:
Fragile: Somewhat fatiguing
Be Still My Beating Heart: The supporting chorus was clear
Sugar: Midrange was better than high frequencies (which sounded a little recessed)
Good supporting vocals

Classic:
Fragile: Chorus sounded good
Be Still My Beating Heart: The Guitar sounded nicer than the chorus. Delicate high hats
Sugar: Even better Midrange instruments. Voices had more emotion.
Lies: More complex presentation of instruments
Breakable: The hand drum in the left channel was fantastic. Beautiful lower bass.

Vivid made instrument separation good. Classic let me distinguish between the different notes made by those instruments.
With the Classic, I started to enjoy the music.

I'll keep the Classic in my Whammy. 

 

 

Review of Burson Audio Vivid V6 op amp in a DIY WHAMMY headphone amplfier

 

Thanks to Burson Audio for the samples of Supreme Sound OpAmp Vivid V6.

Marking on the box: V6V-D-2

It came thoughtfully packaged with 2 DIP-8 adapters. I had already installed such an adaptor in my Whammy.

My build was with the PCBA from https://diyaudiostore.com/. I sourced parts myself and stumbled many times with lots of rework.

Supply: +/- 15 V straight regulators. no LED or voltage divider

Input:  Samsung Galaxy S9 plus. Volume two notches below maximum

Headphones: Sony MDR-7506

Gain with the Vivid V6 seems to be higher than with the baseline OPA2134PA. Gain matching was by ear. I realize this is not as accurate as with instrumentation. This was not a blind test. I heard the songs below with the OPA2134PA and then swapped it out for the Vivid V6, leaving everything else the same.

I had to move surrounding components a little. The footprint of the Vivid V6 is a little larger. Luckily, the box I used is big enough for height. so I'll let it stay a while.

(1) Track 1 Unaccompanied Cello Suite No. 1 in G Major, BWV 1007: I. Prélude

from Six Evolutions - Bach: Cello Suites, Yo-Yo Ma (2018)
(2) Track 4 The Four Seasons, Violin Concerto in F Minor, Op. 8 No. 4, RV 297 "Winter": II. Largo from Appassionato, Yo-Yo Ma (2007)

(3) and (4) The Hat and The Way I Am, Tracks 4 and 5 from Girls and Boys, Ingrid Michaelson (2006)

(5) Track 2 Künstliche Welten (Praha-Edit) from Künstliche Welten, Wolfsheim (2004)

(6) Track 10 How Deep Is the Ocean (How High Is the Sky) from Love Scenes, Diana Krall (1997)

The sound: there is more detail and more bass. Notes, and instruments are separately identifiable.

After this I continued to listen to many songs with the Vivid V6. In familiar songs, I was surprised, especially at the start and end of songs: sometimes I could discern extra vocals, instruments or notes.

That said, I think I am spoiled by ZenMod's Iron Pre. With that, I enjoy the music without paying attention to accuracy or anything else. With the Vivid V6, with my setup, to my ears, there seems to be something amiss. I don't know how else to say it.

In the words of our resident wise man "this is Entertainment - not Dialysis". It is good to have choices and even better to listen to a few.

Links:

https://www.bursonaudio.com/products/supreme-sound-opamp-v6/

https://www.ti.com/store/ti/en/p/product/?p=OPA2134PA

https://pro.sony/ue_US/products/headphones/mdr-7506

https://guides.diyaudio.com/Guide/WHAMMY+headphone+amplifier/3

"this is Entertainment - not Dialysis" from http://www.firstwatt.com/pdf/art_h2_v1.pdf