[jeffreybehr]

I love the sounds of my '750s so much, I bought a DNA-HT5 from Spearit. 

This 5-channels-times-150Watts poweramp has replaced the trio of Marantz MA500s that have been driving my center and surround speakers.  I had finally gotten around to comparing the sounds of the improved MA500 to a known-great-sounding monoamp, one of my former Monarchy SE160s.  The SE160 sounded slightly 'fuller', more 'blooming' and attractive, tonally, and the MA500 sounded slightly edgy and harsh.

It certainly has more parts in it than my single-channel '750s, and some parts are not as high in quality as those in the '750.






It's capacitively coupled, with a high-pass filterpoint (FP) of 0.3HZ(!).


All silver-gray.


I won't be improving this one to nearly the extent I did the '750s, but I will replace some parts, starting with the main-powersupply caps, again with Nichicon KG-Muse series, but this time the 2nd-best Gold series.  In the channel driving the CC, I'll replace the DNA caps, again using Blackgate-N 680/65s.  Will replace the original 0.5uF input-filter cap with a much-lower-value Mundorf S/G, resulting in a high-pass filterpoint of 16Hz, much-more suitable than 0.3Hz for a bass-bandwidth-limited CC speaker. 

Also will be building a bass system to augment the VCC-1 CC speaker.  The latter will sit atop the bassbox, and I'll drive the bassbox with another channel of the 'HT5.

The fun never stops.   

[tdinut]

Sweeeeet Jeff!
Beautiful, and no, the fun never stops! 

[jeffreybehr]

I'll have to build another amppad for the 'HT5, and I plan to buy an inexpensive slab of Ikea countertop.  It's beech, 1-1/8" thick by 2+ feet deep by 8+ feet long.  I'll laminate 2 layers for this MC amp while adding a layer of that to the bottoms of the pads for the '750s, thereby sort of leveling the tops of the amps.  Only $59 for all that solid (laminated) wood.

http://www.ikea.com/us/en/catalog/products/10146525/#/80145749

[jeffreybehr]

Its 30dB of Voltage gain is WAY more than that of my improved '750s, so I added a resistor in series from the input jack; it cut 10dB of gain.  Now the CC-level control is about zero (relative).

[jeffreybehr]

Finally got around to replacing some parts.  Since I'll be improving the parts in only one channel* plus some in the common powersupplies, and because I'm simply not going as far as I did in the '750s, this one will be quicker and easier.

I replaced the emitter resistors (the output-transistor output-coupling resistors; the 2 white rectangular things far left), with Mills MRA-5s mounted on the bottom of the board.

I did this for 2 channels because I haven't decided which of these 2 I'll use for the centerchannel.

In the frontend-PS, replaced the output caps with BlackGates and a pair of Orangedrops with SoniCap 1s.


I was surprised to see Nichicon Muse KG Gold Tunes in the initial filtering positions of the frontend PS.  Those are the 'gold'-colored pair visible in the 2nd and 3rd pics of my initial post.

Will be replacing a few more caps in the CC-channel's active circuitry--after I choose it--these being the frontend circuitry's 'DNA' equivalents, and one set of bindingposts.  Also will replace the CC's four DNA caps with triple BlackGate-Fs plus a SoniCap Platinum bypass.  That will take some time.   

* The 3 channels driving the surrounds and yet-to-be-built-CC-bassbox are far less critical than the full-range-CC channel.  In a probably-futile jesture, I've removed the output-stage DC-rail fuses from the 5th channel, thereby 'saving' a little power for the 4 other channels.   

[jeffreybehr]

Got two trios of 680/65 BlackGate-Ns built and installed today, around a WONDERFUL Father's Day dinner with wife, 2 adult children, 2 granddaughters, and son's very nice GF.


The two small 'lytic DNA caps on the board between the stacks of BGs will be replaced with pairs of BG 680s.  Where there was 4000uF of inexpensive Nichicon caps in this channel, there will be 6800uF of BGs plus a pair of 0.47uF Sonicap Platinums.  Onward we go.

[jeffreybehr]

Got the DNA-cap project finished.  Where this channel had 4000uF of Nichicon caps, it now has 6800uF of BlackGate-N 'lytics plus 2 '0.94uF' SoniCap Platinums.


Also visible are the frontend-PS output caps, now Blackgate 470/160s, left of center and low in the pic and 2 SoniCap 'propylenes that replace a pair of Orangedrops.  There are no bypasses on the BlackGate 470s because the bypasses live within each channel's active circuitry--'DNA' caps for the Voltage-gain circuitry.

I have a couple more caps to replace in the frontend circuitry, plus one set of Cardas bindingposts.

I've decided to use (viewed from the rear in this 'old' pic)...

...the front-left channel for Center (main), the center-left channel for Center bass (when that is together), the channel spread across the bottom of the amp for one surround, and the right-center channel for the other surround.  I've removed the output-stage rail fuses from the right-front channel, most of which lives under the turn-on relay.

[jeffreybehr]

All in the main-centerchannel channel:
1. Replaced the 0.5uF input-coupling cap with a 0.01 Mundorf Silver/Gold left over from my powerconditioner projects.  That moved the highpass filterpoint from 0.3Hz to 16Hz (calculated, not measured), a reasonable compromise for a CC speaker that starts rolling off in the lower end of the upper bass; this will also reduce the possibility of distortion, etc., from overdriving it in the bass.  Added a 100K resistor on the RCA jack to reduce the Voltage gain a bit...and that decrease turned into 6dB.


2. Replaced the frontend-circuitry 'DNA' caps with pairs of 22uF BlackGates and 0.33uF SoniCap Platinums.  This quad is difficult to recognize since one BG is on the boardbottom and one SCP is white.


3. Replaced the inexpensive stranded speaker-connections internal wire with stuff I wound, all with Neotec UP-OCC solid-conductors in Teflon...two 18g. coppers and one 23g. silver.

I wasn't going to do this until I realized that I was driving 1-1/2 feet of all-solid-UPOCC-silver speakercable with a foot of this che...er...inexpensive stranded stuff.  I got lucky with this rather-expensive all-silver wire--I had ordered a length for the upper frequencies of the V-steen 5As.  That turned out to be about 1-1/2 feet too long, so onto the centerchannel V-steen the excess went.   

4. Replaced one channel's bindingposts with Cardas CCGRs, placing the pair high above the AC-power wiring in the amp and close to the CC speaker.  The 'C-B' label means Center-Bass; that channel will drive the new bassbox I'll build for the V-steen VCC-1 to sit upon.


I think I'm finished!

[Frisco]

Congrats Jeff......you got some skills.

[jeffreybehr]

Congrats Jeffrey......you got some skills.

TYVM.  I'm NOT an electrical technician or engineer...just an adventurous music-loving DIYist.  I've accumulated what little skills I have over about 35 years, and I was lucky to find an audiofool friend who knew something about this kind of stuff to get me started...in the era of WonderCaps and Siemens Styroflexes!  I know little about circuit design, and if things in a schematic aren't obvious, I don't fool with it.

One concept that has become more important to me over the years--the DC power delivered by the powersupplies is MORE important than the active circuitry modulating that power, and that's why I spend most of my money and time improving parts in powersupplies.

Again, thank you for your kind comment.

[sts9fan]

 My warranty voiding threads

[jeffreybehr]

My warranty voiding (sic) threads (sic)

Did you intend to list them but forgot?

[jeffreybehr]

Couldn't find exactly the pot I wanted, but found one plenty good enough, an Alps double-100K.  Wired the 2 variable resistors in series; the added 180K resistance will cut the level about 12dB, plenty enough to match levels between the new centerchannel bassbox and the V-steen VCC-1.




I'm about 99% finished.   

[jeffreybehr]

The old left and right pads are built of curupay, perhaps the most-beautiful wood I've ever seen.  The (new) center pad is built of two layers of laminated beech from IKEA.  http://www.ikea.com/us/en/catalog/products/10146525/#/80145749

It's heavy, dense, and my woodmeister says it machines and finishes very nicely.  It, like unsealed maple, stains rather blotchily, but applications of WATCO Danish Oil Finish, Dark Walnut first and then Cherry, made me happy.  Maybe in a few months...during our 7 months of nonsummer...I'll make it a little darker.

I had a layer of this beech added to the left and right pads...

...as much to about-level the top edges of the three amps as anything else.  An application of Howard Feed-N-Wax added the low gloss visible in the above pic.

They look pretty good, huh?


My woodmeister is now building a centerchannel bassbox of this laminated beech; we'll see how that goes.