# MonoGizmo



## dweeke (Oct 30, 2006)

I finally got around to finishing up some monoblocks. Pics!










Here are the parts for each Gizmo.

2x 1.0uf Obbligato Gold Caps
3x Panasonic FM 470uf 35V caps
4x Wima MKP2 0.33uf










Removed R2 and R4 next to the RCA inputs.









Removed the 5 black electrolytic caps and 2 yellow film caps in the amp section. Wire links were added across the C35 and C36.









The 3 new Pansonic FM caps and 2 Wima caps added. 









C50, C51, R34, R35 removed on bottom of board.









Wire added across pads of R34 and R35.









2 Wima caps added to bottom of the board. Leads are in exactly the same hole as the top Wima caps. This doubles the capacitance of the caps to equal the value of the original caps (the orignal yellow caps are 0.68uf whereas the Wimas are 0.33uf each). 









Wires added to right channel input and ground.









Cap added to the previously soldered wires. This directs the signal directly from the rca jacks through the caps to the amp chip. 









Top view.









The black lead of the right speaker-out wires is spliced into the red lead of the left speaker out. 









That's it! Only the right channel inputs and outputs are used for each monoblock. The volume control does not function, and the volume is always at maximum like power amps. I originally wanted to add a transformer to allow for differential inputs into the amplifier chip, but the transformer I had on hand degraded the sound too much for my tastes. Since there is no differential input, there is no increase in power. 

It is a relatively easy mod, and the sonic gains are very noticeable. The power supply is the only thing holding it back right now (slight grain, slight treble harshness), but it still sounds better than it should.


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## nwboater (Dec 28, 2007)

dweekie said:


> I finally got around to finishing up some monoblocks.
> 
> Here are the parts for each Gizmo.
> 
> ...



Hi Dweekie,

Thanks for the helpful guide - looks really good and fairly straightforward. Have a few questions:

1.Where would you suggest getting these parts in small quantities?

2.When you say no increase in power, do you mean that whatever the power originally in one channel was, that the total power out of the monoblock will equal that?

3. What kind of power supply would you recommend for an external replacement? Any idea of the voltage and amperage required?

Thanks,
Rod


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## dweeke (Oct 30, 2006)

nwboater said:


> Hi Dweekie,
> 
> Thanks for the helpful guide - looks really good and fairly straightforward. Have a few questions:
> 
> ...



1. 
Obbligato films (http://www.diyhifisupply.com/?q=node/158)
Panasonic FM (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P12415-ND)
Wima MKP2 (http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMvCt%2bwg%2braTuiEXhpIo3SenEXlgDct4qn4=)

Now that presents a bit of an issue with very small orders and high shipping costs, not to mention the minimum order requirement at digikey (and import fee from shipping from Mouser if that applies). 

If there are others interested in the mods, a very small group buy could probably be arranged. Let me know if anyone is interested. I could probably substitute the input caps with some others from Digikey to drop the cost of parts down to about $15 + shipping. You do have to factor in the cost of 2 Gizmos, but the difference in performance is quite large in my opinion. 

2. Yes, on paper the power level will be the same as what a single channel was before. It will sound a bit more dynamic and clean, so there may be a perception of more power (dedicated power supply per channel probably helps here). The added benefits of complete stereo seperation is noticeable.

3. I don't have any specific recommendations off the top of my head for power supplies. Anything with equal or less voltage and equal or more current than the stock power supply will work. I've used my 12V supply without any issue, although the power rating falls at that voltage. 24V supplies seem common enough to get hold of easily.


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## nwboater (Dec 28, 2007)

Hi Dweekie,

Thanks for your prompt response. I am planning to do these mods so a group buy would be very helpful to me. I already have one Gizmo and another on it's way.

Are you planning to mention this at AV123? Might gather some interest there.

Rod


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## dweeke (Oct 30, 2006)

:toilet:
I forgot to double the cost to account for each gizmo, so it's actually around $30 + shipping. 

They're on their way to the VA GTG this weekend. Some listening impressions should show up afterwards, I assume.


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## nwboater (Dec 28, 2007)

dweekie said:


> 1.
> Obbligato films (http://www.diyhifisupply.com/?q=node/158)
> Panasonic FM (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P12415-ND)
> Wima MKP2 (http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMvCt%2bwg%2braTuiEXhpIo3SenEXlgDct4qn4=)
> ...


Hi Dweekie,

I now have two Gizmos and would like to do the monoblock mods. Have you drummed up any more interest so a group buy can be done?

Thanks,
Rod


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## dweeke (Oct 30, 2006)

nwboater said:


> Hi Dweekie,
> 
> I now have two Gizmos and would like to do the monoblock mods. Have you drummed up any more interest so a group buy can be done?
> 
> ...


Nope. Let me see what parts I can dig up for you.


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## nwboater (Dec 28, 2007)

dweekie said:


> Nope. Let me see what parts I can dig up for you.


Bummer! Hate to see you bothering with this but sure do appreciate it. Surprised more arent interested! Think I'll take any more messages to PM after this.

Thanks again Dweekie,
Rod


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## woofersus (May 6, 2008)

I've been harboring some interest in doing this, but have been waiting for the timing to be right with other bits of gear and all. I'd be willing to participate in a group buy of the parts if it helps. 2 people isn't much of a group buy though...

btw, are the sub outputs still sending any signal after doing this mod? It would appear that you've bypassed that section altogether. If so, is that because the crossover circuitry degraded sound? I'd imagine that the sub volume control becomes irrelevant with the volume always at max.


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## dweeke (Oct 30, 2006)

woofersus said:


> btw, are the sub outputs still sending any signal after doing this mod? It would appear that you've bypassed that section altogether. If so, is that because the crossover circuitry degraded sound? I'd imagine that the sub volume control becomes irrelevant with the volume always at max.


Some people did note distortion due to that buffer, which seemed to add a bit of gain. Bypassing it fixed that issue. You may be able to hook up the inputs to the subout just fine, from the rca straight into the points shown in the sub-fix thread. This will still give you full range output with a 100hz lowpass for the subwoofer. The volume control will be irrelevant since you'll need a pre-amp before it anyway.


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## woofersus (May 6, 2008)

Good idea. Might be worth trying. I suppose I'd rather cross the sub over before the amp though if it's going to be mono blocks. I just don't have a good way to do that at the moment. I'm still interested in modding gizmos though. I'm not interested in paying $400 for something else that sounds better, and I'm suspicious that's what it would take.


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## dweeke (Oct 30, 2006)

woofersus said:


> Good idea. Might be worth trying. I suppose I'd rather cross the sub over before the amp though if it's going to be mono blocks. I just don't have a good way to do that at the moment. I'm still interested in modding gizmos though. I'm not interested in paying $400 for something else that sounds better, and I'm suspicious that's what it would take.


The biggest benefit is probably the stereo seperation, which is nearly impossible to match at this particular pricepoint. A tube pre would mate very well overall by adding a bit of body, although I use a passive right now. 

I didn't like the sound degradation of the Neutrik NTE1 input transformer, so I left it out in the first mods. I didn't want to use more expensive transformers since it didn't fit the theme of the mods. Thanks to V-bro from 41hz, I found a correction filter that might make it sound a lot better. This will bump the power back up to 40 watts into 8 ohms for those that need the power. I'll try it out again when time allows.


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## dweeke (Oct 30, 2006)

When'd I become a senior member? I'm not that old yet, am I? :hissyfit:


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## nwboater (Dec 28, 2007)

dweekie said:


> The biggest benefit is probably the stereo seperation, which is nearly impossible to match at this particular pricepoint. A tube pre would mate very well overall by adding a bit of body, although I use a passive right now.
> 
> I didn't like the sound degradation of the Neutrik NTE1 input transformer, so I left it out in the first mods. I didn't want to use more expensive transformers since it didn't fit the theme of the mods. Thanks to V-bro from 41hz, I found a correction filter that might make it sound a lot better. This will bump the power back up to 40 watts into 8 ohms for those that need the power. I'll try it out again when time allows.


The mod to get the power back up is very appealing - hope it will work out. If that approach doesn't what might a good transformer add to the cost?

A tube pre is also appealing. When my system is complete it's primary source will be from a PC music server to a DAC (TCA DacMan perhaps?). Since the DacMan has it's own volume control I wouldn't need a preamp just for it, but there will be secondary sources - DVD player, cable TV and possibly turntable. These would need volume control. Also even though it's not proper modern audiphile, tone controls have some appeal. Any suggestion here?

Thanks,
Rod


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## dvenardos (Sep 27, 2008)

dweekie said:


> When'd I become a senior member? I'm not that old yet, am I? :hissyfit:


You and me both. :crying:


nwboater said:


> When my system is complete it's primary source will be from a PC music server to a DAC (TCA DacMan perhaps?). Since the DacMan has it's own volume control I wouldn't need a preamp just for it, but there will be secondary sources - DVD player, cable TV and possibly turntable. These would need volume control. Also even though it's not proper modern audiphile, tone controls have some appeal. Any suggestion here?


This would be much cheaper to build with a two channel volume control.
http://www.tweakcityaudio.com/forum/showthread.php?p=10581


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## nwboater (Dec 28, 2007)

dvenardos said:


> You and me both. :crying:
> 
> This would be much cheaper to build with a two channel volume control.
> http://www.tweakcityaudio.com/forum/showthread.php?p=10581


Thanks for the suggestion - looks like a neat project you are doing, although making it 6 channel sure did run the price up on the attenuator! It would mostly meet my needs, with the exception of tone controls.

Dweekie had mentioned a tube preamp for adding some "body" (warmth?). Class D amps I believe can sound a bit clinical, perhaps even more so on my 50 year old Klipschorns! My gosh, I just realized they are that old - and I'm even much more so! But with new crossovers and some driver upgrades I still love em. Now if I could only get some driver upgrades! :yes:

Rod


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