@jji666 TNT200'S are stable below 2ohms. Roy Esposito was one of the original engineers for Acoustat he is the person who rebuilt and upgraded my Amps and Speakers.
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Working with electronics is like baking, you have to follow the recipe. If you change the caps by adding more or bigger it’s about the same as changing the amount of baking powder you add to the mix. It might not do much or it might change everything.
All the best.
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OP, keep in mind that bridging stereo amps into mono isn't a free lunch. For example many stereo amps don't do well bridged into 4 ohm loads. You need amps rated stable down to 2 ohms do that.
Monoblocks typically are not bridged stereo amps, though, so true monoblocks stable to 4 ohms would be fine.
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I purchased 2 Acoustat TNT200’s to have rebuilt and converted to Monoblocks.
They were purchased to power my Acoustat Spectra 33’s, which I also have rebuilt and upgraded. Before the conversion I used 1 amp in stereo mode to power the Spectra 33’s and a Acoustat passive sub that came with the panels. Sub sounded bloated soft and slow. The panels alone sounded good but did not deliver what I was expecting from all the hype surrounding these panels. I was ready to sell the lot. Fast forward, panels are rebuilt, amps are rebuilt, pushing somewhere around 900watt @4ohms per side. These things sound spectacular, airy, controlled and Soundstage that puts you right there. Base on your comment, no not a bigger transformer or larger caps, rebuilt transformers and new caps. Each amp is now a monoblock which essentially more than doubles the power rating. This makes a big difference at low listening levels. Dynamics from a Electrostats is rare. IMO, improving the power supply and larger caps associated with what’s required for those upgrades, would give you a better sounding amp. Converting them to monoblocks would be enjoyment ×2....
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Thank you everyone for the wealth of info on this topic. I am learning a lot more than I had known prior to asking. This is not a DIY question although the responses should help those folks. The nuts and bolts of this are:
A: one Kismet Stereo: claims 160wx2, (850VA toroidal, 4qty x 35mf caps total, 70mf/side)
B: two Kismet monoblocks, per amp: 200wx1 one 850VA transformer and 140mf output capacitance (each channel has twice, plus the entire audio board too).
Now we're down to brass tacks. Might I expect to hear subtle gains in noise floor, PRAT, piano weight (e.g.) bloom, etc? I experienced a lot with the Kismet stereo. Is it wishful thinking; have diminishing returns set in? Thanks all.
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I'm speaking in regard to my experience with older chrome bumper Naim Audio gear. IME, the difference between using a Naim NAC 42.5 preamp and NAP 110 power amp on their own vs with a dedicated HICAP power supply: Lower noise floor, greater sense of control, better PRAT. At first differences are subtle but appear to be more noticeable over time. I never regretted spending the extra money for the HICAP.
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Music, not necessarily better
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Quiet. That’s the most prominent thing and from that a better presentation, which looks like everyone here may be eluding to.
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I doubled the capacitance in my Hafler DH-200 many years ago. Most immediately noticeable was that the bass was stronger and dug deeper. Solo piano had more body. It was not subtle.
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Bridging the amps will give you 4X the power from each bridged amp. That sounds like a big deal but it is only 6db louder than the single channel rating of the stereo amp. That assumes that the power supply will handle it. If upgrading an existing amp with bigger capacitors, be sure the wiring to the output devices is 18 or 16 (or more) gauge wire, not ordinary hookup wire which may have been adequate before the mod. Also, at "turn on" the larger capacitors (don't go more than triple the stock values) will pull a lot more current from the rectifiers. Are they up to it? If using tube rectifiers, may get away with it as they warm up slowly. If your amp has solid state rectifiers, be sure their rating is at least 10 amps. Don't change power transformers unless you really know what you're doing. (Many of my power supplies have 120,000 mfd caps on both the + and - sides of the power supply, so I use 20 amp diodes as rectifiers. Be sure your fusing is adequate. You MUST HAVE fusing. The fuse will not degrade the sound unless you are pushing the amps really hard (like in stadiums).
You can purchase surpus regulated power supplies for under $100 easily, in voltage ratings up to 70 volts or so at 10 amps (700 watts!). Buy two. Use one for + and the other for - sides of the amps power supply. Modest size capacitors (or the original ones) will be more than adequate. Just be absolutely sure the supplies give exactly the same voltage to both + and - sides. I used a pair of such supplies to feed a six channel power amp running 65wpc with terriffic results. Use at least 14 guage wire to feed the amps. By the way, don't allow any magnetic (ferrous) output terminals or wire between the amp and the speakers. I just upgraded the speaker terminals to non-ferrous terminals - big difference! Bare wire or spade connectors give you more contact area than banana plugs. Happy Listening.
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If you bridge two amplifiers it will be difficult to tell if the change in sound quality is from the doubled capacitance or the doubled power rating of the xfmr's. However, monoblock amplifiers themselves have no sonic advantage over a single box stereo. The reason mono's exist is for thermal management. It is very difficult to build a Class A stereo amp more than 50 or 60 wpc -- the amount of heat sinking would be ridiculous. To go above that, only mono's are economically feasible. For tube amps, mono's are common because of real estate reasons as the transformers are relatively big per unit of power and need to be separated (magnetic field reasons) and the tubes need space for dissipation.
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Typically more watts claim more headroom on transients and long loud passages.
No, not really. Our Class A 40wpc mono blocks outperform large mega watt amps. In general terms, when you upgrade the parts in the power supply with better parts like Nichicon, Audio Note and Amtrans capacitors, you usually get improvements in bass like deeper, faster, more defined and definition. You should also hear more openness and separation, more details. Highs and mids can have better separation and notes can seem to float. Sound stage can open up wider and deeper. For starters, replace the large power supply capacitors with Nichicon superthroughs. You can get them at Parts Connexion now called Audio Connexion. You can go up a size but just make sure they will fit in the chassis. They are not that expensive and you can see for yourself if you hear a difference. Form there if you like what you hear, send it out to a qualified tech to upgrade the other parts. We typically begin there and achieve excellent results.
Happy Listening.
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See the very first sentence in my first reply.
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No throwing components in DIY; certainly not qualified to. I'm talking upgrading to the mfr's mono version of a good stereo amp.
E.G. a 'Mark L' 200wpc stereo w/one large toroid and lots of capacitance. Say you converted that to bridged mono (and added one more amp). Would that new additional output capacitance (double the caps from before) and the same transformer to power only one channel, would one hear anything? I'd hope on extended dynamic passages it would help? Might there be more air/bloom/body/detail, etc?
If the stereo version is all you're (me) gonna get, why monos? My speakers are small inefficient (85?) D2 towers (raidho) and seem to like power...
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It may help a little to understand that the power supply has to provide DC voltages. Say + and - 50 VDC.
That voltage will drop, or sag, as the current needed by the amp stages increases.
The larger the power supply, the less sag in the voltage. That is, the voltage will remain + and - 50 Volts, allowing the amplifier circuits to perform optimally. this is what we call a "stiff" supply, because the power supply's output is constant despite the demand on it.
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, including the number of output stages
Sorry, I meant to write: "... number of output devices" not stages.
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Hey OP,
Well, maybe nothing. We can talk some theory though.
When we imagine how things change from say, an undersized power supply to an oversized power supply the practical difference would be described as reduced output impedance.
The output impedance of an amp is a combination of many factors, including the number of output stages, amp topology (zero feedback vs. feedback) and the power supply sizing relative to the load.
With a purely resistive 8 Ohm load it is relatively easy to design an adequate power supply that ensures the amplifier performs up to it’s specified output, with a flat frequency response.
When impedances drop, and reactances rises is where things get more interesting and, generally speaking, a larger power supply will support the output stage and keep it "stiffer." That is, the amplifier performs equally well at all frequencies up to rated output.
In other words, along with the right amplifier circuitry, a low impedance power supply makes sure you get consistent performance regardless of load. As your power supply gets smaller, the amp becomes more sensitive to the speaker load and the output will stop being flat and will start to track the speaker impedance.
So, all kind of depends on your speaker load, volume, speaker efficiency, etc. as to whether or not you’d hear any difference at all.
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Just throwing components at an amp would be like buying a lottery ticket. You have to know what you are doing. I have a friend whose Almarro amp sits on top of a bank of capacitors twice as large as the amp. It is the second best amp I've ever heard. But he is a wizard at amp design and it is implemented perfectly.
Jerry
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