[mfsoa]

Hi there CSI and Jman,
Glad to see you are pleased with your DAC amps, and I'm not the only one touting their virtues arond here 

My impressions, after 3 weeks with a Cherry (loaned - not purchased/auditioned and returned) very much mirror yours.

Incredible dynamics yet no strain 

Class D efficiency and power without glare 

Breathtaking imaging precision yet emotionally involving 

Superb bass controll and airy highs 

The ICE and UcD solutions I've tried have not been able to pull off these balancing acts.

Very wide soundstage - much more so than my VAC amp (One of the Ravers commented that w/ the DAC in place of the VAC, he was now able to easily hear the R speaker from the L side of the room, while he could not at all w/ the VAC, whatever that indicates)

CSI - I used a good tube pre in front of the Cherry and they got along really well - Maybe if you can borrow one it'd be a worthwhile learning experience one way or the other.

And yes, changes to power cords made a difference, can't say if it was more or less so than other amps, but different it was.

Keep us posted if you don't mind

-Mike

[orientalexpress]

i really like this amp with my revalation.it's sound exactly how u guys describe it.i was wondering since tommy built this amp .Can He's separated the power supply from the amp.like Naim does their?maybe That will take this amp to another level. aa


lapsan

[jhm731]

i really like this amp with my revalation.it's sound exactly how u guys describe it.i was wondering since tommy built this amp .Can He's separated the power supply from the amp.like Naim does their?maybe That will take this amp to another level. aa


lapsan

What will take this amp design to another level, are mono versions that put out over 1000 watts into 8 ohms. I suggested this to Tommy when I had the DAC4800A here for evalution.

BTW- IMO, the DAC4800A is a better sounding amp than the AVA Insight 440H, I recently tested (see review: http://www.audiocircle.com/index.php?topic=62866.0)

[mfsoa]

i really like this amp with my revalation.it's sound exactly how u guys describe it.i was wondering since tommy built this amp .Can He's separated the power supply from the amp.like Naim does their?maybe That will take this amp to another level.

I hope I'm not spilling any beans Tommy doesn't want spilled, but I've had the pleasure of talking amps for several hours with him - I have almost no technical abilities re electronic designs so he brings 100% of that to the table, but I have been an audiophile for decades and largely because of AudioCircle and the NYAudioRave my interest has really peaked in the last few years, so I've been able to bring some of the "tweako audiophile" perspective to Tommy, I hope. (had the great pleasure of blowing his mind with the sound of a power cord change!  )

We've discusssed something that's either in his head or maybe he's done some work on it, but it sounds cool - Target is an ultra high perf design - Separate power supply as lapsan suggests, which would leave the actual amp part really small and able to maybe be speaker-mounted w/ really short cables. But the cool part is that the power supplies could be either battery-based, switching, or transformer based (forget which of the last two Tommy said would be for max power - I guess the latter, with the switcher maybe for best efficiency and weight?). Anyway, sorry Tommy if I misspoke, but this concept seems just what laspan suggested, and w/ the battery wrinkle I couldn't keep it in 

What will take this amp design to another level, are mono versions that put out over 1000 watts into 8 ohms. I suggested this to Tommy when I had the DAC4800A here for evalution.

BTW- IMO, the DAC4800A is a better sounding amp than the AVA Insight 440H, I recently tested.

AFAIK the amps are bridgeable for the power you seek, but I know that's not really mono. But I had another idea - "Mono" amps that are two-channel for vertical bi-amping. So, each amp would have a single input but that would get split into two channels, so the bass can use the 90+% (?) of the power supply that it needs in one chanel, and the treble can use the bit that it needs from the single power supply w/out being bothered by the demands of the bass. Separate speaker jacks of course.
Just a thought...

And since I've already blapped more than I should I can tell you guys that he is intimately familiar with the operation of the UcD and ICE modules, and feels absolutely confidant that his designs are superior in both theory and implementation. This may not mean much coming from him if it was ad copy, but this is what I asked him point blank in person. Is it true? I don't have the tech knowledge to know, but I wanted to give you some idea of what Tommy is about and what he's shooting for here.

Tommy - Hope I didn't blather too much or give away your shoe size- just giving my $0.02, FWIW.

-Mike

[jhm731]

AFAIK the amps are bridgeable for the power you seek, but I know that's not really mono. But I had another idea - "Mono" amps that are two-channel for vertical bi-amping. So, each amp would have a single input but that would get split into two channels, so the bass can use the 90+% (?) of the power supply that it needs in one chanel, and the treble can use the bit that it needs from the single power supply w/out being bothered by the demands of the bass. Separate speaker jacks of course.
Just a thought...

-Mike

First, a two channel amp ain't mono.

How does your "Mono" know what frequency to split the signal at?

Unless there's a crossover inside your "Mono" that can be set by the users to match their speakers, both channels will draw the same amount of current from the power supply.

The only amp I know of that shares a common power supply and has user programmable crossovers is the BOZ 216/2200.

[mfsoa]

First, a two channel amp ain't mono

  Hence the quotes around "Mono"

Each of the 2 channels in the amp would receive the same info (either the L or R output from a preamp) so in that sense it would be mono, in addition you'd need two of the VBA (vertical biamp) amps for stereo operation so that's kinda mono too  - It would be up to the biwire-ready speaker's internal crossover (or an external crossover before the amp I guess) to select what frequencies go where. This way the "side" of the amp doing the upper frequencies would be relieved of putting out the bass since the mid/tweeter never asked for any bass. I don't think the bass and mid/tweets (separate channels of the VBA amp)  would draw the same power from the power supply - Does a tweeter crossover really dissipate the perhaps hundreds of watts that its corresponding woofer turns into mechanical energy? I think that the power sent to the woofer is never sent to the tweeter in the first place (the voltage would be), but I've seen this argued over before.

Didn't ever say it was actually a good idea did I? 

Happy holidays! 

-Mike

-Mike

[jhm731]

Didn't ever say it was actually a good idea did I? 

I agree it's not a good idea.

Unless there's a crossover before or inside your "Mono" amp both channels will get a full range signal, draw the same amount of current from the power supply, output a full range signal on both channnels and the speaker's crossover
will have to dissipate the wasted power sent to the mid/tweets.

Mele Kalikimaka!

[opnly bafld]

Didn't ever say it was actually a good idea did I? 

I agree it's not a good idea.

At times, in certain setups it can be very beneficial and yes vertical biamping is mono.

Lin

[mfsoa]

Given a conventional biwire-ready speaker w/ internal crossovers biwired to a single amp tap, the tweeter/mid aren't drawing the same power that the woofer is (I'm pretty sure). The crossovers see the same voltage, but the drivers don't see the same power. Otherwise if you biamped with lets say a 400 watt amp on the woofer portion, you would need the same 400 watts for the tweeter, which is not the case. When biwiring, the tweeter is probably using fractions of a watt even though it is connected to the same thing the woofer is. The crossover doesn't dissipate the extra energy, it simply never asks for that energy to be sent to its drivers. (Again, I think this is the way to think of it, please 'splain it better to me if you can ).  I can't imagine the heat that would be cooped up in a little mid/tweeter cabinet if the crossover actually had to dissipate that much energy 

Therefore, in a stereo amp w/ one transformer used for vertical biamping, the majority of the power would be available for the bass and the treble would use very little. The channel that produces the treble would then have a much easier task of things, which I could certainly see resulting an an improvement in sound. Therefore in my theoretical VBA amp that uses only 1 input for both the L and R channels (actually, bass and treble channels), you can vertical biamp a 2 ch stereo with a single pair of interconnects, making this a possibility for people with only 1 pr of preamp outs, or freeing up a pair for some other use if the pre has 2 pr of outputs.

See, not so bad an idea after all 

-Mike

[AmpDesigner333]

Given a conventional biwire-ready speaker w/ internal crossovers biwired to a single amp tap, the tweeter/mid aren't drawing the same power that the woofer is (I'm pretty sure). The crossovers see the same voltage, but the drivers don't see the same power. Otherwise if you biamped with lets say a 400 watt amp on the woofer portion, you would need the same 400 watts for the tweeter, which is not the case. When biwiring, the tweeter is probably using fractions of a watt even though it is connected to the same thing the woofer is. The crossover doesn't dissipate the extra energy, it simply never asks for that energy to be sent to its drivers. (Again, I think this is the way to think of it, please 'splain it better to me if you can ).  I can't imagine the heat that would be cooped up in a little mid/tweeter cabinet if the crossover actually had to dissipate that much energy 

Therefore, in a stereo amp w/ one transformer used for vertical biamping, the majority of the power would be available for the bass and the treble would use very little. The channel that produces the treble would then have a much easier task of things, which I could certainly see resulting an an improvement in sound. Therefore in my theoretical VBA amp that uses only 1 input for both the L and R channels (actually, bass and treble channels), you can vertical biamp a 2 ch stereo with a single pair of interconnects, making this a possibility for people with only 1 pr of preamp outs, or freeing up a pair for some other use if the pre has 2 pr of outputs.

See, not so bad an idea after all 

-Mike

Bi-amping --- better than passive xover, but ultimate is active crossover...

Yes, Mike, you spilled the beans.  There is a behind-the-scenes design going on, very active now.  However, the power output is expected to be less than the DAC4800A.

For BIG power, we suggest bridged DAC4800A or Cherry, at 1000W and 1200W into 8 ohms respectively (one channel per amp).  They are internally and externally bridge-able already.  We sold a few pairs for this reason.  Thanks, all, for the comps, and Happy Holidays.  Oh yeah, p.s. we're going to send out a special end-of-year subscriber-only offer, so sign up for the Digital Amp newsletter if you want to get the email.

Warm Regards,
Tommy

[jman66]

My passive is the Channel Islands Audio PLC.1....

I'm curious to learn how a passive attenuator could work assuming the input Z on the Cherry is very low as is the DAC4800A?


-jim

[AmpDesigner333]

Didn't ever say it was actually a good idea did I? 

I agree it's not a good idea.

Unless there's a crossover before or inside your "Mono" amp both channels will get a full range signal, draw the same amount of current from the power supply, output a full range signal on both channnels and the speaker's crossover
will have to dissipate the wasted power sent to the mid/tweets.

Mele Kalikimaka!

Actually, typical crossovers will NOT load the amp across the band.  For instance, the simplest of crossovers is merely an inductor or cap in series with the driver.  A cap to reject lows or an inductor to reject highs.  In this simple example, the amp is not loaded with bass if it only drives the tweeter through a cap --- even if the input to the amp has lots of bass.  The advantage of driving a high frequency element, even though a crossover, directly with a separate amp is that there is definitely a smaller power requirement than full range.  Mike's idea is not new, and definitely not bad.

By the way, some fancier crossovers try to look as resistive as possible to make them easier to drive and that can add load farther out from the drivers range.  Now, somewhere, I have info on spectral content for specific music tracks...  Using that info, it's possible to determine high/low bi-amping power requirements.  It certainly varies based on content (or genre).

Happy New Year to all.

[AmpDesigner333]

My passive is the Channel Islands Audio PLC.1....

I'm curious to learn how a passive attenuator could work assuming the input Z on the Cherry is very low as is the DAC4800A?


-jim

Jim,

The balanced inputs on the Cherry have the same electrical characteristics as the DAC4800A --- about 10K impedance from + to -...

Most sources have adequately low output impedance for a passive pre to work just fine.  The question becomes about output level...
   Rated power for DAC4800A (clipping into 8 ohms):
      one ch driven --- 380W --- 2.36Vin
      both ch driven --- 330W --- 2.20Vin
   Rated power for Cherry (clipping into 8 ohms):
      one ch driven --- 400W --- 2.42Vin
      both ch driven --- 380W --- 2.36Vin

Hope you are well, and thanks for the post.

BR,
Tommy

[AmpDesigner333]

Didn't ever say it was actually a good idea did I? 

I agree it's not a good idea.

Unless there's a crossover before or inside your "Mono" amp both channels will get a full range signal, draw the same amount of current from the power supply, output a full range signal on both channnels and the speaker's crossover
will have to dissipate the wasted power sent to the mid/tweets.

Mele Kalikimaka!

Actually, typical crossovers will NOT load the amp across the band.  For instance, the simplest of crossovers is merely an inductor or cap in series with the driver.  A cap to reject lows or an inductor to reject highs.  In this simple example, the amp is not loaded with bass if it only drives the tweeter through a cap --- even if the input to the amp has lots of bass.  The advantage of driving a high frequency element, even though a crossover, directly with a separate amp is that there is definitely a smaller power requirement than full range.  Mike's idea is not new, and definitely not bad.

By the way, some fancier crossovers try to look as resistive as possible to make them easier to drive and that can add load farther out from the drivers range.  Now, somewhere, I have info on spectral content for specific music tracks...  Using that info, it's possible to determine high/low bi-amping power requirements.  It certainly varies based on content (or genre).

Happy New Year to all.

Before I forget...  For bi-amping to work correctly, the amplifier power can be different for high/low, but the gain should be the SAME (matched) for high/low.  Also, there is another advantage to having, say, a 10/90 power ratio between high/low.  The "high amp" can be made with much smaller heat sinks and maybe even faster output devices (especially with digital or Class-D amps) on the lower power channel that you can't get away with on the lows.  This is even true when the same rails (voltages) are used for both amps.  By the way, Mike has me thinking quite a bit about this idea now...  Hmmmmmm...

[AmpDesigner333]

The email went out this morning, so if you didn't get it, please send a message to DACSales@DigitalAmp.com.  My PM box is 99% full, so please don't use that.  Thanks, all.

BR,
Tommy

[NewBuyer]

Tommy, perhaps you can please answer this question, which I know for a fact is scaring away a few potential buyers of these new switching technology amps.

I have been hearing some rumor lately, that some of these new types of switching amps can have high enough switching-frequencies and voltages, that they can thus actually produce and emit some low-level x-ray radiation.  Is this potentially correct, even in theory?

I realize this is a weird question, but I don't like to settle for anecdotal information - I'd rather ask an expert (you) for a detailed reply.

Thanks in advance.

[AmpDesigner333]

Tommy, perhaps you can please answer this question, which I know for a fact is scaring away a few potential buyers of these new switching technology amps.

I have been hearing some rumor lately, that some of these new types of switching amps can have high enough switching-frequencies and voltages, that they can thus actually produce and emit some low-level x-ray radiation.  Is this potentially correct, even in theory?

I realize this is a weird question, but I don't like to settle for anecdotal information - I'd rather ask an expert (you) for a detailed reply.

Thanks in advance.

Switching amplifiers emit a small amount of EMR at frequencies from 100KHz to 10MHz just like any switching power supply you might find in your house.  No X-RAY radiation (30 petahertz to 30 exahertz)!  Thanks for the post.

[rpm]

X-Ray radiation...  lol.

Switching power supply technology is no where near that fast yet.

When you see the first petahertz CPU let me know though...  I will sacrifice my fertility for a PC that quick!

[NewBuyer]

...Switching amplifiers emit a small amount of EMR at frequencies from 100KHz to 10MHz just like any switching power supply you might find in your house.  No X-RAY radiation (30 petahertz to 30 exahertz)!  Thanks for the post.

Thanks Tommy!   I am glad to have a chance, to ask an expert about that new rumor.  I wonder how it got started - you might be surprised to know how many people are believing/spreading this rumor, that these new types of powerful switching amplifiers emit small amounts of low-level radiation that are actually dangerous with long-term exposure in the household.

As follow-ups please: In the emission frequency range you specified, can you say approximately what amount of EMI your amps (and to your knowledge, other manufacturers' switching amps) actually do emit?  Is there any possibility (even remote) of any health impact or danger, from long term exposure to these emissions at close ranges?

[cab]

And since I've already blapped more than I should I can tell you guys that he is intimately familiar with the operation of the UcD and ICE modules, and feels absolutely confidant that his designs are superior in both theory and implementation.

Would very much like to hear how exactly his designs better the UcD in theory and implementation....