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TGA-2375 AKA the I-Mag

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AlexSauter

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Location: Fort Myers FL

Post Fri Apr 27, 2012 3:06 am

TGA-2375 AKA the I-Mag

About a year before Elan bought Sunfire and started out-sourcing to China, Bob started working on a pet project called the I-Mag. He tweaked and tweaked and tweaked until he had, what he states, is the best of all his creations and innovations. Over the last four weeks, Angelo, James and I have stumbled across a few of the TGA-2375 amps and had no idea what they were. After questioning Bob about them, he informed us that there was a prototype production run (company standard), all of which he hand tweaked another time and then released them for production. At that same time, Elan was taking the reigns of Sunfire and went to China. Unfortunately, The I-Mag design was not one that made it through the cutback.... To this day, Bob owned (3) out of the original (10) amplifiers, of which he gave one to a friend, he kept the other (2).

That all said, while here on my stay at Bob's Fun-House, full of audio gear of all brands, I asked what he would accept for one of the I-Mags. Let's just say it wasn't cheap.... In the end, Bob was willing to part with one of the two, the serial number of which is, TGA2375-A01-101500-05. I must say, I am deeply humbled to own this piece of Bob Carver/Sunfire History. It does not have a cover, which will set mine apart from Bob's and the other (8) that are out there. The original cover has about 40-50 small slits across the front and back for ventilation, but I plan on making a cover that matches the 300-2 and 600-2, a solid, brushed black anodized aluminum lid.

This message was Bob - Approved!

Here are a few photos of the amplifier:

IMG_5052.jpg


IMG_5062.jpg


IMG_5064.jpg


IMG_5060.jpg
RIP BillD
BillD wrote:Well, some people are glass half empty people and some are glass half full. Being an engineer, I just think the glass is the wrong size.


My system (sitting in the garage):

(Stereo System)
Modified Carver AL III+'s (Pushed into the corners to make room for the ALS speakers)
Modified CarverFest 2011 20w tube amplifier
Carver Pro PT-1800
Sunfire Prototype TGA-2375
Carver TX-2 Tuner (not used)
Logitech Squeezebox (replaced Tuner & dad's CD player)
CARVERaudio Directional RCA interconnects
RCA-Headphone jack for iPod & iPhone
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AlexSauter

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Location: Fort Myers FL

Post Fri Apr 27, 2012 3:13 am

Re: TGA-2375 AKA the I-Mag

Also, on Facebook, about an hour ago, I posted this:

HOLY FUCK MY ASS!!!!!!!! We hooked the I-Mag prototype up to the ALS's and hit 106 DB WITHOUT CLIPPING!!!!!!!!! We were using the Current Source, not Voltage!

For those who do not know the differance between the Voltage and Current Sources, The Current has a 1 Ohm resistor in line with the positive lead to the speaker to give it the "tubey" sound that we have all come to love with Bob's creations. Using the Current Source is less efficient and wastes a small amount of power... Next we will try to clip the amp, lets see how loud it gets then!!!! :D :D :D

Image

the song played: Shots
Song Artist: LMFAO & Lil' Jon

RIP BillD
BillD wrote:Well, some people are glass half empty people and some are glass half full. Being an engineer, I just think the glass is the wrong size.


My system (sitting in the garage):

(Stereo System)
Modified Carver AL III+'s (Pushed into the corners to make room for the ALS speakers)
Modified CarverFest 2011 20w tube amplifier
Carver Pro PT-1800
Sunfire Prototype TGA-2375
Carver TX-2 Tuner (not used)
Logitech Squeezebox (replaced Tuner & dad's CD player)
CARVERaudio Directional RCA interconnects
RCA-Headphone jack for iPod & iPhone
<<

TNRabbit

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(pair of) SILVER-7 TUBE AMPs

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Post Fri Apr 27, 2012 3:24 am

Re: TGA-2375 AKA the I-Mag

I read that as 106 dB....
TNRabbit
Image

From FrankieD's lips to your ears: Sunfire - a quiet box of endless power.

Sunfire TG-IV/400~7 Amp
Carver SD/A-360 CDP
Benchmark DAC-1
Sony SACD/DVD-A
Active bi-amp: Ashly XR-1001 & 2 Rane PEQ-15s
Main: HotRodded AL-IIIs
Sub: Klipsch RT-12d
Center: Sunfire CRS-3c
Surround: Sunfire CRS-3 (x 2)

OconeeOrange wrote:"Gary likes to play it 'loud' as do I. His system begs you turn it up until you die"

RIP WIlliam B. Dibble, 1948-2012. I'll miss you my friend.
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AlexSauter

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Post Fri Apr 27, 2012 3:37 am

Re: TGA-2375 AKA the I-Mag

TNRabbit wrote:I read that as 106 dB....



Yeah i just caught that too.... ](*,) ](*,) ](*,)

We did a scientific experament just now, on the Current Source, we were peaking at 106 DB with 787 WPC and on the Voltage Source, we peaked 110 DB with 1422 WPC!!! Needless to say, its fucking loud!!!!
RIP BillD
BillD wrote:Well, some people are glass half empty people and some are glass half full. Being an engineer, I just think the glass is the wrong size.


My system (sitting in the garage):

(Stereo System)
Modified Carver AL III+'s (Pushed into the corners to make room for the ALS speakers)
Modified CarverFest 2011 20w tube amplifier
Carver Pro PT-1800
Sunfire Prototype TGA-2375
Carver TX-2 Tuner (not used)
Logitech Squeezebox (replaced Tuner & dad's CD player)
CARVERaudio Directional RCA interconnects
RCA-Headphone jack for iPod & iPhone
<<

BrianT

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Pair of Silver Sevens

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Location: Ottawa, Canada

Post Fri Apr 27, 2012 5:59 am

Re: TGA-2375 AKA the I-Mag

Alex.

Nice pickup, looks so different inside with no large power transformer.

Brian
VPI Classic Turntable (blk)
Transfiguration Phoenix Cartridge
Sunfire Vacuum Tube Control Centre. C/W Mod'ed Phono Stage
Carver Silver 7's Tube Amps
Raysonic CD-168 CDP (silver)
Carver TX11.
B&W 802D's Rosenut
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kingman

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Post Fri Apr 27, 2012 6:20 am

Re: TGA-2375 AKA the I-Mag

Congrats on the acqusition Alex! Bring it to Carverfest for all of us to enjoy. =D> =D> =D>
In reality, it only matters what it sounds like to YOU!!!
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treitz3

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Post Fri Apr 27, 2012 11:21 am

Loud is one thing. Sound is another. How does it sound? [at reasonable levels]

Congrat's, Alex!
In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence.

The best way to enjoy digital music reproduction is to never listen to a good analogue reproduction.

Robert R. - "Did you see my North Korea analogy? I should have named it Carversite.kim"
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EndersShadow

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TFM-45

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Post Fri Apr 27, 2012 12:29 pm

Re: TGA-2375 AKA the I-Mag

Dont forget to get him to sign it too \:D/ \:D/ ..... not that it isnt rare enough already lol....
"You were on my Ignore List, but you are too damn entertaining, like a circus monkey, so I took you off" - H9
"We shouldn't laugh at people like you, we should pray for them. You have my prayers for a speedy rehabilitation you sad, silly little man" - Jstas
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AlexSauter

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Location: Fort Myers FL

Post Fri Apr 27, 2012 2:22 pm

Re:

treitz3 wrote:Loud is one thing. Sound is another. How does it sound? [at reasonable levels]

Congrat's, Alex!



Suprisingly, the Current and Voltage do not sound too much different, we stayed up until 3am last night comparing Sunfire products from the lokes of a modded 300-2, a standard 300-2, a 500-2 a 5-200, 7-400, and more. We were surprised that they were all VERY similar, but the I-Mag brought the music to life in a way that none of the other models could, on both Current and voltage. There is something i cant put my finger on, but Bob explained it as "more musical". It is definately a unique amp and the clarity up into the 90 DB to 100 DB range is amazing!

The amp will most definately make it to CarverFest with its new cover, but i am ot exactly going to have Bob sign it, I am going to have him sign a sheet of paper with a medium sized sharpie with whatever he would like to write, and i am going to laser etch the paint away when i finish my cover so it comes out a brught, raw aluminum signiture. Over time it may oxidize, creating a white signiture, matching the silkscreened faceplate.
RIP BillD
BillD wrote:Well, some people are glass half empty people and some are glass half full. Being an engineer, I just think the glass is the wrong size.


My system (sitting in the garage):

(Stereo System)
Modified Carver AL III+'s (Pushed into the corners to make room for the ALS speakers)
Modified CarverFest 2011 20w tube amplifier
Carver Pro PT-1800
Sunfire Prototype TGA-2375
Carver TX-2 Tuner (not used)
Logitech Squeezebox (replaced Tuner & dad's CD player)
CARVERaudio Directional RCA interconnects
RCA-Headphone jack for iPod & iPhone
<<

mbskeam

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Location: Woodinville Wa

Post Fri Apr 27, 2012 2:56 pm

Re: TGA-2375 AKA the I-Mag

what is the theory behind I-mag?
how does it work?...etc
Mbskeam


#1 BLACK BEAUTY's made by the man, the myth, the legend Bob Carver
CARVER: TFM-75, TFM-45(3), SD/A-490T
SUNFIRE: Tube pre
2 sets of ALS'3, set of SILVERS, set of PLATS
AUDIOCONTROL: phase coupled activator
KENWOOD: BASIC M2a (2)

“Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever.”
― Aristophanes

The only thing I'll feel......will be the RECOIL
Necronomicon Ex-Mortis....... Klaatu Barada Nikkto
"We should seek the greatest value of our action"
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TNRabbit

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Post Fri Apr 27, 2012 3:07 pm

Re: TGA-2375 AKA the I-Mag

And why no HONKIN' BIG transformer??
TNRabbit
Image

From FrankieD's lips to your ears: Sunfire - a quiet box of endless power.

Sunfire TG-IV/400~7 Amp
Carver SD/A-360 CDP
Benchmark DAC-1
Sony SACD/DVD-A
Active bi-amp: Ashly XR-1001 & 2 Rane PEQ-15s
Main: HotRodded AL-IIIs
Sub: Klipsch RT-12d
Center: Sunfire CRS-3c
Surround: Sunfire CRS-3 (x 2)

OconeeOrange wrote:"Gary likes to play it 'loud' as do I. His system begs you turn it up until you die"

RIP WIlliam B. Dibble, 1948-2012. I'll miss you my friend.
<<

AlexSauter

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Site Admin

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Joined: Sun Apr 13, 2008 5:41 pm

Location: Fort Myers FL

Post Fri Apr 27, 2012 3:30 pm

Re: TGA-2375 AKA the I-Mag

mbskeam wrote:what is the theory behind I-mag?
how does it work?...etc


From what i understand, the board that the small black transformer is sitting on is the home dividing network, it makes the amp actually work, the two boards that are on the right are the amp boards with all the vocing, and the front board is the amplification board. Bob says that each of those small yellow transformers pull in 50 or so watts and somehow, magicly turn it into 2500 watts each. Then it all goes to the terminal board which has a 1.3 ohm resistor in line with the Current Source to give it the "Tubey" sound.

TNRabbit wrote:And why no HONKIN' BIG transformer??


Bob wanted an amp he could pick up! :lol: :lol: :lol:
No, really, out of all seriousness, he designed those small yellow transformers to do magic!
RIP BillD
BillD wrote:Well, some people are glass half empty people and some are glass half full. Being an engineer, I just think the glass is the wrong size.


My system (sitting in the garage):

(Stereo System)
Modified Carver AL III+'s (Pushed into the corners to make room for the ALS speakers)
Modified CarverFest 2011 20w tube amplifier
Carver Pro PT-1800
Sunfire Prototype TGA-2375
Carver TX-2 Tuner (not used)
Logitech Squeezebox (replaced Tuner & dad's CD player)
CARVERaudio Directional RCA interconnects
RCA-Headphone jack for iPod & iPhone
<<

EndersShadow

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TFM-45

Posts: 633

Joined: Thu Jun 30, 2011 3:58 pm

Location: Indiana

Post Fri Apr 27, 2012 3:33 pm

Re: Re:

AlexSauter wrote:The amp will most definately make it to CarverFest with its new cover, but I am not exactly going to have Bob sign it, I am going to have him sign a sheet of paper with a medium sized sharpie with whatever he would like to write, and I am going to laser etch the paint away when I finish my cover so it comes out a bright, raw aluminum signiture. Over time it may oxidize, creating a white signature, matching the silkscreened faceplate.


Jesus.... I expect some pics of that for sure......
"You were on my Ignore List, but you are too damn entertaining, like a circus monkey, so I took you off" - H9
"We shouldn't laugh at people like you, we should pray for them. You have my prayers for a speedy rehabilitation you sad, silly little man" - Jstas
<<

angelod307

SILVER-7 TUBE AMP

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Location: manning, sc

Post Fri Apr 27, 2012 4:26 pm

Re: TGA-2375 AKA the I-Mag

so tom, you ask how does it sound. well, after two dozen plus swaps between the 300x2 and 400x7 the imag in my view has a suttle yet more delicate presentation of the program material. in this case, roger waters ca-ara. on track 7 first disc, there are five singers spread throughout the sound stage. with the imag, they are spread out just on the wall itself. then there is a thunder crackle behind the wall/window in this case that has such realism you would think that a storm is infact going on outside. let me also mention that the new amazings are what i think are just as responceable for the sound doing what it does as is the amp. so, this is on the current setting not the voltage. now come in the 300x2. the stage is a little more narrow in that the performers that are singing are now about 2-4 inches in towards the center. the stage is not quite as wide. the tonal characteristics although simular are more delicate in the imag. the stage is further back as mention with the imag so the 300 has a more forward quality. the midrange has a fuller quality in that it is not as realistic as the imag because it is a more speaker sounding quality the realistic. hard to describe as this is not my calling, writing reviews. anywho, the next up is the 7400. it has a cleaner sound than the 300, yet still laking the character of the imag. the thunder is not as believable though. i could kind of describe this as pelling off thin layers dark tint on glass. the singer on the 7400 are spread out as good, but the stage is still a little more forward.
so after going back and forth many times, i start to look into the eq to get a simular effect, but i come up short in that i get close, but not exact. keep in mind i only worked at the eq for 5 minutes. so next i start to look at the oscilloscope to see if there are any clues to why the imag sounds a little more realistic over the other amps. well, i notice that even though the middle/high of the frequency band width is not as full by ear on the imag , the soundstage being further back due to the i would guess at 2k-4k being a db or less down maybe and the 400-600 thinned out a hair , the scope shows a wider trace. huh,what is going on. the 300 and 400 have a fuller tone to them on the voices, yet the scope says the trace is a little smaller. hmm. so i turn the volume up just a notch, and even though the the dynamics are closer to the imag on the scope, it is clearly a little louder to the ear. so the imag is a little more delicate yet just as powerful with the volume a touch lower. this is more than likely due to the sound signature bob put in the amp. well, now a little envious of alex, what a great amp, i start to try different combo's on the voltage/current outputs. first up is the 300. the sound is a little less clouded, cloudy, hell, muddy might be the word. again, writing is not my cup of tea. still the singers are not as wide and the thunder is not as real sounding. next the 400, again this amp is better than the 300 and almost the same as the imag in the voices and clarity, yet the imag still edges it out when the thunder hits even though the stage is still a touch more forward. that might also be why the thunder sounds so real with the imag due to the sound coming from the other side of the window. no, that would not be entirely correct as the imag has the crackle of the thunder sounding real, even with the eq adjusted, the other two just come up short somehow. another thing that is noticed with the imag is that the treble is over bearing at high volumes. it can be described as less/not as much ssssss in the voices as compared to any other amp i have listened to. it is warm and inviting at high volumes. with the new amazings, this becomes very evident as there are 26 ribbons telling you of every, and i mean every detail. they do not forgive i say. you better come correct, as these speakers will reveal any flaws in your system as they have the ability to amplify the program material like none have been able to do before their arrival. wow.
so now for the scientic discussion of what i am hearing with bob. bob states that as hard as the imag was to design, the sound signature of the amp took the longest to get right(to his liking). he states that the gundry is what i am noticing, and it is just so hard to get to a proportion that is realistic yet not over done. well, my hats is off. well done indeed. another thing in the imag is that like a tube amp, the feedback from the room though the speakers is also part of the picture. next we talk about the treble, and he states that like a riaa equalization on a phono section, the amp has a simular quality. wow again.
so now i state that i wish there were more of these amps, and bob say says, you know, with a few parts, we could make modify the parts values in the circuit that does the same for the amps you have more or less. now excited, i await the time later that we will sit and follow through and make the amp listen to the room better as a mod to my current amps. more later on this. that's all for now, over and out.
CarverFest: I just go for the arts and crafts
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radioeng2

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Post Fri Apr 27, 2012 8:32 pm

Re: TGA-2375 AKA the I-Mag

Very interesting this I-Mag thing! Cool for you Alex!

The Gundry dip is a technique used to soften the typical harseness found in the presence region. I've heard a specific freq as the center...2.8 or 3.2Khz...I can't remember which. Also don't know that it's super key exactly what frequency is center either. This area is a traditional crossover region for a 3-way and I think that sometimes designers would specific design to allow the summed result to not quite be flat, a dip, in response in that region.

I believe you could theorize that some harseness in that area could be from our electronics not being perfect and falling at a freq that the ear is sensative too. Or that the crossover timing distortions, being at a key point in hearing is better being slighty recessed and decreasing the brain noticing the electronic defects that otherwise are more obvious.

That's what I know about it. I have played with using the technique to some degree of success.

Mark
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