ADCOM GFA 555se

[APAPAS]

Just purchased 2x Adcom GFA 555se. Listening and owned a lot of amplifiers I always thought my Adcom GFA 545 mkII sounded more precise,detailed and with much tighter and better low end than my i.e Cambridge Audio CXA80 (2016) design.
With this criteria i purchased two 2x Adcom GFA 555se, intending to use them in vertical passive bi-amping configuration for my B&W 805s. Mainly I am using The Audio Cambridge CXN as a digital source for TIDAL, Spotify, and FLACK from NAS drives. using one of the new Adcoms on stero mode after few days of burning inn, i notice great improvement in all areas apart than I would have to say the bass was a bit bloated compared to the 545 MKII,
Also i noticed the heat-sinks temperatures had a really big difference working under the same conditions. Left Chanel with right Chanel unit 1 ( L slightly warm, R Almost cold). Unit 2 ( L warm to Hot , R Almost warm).
1. Can anybody explain why, and if Bias , dc offset has something to do with it.
2. Any ideas why the bass sounds bit bloated and if any cure.

 

[AcuDefTechGuy]

Any sound anomalies or changes can be attributed to the original recording/source, sound processing (EQ), difference in volume level (+ 1 dB difference will favor the louder one), speaker placement, room acoustics, or just placebo/bias.

Bypass bi-amp is also a waste of time and money, but it can seem really cool, just like my Kimber Kable look really cool.

But the main thing is that you ENJOY it. So if it makes you happy, it can't be that bad.

 

[APAPAS]

Hi AcuDefTechGuy

If i was planing to buy a new amp do you believe is a good idea?
i am between ATI 4002 and 4004 (biamp) I am a vertical passive bi-amping believer.
- As far as placebo bias, when you compare two identical amps and one gets hotter that the other, must be something wrong or different on the amps tuning.

 

[Irvrobinson]

I'm not ADTG, but I'd recommend:

1. Forget about the ATI amps, they're over-priced overkill for your speakers.
2. Forget about passive vertical bi-amping. In >99% of cases it has no benefit.
3. Sell one of the Adcom amps.
4. Sell the B&W 805s.
5. Take all of the proceeds, and whatever money you were planning to spend on the ATIs, and get better speakers. With a $4000 speaker budget you can have awesome sound. If your room isn't very large, $4000 might buy speakers pretty close to the best available.

 

[AcuDefTechGuy]

Hi AcuDefTechGuy

If i was planing to buy a new amp do you believe is a good idea?
i am between ATI 4002 and 4004 (biamp) I am a vertical passive bi-amping believer.
- As far as placebo bias, when you compare two identical amps and one gets hotter that the other, must be something wrong or different on the amps tuning.

This is a hobby, so it's usually not about "needs", but rather about desires.

I personally don't think it's a great idea to spend a lot of money on any amps, especially for any kind of passive bi-amping. You certainly don't need to buy a new amp.

But if you desire it and have plenty of disposable income, I also understand.

I have spent WAY TOO MUCH money in this hobby over the years. And it was NEVER about NEEDS or RATIONALE.

As far as the actual amps, I personally would go for the ATI 2002 or 2004 because I don't think amps will make a significant difference.

 

[KEW]

Were your GFA's used? Always a chance that they were abused resulting in one running hotter than the other.
Irv (and less directly, ADTG) give you good advice. The sound improvement from getting better speakers is far greater than that of changing amps.
All modern amps do a pretty darn good job of avoiding distortion o any sonic contamination/coloration of the music. Differences between good amps from good audio companies will be subtle, to say the least.
It is much more difficult (as in impossible, AFAIK) to make speakers that do not introduce their own audible distortion/coloration, thus, the designers of speakers are confronted with compromises and the consequential sonic differences in these design choices are much greater than those of amplifiers.

 

[APAPAS]

Also i noticed the heat-sinks temperatures had a really big difference working under the same conditions. Left Chanel with right Chanel unit 1 ( L slightly warm, R Almost cold). Unit 2 ( L warm to Hot , R Almost warm).
1. Can anybody explain why, and if Bias , dc offset has something to do with it.
2. Any ideas why the bass sounds bit bloated and if any cure.


KEW,
Just purchased 2x Adcom GFA 555se brand new. they did not run in yet properly. But due to the fact there is a difference in temperature between them and also between L & R channels makes you wonder about quality control when they get out of the factory. Bias , dc offset has something to do with it. How to adjust if anybody know.

Regarding the speakers ... B&W 805s they can not be that bad and how can someone reject a reference speaker without auditioning first. I am talking about people they do not have any experience with this particular pair. I purchased these from a dealer brand new sealed in original boxes. They just have been sitting there for few years.

http://www.whathifi.com/bw/805s/review

Suggestions always welcome.
$4000 bookshelf speaker budget any recommendations for bookshelf speakers

 

[APAPAS]

 

[PENG]

Also i noticed the heat-sinks temperatures had a really big difference working under the same conditions. Left Chanel with right Chanel unit 1 ( L slightly warm, R Almost cold). Unit 2 ( L warm to Hot , R Almost warm).
1. Can anybody explain why, and if Bias , dc offset has something to do with it.
2. Any ideas why the bass sounds bit bloated and if any cure.


KEW,
Just purchased 2x Adcom GFA 555se brand new. they did not run in yet properly. But due to the fact there is a difference in temperature between them and also between L & R channels makes you wonder about quality control when they get out of the factory. Bias , dc offset has something to do with it. How to adjust if anybody know.

Are you sure they are brand new, just sitting somewhere for so many years? That is hard to believe. To double check if this is a real problem, try feeding both channel with the same signal using a Y-connector. Move it to an open area such as sitting on the floor with no obstructions nearby and check the temperature again after playing both channel via the Y connector to the point the unit gets really warm. You may also check the sound level output with a sound level meter to see if the average sound level for the channels are the same. You can measure the output voltage too with a multimeter when playing a test tone.

 

[APAPAS]

PENG,

1- The B&W 805s i got them brand new in sealed boxes. Yes and i checked the serial numbers were one of the last 805s B&W made before moving to D series. Everyone buys the D2s and D3s as usual.There was not A demand for the forgotten 805s so the dealer had two pairs in his warehouse and i purchased one for a good price. I compared them with the D series and the s won my choice.

2- The Adcoms GFA 555se was purchased from the new company that is trading Adcom. http://www.adcom.com/
I received the two units two weeks ago in their original boxes stabled and sealed.

Regarding your recommendations i will check and advise shortly but i tried last night connecting the two amps with y connectors as per diagram below with outstanding results in every aspect. The heat issue remains.

Thanks very much.

 

[APAPAS]

PENG,

try feeding both channel with the same signal using a Y-connector. Move it to an open area such as sitting on the floor with no obstructions nearby and check the temperature again after playing both channel via the Y connector to the point the unit gets really warm. You may also check the sound level output with a sound level meter to see if the average sound level for the channels are the same. You can measure the output voltage too with a multi-meter when playing a test tone.

I am trying really hard to understand what do you mean

 

[Irvrobinson]

There is no such thing as "run-in" for electronics (or cables, for that matter). "Burn-in" is a quality-control process used by manufacturers to detect faulty components which will fail very early in their projected life.

I have heard the B&W 805 (and the 805D), and for the money you're spending on amplifiers it's my opinion that you can do better on your overall investment. Though the 805s are good, they are mini monitors, and they have limited bass capabilities.

 

[PENG]

PENG,

1- The B&W 805s i got them brand new in sealed boxes.

I don't doubt the 805 being brand new. My question was about the Adcom 555SE because I thought they were out of business. I own the original 555 that lasted about 20 years before one channel failed so naturally I have faith in their products. I was just wondering how you could still get two brand new 555 SE. I guess they must have been reborn somehow and making the 555 SE again!

 

[PENG]

I am trying really hard to understand what do you mean

My points were:

1. Using a test tone signal ensures both channels are getting the same input signal all the time. If you don't feed them the exact same signal, then it is possible that one channel has to work harder and therefore warmer. Using a Y connector is just to make doubly sure both channels are getting exactly the same signal. This is less important if you are using a test tone signal, but is imperative if you are playing a music signal.

2. If you don't put the amp in a very open area, it may be possible that one side of the amplifier may be getting better ventilation than the other side.

3. Using a sound level meter will ensure both channels are playing equally loud, obviously you have to measure the sound level one channel at a time.

I hope you can now follow what I was trying to say.

 

[lovinthehd]

I had thought Adcom was no longer around but appears someone called Everest World Co Ltd, a distributor of luxury brands, seems to have resurrected the brand.

 

[everettT]

I had thought Adcom was no longer around but appears someone called Everest World Co Ltd, a distributor of luxury brands, seems to have resurrected the brand.

Wonder if the boards are US, or far east spec. A couple of classic 80s/ 90s amps have have resurfaced witch Chinese boards and weak PSs.

 

[lovinthehd]

Were the boards ever US? The brand owners may have better factory connections, who knows? If they're paying attention to spec and doing good qc there's probably no reason they can't be as good as the original amps (which I couldn't say were anything special myself, I just have an old Adcom pre-amp from that era and its okay but wouldn't call it extraordinary).

 

[APAPAS]

Irvrobinson
I have heard the B&W 805 (and the 805D), and for the money you're spending on amplifiers it's my opinion that you can do better on your overall investment.
Any recommendations will be appreciated. Insisting on bookshelf speakers.

 

[APAPAS]

It seems that we missed the point....
The issue is that one of the amps on the left Chanel raises the temperature to 42 C on low volume, the Right Chanel is 20 C and there is a slight buzz from the transformer.
On the other amp both channels are running cool 20-25 C.
They both stand at the moment one on top of the other with plenty of ventilation.
Photo shows that there is plenty of room around it.
I am asking if the bias/ dc offset has something to do with it at least for this Chanel.

 

[APAPAS]

This is from their website

A Classic reborn and enhanced!

• 200 watts per channel, 8 ohms
• 300 watts per channel, 4 ohms
• 600 watts, 8 ohms BRIDGED
• Balanced and Single-Ended Inputs
• 16 Discrete metal cased bipolar output transistors
• Custom 700 watt toroidal transformer
• 60,000uF total storage capacitance
• Ultra-Stable Bias Circuitry
• Direct-Coupled Input & Output Circuitry
• No Current Limiting
• No Output Inductor

All circuitry meets ETL/ETLc, FCC, LVD and CE/EMC requirements using UL approved FR-4 printed circuit boards. High performance component selections include ultra low ESR electrolytic capacitors. The result is lower distortion, better dynamic range, improved damping factor and greater stability and separation of individual instruments on the sound stage.