I just bought a used and abused 5800 on Ebay. After fixing some problems with it, I played it through my Accoustat Spectra 2200 speakers. I have a homebuilt 6SN7 mu-follower tube preamp that I've used for a decade now.
I have heard a scratchiness to the treble on the 5800 with both my stats and my ancient ADS L810 speakers as well.
I read that a HiFi shop which upgrades Adcoms hard solders all the spade lug connections in the amp to eliminate crackles and scratchy sound resulting from the "diodic" action of oxidized connectors. It makes sense to me, the scratchiness does sound like a preamp with a bad selector switch that I fixed a while back. I plan to try cleaning my connections with De-oxit first as the poor amp was a dustbin when I got it.
I think Mr Pass and KBK both have valid points. CLS should definitely address all of Mr Pass' concerns about cabling and such. Mr Pass has 1uf mylar bypasses on the supply rails right next to the active circuits in the GFP-750 preamp but there are none on the GFA-5800 amplifier channel pcb supply rails. Perhaps adding some compact Panasonic 1uF 250V polypropylene caps from the supply rails to ground would be beneficial in the amplifier?
Thanks for the awesome design Nelson Pass!
I have heard a scratchiness to the treble on the 5800 with both my stats and my ancient ADS L810 speakers as well.
I read that a HiFi shop which upgrades Adcoms hard solders all the spade lug connections in the amp to eliminate crackles and scratchy sound resulting from the "diodic" action of oxidized connectors. It makes sense to me, the scratchiness does sound like a preamp with a bad selector switch that I fixed a while back. I plan to try cleaning my connections with De-oxit first as the poor amp was a dustbin when I got it.
I think Mr Pass and KBK both have valid points. CLS should definitely address all of Mr Pass' concerns about cabling and such. Mr Pass has 1uf mylar bypasses on the supply rails right next to the active circuits in the GFP-750 preamp but there are none on the GFA-5800 amplifier channel pcb supply rails. Perhaps adding some compact Panasonic 1uF 250V polypropylene caps from the supply rails to ground would be beneficial in the amplifier?
Thanks for the awesome design Nelson Pass!
My Gen1 5800 is sounding smoother after its De-Oxit treatment. Also it's new Panasonic HF Polypropylene input-coupling caps have broken in. These were chosen mainly for compactness and economy. The amp occasionally has a bit of a "spitty" quality on some transients. I'm wondering if this is due to my using polarized Elna Sil-Mic electrolytics for input coupling. I've gotten some Bi-polar Nichicon Muse lytics to try in their place.
I couldn't recommend a totally passive preamp. Read Mr. Pass' DIY article on the B1 buffer. It wouldn't take much to make a balanced version. I just completed a B1 using mainly parts found on Ebay (matched Fets, etc.), and I'm quite impressed with the clarity and smoothness of the sound. It's lacks the warmth and soul of my tube preamp, but it's eminently listenable.
I couldn't recommend a totally passive preamp. Read Mr. Pass' DIY article on the B1 buffer. It wouldn't take much to make a balanced version. I just completed a B1 using mainly parts found on Ebay (matched Fets, etc.), and I'm quite impressed with the clarity and smoothness of the sound. It's lacks the warmth and soul of my tube preamp, but it's eminently listenable.
Thanks for the reply, Mr. Pass!
The Silmics I got were from China, who knows if they were genuine? The casings were blue instead of the brown on the domestic Silmics I got. They fit in the amp without cobbling so I used them. The amp had huge bass with overblown dynamics and the aforementioned spitty quality occasionally.
The last time I opened the amplifier I double-checked the output Zobel capacitors and they were fine. After finding a negligible voltage difference across the input coupling capacitors, I went ahead and replaced the polarized Silmics with some Nichicon Muse nonpolarized caps. I bypassed these with a 0.47uF Dayton polypropylene film/foil unit and a 0.01uF RelCap theta. I had to hang the big Daytons under the pc board.
The amplifier now sounds much more refined and controlled. The bass and dynamics aren't larger than life anymore, but everything sounds more coherent. The spitty quality is gone. I'm not sure if the improvement is due to the NP electrolytics or that I'm using larger and better polypropylenes across them..
I replaced the 100uF 100V capacitors in the power supplies with Elna Silmic IIs and changed the film bypasses on the big main filter caps to 1uF Panasonic polypropylenes.
I have gotten some domestic Elna Silmic IIs from Mouser but I am reluctant to put them in the amp. I have always heard you need a few volts difference across a polarized electrolytic for them to sound their best.
If my preamps all have output capacitors to block DC, is there even a reason to keep the input coupling capacitors on the amplifier?
The Silmics I got were from China, who knows if they were genuine? The casings were blue instead of the brown on the domestic Silmics I got. They fit in the amp without cobbling so I used them. The amp had huge bass with overblown dynamics and the aforementioned spitty quality occasionally.
The last time I opened the amplifier I double-checked the output Zobel capacitors and they were fine. After finding a negligible voltage difference across the input coupling capacitors, I went ahead and replaced the polarized Silmics with some Nichicon Muse nonpolarized caps. I bypassed these with a 0.47uF Dayton polypropylene film/foil unit and a 0.01uF RelCap theta. I had to hang the big Daytons under the pc board.
The amplifier now sounds much more refined and controlled. The bass and dynamics aren't larger than life anymore, but everything sounds more coherent. The spitty quality is gone. I'm not sure if the improvement is due to the NP electrolytics or that I'm using larger and better polypropylenes across them..
I replaced the 100uF 100V capacitors in the power supplies with Elna Silmic IIs and changed the film bypasses on the big main filter caps to 1uF Panasonic polypropylenes.
I have gotten some domestic Elna Silmic IIs from Mouser but I am reluctant to put them in the amp. I have always heard you need a few volts difference across a polarized electrolytic for them to sound their best.
If my preamps all have output capacitors to block DC, is there even a reason to keep the input coupling capacitors on the amplifier?
My system with an ADCOM 555II works but with 5802 is not
Dear Mr. Nelson
Some days ago I managed to buy my dream power amplifier ADCOM 5802 in order to replace my ADCOM 555II in my system.
For 10 years I am using the RCA output of a Benchmark DAC1 USB Pre to drive the 555II for powering a Greek set of magnetostatic panel speakers (Analysis Omega) in parallel with a privet sub. Although my speakers set impedance is very low (about 2 ohms) my 555ii works so far perfect and drives them loud.
Unfortunately when I tried the 5802 either with the same RCA and with a KIMBER XLR cables the sound is faint (not strong at all) without volume and bass. As I tested the 5802 at the sellers home with an other system I am not sure what to do for the next step. Is it a compatibility problem or a problem that was not apparent in the other audio system.
Please note that Benchmarks balanced signal output was tested both at 20 & 30 db. (table at the attached file).
I would appreciate your suggestions so my dream come true.
Best Regards
Manos from Athens Greece
man.chryssag@gmail.com
Dear Mr. Nelson
Some days ago I managed to buy my dream power amplifier ADCOM 5802 in order to replace my ADCOM 555II in my system.
For 10 years I am using the RCA output of a Benchmark DAC1 USB Pre to drive the 555II for powering a Greek set of magnetostatic panel speakers (Analysis Omega) in parallel with a privet sub. Although my speakers set impedance is very low (about 2 ohms) my 555ii works so far perfect and drives them loud.
Unfortunately when I tried the 5802 either with the same RCA and with a KIMBER XLR cables the sound is faint (not strong at all) without volume and bass. As I tested the 5802 at the sellers home with an other system I am not sure what to do for the next step. Is it a compatibility problem or a problem that was not apparent in the other audio system.
Please note that Benchmarks balanced signal output was tested both at 20 & 30 db. (table at the attached file).
I would appreciate your suggestions so my dream come true.
Best Regards
Manos from Athens Greece
man.chryssag@gmail.com
Thank you very much for spending your valuable time to reply. I am waiting for ADCOM Greek Agent to re-open after summertime holidays. I will give it to test it and see,,,. I will keep you informed.
Sorry I didn't know that 5802 is an other completely redesigned model. In the articles I read from audio fans every body believes that 5802 is your design also!!
Best Regards
Manos from Athens Greece
Sorry I didn't know that 5802 is an other completely redesigned model. In the articles I read from audio fans every body believes that 5802 is your design also!!
Best Regards
Manos from Athens Greece
Good afternoon Mr. Nelson from Athens Greece.
This is an update regarding the 5802 that is not working properly (faint sound) when connected at the same system where my 555ii has no problem.
The Greek Agent of ADCOM has tested the 5802 and they refer that the amplifier is correct. Actually the 5802 is giving more than the nominal power in the total spectrum. Test has been made by a signal generator and the amplifier was connected to resistors.
Agents technician said that it could be a problem from less signal (input voltage) of my Benchmark DAC1 USB Pre although the same signal is enough for my 555ii. I remind you that I have made tests both with 20 and 30db output (can be selected on my Benchmark).
Now I am confused as I don't have any option except to increase my Preaplifier's XLR output with the appropriate calibration potentiometers according to manufacturers instructions (from user's manual).
What is your opinion ? Is the technician's point of view right? What shall I do next as I don't have any <<excuse>> to return it back.
Thank you for your time
Emmanuel
This is an update regarding the 5802 that is not working properly (faint sound) when connected at the same system where my 555ii has no problem.
The Greek Agent of ADCOM has tested the 5802 and they refer that the amplifier is correct. Actually the 5802 is giving more than the nominal power in the total spectrum. Test has been made by a signal generator and the amplifier was connected to resistors.
Agents technician said that it could be a problem from less signal (input voltage) of my Benchmark DAC1 USB Pre although the same signal is enough for my 555ii. I remind you that I have made tests both with 20 and 30db output (can be selected on my Benchmark).
Now I am confused as I don't have any option except to increase my Preaplifier's XLR output with the appropriate calibration potentiometers according to manufacturers instructions (from user's manual).
What is your opinion ? Is the technician's point of view right? What shall I do next as I don't have any <<excuse>> to return it back.
Thank you for your time
Emmanuel
I am short of advice here, and I also do not have the schematics. If the 555 works
and the 5802 is giving faint sound on both channels then I suspect a mis-wiring
of the connections. Keep in mind that probably the 5802 requires that the -
xlr input should be grounded when driving the RCA inputs. This may be done with
a jumper between pins 1 and 3. I recall that the pins can be different in some
countries, so you want to check on that.
I think it is likely to be something simple like this, not that the equipment is broken.
and the 5802 is giving faint sound on both channels then I suspect a mis-wiring
of the connections. Keep in mind that probably the 5802 requires that the -
xlr input should be grounded when driving the RCA inputs. This may be done with
a jumper between pins 1 and 3. I recall that the pins can be different in some
countries, so you want to check on that.
I think it is likely to be something simple like this, not that the equipment is broken.
Thiel CS 3.6 - YouTube
Well the amp didn’t get hot over three songs nor did the distortion light come on. Probably play around a bit more tomorrow. My concern is when turning on the adcom I know the woofer push out is a normal but how hard is normal? Seems to extend quite a bit on one channel while the other barely does it.
Well the amp didn’t get hot over three songs nor did the distortion light come on. Probably play around a bit more tomorrow. My concern is when turning on the adcom I know the woofer push out is a normal but how hard is normal? Seems to extend quite a bit on one channel while the other barely does it.
usual rotation game should help in determining what's culprit
- change speakers (L to R, R to L) at amp output; if problem stays with speaker, then it is speaker; if problem stays with amp channel, it's amp
- change cables (L to R, R to L) at amp input; if problem stays on same speaker , amp is to blame; if problem goes to other speaker, preamp is to blame
same for preamp and source ; finally, you'll find exact culprit
- change speakers (L to R, R to L) at amp output; if problem stays with speaker, then it is speaker; if problem stays with amp channel, it's amp
- change cables (L to R, R to L) at amp input; if problem stays on same speaker , amp is to blame; if problem goes to other speaker, preamp is to blame
same for preamp and source ; finally, you'll find exact culprit
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