I'm wondering to "tweak" my Arcam Alpha 9 amplifier. Does anyone already made it? Have ideas??
I already made:
-replace the tl072 (pre)+ ne5534(dc servo)...I think that's their functions... with opa604 series.
- add 100nF Philips bypass capacitors in Mains Capacitors, diode, opamp supply pins
- replaced original 100mF with 1000mF capacitor used in opamp regulators
- ferrite in toroidal cables
- some chassis damping
I already made:
-replace the tl072 (pre)+ ne5534(dc servo)...I think that's their functions... with opa604 series.
- add 100nF Philips bypass capacitors in Mains Capacitors, diode, opamp supply pins
- replaced original 100mF with 1000mF capacitor used in opamp regulators
- ferrite in toroidal cables
- some chassis damping
audiocrow,
I have a late model Delta290 which appears very similar to the Alpha9 (if not identical).
I'm going to try the following ...
PSU
1. Put transient suppressor (and 1nF to gnd) before transformer.
2. put 8R/17W + 220nF in series before transformer.
3. put 2 x 100nF polyproplene 100V+ before bridge.
4. Replace the main caps with 4x10000 or 2x22000 63V (longer life than the 50V fitted).
5. Put 1ohm/17W in series with 680nF at the end of this lot.
6. Try a second bridge, so one for each supply rail.
7. Provide seperate trafo for the +/-15V supply
8. Replace the 317/337 with lower noise regulators.
PRE-AMP
9. Replace the tone-control NE5532 with OPA2134.
10. Replace TL072 with OPA2134.
POWER-AMP
11. Add 0.22uF across the zeners to shunt out noise
12. Think about removing the DC servo and replacing with a good 2.2uF cap or replace the opamp with a AD8620, decoupled with 100uF + 100nF X7R on each supply pin (or OPA627).
Could also replace NE5532 with class-A biased OPA2604, replace DCservo NE5534 with OPA134.
Have you tried anything else ?
Cheers,
Jon
I have a late model Delta290 which appears very similar to the Alpha9 (if not identical).
I'm going to try the following ...
PSU
1. Put transient suppressor (and 1nF to gnd) before transformer.
2. put 8R/17W + 220nF in series before transformer.
3. put 2 x 100nF polyproplene 100V+ before bridge.
4. Replace the main caps with 4x10000 or 2x22000 63V (longer life than the 50V fitted).
5. Put 1ohm/17W in series with 680nF at the end of this lot.
6. Try a second bridge, so one for each supply rail.
7. Provide seperate trafo for the +/-15V supply
8. Replace the 317/337 with lower noise regulators.
PRE-AMP
9. Replace the tone-control NE5532 with OPA2134.
10. Replace TL072 with OPA2134.
POWER-AMP
11. Add 0.22uF across the zeners to shunt out noise
12. Think about removing the DC servo and replacing with a good 2.2uF cap or replace the opamp with a AD8620, decoupled with 100uF + 100nF X7R on each supply pin (or OPA627).
Could also replace NE5532 with class-A biased OPA2604, replace DCservo NE5534 with OPA134.
Have you tried anything else ?
Cheers,
Jon
Good tips!
Thank you!
some questions about your tips:
PSU
8- wich regulators?
PRE-AMP
9- i've replaced tl072 with opa2604 Class A biased...does opa2134 will improve my current performance?
Power-AMP
-dc servo now using opa134...cristal clear 😉 does AD8620 will improve?
Thank you!
some questions about your tips:
PSU
8- wich regulators?
PRE-AMP
9- i've replaced tl072 with opa2604 Class A biased...does opa2134 will improve my current performance?
Power-AMP
-dc servo now using opa134...cristal clear 😉 does AD8620 will improve?
João,
>Which regulators ?
Regulators, I hadn't really given much thought to. I'd probably go for a low noise Linear Technologies adjustable regulator and then reuse the 317/337 as a pre-regulator. Also, I'd probably try and seperate the supplies to the pre-amp and gain stage. From what I remember the uP control has a discrete regulator. Perhaps I'd do some work to ensure that any HF noise present doesn't come back and polute the other supplies. I'd start with a scope and spectrum analyser and actually look at the supply rails first though. Can you switch the display and remote circuitry off on the Alpha 9 ?
>I've replaced tl072 with opa2604 Class A biased...does opa2134 will improve my current performance?
I haven't actually listened to the OPA2604 or the OPA2134 yet so I am not really in a position to comment. However, on paper, the OPA2134 is superior, and people who have used it in similar applications seem to be pleased with the results so why not give it a try and see what you think.
>dc servo now using opa134...cristal clear does AD8620 will improve
If you're happy with the OPA2134 than stick with it. The AD8620 will inject less noise back into the signal path. It also has a higher slew rate and faster settling time so it should be better in that respect as well. It's not cheap though !
Regards,
Jon
>Which regulators ?
Regulators, I hadn't really given much thought to. I'd probably go for a low noise Linear Technologies adjustable regulator and then reuse the 317/337 as a pre-regulator. Also, I'd probably try and seperate the supplies to the pre-amp and gain stage. From what I remember the uP control has a discrete regulator. Perhaps I'd do some work to ensure that any HF noise present doesn't come back and polute the other supplies. I'd start with a scope and spectrum analyser and actually look at the supply rails first though. Can you switch the display and remote circuitry off on the Alpha 9 ?
>I've replaced tl072 with opa2604 Class A biased...does opa2134 will improve my current performance?
I haven't actually listened to the OPA2604 or the OPA2134 yet so I am not really in a position to comment. However, on paper, the OPA2134 is superior, and people who have used it in similar applications seem to be pleased with the results so why not give it a try and see what you think.
>dc servo now using opa134...cristal clear does AD8620 will improve
If you're happy with the OPA2134 than stick with it. The AD8620 will inject less noise back into the signal path. It also has a higher slew rate and faster settling time so it should be better in that respect as well. It's not cheap though !
Regards,
Jon
A warning on modding the PSU with twin bridges. Unless the transformer has twin secondaries then you are wasting your time. If it's just a centre-tapped type then half of each will be shorted out if you put two in.
Otherwise, mods sound good. I wonder how you have arrived at the component value for your 8R/220nF and 1R/680nF snubbers? Also, unless you use non-inductive (i.e. not wirewound) resistors you will simply be adding more unwanted inductance. I'm not sure you need such high wattage either.
Otherwise, mods sound good. I wonder how you have arrived at the component value for your 8R/220nF and 1R/680nF snubbers? Also, unless you use non-inductive (i.e. not wirewound) resistors you will simply be adding more unwanted inductance. I'm not sure you need such high wattage either.
Hi richie00boy,
Thanks for the advice on the bridges.
I've just taken the lid off and it doesn't have split secondaries, so as you say a twin bridge here would be a bad idea.
The snubber values were just taken from the TNT Solid State Power Amplifier Supply ( http://www.tnt-audio.com/clinica/ssps2_e.html ). The values probably aren't optimised for this supply but ok as a starting point and better than nothing (I hope). When I get around to actually tinkering with the amp I'll measure the leakage inductance of the secondary and inter-winding capacitance and have a go at calculating some better values from that.
Cheers,
Jon
Thanks for the advice on the bridges.
I've just taken the lid off and it doesn't have split secondaries, so as you say a twin bridge here would be a bad idea.
The snubber values were just taken from the TNT Solid State Power Amplifier Supply ( http://www.tnt-audio.com/clinica/ssps2_e.html ). The values probably aren't optimised for this supply but ok as a starting point and better than nothing (I hope). When I get around to actually tinkering with the amp I'll measure the leakage inductance of the secondary and inter-winding capacitance and have a go at calculating some better values from that.
Cheers,
Jon
arcam sound
I've never seen an arcam circuit, but I'm wondering if they have anything unique in there? Arcam always sounds a little different to me (colored), and I tend to like the sound. I'm curious how thye achieve it.
I've never seen an arcam circuit, but I'm wondering if they have anything unique in there? Arcam always sounds a little different to me (colored), and I tend to like the sound. I'm curious how thye achieve it.
Re: arcam sound
With this in mind, it might not be a good idea to damp the chassis! And by the same token, think carefully before increasing psu capacitance. Why not tune the sound with cones or soft feet? What's your preference?
Best of luck whatever you do, I love to see people upgrading ordinary commercial kit 🙂
I heard the 8 and 9 once. To me, it was like a duvet covering the speakers. Not surprised they moved to the DIVA range.Evaas said:
With this in mind, it might not be a good idea to damp the chassis! And by the same token, think carefully before increasing psu capacitance. Why not tune the sound with cones or soft feet? What's your preference?
Best of luck whatever you do, I love to see people upgrading ordinary commercial kit 🙂
Arcam seem happy to give out the service manuals.
The Alpha range was N-Channel MOSFET output based, pretty conventional asymmetric design with current mirroring. The outputs are IRF540's and the rest of the transistors are BC547/557 and BC546/556. The preamp uses 4560's capacitively coupled.
The DiVA range uses an opamp frontend which drives a pair of Sanken SAP15 darlingtons using a Wilson current mirror that picks up the changes in the supply rails of the opamp, which drives a constant resistive load. The opamp is only a TL072 so maybe replacing this would bring a great improvement to this design (the preamps are OPA2134's though). I think the biggest flaw in this series is the tone control section, which uses Dallas digital potentiometers and limits the signal to 2.5v swing.
The Alpha range was N-Channel MOSFET output based, pretty conventional asymmetric design with current mirroring. The outputs are IRF540's and the rest of the transistors are BC547/557 and BC546/556. The preamp uses 4560's capacitively coupled.
The DiVA range uses an opamp frontend which drives a pair of Sanken SAP15 darlingtons using a Wilson current mirror that picks up the changes in the supply rails of the opamp, which drives a constant resistive load. The opamp is only a TL072 so maybe replacing this would bring a great improvement to this design (the preamps are OPA2134's though). I think the biggest flaw in this series is the tone control section, which uses Dallas digital potentiometers and limits the signal to 2.5v swing.
Re: Re: arcam sound
hmm - that's how I feel about classe, but not arcam. I wouldn't say they're the best I've heard, but they have a great euphoric sound. the pass aleph is the only amp I've heard that can drive my speakers, but the arcam was the closest runner up.
interesting. maybe it's the mosfet sound that I like. I haven't heard any of the DiVA's but they seem a step down to me. Maybe if the opamp is good and layout is great then it will sound good
Evan
SimontY said:
hmm - that's how I feel about classe, but not arcam. I wouldn't say they're the best I've heard, but they have a great euphoric sound. the pass aleph is the only amp I've heard that can drive my speakers, but the arcam was the closest runner up.
jaycee said:
interesting. maybe it's the mosfet sound that I like. I haven't heard any of the DiVA's but they seem a step down to me. Maybe if the opamp is good and layout is great then it will sound good
Evan
Re: Re: Re: arcam sound
I've only heard one DIVA amp, and was rather unimpressed (but the whole setup was wrong). The CD72 sounds fantastic in my brothers system though... The FMJ range is quite listenable, and I would possibly call that euphonic - pure audio syrup with B&W CDM-1NTs....
Sorry if this discussion is off-topic
Well, I only listened with one or two sets of speakers, including B&W DM602 s2, which was my speaker at the time, and as a budget design, can't be called a good reference. DIY speakers since! I should say that I was comparing with Rotel RA-971mk2, RA-972, Musical Fidelity XA-2 (best sounding), and Roksan Kandy (2nd best). Just a speaker matching and music choice thing I guess.Evaas said:
I've only heard one DIVA amp, and was rather unimpressed (but the whole setup was wrong). The CD72 sounds fantastic in my brothers system though... The FMJ range is quite listenable, and I would possibly call that euphonic - pure audio syrup with B&W CDM-1NTs....
Sorry if this discussion is off-topic
my system with my tweaks
I will describe my system in order to You know what's in my "benchmark":
Amp: Arcam Alpha 9 Integrated
- opa2604 Class A-biased instead of tl072
- opa134 in DCservo instead of ne5534-A
- bypass capacitors all over....100nF MKP philips
- chassis damping
- ferrite in toroidal cable
- dc servo capacitor is now a Low ESR Elna instead of a standard Rubycon
-IRFP240 Fairchild Power Mosfet
- increase in power rails and regulators capacitors capacitance
CD Player: Arcam Alpha 7SE
- Chassis damping
- bypass capacitors all over
- Sanyo OsCon capacitor in digital section
- rubycon cerafine in analogue
- opa2604 in I/V converter +analogue output Class A biased instead of jr2114 normal bias.
- mute transistor removed - GREAT IMPROVEMENT
- small capacitors of 680pF removed (from the output to gnd)
- 10Kilogram granite piece on top of the player
Speakers: B&W CDM1-NT originals ( I love this babes...they should be called -B&W REVELATORS)
Interconnect cable : Van Den Hull The First (Carbon rocks!!)
Speaker cable: diy with coaxial copper/teflon coaxial cable
Power cables : diy with Pirelli cable (over 5000Watts)+Legrand industrial ceramic plugs...build to last!!
Speaker Stand : Home made MDF/sand - 3 points -over 30 Kilograms
System Stand : Home made - Chromated Iron-Black granite- over 40Kilogrrams with 3 shelfs + sand filling the iron tubes
How does it sound:
Holographic! the updates created a sharper scenario (byebye tl072 😀 ) fast hitting bass roooooooolling down to bottom easily. precise detailed and clean-not harsh- highs. very large soundstage...no surround speakers required 😉 ... I really like my sound...but never satisfied.
Maybe a factory upgrade in my cd player 7SE->9 would be excellent! I know that the dac is very important to get a little bit of deepness in the soundstage...but € needed...
More sugestion please 🙂
I will describe my system in order to You know what's in my "benchmark":
Amp: Arcam Alpha 9 Integrated
- opa2604 Class A-biased instead of tl072
- opa134 in DCservo instead of ne5534-A
- bypass capacitors all over....100nF MKP philips
- chassis damping
- ferrite in toroidal cable
- dc servo capacitor is now a Low ESR Elna instead of a standard Rubycon
-IRFP240 Fairchild Power Mosfet
- increase in power rails and regulators capacitors capacitance
CD Player: Arcam Alpha 7SE
- Chassis damping
- bypass capacitors all over
- Sanyo OsCon capacitor in digital section
- rubycon cerafine in analogue
- opa2604 in I/V converter +analogue output Class A biased instead of jr2114 normal bias.
- mute transistor removed - GREAT IMPROVEMENT
- small capacitors of 680pF removed (from the output to gnd)
- 10Kilogram granite piece on top of the player
Speakers: B&W CDM1-NT originals ( I love this babes...they should be called -B&W REVELATORS)
Interconnect cable : Van Den Hull The First (Carbon rocks!!)
Speaker cable: diy with coaxial copper/teflon coaxial cable
Power cables : diy with Pirelli cable (over 5000Watts)+Legrand industrial ceramic plugs...build to last!!
Speaker Stand : Home made MDF/sand - 3 points -over 30 Kilograms
System Stand : Home made - Chromated Iron-Black granite- over 40Kilogrrams with 3 shelfs + sand filling the iron tubes
How does it sound:
Holographic! the updates created a sharper scenario (byebye tl072 😀 ) fast hitting bass roooooooolling down to bottom easily. precise detailed and clean-not harsh- highs. very large soundstage...no surround speakers required 😉 ... I really like my sound...but never satisfied.
Maybe a factory upgrade in my cd player 7SE->9 would be excellent! I know that the dac is very important to get a little bit of deepness in the soundstage...but € needed...
More sugestion please 🙂
The ringdac in the 9 is superb, the best dac I have ever heard. I borrowed one from a mate who was thinking of upgrading his cdp, but after auditioning several players at around the £2000 mark he gave up and wanted it back.🙁
I do have a 7 though, and I would be interested in the details of your upgrades.
I do have a 7 though, and I would be interested in the details of your upgrades.
Re: my system with my tweaks
I did dozens of mods to my Marantz CD63ki and this was probably the biggest single improvement I found - the improvement in bass agility/control/funkiness made me very excited! This effect may be less pronounced for you, as you are using speakers with limited bass extension (I like them tho!).
I don't know anyting about the innards of your player, but if the output goes through capacitors for DC blocking, then your biggest possible improvement will be in removing these. You need to jumper the circuit with wire afterwards.audiocrow said:
I did dozens of mods to my Marantz CD63ki and this was probably the biggest single improvement I found - the improvement in bass agility/control/funkiness made me very excited! This effect may be less pronounced for you, as you are using speakers with limited bass extension (I like them tho!).
Don't ignore output coupling capacitor
well....unless you like the hear DC 😀 dont' remove the output capacitor (10uF Elna Cerafine). This capacitor blocks over 5V of DC voltage...so I wouldn't try to remove this guy in the easy way.
Try bypassing it with 2uF multi layer metal film capacitor...nice result for sure.
BUT If you really don't want it in the signal path (I agree!) you will have to do something with the output stage od you CDplayers...a level-shift (I'm sorry but I don't know the exact term in English) intending to get a almost pure 0V DC Ofset. Well if someone have a better idea to solve this "issue"....
-****
About CDM1-NT they are perfect for the size of my music-room so maybe thay are a little bassless in bigger rooms but in smaller ones they are perfect. You get perfect low end without boominess of bigger boxes in smaller rooms...so to me they aren't bass limited. Very happy with them! 😉
-*****
PS...I'm making a new speaker cable based in silver leads from VanDenHull. In my internal cabling they are just soooo beautiful and audio-perfect...You should give them a try.
well....unless you like the hear DC 😀 dont' remove the output capacitor (10uF Elna Cerafine). This capacitor blocks over 5V of DC voltage...so I wouldn't try to remove this guy in the easy way.
Try bypassing it with 2uF multi layer metal film capacitor...nice result for sure.
BUT If you really don't want it in the signal path (I agree!) you will have to do something with the output stage od you CDplayers...a level-shift (I'm sorry but I don't know the exact term in English) intending to get a almost pure 0V DC Ofset. Well if someone have a better idea to solve this "issue"....
-****
About CDM1-NT they are perfect for the size of my music-room so maybe thay are a little bassless in bigger rooms but in smaller ones they are perfect. You get perfect low end without boominess of bigger boxes in smaller rooms...so to me they aren't bass limited. Very happy with them! 😉
-*****
PS...I'm making a new speaker cable based in silver leads from VanDenHull. In my internal cabling they are just soooo beautiful and audio-perfect...You should give them a try.
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