hi to everybody.
great thread with great info.
anyone did this (100uf silmic on 4 resistors and higher driver current)
mods on hca-2200mkii?
its applicable on the 2200ii?
ive already did in the past all the mods that jc suggests (holco 47k in fb)+
full recap (nichicon muse,gold fw,4 big caps ncc u36d 33000uf) 2 ixys 60a soft recovery bridges and vishay soft recovery diodes to input stages regulators and replaced all the resistor in the signal circuits to prp audio non magnetic also replace all the screws on psu capacitors and ground buss to brass non magnetic instead the original magnetic screws with great result.
also added relay with delay to bypass the soft start ntc as john curl suggests somewhere .
thanks
Eldad.
great thread with great info.
anyone did this (100uf silmic on 4 resistors and higher driver current)
mods on hca-2200mkii?
its applicable on the 2200ii?
ive already did in the past all the mods that jc suggests (holco 47k in fb)+
full recap (nichicon muse,gold fw,4 big caps ncc u36d 33000uf) 2 ixys 60a soft recovery bridges and vishay soft recovery diodes to input stages regulators and replaced all the resistor in the signal circuits to prp audio non magnetic also replace all the screws on psu capacitors and ground buss to brass non magnetic instead the original magnetic screws with great result.
also added relay with delay to bypass the soft start ntc as john curl suggests somewhere .
thanks
Eldad.
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Hi, 2200ii driver current is much higher than my suggestion for the 1500A driver current mod.
2200ii mosfet drivers drive a total of 20 ohm(my suggestion for 1500A only 47 ohm) resistance, so that the 2200ii driver current will be doubled my mod suggestion for 1500A model, therefore you no need to mod 2200ii for this.
In other words, JC designed the later 2200ii model with a much higher driver driving current which proved my higher driver current mod appropriate for 1500A.
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Patrick thanks alot.
any other mods to the 2200ii?
the amplifier sounds great but the bass too tight and controlled for my taste ,
ive got many ss amps to compare for example my yamaha mx-1 with recap +upgrade the x 4 diode bridges to schottky and hexfred and bypass the gain contorls and some signal resistor replaced with prp non magnetic the bass amazing is almost tube like,with same modded cj pv10a preamp with same TL speakers same room.
the yamaha is 200 DF and the para 2200ii has 1000 DF maybe thats the cause?
any other mods to the 2200ii?
the amplifier sounds great but the bass too tight and controlled for my taste ,
ive got many ss amps to compare for example my yamaha mx-1 with recap +upgrade the x 4 diode bridges to schottky and hexfred and bypass the gain contorls and some signal resistor replaced with prp non magnetic the bass amazing is almost tube like,with same modded cj pv10a preamp with same TL speakers same room.
the yamaha is 200 DF and the para 2200ii has 1000 DF maybe thats the cause?
Maybe you can try adj the driver current to a bit lower to adj the bass, just like my suggestion to 1500A, replacing a single 47 ohm 2w resistor and don't join the middle point(the output).
Disclaimer; I have no expertise in the audio world. I am thinking here out loud about the driver mod, ( suggested by patrick101) . As I indicated previously, I like to understand a proposed circuit change before emplimenting. My limited knowledge tells me that the mod not only increases the driver current, but also removes the feedback from the input and driver stage(voltage gain). This leaves only a global feedback network(I assume). I also recall in my reading that to meet HTX certification requirement, more feed back might have been required. Is this reasonable thinking? Where does this lead us?
Any ideas for discussion?
Sent from Yahoo mail
Any ideas for discussion?
Sent from Yahoo mail
It's amazing what you might dream up while sheltering in place. Some simplistic thoughts. Ok, the driver mod.
Brainstorming about this mod I came up with this idea as to why this might be a pleasing change. The front end of the amp is operating Class A( generates pleasing even harmonics ). Output is operating Class AB (creating not pleasing odd harmonics ).
The mod removes the cancelation feedback of the even harmonics, thus these harmonics come through in the output signal, more like a tube preamp. The odd harmonic distortion from the output stage is still in the feedback, thus the less pleasing odd harmonics are cancelled in the output signal. Overall the sound tilts closer to a "tube" amp sound.
The problem with this scenario is push- pull amp(I believe) suppress even harmonics.
These simple thoughts make me so appreciative of the work done by the designers.
Brainstorming about this mod I came up with this idea as to why this might be a pleasing change. The front end of the amp is operating Class A( generates pleasing even harmonics ). Output is operating Class AB (creating not pleasing odd harmonics ).
The mod removes the cancelation feedback of the even harmonics, thus these harmonics come through in the output signal, more like a tube preamp. The odd harmonic distortion from the output stage is still in the feedback, thus the less pleasing odd harmonics are cancelled in the output signal. Overall the sound tilts closer to a "tube" amp sound.
The problem with this scenario is push- pull amp(I believe) suppress even harmonics.
These simple thoughts make me so appreciative of the work done by the designers.
I have lived with this amp for some time with my previous mentioned mods. I was impressed with what could be done to this amp to improve the sound. A few days ago I made an additional change. Replace R103 - 106/ 203-206 with vishay RN65 of the same value. I had also improved the feedback resistors R119-120/219-220 a while back. Most of my mods for this amp mirror what JC had suggested for the 3500. What those mods did for the 3500 is quite applicable to the 1500. The latest mod brought a real, significant improvement in the frequency extremes. Large increases in both definition, dynamics and presents in the extremes. Hard to explain why, but are real. I'm impressed. I have also increased the bias to 21ma. Quite warm, but continues to survive.
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Parasound HCA-1500A Upgrade
Our audio shop has closed due to retirement and I would like to share our mod for the HCA-1500A. The only person we have ever shared this with was John Curl many years ago. I hope that this will help some of you who would like a little better sound quality but the mod will improve clarity first and foremost.
Our audio shop has closed due to retirement and I would like to share our mod for the HCA-1500A. The only person we have ever shared this with was John Curl many years ago. I hope that this will help some of you who would like a little better sound quality but the mod will improve clarity first and foremost.
Thanks so much for the pdf Big Sky. I have one of these that I was waiting for winter to come to start working on. The pdf made no mention of changing the filtering caps, C001/006/011/016. The 80mm tall caps are a thing of the past so I'm going to install 100mm alternatives. Any suggestions?
I've owned this amp for about 10 years and always thought it had great sound as it bested so many other amps in my system. But it was stored for the last 5 years as I went in to tube stuff and when I pulled it out it didn't sound as good as I remembered. So I pulled it apart and the only thing I see possibly wrong is a bulged AC cap. Is it just my musical tastes have changed or does it not sound as good as I thought? I appreciate some of the mod suggestions on here that I would implement but would need pictures as I'm a bit of a noob. I'm horrible at reading schematics but good at copying others work.
I would like to bypass the stereo/mono switch and the pots on the back but would like to see what everyone has done to do this.
Thanks for any and all input.
Trevor.
I've owned this amp for about 10 years and always thought it had great sound as it bested so many other amps in my system. But it was stored for the last 5 years as I went in to tube stuff and when I pulled it out it didn't sound as good as I remembered. So I pulled it apart and the only thing I see possibly wrong is a bulged AC cap. Is it just my musical tastes have changed or does it not sound as good as I thought? I appreciate some of the mod suggestions on here that I would implement but would need pictures as I'm a bit of a noob. I'm horrible at reading schematics but good at copying others work.
I would like to bypass the stereo/mono switch and the pots on the back but would like to see what everyone has done to do this.
Thanks for any and all input.
Trevor.
I really hate threads that just dead end so I thought I'd give a quick update. Managed to figure everything out on my own and completely eliminated the stereo/mono and pot PCB in the back. I kept the looping RCA to run a sub off in the future. I re-used the input cable from the PCB on the rear and soldered the leads to new RCA jacks on the rear. It can be easily reversed. But the sound has definitely improved with the changes. Also reset bias (LH was 4.5mv and RH was only at 2.5mv) so I'm sure that made a difference.
Did not change any capacitor yet.
Next up will be to try a few of the other mods mentioned in this thread.
Trevor.
Did not change any capacitor yet.
Next up will be to try a few of the other mods mentioned in this thread.
Trevor.