Hi,
In a current thread, it is suggested that bypassing the HDAM modules in a Marantz CD63 improves the sound.
( Bypassing the HDAM was also suggested in another thread for the CD6000 )
Is this a case of 'less is more'? or does the HDAM design require improving?
Looking at the HDAM circuit, the output fet's seem to be in class B.
Would a change of biasing or loading the output into class A with a ccd lead to an improvement??
Has anyone done this?
Andy
In a current thread, it is suggested that bypassing the HDAM modules in a Marantz CD63 improves the sound.
( Bypassing the HDAM was also suggested in another thread for the CD6000 )
Is this a case of 'less is more'? or does the HDAM design require improving?
Looking at the HDAM circuit, the output fet's seem to be in class B.
Would a change of biasing or loading the output into class A with a ccd lead to an improvement??
Has anyone done this?
Andy
Approx 8 years ago i modified my CD63. One of the big improvements was HDAM bypass. 2114 was replaced with 826 coupled via AuriCaps straight from 826 output pins to RCA's. HDAM was disconnected off the power supply rails, and all tracks / components grounded to power supply ground. I did a lot of mods to this little player - an icon and object of drooling desire to many who come to me with 3-4000 AU$ CD players for modifications.
Try for yourself: lift one side of power supply feed resistors to the HDAM blocks (I think there are 4 in total of approx. 4.7 or 10 ohms each), lift one side of signal feed resistors between IC OP and HDAM, and feed this signal (out of IC OP) straight to RCA's. Install IC sockets and try different OP’s. My choice is 826, BUT ONLY if you modify the whole unit, transport section INCLUDED. If you just replace the 2114 with 826, you'll end up with sound being too bright / revealing.
Many DIY-ers hope that replacing cheap 2114, 2134 and similar with fast revealing OP's will bring benefits. It usually does not because they just emphasise the harsh sounding player that is still just the harsh sounding player with fast OP's – and that’s it.
Extreme_Boky
Try for yourself: lift one side of power supply feed resistors to the HDAM blocks (I think there are 4 in total of approx. 4.7 or 10 ohms each), lift one side of signal feed resistors between IC OP and HDAM, and feed this signal (out of IC OP) straight to RCA's. Install IC sockets and try different OP’s. My choice is 826, BUT ONLY if you modify the whole unit, transport section INCLUDED. If you just replace the 2114 with 826, you'll end up with sound being too bright / revealing.
Many DIY-ers hope that replacing cheap 2114, 2134 and similar with fast revealing OP's will bring benefits. It usually does not because they just emphasise the harsh sounding player that is still just the harsh sounding player with fast OP's – and that’s it.
Extreme_Boky
Re: How about
Hi.
Checking the circuits for the CD63 and CD6000 OSE, the basic HDAM is the same. There are some minor value changes and also the CD63 uses a dual fet for the input pair whereas the '6000 seems to use a 2 fets. The other major point is that the'63 is a buffer with no (0 ohm ) feedback resister, the '6000 in a differential mode with gain of 1 set by 10k resisters (in the output) and in a similar fashion in the other HDAMs.
BURSONAUDIO have produced the 'Burson HDAM module' (http://users.tpg.com.au/myfdd78/prod01.htm) as a dropin replacement for common opamp types. The circuit is, however, almost the same as the Marantz version. (They also produce a 'super-opamp' built into what looks very like a plumbing fitting!)
Presumably, the basic HDAM is effective as a buffer in isolating the preceding stages from the effects of the output until that is mods are carried out.
So, I repeat my original question?
Andy
Cobra2 said:
Hi.
Checking the circuits for the CD63 and CD6000 OSE, the basic HDAM is the same. There are some minor value changes and also the CD63 uses a dual fet for the input pair whereas the '6000 seems to use a 2 fets. The other major point is that the'63 is a buffer with no (0 ohm ) feedback resister, the '6000 in a differential mode with gain of 1 set by 10k resisters (in the output) and in a similar fashion in the other HDAMs.
BURSONAUDIO have produced the 'Burson HDAM module' (http://users.tpg.com.au/myfdd78/prod01.htm) as a dropin replacement for common opamp types. The circuit is, however, almost the same as the Marantz version. (They also produce a 'super-opamp' built into what looks very like a plumbing fitting!)
Presumably, the basic HDAM is effective as a buffer in isolating the preceding stages from the effects of the output until that is mods are carried out.
So, I repeat my original question?
poynton said:
Andy
Well...
I couldn't imagine that Marantz made a class-B HDAM....
so I couldn't resist taking a look at the datasheets of the FET's, and it seems that you're wrong
The FET's are of the 'normally-on' type, so with an Ugs of 0V there will be a current flowing, somewhere between 6 and 12mA (?) for the BL version, according to the datasheet. Fweew....
The CD63 and CD67 schematics indicate that there's 0.0V across the 27R resistors, but that must be a typo.
Regards,
Ray.
I couldn't imagine that Marantz made a class-B HDAM....
so I couldn't resist taking a look at the datasheets of the FET's, and it seems that you're wrong
The FET's are of the 'normally-on' type, so with an Ugs of 0V there will be a current flowing, somewhere between 6 and 12mA (?) for the BL version, according to the datasheet. Fweew....
The CD63 and CD67 schematics indicate that there's 0.0V across the 27R resistors, but that must be a typo.
Regards,
Ray.
Attachments
The HDAM circuit can be improved, the first thing I would do is put in 1% resistors. But the main reason I don't like it is because it has very high feedback. And I know from my tubeamp that too much feedback doesn't do much good to the sound.
So i'm going to stick to the 'less is better' approach -> out it goes
I'm hoping to get rid of the opamps too, i'm working on a tubestage.
Regards,
Ray.
So i'm going to stick to the 'less is better' approach -> out it goes
I'm hoping to get rid of the opamps too, i'm working on a tubestage.
Regards,
Ray.
weak bass in my modded marantz 6000OSE
Hello,
I've been very busy with other stuff in my life, and almost forgot my audio hobby.
But now the "bug" has biten me again - my brother asked me to store his Sony 202ES CDP for a while, and I could not resist a temptation to compare it with my highly modded marantz 6000 OSE.
And the bass of the Sony is much better. I want such kind of bass !!
Of course Sony is more serious machine with much better transport (I suppose), so perhaps there is nothing I can do about my marantz.
On the other hand, I''ve invested quite a lot in my maranzt 6000, and like its other properties, so if you think there is something I can do to improve it, please give me advice.
All the major mods to my CDP have been done:
Tent's XO3 clock + independant PSU, separate PSU for analog, all three PSU-s are in a separate case, better caps, case dampening, muting transistors removed, etc.
But you think the bass can be improved by replacing the HDAMs with op-amps?
Or the bass I get know is all marantz's VAM1201 transport is capable of?
Your help would be much appreciated.
Hello,
I've been very busy with other stuff in my life, and almost forgot my audio hobby.
But now the "bug" has biten me again - my brother asked me to store his Sony 202ES CDP for a while, and I could not resist a temptation to compare it with my highly modded marantz 6000 OSE.
And the bass of the Sony is much better. I want such kind of bass
!!Of course Sony is more serious machine with much better transport (I suppose), so perhaps there is nothing I can do about my marantz.
On the other hand, I''ve invested quite a lot in my maranzt 6000, and like its other properties, so if you think there is something I can do to improve it, please give me advice.
All the major mods to my CDP have been done:
Tent's XO3 clock + independant PSU, separate PSU for analog, all three PSU-s are in a separate case, better caps, case dampening, muting transistors removed, etc.
But you think the bass can be improved by replacing the HDAMs with op-amps?
Or the bass I get know is all marantz's VAM1201 transport is capable of?
Your help would be much appreciated.
.
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