Nakamichi pa-5 vs Hitachi hma-7500 II
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silversport
Super Member
I wonder how the Nakamichi version of STASIS differs from Threshold's version beyond quality/price of parts used...Nelson Pass hasn't seemed to have any real issues with Nakamichi's versions in all these years...other than some stuff reported on this and other Forums that Mr. Pass denies ever criticizing...
As for the grating high ends especially on female vocals all I can contribute is this is why there are so many choices in audio as that has never been the case with my Nakamichi STASIS receivers since about 1989...2 TA-2As and an SR-2A as well as my brothers own PA-7s...
people many times end with YMMV...well it certainly does IMO...
...good luck with your choice
Bill
As for the grating high ends especially on female vocals all I can contribute is this is why there are so many choices in audio as that has never been the case with my Nakamichi STASIS receivers since about 1989...2 TA-2As and an SR-2A as well as my brothers own PA-7s...
people many times end with YMMV...well it certainly does IMO...
...good luck with your choiceBill
alanst
Active Member
Thank you all very much.It is possible that soon I will get a Nakamichi ca-7 for a second team and acquire another stage.
This would come to replace my Sansui AU-9500.
Threshold is too expensive and I suspect I will like the Nakamichi sound better (Threshold could be a brighter, higher-pitched sound with coloration ?????)....too modern sound ????
Adcom seems cheaper than Nakamichi.
Hitachi mosfet sound is soft, velvety and very nice but it may change for a change.
This would come to replace my Sansui AU-9500.
Threshold is too expensive and I suspect I will like the Nakamichi sound better (Threshold could be a brighter, higher-pitched sound with coloration ?????)....too modern sound ????
Adcom seems cheaper than Nakamichi.
Hitachi mosfet sound is soft, velvety and very nice but it may change for a change.
alanst
Active Member
Thanks again. I am so lucky!! I just sold my Sansui AU-9500 and have seen a Nak pa-5E II that I am going to buy. It is possible that you will acquire another pre one but in this case the ca7 by your remote control. What do you say about the pre Nak? People talk more about amps but I love the sound of the pre wide, detailed and smooth
alanst
Active Member
I already received the Nakamichi pa.5E II. Tried it for a short time but may need a refresher. I'm not sure.
The speakers are Celestion Ditton 33 (recommended amp 10 to 80W), the Naka has 150W .........
It may be too much for my speakers, in principle my Nak ca-5E sounds better with the Hitachi Hma-7500 mk2
The speakers are Celestion Ditton 33 (recommended amp 10 to 80W), the Naka has 150W .........
It may be too much for my speakers, in principle my Nak ca-5E sounds better with the Hitachi Hma-7500 mk2
northpaw
Super Member
Before doing anything else, it would be prudent to give the PA-5 a simple health check in terms of bias (idle) and DC offset settings, once warmed up. A simple check on the bias is to feel how warm the heat sinks are after a 15-20 min warm up. They should feel moderately warm but not so hot that you can't keep your fingers between the fins, and the right and left channel should feel about the same. If this is true, the bias should be reasonably close to the correct values.
You don't mention what you don't like about the sound with the Ditton 33s playing; it would be helpful to know. Whatever it is, I assume it is not so bad with the Hatachi amp driving them. That said, I think the Dittons must be least 40 years old, so it is useful to verify that they are in good health as well. In addition to the drivers and their surrounds looking good, the crossovers might need some attention. The 33s have a fairly complex crossover with 7 caps. They range from 8µF to 72µF, with 4 of them >30µF, which almost certainly will be electrolytic. If they have not yet been replaced at some point, it is very likely that this speaker will only perform its best with renewed caps. I have a similar vintage but lesser Ditton, and the electrolytic caps had drifted upward out of spec, and had high ESR and Vloss; replacement did improve their sound.
I would doubt that the Nak PA-5 is "too much" for the Dittons, as long as you are not attempting to drive them to very high volumes. It is possible that the PA-5 is more revealing of weaknesses in the DIttons, if they have any in their current condition, or the PA-5 and the DIttons are not a good pairing. But I doubt the latter is true as the Nak is a very robust and pretty forgiving amp for almost any kind of load.
You don't mention what you don't like about the sound with the Ditton 33s playing; it would be helpful to know. Whatever it is, I assume it is not so bad with the Hatachi amp driving them. That said, I think the Dittons must be least 40 years old, so it is useful to verify that they are in good health as well. In addition to the drivers and their surrounds looking good, the crossovers might need some attention. The 33s have a fairly complex crossover with 7 caps. They range from 8µF to 72µF, with 4 of them >30µF, which almost certainly will be electrolytic. If they have not yet been replaced at some point, it is very likely that this speaker will only perform its best with renewed caps. I have a similar vintage but lesser Ditton, and the electrolytic caps had drifted upward out of spec, and had high ESR and Vloss; replacement did improve their sound.
I would doubt that the Nak PA-5 is "too much" for the Dittons, as long as you are not attempting to drive them to very high volumes. It is possible that the PA-5 is more revealing of weaknesses in the DIttons, if they have any in their current condition, or the PA-5 and the DIttons are not a good pairing. But I doubt the latter is true as the Nak is a very robust and pretty forgiving amp for almost any kind of load.
alanst
Active Member
Thank you very much, I liked that detailed answer.
The Ditton 33 are in good condition, I have tested them with various amplifiers and there is punch, detail etc ...
Today I did another test. I changed the digital source and the Pa-5e II sounds much better and more correct. I guess it will all be synergy.
I have two sources based on Raspberry Pi3:
1.Only for transport ... rpi3 + Digi One + Benchmark dac1.
The Digi One is a specific board for connecting an external dac.
Galbanic isolator, clock and a series of very good improvements.
2. Source with internal dac:
rpi3 + kali (relocker) + dac Piano 2.1 + hum linear font
The N1 transport is the one that brings more scene and detail thanks to a dac like the Benchmark ... however the gain is high when connecting several devices, the synergy is fabulous with the N2 source
The Pa-5EII has flourished with the rpi3 N2 based streamer but very poorly with the N2 (a lot of gain, impedance I guess).
Still it may need some maintenance ???? Or am I used to the Hitachi hma-7500 mk2 mosfet stage and its exquisite enhancement and now the Nak sounds a bit dark to me?
I didn't like it that much with the record player, very dark, with the CD I didn't like it too much either.
He may need a slight, little refresher, I'll take him to a known technician next week
I checked the temp. It's just a little warm. No problem. Right / left channel perfect.
The Ditton 33 are in good condition, I have tested them with various amplifiers and there is punch, detail etc ...
Today I did another test. I changed the digital source and the Pa-5e II sounds much better and more correct. I guess it will all be synergy.
I have two sources based on Raspberry Pi3:
1.Only for transport ... rpi3 + Digi One + Benchmark dac1.
The Digi One is a specific board for connecting an external dac.
Galbanic isolator, clock and a series of very good improvements.
2. Source with internal dac:
rpi3 + kali (relocker) + dac Piano 2.1 + hum linear font
The N1 transport is the one that brings more scene and detail thanks to a dac like the Benchmark ... however the gain is high when connecting several devices, the synergy is fabulous with the N2 source
The Pa-5EII has flourished with the rpi3 N2 based streamer but very poorly with the N2 (a lot of gain, impedance I guess).
Still it may need some maintenance ???? Or am I used to the Hitachi hma-7500 mk2 mosfet stage and its exquisite enhancement and now the Nak sounds a bit dark to me?
I didn't like it that much with the record player, very dark, with the CD I didn't like it too much either.
He may need a slight, little refresher, I'll take him to a known technician next week
I checked the temp. It's just a little warm. No problem. Right / left channel perfect.
northpaw
Super Member
I'm glad you are getting more joy out of it with certain hook ups, but with the CA-5 sitting between either your amps and your sources, I'm not sure the differences you are experiencing can be due to impedance or gain differences concerning the connections between the sources and the preamp, which are unchanged. The CA-5 pre should be an effective buffer for either amp; it is not a passive pre. I don't know anything about the Raspberry Pi end of things and what it takes to get signal from there into your system, so I can't comment there. In any case, a visit to the technician should reveal if there is an underlying issue with the PA-5.
The PA-5 mated with the CA-5 should be quite uncolored (barring issues with high capacitance in either your interconnects or speaker cables, not common conditions but sometimes occurs with certain designs), but might seem dark if you are used to listening to a combination that is more colored. I have no experience with a Hitachi amp, so I can't comment, but listening to one combination and then another over a longer period, allowing yourself at least several days or a week or so between switches to adjust to the changes, is sometimes helpful and revealing.
One other thing from looking at your photo (very nice system, BTW) is you might want to get a little more separation between the CA-5 and the Hitachi amp, both to improve air flow for the Hitachi and to minimize stray fields from the large transformer(s) in the Hitachi affecting the low-level circuits in the CA-5, especially the phono. Either some spacers between them (I like thicker marble drink coasters, or sometimes ice hockey pucks), or rearranging the components to separate them, might make a difference.
The PA-5 mated with the CA-5 should be quite uncolored (barring issues with high capacitance in either your interconnects or speaker cables, not common conditions but sometimes occurs with certain designs), but might seem dark if you are used to listening to a combination that is more colored. I have no experience with a Hitachi amp, so I can't comment, but listening to one combination and then another over a longer period, allowing yourself at least several days or a week or so between switches to adjust to the changes, is sometimes helpful and revealing.
One other thing from looking at your photo (very nice system, BTW) is you might want to get a little more separation between the CA-5 and the Hitachi amp, both to improve air flow for the Hitachi and to minimize stray fields from the large transformer(s) in the Hitachi affecting the low-level circuits in the CA-5, especially the phono. Either some spacers between them (I like thicker marble drink coasters, or sometimes ice hockey pucks), or rearranging the components to separate them, might make a difference.
alanst
Active Member
Thank you very much again. The synergy issue is complicated .... impedance, gain etc. I could say that with the Nak ca + pa only changing the source there is a lot of difference in the electrical synergy Adding an external dac to the equation like the Benchmark dac1 gives more scene, detail ... higher quality but the problem is that sometimes many devices together add profit and the system sounds overloaded. Without the dac I notice everything more correct but the scene is less revealing. It is true that Nak + Nak is very colorless and does not have that valve-like hue like the Hitachi mosfet. I use very simple cables because hifi cables distort the tonality and as it says they are very capacitive. I usually place the braces separately but these are provisional tests. I like the colorless sound but I notice this needs a little overhaul. Something too dark. I also like the sound of the Hitachi mosfet amplifier but I would not put it with its mosfet preamp because it could be excessive, better a more colorless preamp like Nak, Kenwood 80s.
alanst
Active Member
I notice that with my Hitachi the bass has more punch although it seems to be in better condition and the Nak needs an overhaul. Nak seems deeper and softer on the bass at the moment.
northpaw
Super Member
I could be quite wrong about this, but the sensitivity to different sources seems more like a preamp-source interaction issue than something with the power amp.
For the high-level inputs (i.e., non-phono), the CA-5 has an input impedance of 12.5KΩ. This is at the lower end of the range of input impedances commonly found in active preamps, which from my experience and knowledge range from about 10KΩ to 47KΩ. The CA-5 has a lot of company at the lower end of this range, as this is where many quality preamps are.
A preamp with a low input impedance could overload a source component if that source component has a high output impedance. Perhaps you are fully aware of this, and I don't need to mention it. But to be complete, to my understanding, a useful rule of thumb is that the input impedance of the preamp should be 10x or more of the output impedance of the source (such as a DAC, or a CD player if that is connected directly to the preamp) for a reasonable level of immunity from source loading effects.
Many quality sources have output impedances of several 100Ω or less, and most have impedances of no more than 1KΩ. So most should be able to drive the CA-5 without issue, but it might be good to double check the output impedance specifications of your sources (that is, the last thing to connect to the CA-5), to be sure they are not too high for the CA-5.
Also, if the information is available to you, you might check how the output-input impedances pair between devices within your "source chain" (that is, the Raspberry Pi and other devices you mention in post #10). They should also meet the 10x rule of thumb, or at least be close to it.
One other thing that might be an issue: I don't know if there are volume controls within your "source chain", resulting in two volume controls in your system (one in the source, a second in the CA-5). If so, it would be best if only one of those controls is actually in use (the other being set to max). Please forgive my mention of this issue if you are completely on top of it.
For the high-level inputs (i.e., non-phono), the CA-5 has an input impedance of 12.5KΩ. This is at the lower end of the range of input impedances commonly found in active preamps, which from my experience and knowledge range from about 10KΩ to 47KΩ. The CA-5 has a lot of company at the lower end of this range, as this is where many quality preamps are.
A preamp with a low input impedance could overload a source component if that source component has a high output impedance. Perhaps you are fully aware of this, and I don't need to mention it. But to be complete, to my understanding, a useful rule of thumb is that the input impedance of the preamp should be 10x or more of the output impedance of the source (such as a DAC, or a CD player if that is connected directly to the preamp) for a reasonable level of immunity from source loading effects.
Many quality sources have output impedances of several 100Ω or less, and most have impedances of no more than 1KΩ. So most should be able to drive the CA-5 without issue, but it might be good to double check the output impedance specifications of your sources (that is, the last thing to connect to the CA-5), to be sure they are not too high for the CA-5.
Also, if the information is available to you, you might check how the output-input impedances pair between devices within your "source chain" (that is, the Raspberry Pi and other devices you mention in post #10). They should also meet the 10x rule of thumb, or at least be close to it.
One other thing that might be an issue: I don't know if there are volume controls within your "source chain", resulting in two volume controls in your system (one in the source, a second in the CA-5). If so, it would be best if only one of those controls is actually in use (the other being set to max). Please forgive my mention of this issue if you are completely on top of it.
alanst
Active Member
I was aware of the importance of input / output gain and impedance between preamplifier and amp but had never given that importance between preamplifier and source. Thank you. What happens is that when there is an external dac, two sources are added to the equation and it is more complex. On Monday I will take the pa-5E II to the technician to check and also the preamp one because the potentiometer makes a little noise. I have tried to clean it but the alps is closed / encapsulated.
northpaw
Super Member
Yes, attention should be paid to each connected unit for input-output impedance, but to be clear, each pair (one unit's output to the next's input) can be evaluated just as that pair, not as a system as a whole. As long as the focus is kept on each pairing, it shouldn't get complex, either for the system, or us.
Which potentiometer on your CA-5 preamp is noisy? I've not had a problem on the volume pot (a Noble pot), but my balance pot (an Alps pot) was a bit noisy at the time I bought it. Attached is a photo of mine (sorry for the blurriness). I thought it looked sealed too, but there is a very small squarish notch or two one or both sides, along the seam between the sections. I was able to get some Deoxit in there, and it solved the problem. Note: at first I used the Fader version of Deoxit (F100) thinking it was a carbon track pot, but it made the pot unusable; I flushed with pure contact cleaner then added a bit of regular Deoxit, and all was well.
If your Alps pot looks the same as mine, look carefully for the tiny port on the side and see if applying cleaner directy in there helps.
Photo of my unit. Alps balance pot in middle, Noble volume pot on left. Again, sorry for the blurriness.
Which potentiometer on your CA-5 preamp is noisy? I've not had a problem on the volume pot (a Noble pot), but my balance pot (an Alps pot) was a bit noisy at the time I bought it. Attached is a photo of mine (sorry for the blurriness). I thought it looked sealed too, but there is a very small squarish notch or two one or both sides, along the seam between the sections. I was able to get some Deoxit in there, and it solved the problem. Note: at first I used the Fader version of Deoxit (F100) thinking it was a carbon track pot, but it made the pot unusable; I flushed with pure contact cleaner then added a bit of regular Deoxit, and all was well.
If your Alps pot looks the same as mine, look carefully for the tiny port on the side and see if applying cleaner directy in there helps.
Photo of my unit. Alps balance pot in middle, Noble volume pot on left. Again, sorry for the blurriness.
