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Old 29th July 2012, 07:03 PM   #61
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Quote:
Originally Posted by tvrgeek View Post
I figure I want to round out my Nakamichi ST-7 & CA-5 with an amp designed by our friend Mr. Pass. I have other amps designed by most of the names that are recognized. (Jim, John, Erno etc) The PA-5 comes to mind. I thought about a smaller Adcom, but sorry to say, I really don't like the larger ones so I was not going to jump. The Thresholds are pretty tough on the budget, considering anything that old needs at least caps, it adds up quick. Or do I jump on one of these "hot" DIY jobs?

No one has convinced me I need a kazillion Watts, but my 6P1 tube amp won't cut it either. Smooth is the word of the day as some of my big-band and a lot of older CD's can make some amps a tad edgy. Source is a NAD 565 CD, with or without a BurrBrown external DAC.

Speakers will be my own.

So what's the word over here in Pass-land; used, modded, or scratch? I'm partly fishing for word on how good the PA-5 was. The Hafler is several steps above it's original design, and I could always use one of my many slightly cleaned up Rotel 951's as they are beguine, if not very detailed. I want more.
Sorry - I took this forum off topic.

Sonically, a MOSFET amp would be miles above the Rotel.

1980's digital recordings were not good.
I think the reason was linearity issues with the ADC's.
Laser trimming improved the linearity issue.
So circa 1990 digital recording equipment improved.

To answer to your question - more info is needed about your speakers.
Specifically - about their impedance.
To select an amp - the speaker impedance should be known.

Before making your own speakers, you may want to browse through Troels Gravensen's website.
DIY Loudspeaker Projects Troels Gravesen

I'd suggest a 3 way design from Scan Speak and Seas.
Note how they stay above Z >= |5| ohms.

Crossover components can get quite expensive.
but the crossover is the soul of a speaker
So suggest picking a speaker with a minimum number of crossover components.
.
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Old 30th July 2012, 06:30 PM   #62
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I must admit I only built the F5 (Basic) as a sonic experiment.

My B-I-L built the Aleph 4 as a full Gun Ship with a massive 500VA x 2 PSU with huge 400000uF (yes nearly 0.5F) of supply caps.

I'm surprised by the comments about the B&W crossovers. My 603s3's had Mundorf Caps which I assumed were good. They've gone now to be replaced by the ODD yellow 802D's. They're away being De-Yellowed at a cabinet refinisher. I'm surprised that with an 11000 price tag B&W have taken 100 corners with componets.
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Old 30th July 2012, 07:46 PM   #63
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Fancy crossover parts is a relatively new phenomenon from what i understand. Over the years, the selection of Primo parts has grown. This is either a result of results or marketing, or perhaps a little of both. I must admit I have heard differences, but would not recommend cap switching until you are sure that your current whatever is the your final whatever, as it will get expensive quickly. I chuckle when i see NElson using Panasonic in the signal path of some of his amps receiving highly praised reviews. Small lesson in that i believe.
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Old 30th July 2012, 08:34 PM   #64
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B&W actually use the term "Specially selected components" in their sales info.

At the 802D level, I seriously doubt that you can make any improvement to what has been tested and proven.

Someone is going to come in and say that they have improved the Nautilus itself - a mere bargain at 32000 a pair.

I'm going to be looking after a pair next month only because the owner cant get insurance for them while he is globe trotting - NIRVANA.

Last edited by KatieandDad; 30th July 2012 at 08:36 PM.
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Old 30th July 2012, 08:58 PM   #65
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one can ALLWAYS make improvements. B&W (or any other) has not developed the products for your room, your eletronics and your ears
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Old 30th July 2012, 09:03 PM   #66
tvrgeek is offline tvrgeek  United States
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Quote:
Originally Posted by Uunderhill View Post
Sorry - I took this forum off topic.

Sonically, a MOSFET amp would be miles above the Rotel.

1980's digital recordings were not good.
I think the reason was linearity issues with the ADC's.
Laser trimming improved the linearity issue.
So circa 1990 digital recording equipment improved.

To answer to your question - more info is needed about your speakers.
Specifically - about their impedance.
To select an amp - the speaker impedance should be known.

Before making your own speakers, you may want to browse through Troels Gravensen's website.
DIY Loudspeaker Projects Troels Gravesen

I'd suggest a 3 way design from Scan Speak and Seas.
Note how they stay above Z >= |5| ohms.

Crossover components can get quite expensive.
but the crossover is the soul of a speaker
So suggest picking a speaker with a minimum number of crossover components.
.


Relevant to this thread. The DIY amps I am looking at are the Pass MOSFET low power class A designs vs. larger more conventional Pass designed amps. A bit bigger, but not much ( 60 to 100W), some requiring modifications ( GFS 535 maybe) and some not ( PA-5 I would hope)

Take a deep breath, I know I am in MOSFET land. I am not sure MOSFETs are miles ahead as a categorical statement. I own both. I have learned so much about amp design ( like .1% of what the real experts know) to know that there is way more to it than that.

The Rotels have an advantage in they MASK some problems typical of mid-range speakers. I never put them up as truly revealing high end. If you have something like Paradigm Studio 20's (I do) , then they do wonders in masking the tweeter breakup and distortion. My Modified Hafler, Parasound, B&K, and Creek are all more revealing if the speaker quality is sufficient. I consider that good engineering on Rotel's part. Design for the intended use. Their intended use is different than the F5.

For sure, the original Sony 14 bit mastered CD's were poor and are the cause for a lot of the bias against digital. A lot of new music is done in basements with A2D no better than my Behringer. Good source has always been a problem. Bad CD's are probably half my collection. Of the good half, half of them are poor recordings on analog before being digitally remastered. Such is life. Great classical guitar seems to usually be a bad recording.

My current project speakers are very similar to the Zaph SR71. I use the metal dome version of the tweeter and some differences in the box, but wound up with the identical crossover when I was done. They don't go below 6 Ohms. I can't measure absolute SPL because my mike is calibrated to difference, not absolute and I don't have a 100 foot chamber anyway. My simulation leaves them at about 87dB.

It comes down to for this application, in my small office, listening at quite reasonable levels, crossed-over with a sub, (electronic, 2 way, not just a helper) would a 25W class A DIY amp have sufficient power for my speaker, or should I stay with a 100W traditional amp? I know for sure, my 60W Hafler and Rotel do just fine power wise, my 6W tube does not. My 12 might, but it is so poor it was hard to tell if it was the 40 year old caps or running out of oomph. Pushing 50W class A is more than my air conditioning can handle. So, I have set bounds on my requirements.
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Old 30th July 2012, 09:07 PM   #67
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Quote:
Originally Posted by AudioSan View Post
one can ALLWAYS make improvements. B&W (or any other) has not developed the products for your room, your eletronics and your ears
NO ONE has. That is why the whole topic is so subjective.
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Old 30th July 2012, 09:33 PM   #68
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Quote:
Originally Posted by tvrgeek View Post
Relevant to this thread. The DIY amps I am looking at are the Pass MOSFET low power class A designs vs. larger more conventional Pass designed amps. A bit bigger, but not much ( 60 to 100W), some requiring modifications ( GFS 535 maybe) and some not ( PA-5 I would hope)

Take a deep breath, I know I am in MOSFET land. I am not sure MOSFETs are miles ahead as a categorical statement. I own both. I have learned so much about amp design ( like .1% of what the real experts know) to know that there is way more to it than that.

The Rotels have an advantage in they MASK some problems typical of mid-range speakers. I never put them up as truly revealing high end. If you have something like Paradigm Studio 20's (I do) , then they do wonders in masking the tweeter breakup and distortion. My Modified Hafler, Parasound, B&K, and Creek are all more revealing if the speaker quality is sufficient. I consider that good engineering on Rotel's part. Design for the intended use. Their intended use is different than the F5.

For sure, the original Sony 14 bit mastered CD's were poor and are the cause for a lot of the bias against digital. A lot of new music is done in basements with A2D no better than my Behringer. Good source has always been a problem. Bad CD's are probably half my collection. Of the good half, half of them are poor recordings on analog before being digitally remastered. Such is life. Great classical guitar seems to usually be a bad recording.

My current project speakers are very similar to the Zaph SR71. I use the metal dome version of the tweeter and some differences in the box, but wound up with the identical crossover when I was done. They don't go below 6 Ohms. I can't measure absolute SPL because my mike is calibrated to difference, not absolute and I don't have a 100 foot chamber anyway. My simulation leaves them at about 87dB.

It comes down to for this application, in my small office, listening at quite reasonable levels, crossed-over with a sub, (electronic, 2 way, not just a helper) would a 25W class A DIY amp have sufficient power for my speaker, or should I stay with a 100W traditional amp? I know for sure, my 60W Hafler and Rotel do just fine power wise, my 6W tube does not. My 12 might, but it is so poor it was hard to tell if it was the 40 year old caps or running out of oomph. Pushing 50W class A is more than my air conditioning can handle. So, I have set bounds on my requirements.
you can go for a F5 turbo V1 you can easy make that with F5c boards in the store.
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Old 30th July 2012, 09:36 PM   #69
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Originally Posted by KatieandDad View Post
NO ONE has. That is why the whole topic is so subjective.
has no one made improvements on a speaker???
i know plenty. on B&W, DALI, troels designs+++
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Old 30th July 2012, 10:49 PM   #70
tvrgeek is offline tvrgeek  United States
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I think he means no one has figured out how to design speakers for YOUR room. They have to design for everybody's room I can design speakers for MY room. Long live DIY. Have speakers improved? Vastly, but they are still the weakest link in the chain.

Still reading the F5T threads. I have not priced out the BOM.
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