M vs MS

[twisted]

like the m25 and zx475ti in my suburban the m25 had more head room and a warmer sound than my ti amp did.

I might be able to explain the SQ difference you might be experiencing.

There is a adjustment inside each channel of all PG amps. Its the channel bias set point.
Now none of you guys run out and start fiddling with this adjustment as it requires a setup of equipment to do proper alignment of this set point.

I always check this calibration on every amp that hits my bench. this adjustment can cause the amp to sound differently. It can and does influence rated THD and distortion for each channel.
Improperly adjusted it can cause crossover notch distortion <screeching harsh sound in your high end> It can and will affect output power as the the entire output section of the triple Darlington stage needs this to be calibrated properly to achieve best performance and SQ, and to reach rated THD and power out.

Your AB comparison was done without this calibration being checked. AB SQ checking of amps that are off the shelf might need this calibration to be checked. And then the test done again. IMO

apples to apples I say....C

i see sir so my route was cecilized for better quality
i understand now

you da man C

[stipud]

But what are the odds of a Ti being out of bias compared to an M series? Wouldn't you think the older amplifier would need to be calibrated first?

[1moreamp]

I like to think your amp was treated right on my bench, and not shuffled through like cattle at a meat packing plant. Thank you for your kind words.

A job is not done until its done correctly and to its final point of detail. Unlike many others out there I actually sound check each channel against one another for SQ balance across the entire amp. And this after actually measuring rated THD and distortion, and power out up to clipping.

I spend more time on disassemble and reassemble and testing then i do on the original repair work usually. Anybody can toss a amp back together by swapping parts, and saying its fixed. but thats a lie, and I was raised better by my parents. My work is detail oriented, just like your listening is


QC of ones own work is a must not a option! If you want to take pride in your work at all.

C

[Eric D]

- If you can hear the difference between ZX, Ti and M series amp you need to get a girlfriend.

although i may not have as much experience than alot of you guys here i have to disasgree with this statment,
only because not every vehicle has the same acoustics so some amps will have better sound or more headroom in certain vehicles than others.should'nt that be taken into account in a disscusion like this because after all vehicles are what we are using these amps in (mostly except for nico who will undoubtedly have the baddest home stereo on the planet)?

like the m25 and zx475ti in my suburban the m25 had more head room and a warmer sound than my ti amp did.

You can only A/B test amps on a test bench, or in a car which is setup for A/B testing. Listening to one amp in one vehicle, and then listening to another amp in a different vehicle is not a valid or useful test of the amplifiers.

Additionally, I don’t really think Nico’s home setup is all that great of an idea. Taking AC voltage from a wall outlet and converting it to DC, then converting it back to AC inside the amp, and finally back to DC one more time for the amps rails is a noisy process, and inefficient too. High end home amps take the AC wall outlet and directly convert it to the DC rail voltages using what ever filtration they choose to design into it. This is the most efficient way to pull this off, and yields the best overall sound quality.

[Eric D]

Cecil, it is very rare, if ever, which I disagree with you on anything. Your experience with amplifiers is second to none, compared to anyone I have ever met with, either in person, or online.

However, I fully disagree with you here. Adjusting bias controls is more of a “ball park” adjustment, not the precise adjustment you speak of. All of the controls included with these amps (PG is no exception) simply do not offer the level of adjustment you speak of. They physically lack fine control. Unless you replace them with a very quality pot, “getting close” is the best anyone can do. Just some slight pressure on the screwdriver and the settings change considerably.

Additionally, any good amp design will take into account a range of bias adjustment with its design. This is mandatory, as the people out on the assembly line adjust these things in a matter of seconds, not minutes or hours. If an amp required such precision to sound good, high percentages of amps off the line would sound bad.

And lastly, bias point changes with temperature. This is the hardest aspect of adjustment. Do you set it cold, warm, hot, and can you keep the test consistent out on the assembly line?

It is great to hear you THD check amps prior to shipping them. This is something I cannot do, as I lack THD test equipment. I do give each amp I fix a listening test to make sure nothing seems out of place, and generally I can tell right away if the bias is out of whack, as the amp will behave very strangely. But, I do not precisely adjust the bias controls on my amp repairs like you do, as it is impossible to get them as close as you speak of.

[Eric D]

My analogy of setting bias controls on an amp is…

“Like measuring a sponge with a dial caliper”

[1moreamp]

Well Eric no offense taken from you big guy:) , I do check cold, warm, and run at 30% power the exact same reading on each channel while the amp runs in on my soak bench. I have 12 voltmeters on that bench just to monitor bias settings at different temperatures by measuring voltage drop across the emitter resistors.
Bias is worth nothing if it does not track temperature, the amp will self destruct.

I may be paying too much attention to this one adjustment, but I can hear the difference if I don't, so I try to do my best for my clients interests. Most everybody is happy with the way their amp sounds coming off my bench, and that is my motivation to pay so much attention to this one parameter.

It costs time and money to be able to do these things, but I just feel better about my work knowing I put in the extra effort to polish my apple so to speak

Plus Eric there aren't too many people like you and me out there, we both try to do excellent work for our clients, and it shows in their satisfaction with both of our works. So any criticism from you is OK in my book. At least it came from a competent source with common interests like me

[Eric D]

Based on your logic in this area then, I would guess if you bought a new in box amp from a manufacturer, you would take it apart and reset the bias adjustment?

Now, I would not see anything wrong with doing that other than voiding the warrantee possibly, as I tend to make improvements to products above and beyond what the manufacturer sells it as myself.

However, I guess I just think the bias is more smoke and mirrors than anything. Clearly if it is set too low, the amp will sound bad. If set too high, the amp runs excessively hot. And since the bias controls are far from precision, any amount of effort will not get them spot on anyway.

Do you, or have you replaced the cheap controls with a nice 20 turn unit for example? One which would actually allow you to accurately dial in the setting?

There are really endless improvements which can be made to an amplifier, but if any of these can actually be heard, that is the real question.

I suppose you could buy 1,000 transistors, and gain match them all to find the closest ones for replacement in an amp, or even go as far as lapping the back of the transistor so it makes more even contact with the heatsink and dissipates heat faster.

Can you hear differences between two identical amplifier models? If you run a pair of M50s on your A/B setup, could you tell them apart? Could you tell them apart inside a vehicle?

To my knowledge you repair amps for a living. With that in mind, you need to be efficient at what you do. Some amps take awhile to figure out exactly what is wrong with them. Taking the time to adjust the bias with the precision you mention just does not seem economically feasible to me. Now, if you just do this procedure for friends or forum members for example, than I can see the justification. Just like in my case there is no way I would be fixing holes burned through amps in an attempt to make a profit selling them on eBay. There simply is no money in spending 15 hours on one amp and then getting $100 more than you paid for it on eBay.

[Eric D]

I assume any two amps rolling off the assembly line of a quality manufacturer (like PG was, and maybe still is), are sonically identical within a very small percentage of each other. This ability is designed right into the amplifiers circuitry. Feedback for example will help eliminate inconsistencies in devices. PCB construction is far more consistent then back in the day of hand wired point to point amps.

I also assume the manufacturing team does not consist of rocket scientists, and could quite possibly consist of 50 year old women who yell at kids that drive past their house with loud music (true in the case of Rockford’s speaker factory). These women neither have the knowledge of what a bias is, nor would they have the passion for adjusting it to the absolute perfect location. They are trained to adjust the bias with some sort of simple procedure. This could be as simple as “put the DMM leads here and here, and turn the knob until you get between this and this voltage”.

So, where is the real gain in precision bias adjustment other than peace of mind? I would say about 90% peace of mind is all ready built into the amplifier, the remaining 10% comes from installing it correctly.

[1moreamp]

Well Doc here again I believe your right about those factory adjustments.

It would explain why Vin's last M-100 had 5 times as much bias on one channel causing it to overheat by the way, then its partner right beside it that was running cool but not to distortion spec either. I guess PG hired that same old woman lol lol lol...

I see bad bias all the time right out of the box new, and you are correct about it being some ill trained persons fault.

But as long as my clients trust me to try my best, the thats what I will do "My Best".

I don't disagree with you, but I can hear the difference that attention to details like this makes in the end product. I even have a annotation on my house bills where I quote bias settings for my records. I have seen so many RF owners go inside and try to turn up there amps and end up blowing them up, that I seal my set points and a record the spec that each channel was running at leaving my shop. RF now seals there set points also but I was doing 15 years before they did.

Now don't get a old war horse tech like myself wrong. I see the merit in your point, but I hear the difference in my work also. So my catch 22 is living with myself, not making others believe as I do


PS watch out for that old woman doing your amp alignment

[Eric D]

Well put, and well justified.

[fuzzysnuggleduck]

This is a great discussion.

I like hearing multiple views on a subject like this from knowledgeable people, it really helps give a better overall picture of such a topic.

It's also nice to hear differing view points without snide remarks or nastiness.

I'd contribute but alas, I know too little to say anything of value.

[marko]

battle of the titans

i found adjusting the bias on the zpa a real pain and very difficult to achive, i wish they would install more accurate pots in their amps but i guess the accountant put a stop to that before they went into production....

[brenzbmr@sb]

hence the family we have is beautiful.................


thanks for the interesting conversation.

[eyesofra]

makin a pdf of this thread and keepin it for reference ...forever.....

[lopezi]

With all this talk of old school amps, especially M and MS, I was wondering how well these lines stood against the old school Orion HCCA amps (the red ones)? I never had a chance to have any M or MS amps but a friend of mine had an Orion 225HCCA and that thing was insane. I had an old school Soundstream D200II and still could not drive my subs as hard as he did his with that Orion amp.

[twisted]

With all this talk of old school amps, especially M and MS, I was wondering how well these lines stood against the old school Orion HCCA amps (the red ones)? I never had a chance to have any M or MS amps but a friend of mine had an Orion 225HCCA and that thing was insane. I had an old school Soundstream D200II and still could not drive my subs as hard as he did his with that Orion amp.

the hcca orions are little powerhouses!!! i love those amps for sure!
not the sound quality of the Pg amps but loads of power to spare!
my favorite hcca amps are the 250r & 450(i beleive...the hcca version of the 97.1) then of course the concept amps...i love how the 97.3 is stable to almost a dead short
i would love to have the concept 97.1 for my collection.

[lopezi]

With all this talk of old school amps, especially M and MS, I was wondering how well these lines stood against the old school Orion HCCA amps (the red ones)? I never had a chance to have any M or MS amps but a friend of mine had an Orion 225HCCA and that thing was insane. I had an old school Soundstream D200II and still could not drive my subs as hard as he did his with that Orion amp.

the hcca orions are little powerhouses!!! i love those amps for sure!
not the sound quality of the Pg amps but loads of power to spare!
my favorite hcca amps are the 250r & 450(i beleive...the hcca version of the 97.1) then of course the concept amps...i love how the 97.3 is stable to almost a dead short
i would love to have the concept 97.1 for my collection.

Yeah that and the original Lanzar Optis were another small powerhouse. In either case I'm kinda interested in hearing how the output transitor and power supplies of the HCCAs compared with the M and MS lines. Back at this time PG, Orion, and HiFonics seemed to be the major players so I was wondering how they all differenciated themselves product wise. PG used Toshiba, was wondering what Orion used?

[1moreamp]

Orion used 2N6488 and 2N6491 outputs just like PPI, and many others in this smaller amp range.
Later on PPI went to Sanken outputs in there larger like The Xenon amps use

There are like 10 maybe 12 popular sets of outputs used out there in amps , then theres a another 5 or 6 sets of lesser know outputs in use by makes like Macintosh Sinfoni, and others.

Back when PG used the Toshiba's in their amps, Toshiba's were only found in home equipment at that time. No other car amp used these devices. Unlike today where many car amp companies use the devices today

PG caused the industry to rethink and change there designs just to keep up with what PG started in the early 90's.

I was a big PPI fan back then, but changed my tastes to PG only after listening and working with their products first hand as the only dealer in the SF bay area.
Even with the ups and downs of this business I have always felt good about PG products.

[smgreen20]

How does one make a pdf of this page?

LANZAR baby! The 50c was stable down to said dead short. 1/4 ohm stereo, 1/2 ohm bridged. I'm highly estatic about my Opti150 for $30

[twisted]

man i love this thing

Orion Concept 97.3
Output Power at 12V:
Stereo
2 x 0.5W @ 4 ohms
2 x 1W @ 2 ohms
2 x 2W @ 1 ohms
2 x 4W @ 0.5 ohms
2 x 8W @ 0.25 ohms
2 x 16W @ 0.125 ohms
2 x 32W @ 0.0625 ohms
2 x 64W @ 0.03125 ohms
2 x 128W @ 0.015625 ohms
2 x 256W @ 0.0078125 ohms
2 x 512W @ 0.00390625 ohms Bridged
1 x 2W @ 4 ohms
1 x 4W @ 2 ohms
1 x 7W @ 1 ohms
1 x 16W @ 0.5 ohms
1 x 32W @ 0.25 ohms
1 x 64W @ 0.125 ohms
1 x 128W @ 0.0625 ohms
1 x 256W @ 0.03125 ohms
1 x 512W @ 0.015625 ohms
1 x 1024W @ 0.0078125 ohms

[Bfowler]

so you are saying they are 1/128 ohm stable

that sounds like something the dude who's install is in your sig would try

[twisted]

so you are saying they are 1/128 ohm stable

that sounds like something the dude who's install is in your sig would try

that is truley off of amp guts and from what i remember from working at a orion dealer it is pretty accurate

[1moreamp]

so you are saying they are 1/128 ohm stable

that sounds like something the dude who's install is in your sig would try

If you arrange enough output devices on any amp it will do what the concept does, Play into speaker wire loads

[lopezi]

so you are saying they are 1/128 ohm stable

that sounds like something the dude who's install is in your sig would try

that is truley off of amp guts and from what i remember from working at a orion dealer it is pretty accurate

too bad they couldn't update ampguts to also include known facts about the amps, like the output transistors used, power supply fets used etc.