I_Forgot said:
That's intriguing. How does it work? It is a sort of Dolby type L-C-R matrix that drops out the center? Or does it do something trickier, like flip the center out of phase and fold it back into left- right?
Just curious....
panomaniac said:
In your typical stereo speaker set-up, the left ear hears some sound from the right speaker and the right ear hears some sound from the left speaker. This has the effect of reducing the width of the stereo image and "blurring" the localization of instruments/voices.
With cross feed, you send some inverted phase left channel signal to the right speaker (along with the right speaker signal) and vice-versa. Since your ears are on opposite sides of your head, it takes a little longer for the sound from the left speaker to get to your right ear, so you apply a little delay to the cross fed inverted left channel signal that is sent to the right speaker. That way the cross fed signal and the signal from the 'wrong" speaker will arrive at your ear at the same time and cancel each other.
The cross mixing and phase inversion are simple op-amp summing network type stuff. The delays are usually implemented as "all-pass" filters, with op amps and RC networks.
The effect heard varies a lot with the speaker arrangement in the room, reflections from room boundaries, and the techniques used to mix the recording. With some music the box is absolutely fantastic, with other music it sort of muddies up the bass and doesn't sound right. It often has the effect of enabling sound source localization far from the speakers- it is sometimes a little disturbing, especially if you're nodding off and suddenly something starts sounding like it's behind you.
The only person who can hear the full effect is the one located right in the symmetrically centered listening position. I use electrostatic speakers that don't provide a very wide "sweet spot" and the combination of the speakers and crosstalk canceler is absolutely amazing with the right music.
I_F
SleeperSupra said:
In general, an amp that works and keeps working sounds a lot better than one that doesn't. My Soundcraftsmen amp drives any load I connect to it and never suffers component failures or even distorts audibly.
The two Carver amps I have had would both thermal cycle and distort severely if you connected anything but a "standard" speaker to them. Both died when the power transformers burned up. One blew the power fuse before completely destroying the transformer and afterwards it buzzed so loudly I had to throw it away because I couldn't stand to be in the same room with it and it definitely wasn't worth the expense of repair.
I'd say the Carvers were OK when I had them powering the bass drivers in my system when it was biamped. They could not handle driving the ESLs at all.
I_F
Hi I_Forgot,
Carvers could not be used to drive mid or high only. That's probably why you blew them up. They would drive bass or full range all day. The other requirement was a good AC supply.
I don't love these amps, but they were very reliable if properly used.
-Chris
Carvers could not be used to drive mid or high only. That's probably why you blew them up. They would drive bass or full range all day. The other requirement was a good AC supply.
I don't love these amps, but they were very reliable if properly used.
-Chris
anatech said:
When the amps blew up one was being used for full-range and the other was driving bass only.
I think the problem with them is they are designed with zero margin, anywhere. The power supplies are too small, the heatsinking is too small. The output transistors are right up against their SOA limits. The stability is marginal. There's not much to like about them.
Carver's design philosophy was that marketing rules. He wanted to differentiate his stuff from everything else out there, so he went for small size, light weight, and low cost. The marketing dept was the standard over-promise and under perform outfit. Baffle them with BS and they'll buy... hence "magnetic field" power amps, "sonic hologram" and all the other buzzwords they invented or perverted for their use.
Reducing the power transformer size and minimizing heat sinks takes a lot of the cost, size and weight out of an amp. Unfortunately it also takes out a lot of the reliability and performance. They don't make them like Carver did any more for good reason.
I_F
Re C-9 sonic holography. The name is a tad silly, but if you think about trying to describe it to the general public, that phrase is probably easier to grasp than "speaker cross talk cancellation device" Takes up less space on the front panel. I_Forget's description squares pretty closely with mine. It works. Some times really well. Sometime disconcerting. My favorite example of disconcerting is with a closed miked acoustic guitar recording -- make it sound like the instrument is 10 feet wide. Actually, I think is approximates what you might hear during a guitar recital if you listened with your head 6 inches from the instrument. Sometimes with orchestral pieces it gives a more believable simulation of actually being there than some surround recordings. Finally it comes with a bypass switch if you don't like what you hear.
Re" Magnetic Field....." A purist 2 channel 200W amp, i.e., enough transformer VA rating, PS capacitance, output devices and heatsinkage to run full power indefinately, can be a real pain to deal with from the point of view of weight and physical dimension. Carver's orientation starting with the M400 seems to be to get those capabilities into a more use friendly package. I can't fault him for that. If there are compromises in other aspects that's hardly surprising. Life's like that.
Re" Magnetic Field....." A purist 2 channel 200W amp, i.e., enough transformer VA rating, PS capacitance, output devices and heatsinkage to run full power indefinately, can be a real pain to deal with from the point of view of weight and physical dimension. Carver's orientation starting with the M400 seems to be to get those capabilities into a more use friendly package. I can't fault him for that. If there are compromises in other aspects that's hardly surprising. Life's like that.
Hi I_Forgot,
I did "factory warranty" in Canada for many years, and with many brands. The Carver product was more reliable than most.
Ways to kill a Carver:
Run mids and or highs only (locks the commutators up).
Run an extension cord or poor circuit (voltage falls and supply draws more to compensate).
Run off a small gas generator. (love that, both amp and generator become extinct).
Plug into 550 VAC (flames will cut TO-3 cases and bottom cover)
Let moron service it. (most people refuse to read the service manual).
Carver amps have more protecton than normal amps and normally will simply shut down (except in above cases). I've seen racks operate flawlessly for years. Even Clair Bros. used Carver successfully.
I really have to defend this brand for unjust accusations. If they were not serviced or used properly they could be unreliable. You can't blame the amp for that. But then that means you must read the manual.
BTW, they didn't use a normal transformer at all. It's more a current transformer and that's why it's small. They were very efficient, but not cheap.
If you want to see unreliable, look at a brand called Stewart. Bad design and cheap.
-Chris
I did "factory warranty" in Canada for many years, and with many brands. The Carver product was more reliable than most.
Ways to kill a Carver:
Run mids and or highs only (locks the commutators up).
Run an extension cord or poor circuit (voltage falls and supply draws more to compensate).
Run off a small gas generator. (love that, both amp and generator become extinct).
Plug into 550 VAC (flames will cut TO-3 cases and bottom cover)
Let moron service it. (most people refuse to read the service manual).
Carver amps have more protecton than normal amps and normally will simply shut down (except in above cases). I've seen racks operate flawlessly for years. Even Clair Bros. used Carver successfully.
I really have to defend this brand for unjust accusations. If they were not serviced or used properly they could be unreliable. You can't blame the amp for that. But then that means you must read the manual.
BTW, they didn't use a normal transformer at all. It's more a current transformer and that's why it's small. They were very efficient, but not cheap.
If you want to see unreliable, look at a brand called Stewart. Bad design and cheap.
-Chris
anatech said:
It looks like you have more fully fleshed-out the list of reasons to avoid these amps.
An amp that dies because the supply voltage is a little low? An amp that works OK full range but dies when used for only the portion of the audio spectrum where the power demand is relatively low?
It is very narrow definition of quality and reliability that overlooks weaknesses such as those.
I_F
I don't think we're going to reach a consensus on this. The original question asked whazzit? not howzit? I really enjoyed the posts that didn't deal with the quality.
EDIT: Spelling
EDIT: Spelling
Hi I_Forgot,
Everything is in the owners manual. I will not comment further as you seem to have completely missed the importance of some of those things for all amplifiers.
So, operational questions can be answered. If you don't operate these properly, don't blame the amp.
Hi sam9,
Carver's marketing department was brilliant. They drove me nuts, I hated the nonsense they came up with. I pretty much agree with you on your points you've mentioned.
-Chris
Everything is in the owners manual. I will not comment further as you seem to have completely missed the importance of some of those things for all amplifiers.
So, operational questions can be answered. If you don't operate these properly, don't blame the amp.
Hi sam9,
Carver's marketing department was brilliant. They drove me nuts, I hated the nonsense they came up with. I pretty much agree with you on your points you've mentioned.
-Chris
anatech, enjoyed reading your responses in this thread. learned some stuff.
i recently picked up a carver PM 1.5 amp.. i will be looking for some schematics for it soon (nice to have on hand) .. just curious your opinion on that amp. i'll be using it to power a pair of Carver Silver edition Amazing loudspeakers.
thanks,
Richard
i recently picked up a carver PM 1.5 amp.. i will be looking for some schematics for it soon (nice to have on hand) .. just curious your opinion on that amp. i'll be using it to power a pair of Carver Silver edition Amazing loudspeakers.
thanks,
Richard
Magnetic field amp
I did Carver warranty back in the 1980s. Repaired a lot of them in the 90s out of warranty. I owned one of the 1.5T models for years, never broke it.
If you want to get better sound from these amps. change the rectifiers to HEXFRED soft recovery diodes, change the op-amps to newer designs (Burr-Brown, AD, ECT.). I have modified a lot of them this way and they do sound much better.
I think if used for intended purpose they were fairly reliable as I at one point was doing service for almost every Karaoke company in K.C. and most used these amps because of size/weight/power output ratio. I rarely had to repair the amps, even after blowing speakers with them.
As soon as I had a design of my own working, I sold the Carver to a customer who is still running a pair of Magneplaners with it.
I like the sound of my Mosfet amp much better. Regards all.
I did Carver warranty back in the 1980s. Repaired a lot of them in the 90s out of warranty. I owned one of the 1.5T models for years, never broke it.
If you want to get better sound from these amps. change the rectifiers to HEXFRED soft recovery diodes, change the op-amps to newer designs (Burr-Brown, AD, ECT.). I have modified a lot of them this way and they do sound much better.
I think if used for intended purpose they were fairly reliable as I at one point was doing service for almost every Karaoke company in K.C. and most used these amps because of size/weight/power output ratio. I rarely had to repair the amps, even after blowing speakers with them.
As soon as I had a design of my own working, I sold the Carver to a customer who is still running a pair of Magneplaners with it.
I like the sound of my Mosfet amp much better. Regards all.
Hi gearheaddruid,
Some Carver amps are sensitive to the op amp type. Play ever so carefully there. The Lightstar and a few others will not like that game at all.
-Chris
Oh man!!! Don't do that!
Some Carver amps are sensitive to the op amp type. Play ever so carefully there. The Lightstar and a few others will not like that game at all.
I have my doubts there. Simply replacing the caps going open and changing the PCB mount filter caps will do that. There are far more serious things going on that hexfreds will not fix. Keep in mind that the amps are slightly underbiased (do not increase over spec). There is also a commutating transient on the output. Never mind the hash from the mag coil. Hexfreds in this case is only dressing on the window. As long as they make you feel good. Yes, been there, tried that. Everything sounded, measured and looked the same.
-Chris
I still have a Carver PA amp somewhere (PM1400, was there something like that ?) that is used for a small disco PA once in a while.
I don't trust those double electrolytics that much anymore that are used in the PSU. Are they still made or is it better to replace them by normal types (altough one could run into problems with space) ?
Regards
Charles
I don't trust those double electrolytics that much anymore that are used in the PSU. Are they still made or is it better to replace them by normal types (altough one could run into problems with space) ?
Regards
Charles
Hi Charles,
Those were replaced by a PCB assy that fit in where the old dual units were fitted. They are single caps now. If you see any old dual units, they are most certainly bad.
I have heard of some members here fitting singles in on long leads. I don't think that's a secure way of doing this, but it is an option I guess.
-Chris
Those were replaced by a PCB assy that fit in where the old dual units were fitted. They are single caps now. If you see any old dual units, they are most certainly bad.
I have heard of some members here fitting singles in on long leads. I don't think that's a secure way of doing this, but it is an option I guess.
-Chris
Carver mods
Chris, I was reffering to the older Carver Amps, I have been out of the service field for over ten years. The HEXFREDS seemed to help some of the commutating noise generated in the power supply. The op-amps I installed were OPA2604 and such. Did not have any stability problems with them.
I just have to add: "Run for the hills folks, or you'll be up to your ears in Martians"
Regards, Steve
Chris, I was reffering to the older Carver Amps, I have been out of the service field for over ten years. The HEXFREDS seemed to help some of the commutating noise generated in the power supply. The op-amps I installed were OPA2604 and such. Did not have any stability problems with them.
I just have to add: "Run for the hills folks, or you'll be up to your ears in Martians"
Regards, Steve
Hi Steve,
LOL, you're sooooo right!
So, you put the new diodes in the commutator position, or the rectifier banks for supplies 1 and 2? The top rails have a bridge as you know.
I still would be careful with the op amps. They ran into problems when the new designs started using FET input op amps and other high bandwidth devices. They may misbehave in the 200KHz to 1 MHz region. It's like redesigning the front end of a normal amplifier and not looking at the stability. You may have been lucky so far.
-Chris
LOL, you're sooooo right!
So, you put the new diodes in the commutator position, or the rectifier banks for supplies 1 and 2? The top rails have a bridge as you know.
I still would be careful with the op amps. They ran into problems when the new designs started using FET input op amps and other high bandwidth devices. They may misbehave in the 200KHz to 1 MHz region. It's like redesigning the front end of a normal amplifier and not looking at the stability. You may have been lucky so far.
-Chris
phase_accurate said:
Manuel says : Que ?
If you don't mind the dummy asking, what kind of capacitors are that?