monoblock learning needed

[kaliph11]

rescues a Parasound HCA 1200II over the weekend.

It needs new speaker terminals on the left side (cannot even imagine what was done to break the metal posts off) and the mono/stereo switch has to be replaced, but looks quite nice other than that.

Problem for me is what to do once it is fixed. I have never used a monoblock, and was wondering if anyone here can school me or point out a site that would help.

Thanks

 

[dspear99ca]

If it has a mono/stereo switch it's not a monoblock. The definition of monoblock is a single-channel amplifier. It sounds like a stereo power amplifier. I'd test it for DC offset before I hooked up any speakers.

 

[kaliph11]

Lucky you Canadians speak English...obviously I don't.

Further inspection says it is a high-current 2 channel/stereo amp.

I was thrown by the mono on the back...as I said, i need an education.

 

[GOYA]

It sounds as though it can be made into a mono amp by bridging the two stereo amps together. Unless you have another identical amp or your just want to run mono, you'll probably just want to run it in stereo mode.

 

[SoCal Sam]

Unfortunately you do not have a true monoblock amp but I will answer your question.

Monoblocks are the ultimate expression of the art. Typically, they have the best build quality, the best power supplies, the best signal separation, and the highest price tags. The result is usually the best sound quality. I have followed the audio evolutionary path and progressed from receivers to integrateds to separates and now my main system are monoblocks.

 

[dspear99ca]

What most people call an "amp" is actually an integrated amp. An integrated amp is a preamp and a power amp in one box... the power amp is just that, a power stage. The preamp is, at minimum, a volume control. Preamp functions also include input switching, tone controls and filters, etc. A "receiver" is an amp, a preamp, and a tuner all housed in the same chassis. Many amps and some receivers actually have jacks on the back that let you separate the pre and power amps... they'll be labelled "pre-out" and "main-in". You can use just the pre-amp to power external power amp, or just the power amp with another preamp, or connect the two sets of jacks together and use both.

You need a pre-amp to use with your amp.

 

[SoCal Sam]

...You need a pre-amp to use with your amp.

Not true if your sources have variable outputs and/or your separate amp has gain controls.

 

[kaliph11]

follow-up

first, my level of expertise is spotty...not totally noob. I have system running receivers both regular and bi-wired. One system using an integrated amp, and two running amp/pre amp configurations.

next, a question: what is a high-current amp able to run stereo versus both a regular amp and a monoblock amp?

Finally, there is the term "bridge": what is bridging? (Should it have a sticky?)

 

[dspear99ca]

first, my level of expertise is spotty...not totally noob. I have system running receivers both regular and bi-wired. One system using an integrated amp, and two running amp/pre amp configurations.

next, a question: what is a high-current amp able to run stereo versus both a regular amp and a monoblock amp?

Finally, there is the term "bridge": what is bridging? (Should it have a sticky?)

You are confusing yourself unnecessarily. As SoCalSam pointed out in an earlier post, monoblock amplifiers are simply single-channel amps. "Regular" amps are two-channel (stereo) amps, that is, two discrete amplifiers in the same box.

"High current" is a marketing term as much as anything else. An amp designed to deliver "high current" (vs. what? Who knows, "normal current" is not defined) will generally be able to drive more difficult, often lower-impedance, loads (think 4-ohm speakers), but again, these terms are in no way defined or standardized so one man's "high current" amp may not be able to deliver as much power as somebody else's non-"high-current" model...

When an amp is bridged, it means that the two channels are combined so that they work together as a single channel amplifier. In order for this to happen, the input signal must be fed normally to one channel, and inverted to the other channel of a stereo amp. The two positive speaker terminals (L & R) are used as the output, the negative speaker terminals are not used. Due to the decreased load impedance that this bridged amp "sees" (the load impedance is split between the two amp channels) THEORETICALLY you could get 4X the power in bridged mode that you can get in two-channel mode. However, most amps are not designed to dissipate the added heat, and some current-limiting circuit is employed to limit the output power to that which won't smoke any components.

Not true if your sources have variable outputs and/or your separate amp has gain controls.

Yes, you COULD run your iPod right into the power amp. You won't like the full-volume crackle every time you forget to turn off the amp before you connect/disconnect, but it COULD be done. You COULD also use the two gain controls (if this amp has them) as a volume control... PITA in my opinion but certainly possible.

I was speaking to what most ordinary average-joe people would want, the above possibilities notwithstanding. but then you knew that...

 

[SoCal Sam]

first, my level of expertise is spotty...not totally noob. I have system running receivers both regular and bi-wired. One system using an integrated amp, and two running amp/pre amp configurations.

next, a question: what is a high-current amp able to run stereo versus both a regular amp and a monoblock amp?

Finally, there is the term "bridge": what is bridging? (Should it have a sticky?)

Noob is good, ask away!:thmbsp:

High current amp is a marketing term but can also mean the amp has a higher voltage rail with the benefits of being faster and more accurate.

Bridging is taking a 2-channel amp and setting to mono for single channel use. The two channel's power is combined for double power output from a single channel.

 

[SoCal Sam]

...Yes, you COULD run your iPod right into the power amp. You won't like the full-volume crackle every time you forget to turn off the amp before you connect/disconnect, but it COULD be done. You COULD also use the two gain controls (if this amp has them) as a volume control... PITA in my opinion but certainly possible...

From what I understand, iPod's are amp killers so I would never use them directly with an amp or with a preamp for that matter.

Using two volume controls in an amp is less convenient than using a single volume control in a preamp but IMO, the improved sound is worth it. Things get more complicated if you want to use a tuner or TT without a preamp.

 

[barredowl]

How is an ipod an "amp killer" is their output too high for a preamp to handle? I ask because I use an ipod touch to demo amps when I am selling them. Sorry for the thread jack...

 

[dspear99ca]

From what I understand, iPod's are amp killers so I would never use them directly with an amp or with a preamp for that matter.

Using two volume controls in an amp is less convenient than using a single volume control in a preamp but IMO, the improved sound is worth it. Things get more complicated if you want to use a tuner or TT without a preamp.

Okay, fair enough on the two volume controls, to each their own. To be honest I've never tried running a source right into my amps... one day I'll have to try it, but I'll tell you this: my wife would never let me hear the end of it if I put dual volume controls in the livingroom, christ it was difficult enough just getting her to be able to run the TV sound or turn on the radio!

As far as amp killers, there are many millions of people using iPods as sources, their main drawback in my personal experience is that they often do not have enough gain, i.e. their output will be +/- 1V vs. the normal 2V we've come to expect from modern components. However, it's more of a mental problem to overcome: turning the volume control on the amp up past 11 or 12 o'clock will give PLENTY of volume. I don't know the output impedance, but it's gotta' be under 5 ohms to drive 32-ohm headphones decently, I can't see it being any problem whatsoever driving a 47K-100K preamp or amp. As I noted, though, if you're driving the amp directly you better make damn sure it's turned off before you unplug the iPod.

Dave

 

[SoCal Sam]

Okay, fair enough on the two volume controls, to each their own. To be honest I've never tried running a source right into my amps... one day I'll have to try it, but I'll tell you this: my wife would never let me hear the end of it if I put dual volume controls in the livingroom, christ it was difficult enough just getting her to be able to run the TV sound or turn on the radio!

As far as amp killers, there are many millions of people using iPods as sources, their main drawback in my personal experience is that they often do not have enough gain, i.e. their output will be +/- 1V vs. the normal 2V we've come to expect from modern components. However, it's more of a mental problem to overcome: turning the volume control on the amp up past 11 or 12 o'clock will give PLENTY of volume. I don't know the output impedance, but it's gotta' be under 5 ohms to drive 32-ohm headphones decently, I can't see it being any problem whatsoever driving a 47K-100K preamp or amp. As I noted, though, if you're driving the amp directly you better make damn sure it's turned off before you unplug the iPod.

Dave

Yikes, better to KISS for the wife!:yes:

Didn't mean to start a threadjack with my iPod suspicions. However, something that small can't possibly have enough filtering to smooth out spikes. I suspect an iPod is capable of clipping, which could cause havoc down the line. Anyways, I don't know for sure but I won't experiment to find out.

 

[dspear99ca]

Yikes, better to KISS for the wife!:yes:

Didn't mean to start a threadjack with my iPod suspicions. However, something that small can't possibly have enough filtering to smooth out spikes. I suspect an iPod is capable of clipping, which could cause havoc down the line. Anyways, I don't know for sure but I won't experiment to find out.

It's something like 3.7VDC from a battery, there will be no power spikes. Depending on the op-amps used, it may or may not clip at full output, I have my suspicions that they were inherently designed to push -3dbfs all day long into tens of millions of teenaged ears. I'm pretty sure the higher models have line-out... with a decently flat response and reasonably low noise floor from what I've read.

There are some iPod pre-amps on the market which boost the signal to normal line level, i.e. somewhere between 1.5 and 2V, the use of one of these should alleviate concerns about clipping... or you can make your own with a 9V battery, a regulator and a dual op-amp IC, even a trimpot on the feedback to adjust gain if you're feeling fancy.

I have a blackberry I use as a source from time to time (although i am far less than convinced of its' inherent fidelity... let's face it when you pack a camera/video camera/gps/media player/games/calendar/phone/contacts into a device which you then give away for free, sacrifices must be made). What I don't like is that the blackberry's audio out pops in between songs, it pops when the backlight turns on or off, and it pops when the phone rings. iPods I believe are better at this.