Almost all domestic power amplifiers have their various channel ngative (black) terminals tied to common audio ground, as do original Quad products like the 606. The 909 model comes from a new Chinese owner of the Quad brand and I can't say I've seen inside any examples of the 909 but such as they are, the schematics suggest the same arrangement. Note that circuit symbols have changed between the different manufacturers.
Quad 606 - Manual - Stereo Power Amplifier - HiFi Engine
Quad 909 - Manual - Stereo Power Amplifier - HiFi Engine
Quad 606 - Manual - Stereo Power Amplifier - HiFi Engine
Quad 909 - Manual - Stereo Power Amplifier - HiFi Engine
Thanks for the replies, much appreciated.
What would be a good upgrade in sound quality from my humble quad 405.
I have done all the mods on the quad, completely new power supply, caps, transistors, resistors, in fact there is nothing left of it except the chassis.
I still don't like the sound quality. It's okay, but kind of laid back and boring, no matter what i do to it.
Which amp would give me better sound and still retain the tied left and right negative speaker thingy.
What would be a good upgrade in sound quality from my humble quad 405.
I have done all the mods on the quad, completely new power supply, caps, transistors, resistors, in fact there is nothing left of it except the chassis.
I still don't like the sound quality. It's okay, but kind of laid back and boring, no matter what i do to it.
Which amp would give me better sound and still retain the tied left and right negative speaker thingy.
Is it only me that dislikes the sound of the quad 405. What do you think of it?
It seemed a popular amp when i searched. I thought if i purchase one, then with all the mods applied it should sound very good. But it has not turned out like that. Is this something to do with the 70's sound style, or maybe something about the quad circuitry itself. Are you a quad lover or hater.
It seemed a popular amp when i searched. I thought if i purchase one, then with all the mods applied it should sound very good. But it has not turned out like that. Is this something to do with the 70's sound style, or maybe something about the quad circuitry itself. Are you a quad lover or hater.
To get back to the original thread...
Old gits like me, we all played with Hafler arrangements. To argue that Dolby is remotely like Hafler is silly - they are quite different. All the Hafler arrangement did was put the difference signal between the channels into another pair of speakers. Mine were on the ceiling for a while because the bedroom was so small.
Even a tiny low powered amp did not suffer. If you follow the wiring on post #13 you :
a) do not worry about negatives of the amps being tied together - not needed, doesn't matter if they are or not.
b) unlikely to damage the amps - two extra 8 Ohm speakers wired in series and then being driven by the Difference between L + R is naff all power going through the surround.
As to is it worth it....Nope. Fun to play with for while but you soon get bored and that is why for the past several decades you have not heard about it!. Back in 1975 we all played with it!
In a similar vein we also played with some circuits to deliberately modify L and R phase differences to try and change to soundstage width. Some amps even got fitted with controls for this.
Old gits like me, we all played with Hafler arrangements. To argue that Dolby is remotely like Hafler is silly - they are quite different. All the Hafler arrangement did was put the difference signal between the channels into another pair of speakers. Mine were on the ceiling for a while because the bedroom was so small.
Even a tiny low powered amp did not suffer. If you follow the wiring on post #13 you :
a) do not worry about negatives of the amps being tied together - not needed, doesn't matter if they are or not.
b) unlikely to damage the amps - two extra 8 Ohm speakers wired in series and then being driven by the Difference between L + R is naff all power going through the surround.
As to is it worth it....Nope. Fun to play with for while but you soon get bored and that is why for the past several decades you have not heard about it!. Back in 1975 we all played with it!
In a similar vein we also played with some circuits to deliberately modify L and R phase differences to try and change to soundstage width. Some amps even got fitted with controls for this.
The Quad 405 is fine as a straight amplifier but just consider what you expect from your audio system and how that differs from what was considered good when the 405/44 system was introduced in the 1970s. At the time, lowest THD and noise was the be-all of audio and little else seemed to matter to consumers and reviewers. You don't say much about your existing system but you might consider a recap for the preamp if that's Quad too.
Many audiophiles now like to have some "colour" in their audio. For example, a small amount of 2nd order harmonic distortion to sweeten the sound and enhance it with more "detail" than is present in the recording. To me, detail is not the be-all of music enjoyment but some find listening more interesting that way.
As a matter of interest, I have a Quad 34/304 system as well and I find it to have a lively, energetic sound by comparison to the 405 and that suits me fine. It's my favourite Quad system by a clear margin.
Many audiophiles now like to have some "colour" in their audio. For example, a small amount of 2nd order harmonic distortion to sweeten the sound and enhance it with more "detail" than is present in the recording. To me, detail is not the be-all of music enjoyment but some find listening more interesting that way.
As a matter of interest, I have a Quad 34/304 system as well and I find it to have a lively, energetic sound by comparison to the 405 and that suits me fine. It's my favourite Quad system by a clear margin.
Hi. You sound as though you have compared the 306 and 405, if so what were your impressions.
I contacted quad who said there should be no difference in sound quality between the 405, 606 and 909. Funny, i though the higher models ironed out some of the bugs in the 405.
I did hear about the 303 and people say it is the best of the quad range, is that true?
Who do you think would win in a fight, the 303 or 306.
I contacted quad who said there should be no difference in sound quality between the 405, 606 and 909. Funny, i though the higher models ironed out some of the bugs in the 405.
I did hear about the 303 and people say it is the best of the quad range, is that true?
Who do you think would win in a fight, the 303 or 306.
Its easy to preach from a textbook on audio design theory and claim that all amplifiers sound the same etc. so perhaps you were speaking to the wrong people from a user's viewpoint, to find any differences between Quad's old products.
Just about all brands can have family similarities in sound quality but cost priorities and changes in components can still make detectable differences. I'm not going to compare every Quad design but you should be aware that the 303 is nothing like other Quads. It's not a Current Dumping type but an early standard AB design featuring a Quasi-complementary triple output stage, hailed as special many years ago but its only claims to fame now are a beautifully designed case and an ability to drive Quad's ESLs. I have one in excellent original condition but sound-wise, it sucks, even fully recapped. The problem is the age of the electronic design which was a beefed-up version of many others of the time and frankly, decent modern commercial products will walk all over it - no contest with a 306, IMV.
I've never listened to a 909 and only to a demos. of the 707 driving ESLs. Though that was very impressive for detail and refinement, it left one feeling a little cheated of the music's entertainment value. Because they were the popular models, I think you can read comments and reviews of the 405 and 306 models on just about any UK audio chat forum but some guys are just waffling - read their other posts before believing everything you see.
You may be at a point where you need to borrow gear or go and listen to other systems for yourself to get a feel for what really does sound good and why. Buying something old and cheap on Ebay because that's what the other guys do, is no way to assess what you need - listen and decide what you do like first. Surprisingly, some folk actually prefer cheap class D amplification to any of the old Hifi gear
Just about all brands can have family similarities in sound quality but cost priorities and changes in components can still make detectable differences. I'm not going to compare every Quad design but you should be aware that the 303 is nothing like other Quads. It's not a Current Dumping type but an early standard AB design featuring a Quasi-complementary triple output stage, hailed as special many years ago but its only claims to fame now are a beautifully designed case and an ability to drive Quad's ESLs. I have one in excellent original condition but sound-wise, it sucks, even fully recapped. The problem is the age of the electronic design which was a beefed-up version of many others of the time and frankly, decent modern commercial products will walk all over it - no contest with a 306, IMV.
I've never listened to a 909 and only to a demos. of the 707 driving ESLs. Though that was very impressive for detail and refinement, it left one feeling a little cheated of the music's entertainment value. Because they were the popular models, I think you can read comments and reviews of the 405 and 306 models on just about any UK audio chat forum but some guys are just waffling - read their other posts before believing everything you see.
You may be at a point where you need to borrow gear or go and listen to other systems for yourself to get a feel for what really does sound good and why. Buying something old and cheap on Ebay because that's what the other guys do, is no way to assess what you need - listen and decide what you do like first. Surprisingly, some folk actually prefer cheap class D amplification to any of the old Hifi gear
It is the OP who's leading the off-topic here. See #23. I have no agenda in replying to other issues he raises but it seems there is a more fundamental problem here, likely nothing to do with Hafler-Dynaco surround systems which have been tried by other replies and generally found to be not worth the effort. I may agree but won't be disturbing interest in the topic any further. Have at it.
Not directly. See the snip which shows how either channel signal ground is coupled to chassis ground via a low impedance. As the supply windings for each channel are separate and not centre-tapped, signal ground is established by virtual earths generated from the power supplies.
Attachments
Any harm in trying?
I've come across this during my morning bus ride to work.
Some have stated the output negatives need to be bound together, others that this is not necessary.
Will it harm anything in a Behringer A500 to just jump the two negative binding posts together?
Since I crossover my LR speakers actively, with one amp per side, the Behringer would have its own preamp signal from a splitter, and be only for the ambience.
I've come across this during my morning bus ride to work.
Some have stated the output negatives need to be bound together, others that this is not necessary.
Will it harm anything in a Behringer A500 to just jump the two negative binding posts together?
Since I crossover my LR speakers actively, with one amp per side, the Behringer would have its own preamp signal from a splitter, and be only for the ambience.
I don't know why anyone would state that? If you could reference a specific message, that might help?
I don't know about that particular model, but there is no need to jump the negative terminals for the Hafler hookup regardless, when configuring just the ambient/surround speakers. It seems weird, but there it is.
By the way, I know this is an old thread, but I'll just comment that I continue to use a Hafler type circuit for one system to get 3-ch stereo (in my office). It isn't just L+R in the center and a full L and R, it is more complex than that, as far as I can tell. I think it blends the signal across the 3 speakers. It doesn't anchor the center like Dolby Pro Logic, but I think it works well for most music.
For the ambient (traditional) Hafler hook-up, sometimes I've used it in car audio. So, I have found it useful in time periods after the '70s.
I don't know why anyone would state that? If you could reference a specific message, that might help?
I did jump the two neutral posts together, and no harm done.
You won't get a centre channel from this; you'll get the Dolby mono surround channel, from the out of phase information.
I didn't use a preamp after all, just the detected volume pots on the Behringer.
It works well, but I don't need it for vinyl records.
Jumping the two neutral posts assures a common ground for the amp channels, internally.
I don't know about that particular model, but there is no need to jump the negative terminals for the Hafler hookup regardless, when configuring just the ambient/surround speakers. It seems weird, but there it is.
By the way, I know this is an old thread, but I'll just comment that I continue to use a Hafler type circuit for one system to get 3-ch stereo (in my office). It isn't just L+R in the center and a full L and R, it is more complex than that, as far as I can tell. I think it blends the signal across the 3 speakers. It doesn't anchor the center like Dolby Pro Logic, but I think it works well for most music.
For the ambient (traditional) Hafler hook-up, sometimes I've used it in car audio. So, I have found it useful in time periods after the '70s.
Use of powered speakers for Hafler ambient config.
I am interested in trying this setup with a Genelec sub/satellite speaker setup. The L/R speakers are powered & the sub input is low level L/R & routed through a volume control & then to the low level L/R speaker outputs. I can make an adapter so that the powered L/R speakers are connected as specified in the Hafler configuration. Specifically the L/R Pos would be sent to the powered speakers & the - signal would be tied together to put the L/R speakers in series. This Neg connection would not be connected to he sub outputs.
Basically I would be connecting to the pos. low level outputs of the Genelec sub. My main concern is tying the powered speakers together with the negatives tied together on active speakers. Soooo, anyone see a problem here?
Thanks,
Kev
I am interested in trying this setup with a Genelec sub/satellite speaker setup. The L/R speakers are powered & the sub input is low level L/R & routed through a volume control & then to the low level L/R speaker outputs. I can make an adapter so that the powered L/R speakers are connected as specified in the Hafler configuration. Specifically the L/R Pos would be sent to the powered speakers & the - signal would be tied together to put the L/R speakers in series. This Neg connection would not be connected to he sub outputs.
Basically I would be connecting to the pos. low level outputs of the Genelec sub. My main concern is tying the powered speakers together with the negatives tied together on active speakers. Soooo, anyone see a problem here?
Thanks,
Kev
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