Thanks Andrew. I fully concur and actually have little difficulty with the mathematics, but without an understanding of the physics the numbers can be dangerously misleading.
I did indeed download all the application notes and have studied them intensely. And done lots of "what if" calculations to see how various combinations of standard capacitors and resistors coul fit together.
However, as mentioned in my previous post I could not find a good guide to selecting the optimal opamp.
I have subsequently looked at the debate in the filter buy group and have also obtained Product Data Sheets on opamps stocked by local electronics stores.
Ignoring dual and quad models the local stores stock the following opamps:
CA3130, CA 3140
LM301, LM308, LM741, LM748
NE5534AN, NE5534N
OPA2134PA
TL071
I have tentatively opined that the better choice would be the OPA2134PA, followed by the NE5534AN, then the NE5534N. Does my choice look sound or have I missed something basic?
Cheers
Graeme
I did indeed download all the application notes and have studied them intensely. And done lots of "what if" calculations to see how various combinations of standard capacitors and resistors coul fit together.
However, as mentioned in my previous post I could not find a good guide to selecting the optimal opamp.
I have subsequently looked at the debate in the filter buy group and have also obtained Product Data Sheets on opamps stocked by local electronics stores.
Ignoring dual and quad models the local stores stock the following opamps:
CA3130, CA 3140
LM301, LM308, LM741, LM748
NE5534AN, NE5534N
OPA2134PA
TL071
I have tentatively opined that the better choice would be the OPA2134PA, followed by the NE5534AN, then the NE5534N. Does my choice look sound or have I missed something basic?
Cheers
Graeme
Hi Consort
Just realised that I had omitted to acknowledge your post #34. Thanks.
I did download and study the papers, took your guidance and have done a series of calculations with standard capacitor and resistor values to get a feel for how they fit together.
Its been a steep learning curve for me, but I am starting to feel confident that I am getting somewhere.
Cheers
Graeme
Just realised that I had omitted to acknowledge your post #34. Thanks.
I did download and study the papers, took your guidance and have done a series of calculations with standard capacitor and resistor values to get a feel for how they fit together.
Its been a steep learning curve for me, but I am starting to feel confident that I am getting somewhere.
Cheers
Graeme
Hi Jeff
Over the last three weeks I have had several attempts to model the effect of the second order high pass filter on my boxes using WinISD.
So far without success.
WinISD actually includes a "filter calculator" which works out the capacitors and resistors needed for a range of filters. For an active second order high pass filter with Fc=35 Hz it calculates R1=R2=207 ohms, C1=C2=22uF, with a UA741 opamp.
But there seems no way to integrate the filters into the modeling or graphs.
There is one variable in WinISD that I do not understand. It is Ql, and WinISD always seems to set it at a default Ql=7. Their HELP just refers to (Ql=7 Butterworth) and then says that if you do not understand it then do not change the value.
Could this be the link we are searching for? If so, how could one use it?
Cheers
Graeme
Over the last three weeks I have had several attempts to model the effect of the second order high pass filter on my boxes using WinISD.
So far without success.
WinISD actually includes a "filter calculator" which works out the capacitors and resistors needed for a range of filters. For an active second order high pass filter with Fc=35 Hz it calculates R1=R2=207 ohms, C1=C2=22uF, with a UA741 opamp.
But there seems no way to integrate the filters into the modeling or graphs.
There is one variable in WinISD that I do not understand. It is Ql, and WinISD always seems to set it at a default Ql=7. Their HELP just refers to (Ql=7 Butterworth) and then says that if you do not understand it then do not change the value.
Could this be the link we are searching for? If so, how could one use it?
Cheers
Graeme
Read thru the posts here.. Grahame you misunderstood OR missread my post/suggestion. I said you really do need a 20+ AMP capable amplifier to get the most from the HPD's.
There is an intrinsic issue with the Tannoy 15's in that they are streched to acieve a fine transition with the HF section.. smaller LF cones fare somewhat better. But that aside, as secondary info given you cannot readily alter the cone diameter
The Amp requirements mean that to properly control the cone to best advantage , serious current is needed.. Lots live without it.. happliy listening to the weak flabby farty bass thinking that they've died and gone to heaven .. these folks have simply not been exposed to the alternate possibility... period.
Size of enclosure dictates the level of Bass produced Given that you seem unwilling to build adequate sized boxes for easily attainable bass depth.... then I strongly suggest you stop 'dicking around the edges' of the problem and supply the poor things with an Amp that can grab those big heavy cones with authority and produce the dynamics that 300B enthusiasts can only have wet dreams about..
Note that price is not the determinant of an amp with decent Amperage capabilities.. read the specs.. there are a few in the "econo' class that do this well and note that virtually NO tube amp can supply such, regardless of Pedigree OR exhorbitant price.
Ohhh.. and by the way time and inumerable dead ended experiments have taught me that NO opamp iat all is 'better' than any opamp yet devised by man Wally Jung be damned
There is an intrinsic issue with the Tannoy 15's in that they are streched to acieve a fine transition with the HF section.. smaller LF cones fare somewhat better. But that aside, as secondary info given you cannot readily alter the cone diameter
The Amp requirements mean that to properly control the cone to best advantage , serious current is needed.. Lots live without it.. happliy listening to the weak flabby farty bass thinking that they've died and gone to heaven .. these folks have simply not been exposed to the alternate possibility... period.
Size of enclosure dictates the level of Bass produced Given that you seem unwilling to build adequate sized boxes for easily attainable bass depth.... then I strongly suggest you stop 'dicking around the edges' of the problem and supply the poor things with an Amp that can grab those big heavy cones with authority and produce the dynamics that 300B enthusiasts can only have wet dreams about..
Note that price is not the determinant of an amp with decent Amperage capabilities.. read the specs.. there are a few in the "econo' class that do this well and note that virtually NO tube amp can supply such, regardless of Pedigree OR exhorbitant price.
Ohhh.. and by the way time and inumerable dead ended experiments have taught me that NO opamp iat all is 'better' than any opamp yet devised by man Wally Jung be damned
Hi,
R is usually 10 to 100 times larger and C similarly smaller.
QL is the box loss, Bullock says there is something wrong with the box if it's lower than 3, fix the problem don't retune the speaker.
The usual values can go upto QL=15 but this tends to be with smaller boxes.
A good indication of adequate current for a Tannoy amplifier would be nearly double the power into 4ohms
I suppose if I were looking at a real 100W (40Vpk & 5Apk) into 8ohms then 180W (38Vpk & 9.5Apk) into 4ohms would indicate a good 8ohm amp for the Tannoys. Not many commercial HiFi amps in the affordable market place can achieve this.
that's an unusual combination of R & C for an active filter.
R is usually 10 to 100 times larger and C similarly smaller.
QL is the box loss, Bullock says there is something wrong with the box if it's lower than 3, fix the problem don't retune the speaker.
The usual values can go upto QL=15 but this tends to be with smaller boxes.
A good indication of adequate current for a Tannoy amplifier would be nearly double the power into 4ohms
I suppose if I were looking at a real 100W (40Vpk & 5Apk) into 8ohms then 180W (38Vpk & 9.5Apk) into 4ohms would indicate a good 8ohm amp for the Tannoys. Not many commercial HiFi amps in the affordable market place can achieve this.
if the actual test results show 80W (35.8Vpk) then you are looking for <=-0.5db (on output voltage>=33.8Vpk) into 4ohm. This tells you that the output devices and the emitter resistors and the cabling and the driver stage and the smoothing caps and the fuses are designed to allow a decent current to get to the load.GraemeC said:
20k may give a very slightly high output noise. If you can obtain 0.47uF that fit the PCB this will allow a lower value of resistor.GraemeC said:
For mid and treble I would aim for <=12k, just to keep the noise level down.
Andrew, I do not know whether actual test results would show 80 watts, but was quoting from the Yamaha CR1000 Service Manual. It actually says:-
"... POWER OUTPUT
Dynamic Power (IHF)
200 watts (4 ohms)
200 watts (8 ohms)
Continuous RMS Power (each channel driven)
100/100 watts (4 ohms) at 1,000 Hz
80/80 watts (8 ohms) at 1,000 Hz
Continuous RMS Power (both channels driven)
100/100 watts (4 ohms) at 1,000 Hz
80/80 watts (8 ohms) at 1,000 Hz
Continuous RMS Power (both channels driven)
85/85 watts (4 ohms) at 20 to 20,000 Hz
70/70 watts (8 ohms) at 20 to 20,000 Hz ..."
Graeme
"... POWER OUTPUT
Dynamic Power (IHF)
200 watts (4 ohms)
200 watts (8 ohms)
Continuous RMS Power (each channel driven)
100/100 watts (4 ohms) at 1,000 Hz
80/80 watts (8 ohms) at 1,000 Hz
Continuous RMS Power (both channels driven)
100/100 watts (4 ohms) at 1,000 Hz
80/80 watts (8 ohms) at 1,000 Hz
Continuous RMS Power (both channels driven)
85/85 watts (4 ohms) at 20 to 20,000 Hz
70/70 watts (8 ohms) at 20 to 20,000 Hz ..."
Graeme
these show the amp (in the better situation of just one channel driven) pushes a claimed 80W into 8r (35.78Vpk, 4.47Apk) and this increases to 100W into 4r (28.28Vpk, 7.07Apk). This is well short of a good delivery into 4r (144W).GraemeC said:
I wonder if it is even worse into a reactive load?
However, these numbers are based on the published specifications. The figures that matter are the real test values into your loads.
Here at PL we use Tannoy HPD385/8's in Jensen Imperial
enclosures as a primary reference speaker. The crossover
is a variation on the Tannoy design but with air core coils and
no autoformers.
Orange county speakers does a wonderful job of refurbing these
drivers (the also do TAD's) - highly recommended.
They play beautifully with amplifiers with as little as 2 amps of
current.
enclosures as a primary reference speaker. The crossover
is a variation on the Tannoy design but with air core coils and
no autoformers.
Orange county speakers does a wonderful job of refurbing these
drivers (the also do TAD's) - highly recommended.
They play beautifully with amplifiers with as little as 2 amps of
current.
Thanks Nelson. I would love to have Jensen Imperial enclosures which seem to be approximately 5x3x2 feet - 30 cubic feet or 800 liters. This is even larger than the Tannoy Autographs and Westminsters, and I am not looking for a divorce.....
Within the constraints of keeping the boxes within domestic harmony criteria, do you have any suggestions for a possible improvement path for a real newbie.
Graeme
Within the constraints of keeping the boxes within domestic harmony criteria, do you have any suggestions for a possible improvement path for a real newbie.
Graeme
Hi Nelson,
thanks for the correction, but I am not accepting it.
My interpretation of peak is the maximum power available as a sinusoid from the amplifier when playing a transient.
I will not go down the road of doubling up to instantaneous peaks that eventually leads to all sorts of weird numbers being bandied about and now results in the corrupted PMPO (and probably others) that convince only the stupid "want to believers"
thanks for the correction, but I am not accepting it.
My interpretation of peak is the maximum power available as a sinusoid from the amplifier when playing a transient.
I will not go down the road of doubling up to instantaneous peaks that eventually leads to all sorts of weird numbers being bandied about and now results in the corrupted PMPO (and probably others) that convince only the stupid "want to believers"
Hi Nelson,
With your background in single ended and the context of the preceeding discussion of amplifier maximum current requirements into low impedance loading when driving 8ohm speakers, I jumped in with both feet instead of a sqrt foot. OOPS.
it appears from your response that this quote referred to Irms, whereas I interpreted it as Imax, hence the confusion.
With your background in single ended and the context of the preceeding discussion of amplifier maximum current requirements into low impedance loading when driving 8ohm speakers, I jumped in with both feet instead of a sqrt foot. OOPS.
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