Tea-Bag said:
Balanced F5 on top and Aleph 5 on bottom. Just wiring f5s for balancing re your wiring in an earlier post Tea-bag. Will be interested to see how that turns out. i have just bodged an xlr connected to inputs and ground. and I will use the xlr 2 for posative speaker and xlr 3 for negative is that right ? using only the live speaker outs...
OK balanced works just fine. No distortion at any level. Happyness. Just gotta build two more channels Now!
Dave
Dave
Balanced F5's
Dpole, good job.....the balanced F5's should work well into a set of 801's - you should get up to 100 watts in Class AB.
My question to the cognescenti - has anyone hooked a balanced pair of these puppies up to an Audio Precision rig and measured were they clip ?? Us'ens that don't like "tizzy" speakers are dyin' to know.....
Dpole, good job.....the balanced F5's should work well into a set of 801's - you should get up to 100 watts in Class AB.
My question to the cognescenti - has anyone hooked a balanced pair of these puppies up to an Audio Precision rig and measured were they clip ?? Us'ens that don't like "tizzy" speakers are dyin' to know.....
Heretical thought
Late to this party...
Here's a heretical thought?
Perhaps one might carefully select one's IDSS values and parallel two BLs to equal one V JFET's total IDSS? ( I think i recall the BLs are lower IDSS than the V's?)
If one used separate degen resistors on the pair, one might make them act almost perfectly in tandem?
_-_-bear
ttr said:Local supplier stocks only 2SK170 BL and 2SJ74 V types. If I build F5 with these different classification FETs, am I getting myself in trouble? I haven't measured the actual Idss of the components yet, but let's assume 6mA for the BL and 20mA for the V.
Nelson Pass said:
Late to this party...
Here's a heretical thought?
Perhaps one might carefully select one's IDSS values and parallel two BLs to equal one V JFET's total IDSS? ( I think i recall the BLs are lower IDSS than the V's?)
If one used separate degen resistors on the pair, one might make them act almost perfectly in tandem?
_-_-bear
Re: Heretical thought
It would work perfectly if the transconductance varied by the same
ratio as Idss, which unfortunately, it does not.
It would be worth trying, though.
😎
bear said:
It would work perfectly if the transconductance varied by the same
ratio as Idss, which unfortunately, it does not.
It would be worth trying, though.
😎
bear said:
Because of availability, I have used 2SK170BL and 2SJ74V, just on choice at random without measuring IDSS. I have no problem at all.
>🙂<
Because of avability me too and being impatient, i used first 2sk170bl with 2sj108v.
On one channel i could not obtain 1.3 A bias and 0 Volts DC at the output. I had to stay under 1 Amp. This explaining my post 3453: "You risk to have difficulties to obtain 1.3A quiescent and 0v at the output."
Later on, surprisingly, when i got the right 2sj74bl and replaced the 2sj108v with them, my problem was still the same ( not really a prob. as the amplifier was sounding very nice as this).
I had to tweak R3 (or R4 i do no remember) to get the correct bias.
I cannot explain this. ( i use no current limiters).
On one channel i could not obtain 1.3 A bias and 0 Volts DC at the output. I had to stay under 1 Amp. This explaining my post 3453: "You risk to have difficulties to obtain 1.3A quiescent and 0v at the output."
Later on, surprisingly, when i got the right 2sj74bl and replaced the 2sj108v with them, my problem was still the same ( not really a prob. as the amplifier was sounding very nice as this).
I had to tweak R3 (or R4 i do no remember) to get the correct bias.
I cannot explain this. ( i use no current limiters).
Which one is better between 1.3Amp sound and 1 Amp sound?
Big difference? Just curious . . .
>🙂<
I should have said : was sounding to me as nice at 1 Amp as at 1.3.
My hear could not make any difference. Though, as it leaves class A sooner, i guess there is a difference when pushed hard. But it the first watt that counts, isn't-it?!
My hear could not make any difference. Though, as it leaves class A sooner, i guess there is a difference when pushed hard. But it the first watt that counts, isn't-it?!
bobodioulasso said:
Yes, it is!
And, regarding the sound, I had the same feeling.
Thanks for the info.
>🙂<
Thus, why overheat the amp @ 1.3A ?
Everything will be stressed reducing realiabilty and life span.
Or not?
Everything will be stressed reducing realiabilty and life span.
Or not?
Overheating depends on heatsinks size.
The bias value depends on your power needs.
As i personnaly use F5 only for tweeters (electronic crossover) , i'll never reach full power capability. Someone using this amp for full bandwith could like to enjoy the full class A power. This is just my opinion.
The bias value depends on your power needs.
As i personnaly use F5 only for tweeters (electronic crossover) , i'll never reach full power capability. Someone using this amp for full bandwith could like to enjoy the full class A power. This is just my opinion.
It's my opinion that each driver in a multiway speaker should be capable of similar peak SPL.bobodioulasso said:
If all the drivers are the same impedance and have the same sensitivity, than all of them should have an amplifier capable of similar peak voltage ability and as a result sufficient current capacity to meet the transient demands of the driver when peak voltage is delivered.
This matching of sensitivity and impedance requires that each amplifier has the same power delivery.
My recommendation is don't skimp on the peak SPL of the treble driver.
Can we really compare the necessary energies to produce basses with these to produce highs? Aren't the masses of air to move quite different?
I think what Andrew is saying is, in an multi-amplifier system the amplifiers for different drivers should all be the same power if the drivers have the same sensitivity rating. Doesn't really matter how much energy is needed. The amplifier needs to drive the speaker with the same voltage so the SPL is the same.
labjr said:
This is exactly what i understood. But most of systems i have seen use small amps for trebles. The real life tends to show it works.
AndrewT said:
I agree with you on this...
What would you recommend in a slightly different arrangement? Say, ESL of some 88dB and a line array with 8x 6.5" bass-mids pch which will add up to some 98-100dB sensitivity... I am about to finish my set of two dual mono F5s but am not really sure that this will be the best arrangement. I also have just a few days to play to finish Aleph5 (the only problem is to find that time) but in this case, if the F5 can't really push the ES panels as it should, would you suggest using Aleph for that job? The plan is to make the crossover somewhere around 200-350Hz max... And this is how the speakers look like... (the small FR fostex is not part of the system I am talking about)
Attachments
Re: Re: Heretical thought
Speaking of which, I may have missed reading this point either here or on FirstWatt in the F5 paper:
The B+ is spec'd at 24vdc maximum because the breakdown voltage of the JFETs are 50v nominal??
Or is there another reason?
Nelson Pass said:
Speaking of which, I may have missed reading this point either here or on FirstWatt in the F5 paper:
The B+ is spec'd at 24vdc maximum because the breakdown voltage of the JFETs are 50v nominal??
Or is there another reason?