My sources are
Turntable: DIY birch ply Lenco L75 with DIY "Terminator" style linear tracking air bearing tonearm, Shure M97xe MM cart, Salas folded simplistic RIAA (in production!)
DAC: DIY 2x TDA1541A chip with DIY SSRP 6N2P valve output stage, standard output level
My preamp is just:
relay input selector,
DCB1 Buffer,
Lightspeed optical volume resistors, fed by Salas 5v shunt
So, unity gain. I was considering the Juma suggested preamp 2x, but then re-read F5 turbo thread and considered maybe it would give the same result, more simply, cheaper, and more purist. My F5 is vanilla, except for I omitted the current limiters.
My speakers are rebuilt 1971 Celestion Ditton 44 cabinets/ drivers, original paper 12", original paper 5", modern Seas 19mm fabric tweeter. Nominally 6 Ohm. 4 watts pink noise for 90dB SPL. 25Hz - 40kHz Range. Quite a complex passive crossover (4th-order low-pass filter for the bass driver, 2nd-order band-pass filter for the mid and 3rd-order high-pass for the treble). It's all a question of taste with speakers, but for me and many others, they are really, really good.
Turntable: DIY birch ply Lenco L75 with DIY "Terminator" style linear tracking air bearing tonearm, Shure M97xe MM cart, Salas folded simplistic RIAA (in production!)
DAC: DIY 2x TDA1541A chip with DIY SSRP 6N2P valve output stage, standard output level
My preamp is just:
relay input selector,
DCB1 Buffer,
Lightspeed optical volume resistors, fed by Salas 5v shunt
So, unity gain. I was considering the Juma suggested preamp 2x, but then re-read F5 turbo thread and considered maybe it would give the same result, more simply, cheaper, and more purist. My F5 is vanilla, except for I omitted the current limiters.
My speakers are rebuilt 1971 Celestion Ditton 44 cabinets/ drivers, original paper 12", original paper 5", modern Seas 19mm fabric tweeter. Nominally 6 Ohm. 4 watts pink noise for 90dB SPL. 25Hz - 40kHz Range. Quite a complex passive crossover (4th-order low-pass filter for the bass driver, 2nd-order band-pass filter for the mid and 3rd-order high-pass for the treble). It's all a question of taste with speakers, but for me and many others, they are really, really good.
Zen Mod, would adding a gain stage make more sense (sound better) than boosting the existing F5 for some technical reason?
I can see that a preamp gain stage that doesn't send the amp into clipping would work, but would it be better than a larger power amp for some reason?
Thanks
I preferred the sound of the F5 with a preamp into my 90-ish db sensitive speakers. Not really a volume issue but more of a difference in dynamics and weight.
Why don't you put one of these together?
http://www.diyaudio.com/forums/pass-labs/103050-jfet-boz.html
Should be cheap, you can run it off 16 AA batteries and it sounds good. Even if it's just a test to find out if you need more gain.
Why don't you put one of these together?
http://www.diyaudio.com/forums/pass-labs/103050-jfet-boz.html
Should be cheap, you can run it off 16 AA batteries and it sounds good. Even if it's just a test to find out if you need more gain.
it seems , from my chair , that you're not having enough gain , to modulate F5 enough .
whatever - when volume is full throttle - do you have enough SPL in room ?
if yes , and still not satisfied - you need more oomph , so bigger amp
if not , and SQ is good - bring any louder source for test and try
even phone with cable , or anything (stereo , cd player , MPx player), using headphone output with adequate cable - that will likely have enough juice to drive F5 to full steam
Thanks Hikari1.
I was considering this, which Juma suggested was the best of several he tried for the F5:
http://www.diyaudio.com/forums/pass-labs/125893-preamp-ideas-f5-6.html#post1690625
I was considering this, which Juma suggested was the best of several he tried for the F5:
http://www.diyaudio.com/forums/pass-labs/125893-preamp-ideas-f5-6.html#post1690625
Zen Mod, at the weekend, I'll try connecting the CD player and the laptop, iphone etc. to the F5 directly, and see if there is enough SPL in the room. I suspect not though. Not for parties anyway, and not for getting carried away with the music. So, you think preamp gain is the solution, in this case, not higher rails?
Sound quality wise, embarrassingly, my Audiosector LM3875 chip amp sounds a little bit better. Fuller, more involving, warmer, seemingly just as detailed. The F5 does seem a little "polite" to me.
Sound quality wise, embarrassingly, my Audiosector LM3875 chip amp sounds a little bit better. Fuller, more involving, warmer, seemingly just as detailed. The F5 does seem a little "polite" to me.
, finding own THD blend (read turbo article and 6L6 building tutorials)That's a good one, but you can build that jfet box from spare parts if you have a matched set of 2sk170bl. It is extremely simple and cheap to make. That will tell you if you want/need a preamp.
I built the Jfet box then moved on to the BA-3 FE as a preamp for the F5. I like the BA-3 FE a lot.
Lucas,
Your gainclone has about 25db gain built in. The F5 has about 15. You will need a preamp for the F5 to reach similar gain levels as your gainclone. I think the Lm3875 is similar to the F5 wattage wise. It should not be significantly more powerful or louder when fed a similar signal. And for that your have to compare F5 + preamp to the gainclone. I suggest you find a cheap 2nd hand preamp or build one like the Jfet Boz or a cheap IC based design as a test. Or do Juma's preamp or the BA-3 front end.
On the other hand, you can raise the gain of the F5 by switching the 100hm gain resistors on the F5 to 200 ohm. This will get you more gain.
But if you are looking for a "party" amp both of these amps are probably not it. But it depends on how loud your parties are. With a BA-3 preamp and 90db speakers I listen regularly at about 90-95db. That's plenty loud for me.
I have no experience with gainclones. But I have a friend who regularly builds gainclones and Pass stuff (and whose personal amp is an F5). When I asked him to describe the differences his response was "The F5 is basically better at everything".
A gain stage that is optional/switchable before the vol pot will give less added noise whenever the vol pot is turned down a bit from maximum.
Always put the majority of the system gain at the beginning of the signal route.
Moving some of the gain towards the end of the route adds noise.
two examples.
A +80db gain stage can be made from two +40dB stages ganged together. This will result in some noise.
Changing that to a +60dB first stage feeding a +20dB second stage almost always ends up with less noise.
A RIAA stage with +50dB of mid frequency gain feeding a vol pot set to maximum into a Power Amplifier with a gain of +34dB will give a certain amount of noise.
Changing the RIAA gain to +60dB and using the same maximum setting vol pot into a +24dB Power Amplifier will usually result in less noise.
Using extra gain that subsequently needs to be reduced at the vol pot is noisier than using a lower gain stage that does not need to be attenuated at the vol pot. In the above scenario is better for noise performance if the excess gain is removed from the speaker end of the reproduction system.
Further, a switchable gain stage that can be set to +0dB, +6dB, +12dB is very useful provided it is always set to the lowest gain that gives adequate volume for that listening session.
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Well, the Gainclone probably has more gain than that, as the voltage was selected to give the maximum output into 6 Ohms.
I don't share the experience that the F5 is better at everything, although theoretically it certainly should be, if conventional wisdom is anything to go by. I built it to be better! I do think that the F5 has some nice qualities, but warmth is not one of them, and I believe warmth is important (to me).
I agree that I need more gain. I was trying to get opinions about the pros and cons of achieving that by:
a) increasing transformer voltage from 18VAC to 24VAC to double gain of F5, 5W resistors and biasing to 1A-ish
b) adding a preamp gain stage to double gain of F5, complete with power supply
c) one you just mentioned that I hadn't considered (simply up-ing gain resistors)
a and b are different approaches, with roughly similar cost (large new transformer vs. fet circuit and small power supply) but in a sense both achieve the same thing. But which is best?
Still looking for anybody that's tried the 22vAC or 24vAC transformer route for "F5 not-quite-turbo"
I was never going to put the preamp gain stage before the pot though, Andrew. I am well aware of the s/n ratio advantage of placing gain stages before the pot, but I think it's all a bit moot. S/N ratio is fairly trivial, beyond a certain level, don't you agree? Increasing F5 rail voltage may add a trivial level of noise to the circuit, but I'd never hear it, and neither would you.
Yes, Pass Aleph p1.7 is another way to go. I would, but can't afford to build it.
Hi,
im the new from the old continent. bought a f7 and then directly a f5 clone from the internet. the f5 got some security relais to protect the speakers but sometimes fail to start. i fixed it. build some tube gear from kits before.
building all kinds of speakers since 25 years...
normally i m listening to a harman kardon citation 1 with a customs made push pull 16 watts 803 tube power amp without any feedback. very sensitive 8" keller bb speakers with flattened impedance and a 40watts pptube subwoofer amp with a damping around 300 in really large 15"horn and tml subs.
a friend of mine knows about tube gear construction. i had no need to get anything else... but that first watt f5 bla bla... took me to invest a few hundred bucks and now... i m infected! so little parts, a open baffle bb with two 15"woofers and there is a lot of the sound of my best equipment! wow!!
i thought feedback kills always open mids and highs but the f5 is really impressive, and the bass is impressive too.
I ll learn about solid state from the most generous source in hifi. its so much fun without deadly voltages.
thank you.
i m wondering if its possible and helpful to have high damping in bass and low in high frequency?
arndt
im the new from the old continent. bought a f7 and then directly a f5 clone from the internet. the f5 got some security relais to protect the speakers but sometimes fail to start. i fixed it. build some tube gear from kits before.
building all kinds of speakers since 25 years...
normally i m listening to a harman kardon citation 1 with a customs made push pull 16 watts 803 tube power amp without any feedback. very sensitive 8" keller bb speakers with flattened impedance and a 40watts pptube subwoofer amp with a damping around 300 in really large 15"horn and tml subs.
a friend of mine knows about tube gear construction. i had no need to get anything else... but that first watt f5 bla bla... took me to invest a few hundred bucks and now... i m infected! so little parts, a open baffle bb with two 15"woofers and there is a lot of the sound of my best equipment! wow!!
i thought feedback kills always open mids and highs but the f5 is really impressive, and the bass is impressive too.
I ll learn about solid state from the most generous source in hifi. its so much fun without deadly voltages.
thank you.
i m wondering if its possible and helpful to have high damping in bass and low in high frequency?
arndt
Hi Arndt,
since lf-drivers are, unlike hf-drivers, used within their resonance-frequency realm where nearly every driver has a hump in its impedance curve, often some amount of feedback is used to compensate the resulting distortion.
in tube amps this is naturally limited (output transformer)
>>https://en.wikipedia.org/wiki/Damping_factor<<
cheers
A.
since lf-drivers are, unlike hf-drivers, used within their resonance-frequency realm where nearly every driver has a hump in its impedance curve, often some amount of feedback is used to compensate the resulting distortion.
in tube amps this is naturally limited (output transformer)
>>https://en.wikipedia.org/wiki/Damping_factor<<
cheers
A.