Re: speaker efficiency...is it critical?
I think you need another 10 to 15dB of SPL to get this sounding good. i.e. 81dB/W/m can use around 250W of power rather than 25W of Power to match a 91dB set of speakers running on 25W. But personally, I aim for 100 to 200W into 91dB speakers.sonidos said:They were rated at 84 dB/W/m at nominal 4 ohm impedance. This doesn't sound like a whole lotta efficiency.
The F5 sounds tantalizing to build, but will my Spicas sound pfffft with the F5 powering them?
No go with Spica TC-50
Holy Guacamole! Thanks guys for setting me straight!
Can you believe I bought the Spicas with an Adcom GFA-535 amp? I was a young pup at the time and the dealer said both were highly rated as great value and they would work great together. Now you have me wondering what I've missed all these years by driving them with that amount of wattage.
It seems that if I want to play in this game with Nelson's amps, I have to look for more efficient speakers. I already looked at the Lowther web page and their associated lower cost speakers. Seems like these would work MUCH better than what I've got.
Holy Guacamole! Thanks guys for setting me straight!
Can you believe I bought the Spicas with an Adcom GFA-535 amp? I was a young pup at the time and the dealer said both were highly rated as great value and they would work great together. Now you have me wondering what I've missed all these years by driving them with that amount of wattage.
It seems that if I want to play in this game with Nelson's amps, I have to look for more efficient speakers. I already looked at the Lowther web page and their associated lower cost speakers. Seems like these would work MUCH better than what I've got.
Re: No go with Spica TC-50
Have you been able to play loud enough with that combination? If so, then I guess you haven't missed all that much. I would suggest that you build yourself a nice pass amp and see if it plays loud enough right before it starts clipping. If not, replace your speakers.
I have been using normal two way speakers together with my firswatt amps with no problem at all - in my opinion, you don't need to get all too jazzed up about getting some extreme speakers unless thats your ultimate dream.
sonidos said:
Holy Guacamole! Thanks guys for setting me straight!
Can you believe I bought the Spicas with an Adcom GFA-535 amp? I was a young pup at the time and the dealer said both were highly rated as great value and they would work great together. Now you have me wondering what I've missed all these years by driving them with that amount of wattage.
It seems that if I want to play in this game with Nelson's amps, I have to look for more efficient speakers. I already looked at the Lowther web page and their associated lower cost speakers. Seems like these would work MUCH better than what I've got.
Have you been able to play loud enough with that combination? If so, then I guess you haven't missed all that much. I would suggest that you build yourself a nice pass amp and see if it plays loud enough right before it starts clipping. If not, replace your speakers.
I have been using normal two way speakers together with my firswatt amps with no problem at all - in my opinion, you don't need to get all too jazzed up about getting some extreme speakers unless thats your ultimate dream.
cviller:
As you probably know, I've been weighing to join the group buy.
Yes, it's been loud enough because i have a living room that is 16 x 20 ft. and with kids and wife, I don't listen at levels so that I feel like I'm on row 3 at a Led Zep concert.
I'm running Corey Greenberg's buffered passive preamp and setting the volume at 1 o'clock gives me plenty of volume.
I've done some checking this morning and if I decide to retire the Spicas to another room, a set of efficient speakers is not all that much dinero. PSB speakers seem to run about 90 db efficiency and are extremely affordable and well reviewed.
jackinnj - yep...I've gotten the message that something bigger than a TO220 heatsink is the law. I don't know how I'll sneak them into the house without the wife noticing.
As you probably know, I've been weighing to join the group buy.
Yes, it's been loud enough because i have a living room that is 16 x 20 ft. and with kids and wife, I don't listen at levels so that I feel like I'm on row 3 at a Led Zep concert.
I'm running Corey Greenberg's buffered passive preamp and setting the volume at 1 o'clock gives me plenty of volume.
I've done some checking this morning and if I decide to retire the Spicas to another room, a set of efficient speakers is not all that much dinero. PSB speakers seem to run about 90 db efficiency and are extremely affordable and well reviewed.
jackinnj - yep...I've gotten the message that something bigger than a TO220 heatsink is the law. I don't know how I'll sneak them into the house without the wife noticing.
sonidos said:
jackinnj - yep...I've gotten the message that something bigger than a TO220 heatsink is the law. I don't know how I'll sneak them into the house without the wife noticing.
Here's what I do: Sneak them in under the cover of darkness...and
if she does find them, simply insist they've been there
all along.
Choky,
Maybe with Serbian wife. My wife is Peruvian. I thought with the help of some of our Swedish posters that I can convince her that this is an IKEA portable heater for the room. (ok...maybe not so portable)
For summer in Texas, we'll just run a chip amp instead.
I'll have to budget for heatsinks so I'll have to wait for a GB so it is not cost prohibitive.
For my Christmas present, I want pcb's from the group buy.
Maybe with Serbian wife. My wife is Peruvian. I thought with the help of some of our Swedish posters that I can convince her that this is an IKEA portable heater for the room.
(ok...maybe not so portable)For summer in Texas, we'll just run a chip amp instead.
I'll have to budget for heatsinks so I'll have to wait for a GB so it is not cost prohibitive.
For my Christmas present, I want pcb's from the group buy.
Re: No go with Spica TC-50
I agree with cviller. I don't think you have to go to the extreme to get good sound. I used to run my Wavelength Cardinal 8 watt SET amps with Proac Response 2 and they weren't bad. I believe those were 88db sensitivity.
I think the F5 was designed to work well into low inpedence loads and have a reasonably good damping factor so it would sound good with some average middle of the road speakers.
sonidos said:
Holy Guacamole! Thanks guys for setting me straight!
Can you believe I bought the Spicas with an Adcom GFA-535 amp? I was a young pup at the time and the dealer said both were highly rated as great value and they would work great together. Now you have me wondering what I've missed all these years by driving them with that amount of wattage.
It seems that if I want to play in this game with Nelson's amps, I have to look for more efficient speakers. I already looked at the Lowther web page and their associated lower cost speakers. Seems like these would work MUCH better than what I've got.
I agree with cviller. I don't think you have to go to the extreme to get good sound. I used to run my Wavelength Cardinal 8 watt SET amps with Proac Response 2 and they weren't bad. I believe those were 88db sensitivity.
I think the F5 was designed to work well into low inpedence loads and have a reasonably good damping factor so it would sound good with some average middle of the road speakers.
Hi there, I've signed up for the group buy, but I would also like to do it balanced, would it be possible using 2 amp boards for channel?... I am almost finishing an "old" x-css-bosoz, so I really would like to try this one (F5) balanced version!!!
I would like also to say thank you to Mr. Pass for his wonderful sharing attitude towards his designs and the invaluable help that diyAudio has been until now!
regards from Portugal,
CarcasS
I would like also to say thank you to Mr. Pass for his wonderful sharing attitude towards his designs and the invaluable help that diyAudio has been until now!
regards from Portugal,
CarcasS
The F4 does not have NFB, it needs a number of parallel output devices to obtain a sufficiently low output impedance.
The F5 has gain, the F4 has not.
The current that charges/discharges the gates of the F5 output stage has to go through the JFETs, which is not a lot.
In the F4, discharging of the gate capacitance is handled by the TL431.
Also notice that the N- and P-devices have swapped position, which makes a difference.
The F5 has gain, the F4 has not.
The current that charges/discharges the gates of the F5 output stage has to go through the JFETs, which is not a lot.
In the F4, discharging of the gate capacitance is handled by the TL431.
Also notice that the N- and P-devices have swapped position, which makes a difference.
I think it is a very valid question. From my perspective, having a single FET instead of, say 3 as in the F4, increases the risk of a catastrophic failure with the output swinging to full rail voltage. Depending on the speakers this could be very costly. I see there is a kind of current limiting in the F5 (?) but I believe it does not completely shut down the circuit.