B1 Buffer Preamp - Page 112

Nelson Pass · 9th January 2009, 10:03 PM

I use the AP1 - the later products are too fancy for me, but we have an
AP2 on one of our benches here.

Melon Head · 10th January 2009, 08:32 AM

Hi Nelson
It would be nice if you could let us know if the B1 as per the the original design is predominantly 2nd or 3rd order harmonic distortion.

Nelson Pass · 11th January 2009, 01:38 AM

2nd.

Melon Head · 11th January 2009, 08:40 PM

Thanks Nelson
OK then hopefully I have made a mistake somewhere.
Can someone check the way I have drawn the circuit.
I am a little unsure about the signal ground/return and output ground/return, and the DC power ground/return.
Any help would be most appreciated.
Thanks

JimT · 11th January 2009, 09:23 PM

Quote:

Originally posted by thanh1973
Thanks Nelson
OK then hopefully I have made a mistake somewhere.
Can someone check the way I have drawn the circuit.
I am a little unsure about the signal ground/return and output ground/return, and the DC power ground/return.
Any help would be most appreciated.
Thanks

You do not have things setup completely for an FFT with LT Spice. Try adding the following directives.

.tran 0 30m 0.1u
.step param C list .100u .10100u
.option plotwinsize=0

Test at 1000Hz.

If you want to learn more about LT Spice. Try the forum for it on groups.yahoo.com. I am unable to help you further. I just copied the above from an example I found there. It works for me.

Jim

homemodder · 11th January 2009, 10:27 PM

Just simmed tanh s circuit and indeed it shows that h3 dominates.

Tanh do the sim now at 20Khz and I think youll be even more puzzeled

Nelson Pass · 12th January 2009, 12:16 AM

Whenever spice doesn't match measurement, we look for flaws
in the models first. This would not be the first time that Spice JFET
models have come up a little short.

udailey · 12th January 2009, 12:30 AM

Mr. Pass
I read a post by you that mentioned using the AP1 and some other attenuator after the source and before the amp with a buffer or pre inbetween. I cant for the life of me find it now. You talked about maybe having just a few different resistances to choose from before the buffer/pre and then after it to have, I think, the AP1.
Is this to help 'rectify' any source output/amp input impedance issues or what is the reason?
I think this was with a BOSOZ.
Thanks
Uriah

Zen Mod · 12th January 2009, 12:36 AM

Quote:

Originally posted by udailey
Mr. Pass
I read a post by you that mentioned using the AP1 and some other attenuator after the source and before the amp with a buffer or pre inbetween. I cant for the life of me find it now. You talked about maybe having just a few different resistances to choose from before the buffer/pre and then after it to have, I think, the AP1.
Is this to help 'rectify' any source output/amp input impedance issues or what is the reason?
I think this was with a BOSOZ.
Thanks
Uriah

AP1 is measuring gadget , almost capable of computing 42 .

we don't ( we - spoiled kids ) even need to know exactly what's that beast ..........

anyway - I can just imagine using it as attenuator

udailey · 12th January 2009, 12:38 AM

Ah, I thought it was the Apox-1

Uriah

12th January 2009, 12:30 AM	#1118
udailey Passive Aggressive diyAudio Member Join Date: Mar 2008	Mr. Pass I read a post by you that mentioned using the AP1 and some other attenuator after the source and before the amp with a buffer or pre inbetween. I cant for the life of me find it now. You talked about maybe having just a few different resistances to choose from before the buffer/pre and then after it to have, I think, the AP1. Is this to help 'rectify' any source output/amp input impedance issues or what is the reason? I think this was with a BOSOZ. Thanks Uriah __________________ You can purchase LDRs anytime to build a standard LDR attenuator or to build my new LDR Attenuator "A Lighter Note". Email me. diyldr@gmail.com

12th January 2009, 12:38 AM	#1120
udailey Passive Aggressive diyAudio Member Join Date: Mar 2008	Ah, I thought it was the Apox-1 Uriah __________________ You can purchase LDRs anytime to build a standard LDR attenuator or to build my new LDR Attenuator "A Lighter Note". Email me. diyldr@gmail.com

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9th January 2009, 10:03 PM	#1111
Nelson Pass The one and only Join Date: Mar 2001	I use the AP1 - the later products are too fancy for me, but we have an AP2 on one of our benches here.

10th January 2009, 08:32 AM	#1112
Melon Head Banned Join Date: Nov 2006	Hi Nelson It would be nice if you could let us know if the B1 as per the the original design is predominantly 2nd or 3rd order harmonic distortion.

11th January 2009, 01:38 AM	#1113
Nelson Pass The one and only Join Date: Mar 2001	2nd.

11th January 2009, 10:27 PM	#1116
homemodder Account disabled at member's request Join Date: May 2006	Just simmed tanh s circuit and indeed it shows that h3 dominates. Tanh do the sim now at 20Khz and I think youll be even more puzzeled

12th January 2009, 12:16 AM	#1117
Nelson Pass The one and only Join Date: Mar 2001	Whenever spice doesn't match measurement, we look for flaws in the models first. This would not be the first time that Spice JFET models have come up a little short.