I tried to use some Hammond 150H plate chokes in place of the 10K plate resistors. The Hammonds are 3700ohms in resistance and 8mA.
When I fired up the line amp the 5687 was microphonic and ringing. I then returned to the 10K plate resistors and everything was fine once again.
I will attach the schematic. Other modifications to the circuit include the usage of a VR150 and VR90 regulator tubes for a final B+ before the plate resistors of 240volts.
Joe
When I fired up the line amp the 5687 was microphonic and ringing. I then returned to the 10K plate resistors and everything was fine once again.
I will attach the schematic. Other modifications to the circuit include the usage of a VR150 and VR90 regulator tubes for a final B+ before the plate resistors of 240volts.
Joe
Attachments
Frank
Someone had posted before that these chokes were the way to go and they were only $8.00 a pop. I guess that all that glitters isn't gold. Is it possible that they need to be used so that the correct load is put on the plates?
Could you explain the ringing and why it happened? I was under the assumption that the choke would present a load the plate would like better than the resistor.
Could you suggest a choke that would work or am I barking up the wrong tree?
Joe
Someone had posted before that these chokes were the way to go and they were only $8.00 a pop. I guess that all that glitters isn't gold. Is it possible that they need to be used so that the correct load is put on the plates?
Could you explain the ringing and why it happened? I was under the assumption that the choke would present a load the plate would like better than the resistor.
Could you suggest a choke that would work or am I barking up the wrong tree?
Joe
Hi,
You experienced it so you should know by now...
If you read my mail carefully you should notice my warning in that the chokes are non-linear resistances to the plate...
The chokes you put in there are PS chokes, NOT meant for this service as you found out the hard way.
The ringing can come from a number of factors, in this case you have created a resonant tank that's hard to tame.
As I said before, those chokes weren't meant for this service.
No, you're not. Just make sure you understand what it is you're doing...don't expect to learn all this in a few months.
Take your time and try to understand that there's no need to jump a learning process.
Joe, if we're going to be just a bit smart, instead of use a plate choke, why not use a SE xformer and be done with it?
Cheers,
You experienced it so you should know by now...
If you read my mail carefully you should notice my warning in that the chokes are non-linear resistances to the plate...
The chokes you put in there are PS chokes, NOT meant for this service as you found out the hard way.
The ringing can come from a number of factors, in this case you have created a resonant tank that's hard to tame.
As I said before, those chokes weren't meant for this service.
No, you're not. Just make sure you understand what it is you're doing...don't expect to learn all this in a few months.
Take your time and try to understand that there's no need to jump a learning process.
Joe, if we're going to be just a bit smart, instead of use a plate choke, why not use a SE xformer and be done with it?
Cheers,
analog_sa and Frank
Would you say that the LL1668 would work for this line amp or is there something better out there? I have found them listed for $72.00 ea at K&K Audio in NC.
The ringing was like having a mic input turned up all the way and being a foot away from the speaker.
I do believe I have proved the $8.00 choke doesn't work.
Joe
Would you say that the LL1668 would work for this line amp or is there something better out there? I have found them listed for $72.00 ea at K&K Audio in NC.
The ringing was like having a mic input turned up all the way and being a foot away from the speaker.
I do believe I have proved the $8.00 choke doesn't work.
Joe
Joe
I can't quite see what is your PS voltage but you certainly realise that with a plate choke the PS should be lowered. If you simply replace the plate resistor with a choke your plate voltage will certainly raise. As much as i don't advocate the use of PS chokes as plate loads there is no way i can guarantee that the strange sounds you hear are entirely due to the choke. In any case you would hardly regret buying the Lundahls - they make great loads in line and also driver stages. I keep having doubts if i really like the sound of interstage transformers in driver configurations, but the chokes categorically sound good. They may not provide the smoothest possible tonal balance but the improvements in dynamics and rhythm over resistors are well worth the price. Can you do better than Lundahl? No doubt, but the prices of the better stuff are obscene.
cheers
peter
I can't quite see what is your PS voltage but you certainly realise that with a plate choke the PS should be lowered. If you simply replace the plate resistor with a choke your plate voltage will certainly raise. As much as i don't advocate the use of PS chokes as plate loads there is no way i can guarantee that the strange sounds you hear are entirely due to the choke. In any case you would hardly regret buying the Lundahls - they make great loads in line and also driver stages. I keep having doubts if i really like the sound of interstage transformers in driver configurations, but the chokes categorically sound good. They may not provide the smoothest possible tonal balance but the improvements in dynamics and rhythm over resistors are well worth the price. Can you do better than Lundahl? No doubt, but the prices of the better stuff are obscene.
cheers
peter
Hi,
An SE OPT for the 5687 would work as well and would do away with the coupling cap.
This may not be the cheapest solution, maybe not even the best sounding.
As Peter suggested the Lundahl choke should be fine but the PSU voltage should be lowered as the voltage drop of the choke is much smaller than the plate resistor.
There is an advantage here as you could then use a tubed regulator to drop the voltage.
An example:
Cheers,
An SE OPT for the 5687 would work as well and would do away with the coupling cap.
This may not be the cheapest solution, maybe not even the best sounding.
As Peter suggested the Lundahl choke should be fine but the PSU voltage should be lowered as the voltage drop of the choke is much smaller than the plate resistor.
There is an advantage here as you could then use a tubed regulator to drop the voltage.
An example:
Cheers,
Attachments
Hey-Hey!!!,
WIth this schematic that Frank has drawn, you should be able to get away with B+ from 150( a single VR150 ) to 220( maybe three VR75). If yo put in two VR sockets you can do a bit of mix an match to get just the op point you want. I did jsut this for my linestage and now have three 0C3 for a bit over 310 volts.
regards,
Douglas
WIth this schematic that Frank has drawn, you should be able to get away with B+ from 150( a single VR150 ) to 220( maybe three VR75). If yo put in two VR sockets you can do a bit of mix an match to get just the op point you want. I did jsut this for my linestage and now have three 0C3 for a bit over 310 volts.
regards,
Douglas
Frank, This looks allmost like the line-amp i am using which did win a contest in the Japanese MJ magazine. Only 390 Ohm is 300 ohm and 100 mf is 220 Mf. Sounds very good but the Tango permalloy output is a lot more expensive then a power supply choke! Ed
P.s. Frank you surely remember the thread about the tension on the chassis. The 220 volt outlet will show a light on both sides so something is not 100 % in the very old electrical system.
P.s. Frank you surely remember the thread about the tension on the chassis. The 220 volt outlet will show a light on both sides so something is not 100 % in the very old electrical system.
Hi,
Hmmm, I had no idea.
Actually the xformer I had in mind for this cicrcuit is a Bartolucci type D.
BARTOLUCCI.
No idea about the price but expect something around 125 Euro/ea.
A good audio choke probably costs just as much and you still have to capcouple the output at the higher Zo anode side...
Probably 115-0-115?
That still doesn't explain the leakage current on the chassis the amp though.
Cheers,
Hmmm, I had no idea.
Actually the xformer I had in mind for this cicrcuit is a Bartolucci type D.
BARTOLUCCI.
No idea about the price but expect something around 125 Euro/ea.
A good audio choke probably costs just as much and you still have to capcouple the output at the higher Zo anode side...
Probably 115-0-115?
That still doesn't explain the leakage current on the chassis the amp though.
Cheers,
Hi,
As has been suggested before, the Hammond chokes weren't meant for this kind of service but...if the B+ is lowered then it would take more current through it.
This should lessen the ringing as the circuit draws 8ma already which is these chokes practical limit.
May be worth to try out?
Cheers,
As has been suggested before, the Hammond chokes weren't meant for this kind of service but...if the B+ is lowered then it would take more current through it.
This should lessen the ringing as the circuit draws 8ma already which is these chokes practical limit.
May be worth to try out?
Cheers,
analog_sa
Yes I did check the voltages and did see that with the choke I had a higher plate voltage. I did some swapping of the VR tubes(a 90 and a 75) and I ended up real close to what I had with the plate resistors. I believe I was around 140-144 on the plate with the VR150 and VR90. I think I ended up with around 130 something for the choke test. I was trying to come as close as I could.
Frank
Which way do I go now? Do I pop for some Bartolucci (D) transformers or some Lundahl LL1668 chokes?
Bandersnatch and Frank
I have set the chassis up for two VR tubes and I have enough of them to give me different combinations of voltage. The question is do I complicate things a little more and add another set of VR tubes so that each channel has its own regulated supply? Or...do I go one step further and have a separate transformers and such for each channel?
Who sells Bartolucci in the US.?
Joe
Yes I did check the voltages and did see that with the choke I had a higher plate voltage. I did some swapping of the VR tubes(a 90 and a 75) and I ended up real close to what I had with the plate resistors. I believe I was around 140-144 on the plate with the VR150 and VR90. I think I ended up with around 130 something for the choke test. I was trying to come as close as I could.
Frank
Which way do I go now? Do I pop for some Bartolucci (D) transformers or some Lundahl LL1668 chokes?
Bandersnatch and Frank
I have set the chassis up for two VR tubes and I have enough of them to give me different combinations of voltage. The question is do I complicate things a little more and add another set of VR tubes so that each channel has its own regulated supply? Or...do I go one step further and have a separate transformers and such for each channel?
Who sells Bartolucci in the US.?
Joe
Hi,
I'd go with the Bartolucci with my eyes closed, it offers nothing but advantages.
They don't have a distributor in the U.S. but don't let that stop you.
If it were me I'd use a dual mono PSU with not just VR tubes but a fully regulated supply per channel.
I wouldn't use a volpot either, a switched attenuator will always be better...then again not all atenuators do sound alike...
There's just no end to it, is there?
Cheers,
I'd go with the Bartolucci with my eyes closed, it offers nothing but advantages.
They don't have a distributor in the U.S. but don't let that stop you.
If it were me I'd use a dual mono PSU with not just VR tubes but a fully regulated supply per channel.
I wouldn't use a volpot either, a switched attenuator will always be better...then again not all atenuators do sound alike...
There's just no end to it, is there?
Cheers,
I don't know how to fix your ringing. But, regarding the insinuation that you were stupid to try Hammond PS chokes in another application, I have to rise to that bait. I've used Hammond and Magnetek PS filter chokes to load the plate of 2A3s and it sounded great. Hundreds of other tube addicts agree with me (all the Bottlehead Paramour owners out there). Yes, you get better sound if you spend more on chokes specifically designed for the intended duty, but you don't necessarily get crap if you use a PS choke sometimes.
Hi,
The operative word here is "sometimes".
Sure, we can make this choke work...under the current circumstances it won't.
It's not that hard to figure out why either...
And you never wondered what it could sound like with proper audio chokes?
These won't come cheap. Which is why I suggested the OPT as a better alternative; it does away with the cap and solves Zo problems, all in one go.
Cheers,
The operative word here is "sometimes".
Sure, we can make this choke work...under the current circumstances it won't.
It's not that hard to figure out why either...
And you never wondered what it could sound like with proper audio chokes?
These won't come cheap. Which is why I suggested the OPT as a better alternative; it does away with the cap and solves Zo problems, all in one go.
Cheers,
J Basham
Quote
I don't know how to fix your ringing. But, regarding the insinuation that you were stupid to try Hammond PS chokes in another application, I have to rise to that bait.
J
First of all I wasn't trying to bait anyone. I set up a test situation where the plate voltage and the current draw were within reasonable bounds. Unfortunately the PS choke didn't work in this situation. I was told by one of the most competent members of this board that the usage of this choke probably wouldn't provide the best results. I had my doubts so I tried the choke and posted of my results. Now, if you built this preamp and used this choke with remarkable results then I would surely be interested in all your findings, diagrams, and little tricks to make it work.
Until then my opinion will most certainly remain unchanged.
I have not had personal experience with the Bottlehead. I am under the impression from what I have read that it is a borderline entry level kit. Most people seem to be content with its sonic value and I'm sure it has made its company a great deal of money. If I had wanted to jump on the bandwagon I probably would also have purchased this kit.
However, I have always been more content with something a little different from what most people have. In this case it will end up to be a 5687 line amp with dual regulated supplies and Bartolucci transformers(if they ever answer my email requesting price and delivery).
To imply that I have evidently done something incorrectly kind of irritates me. First of all let us compare apples to apples. You build the same circuit I built and make it work correctly with this cheap $10.00 PS choke. Then you can tell me I am wrong.
Joe
Quote
I don't know how to fix your ringing. But, regarding the insinuation that you were stupid to try Hammond PS chokes in another application, I have to rise to that bait.
J
First of all I wasn't trying to bait anyone. I set up a test situation where the plate voltage and the current draw were within reasonable bounds. Unfortunately the PS choke didn't work in this situation. I was told by one of the most competent members of this board that the usage of this choke probably wouldn't provide the best results. I had my doubts so I tried the choke and posted of my results. Now, if you built this preamp and used this choke with remarkable results then I would surely be interested in all your findings, diagrams, and little tricks to make it work.
Until then my opinion will most certainly remain unchanged.
I have not had personal experience with the Bottlehead. I am under the impression from what I have read that it is a borderline entry level kit. Most people seem to be content with its sonic value and I'm sure it has made its company a great deal of money. If I had wanted to jump on the bandwagon I probably would also have purchased this kit.
However, I have always been more content with something a little different from what most people have. In this case it will end up to be a 5687 line amp with dual regulated supplies and Bartolucci transformers(if they ever answer my email requesting price and delivery).
To imply that I have evidently done something incorrectly kind of irritates me. First of all let us compare apples to apples. You build the same circuit I built and make it work correctly with this cheap $10.00 PS choke. Then you can tell me I am wrong.
Joe
Hey-Hey!!!,
There is a distince polarity regarding chokes, especially ones wound in a single coil. You want to have the end of the coil that was wound against the core to B+, and the end of the coil which has signal to it be the last turns wound. This for plate chokes anyway, I think it makes less diff for PS chokes.
I just wound some center tapped chokes for loading a PP driver stage, similar circuit to one of Brook's. It was wound pie style with each half in a partition on the bobbin form and had in the first version one AC end up against the core. I got a distinct improvement when I wound with both halve's center windings at the core and the AC carrying ends at the outside of the bobbin.
Female vocals were lost the schreeeechy tone, silibance I think it is called, with that single change, same amount of Cu and Iron but change the winding geometry and it was a whole different animal. Makse me scared about the stuff involved with the permutations and combinations involved with OPT's
regards,
Douglas
There is a distince polarity regarding chokes, especially ones wound in a single coil. You want to have the end of the coil that was wound against the core to B+, and the end of the coil which has signal to it be the last turns wound. This for plate chokes anyway, I think it makes less diff for PS chokes.
I just wound some center tapped chokes for loading a PP driver stage, similar circuit to one of Brook's. It was wound pie style with each half in a partition on the bobbin form and had in the first version one AC end up against the core. I got a distinct improvement when I wound with both halve's center windings at the core and the AC carrying ends at the outside of the bobbin.
Female vocals were lost the schreeeechy tone, silibance I think it is called, with that single change, same amount of Cu and Iron but change the winding geometry and it was a whole different animal. Makse me scared about the stuff involved with the permutations and combinations involved with OPT's
regards,
Douglas
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