8417
Hi,
Absolutely,the first cap after the rectifier had a value of more than three times the recommend max. value.
I.e. 330microF iso 100.
An other problem with the 8417 was that the bias was nearly impossible to set correctly with some brands of tubes.
I wouldn't be bothered with the 8417s any more...they were already hard to get 10 years ago and the odds are against it ever being manufactured again.
In fact I think they were actually manufacturered for the Fisher company.
Luxman used them in an amp as well but that's about all I can think of .
Cheers,
Hi,
Absolutely,the first cap after the rectifier had a value of more than three times the recommend max. value.
I.e. 330microF iso 100.
An other problem with the 8417 was that the bias was nearly impossible to set correctly with some brands of tubes.
I wouldn't be bothered with the 8417s any more...they were already hard to get 10 years ago and the odds are against it ever being manufactured again.
In fact I think they were actually manufacturered for the Fisher company.
Luxman used them in an amp as well but that's about all I can think of .
Cheers,
hello folks
how do you like my QS8417? It was made in 1982 and I bought it as 2nd hand in 1988. Rplace the caps with Sprague (the old Rubycon was leaking) and RelCap and resistors with Halco, plug with WBT, get 2 pairs of new 8417 from QS. But the good old sweet slow warm sound is then gone, come the more tight transparent new sound...
The GV378 was bought from Triode Electronics in 1989...the price was reasonable then so I bought 4 pairs...you can see that the first bypass cap value was increased, and it caused some firework inside the poor old 5AR4, so far so good with the GV378
A few years later when the 8417 need to be replaced...maybe mod it for KT88...or how about EL34?
how do you like my QS8417? It was made in 1982 and I bought it as 2nd hand in 1988. Rplace the caps with Sprague (the old Rubycon was leaking) and RelCap and resistors with Halco, plug with WBT, get 2 pairs of new 8417 from QS. But the good old sweet slow warm sound is then gone, come the more tight transparent new sound...
The GV378 was bought from Triode Electronics in 1989...the price was reasonable then so I bought 4 pairs...you can see that the first bypass cap value was increased, and it caused some firework inside the poor old 5AR4, so far so good with the GV378
A few years later when the 8417 need to be replaced...maybe mod it for KT88...or how about EL34?
Attachments
LOOKS GOOD TO ME.
Hi,
The 8417 is long gone now and you may have to consider the alternate roads :KT88,KT90 or EL34.
All will reduce the power output a bit but I doubt you'll notice it.
The fat bulb EL34/6CA7 really sounds great with this amp.
Your rectifiers are actually GZ37s AKA CV378 (British military designator).
Why people insist on putting such high capacitance behind these rectifiers is beyond me...according to my datasheets the GZ34/5AR4 take 100 microF per tube and the GZ37 4 microF.
Something must be asking for trouble....
It wouldn't be missed by me but "de gustibus et coloribus non discutandum est".
Cheers,
Hi,
The 8417 is long gone now and you may have to consider the alternate roads :KT88,KT90 or EL34.
All will reduce the power output a bit but I doubt you'll notice it.
The fat bulb EL34/6CA7 really sounds great with this amp.
Your rectifiers are actually GZ37s AKA CV378 (British military designator).
Why people insist on putting such high capacitance behind these rectifiers is beyond me...according to my datasheets the GZ34/5AR4 take 100 microF per tube and the GZ37 4 microF.
Something must be asking for trouble....
It wouldn't be missed by me but "de gustibus et coloribus non discutandum est".
Cheers,
Hi Joe,
I think it's best that Mike Sanders does the upgrade for you, then you can choose your poison as Frank indicated, E34l's, 6550, KT's.
I suggest you rhetorically describe exactly what is under the hood, and we put it back or as close to -- stock as possible.
Mike has told me of several BAST***ized amps that he refused to work on and sent them back. Fret not , as yours is not there *YET*!
As for toooo much uf - yes it will make the bass loose and sloppy
I've tried many combo's and now have one 750 +47 feeding both rails. I believe Mike is also now using just one supply cap.
The results of too much uf--- Kinda like a HUGE HOLLEY on a small 4cylinder!
I wish I had tried the original twin 300's in parallel feeding both rails. 1/2 the ESR which makes a huge difference.
BTW lots have gotten excellent results from swapping the lytic for a.UNLYTIC.
UNLYTIC
Regards,
Mitch
I think it's best that Mike Sanders does the upgrade for you, then you can choose your poison as Frank indicated, E34l's, 6550, KT's.
I suggest you rhetorically describe exactly what is under the hood, and we put it back or as close to -- stock as possible.
Mike has told me of several BAST***ized amps that he refused to work on and sent them back. Fret not , as yours is not there *YET*!
As for toooo much uf - yes it will make the bass loose and sloppy
I've tried many combo's and now have one 750 +47 feeding both rails. I believe Mike is also now using just one supply cap.
The results of too much uf--- Kinda like a HUGE HOLLEY on a small 4cylinder!
I wish I had tried the original twin 300's in parallel feeding both rails. 1/2 the ESR which makes a huge difference.
BTW lots have gotten excellent results from swapping the lytic for a.UNLYTIC.
UNLYTIC
Regards,
Mitch
Hi Mitch
I posted earlier that there was a pair of 8417's on ebay for sale. The buy it now price on them is $900 I believe. I think they were version 2's also. I thought about purchasing them but the price is higher than I think they are worth.
soil
Its nice to hear from another Quickey owner. If you read this topic from the beginning there is information on converting the 8417 to use the other tubes. My KT-88 has seen much modification and currently posesses a 850 and a 300 in the power supply section. The mod makes you wallow in the bass as Frank puts it. It also has diode modification which takes the strain of the 5AR4 tubes.
Frank
Waiting for your analytical evaluation of the bas****ization of my KT-88 amps. You are no doubt responsible for prodding me to draw out the schematic of my modified KT88's a fate worse then death for me as I just hate to draw schematics. I did try to draw it in MS paint but my hand is too shakey so handcad will have to do.
Now if someone could just come up with a stock schematic for a KT-88 amp it would really make my day.
Joe
I posted earlier that there was a pair of 8417's on ebay for sale. The buy it now price on them is $900 I believe. I think they were version 2's also. I thought about purchasing them but the price is higher than I think they are worth.
soil
Its nice to hear from another Quickey owner. If you read this topic from the beginning there is information on converting the 8417 to use the other tubes. My KT-88 has seen much modification and currently posesses a 850 and a 300 in the power supply section. The mod makes you wallow in the bass as Frank puts it. It also has diode modification which takes the strain of the 5AR4 tubes.
Frank
Waiting for your analytical evaluation of the bas****ization of my KT-88 amps. You are no doubt responsible for prodding me to draw out the schematic of my modified KT88's a fate worse then death for me as I just hate to draw schematics. I did try to draw it in MS paint but my hand is too shakey so handcad will have to do.
Now if someone could just come up with a stock schematic for a KT-88 amp it would really make my day.
Joe
MODSQUAD QUICKIES.
Hi Joe,
Sorry to keep you waiting...
How can I comment on the mods if there's no way for me to tell what is stock and what not?
Sorry to make you sweat.
It is OK in its' current form and I don't see any mistakes,so you did a good job.
Once you get the hang of it it is no big deal really.
You know my point of view on the PSU caps already and the UNLYTIC seem a very promising upgrade.
Unfortunately I wouldn't know where to get them,you might stand a better chance in the USA.
Cheers,
Hi Joe,
Sorry to keep you waiting...
How can I comment on the mods if there's no way for me to tell what is stock and what not?
Sorry to make you sweat.
It is OK in its' current form and I don't see any mistakes,so you did a good job.
Once you get the hang of it it is no big deal really.
You know my point of view on the PSU caps already and the UNLYTIC seem a very promising upgrade.
Unfortunately I wouldn't know where to get them,you might stand a better chance in the USA.
Cheers,
Hi Frank,
If you have an LCR, you'd be shocked , or even an accruate DMM.
I have a handheld B&K that's deadly accurate, not very expensive but invaluable for OUR kinda lunacy.
Brett and Frank,
The UNLYTIC are a fine quality metallized PP. Designed for retro of the typical electrolytic. They can be purchased not from Percy, but directly from the source. Click the link and hit HOME. They sell direct..
THEY ARE NOT SMALL!!!!! check the diameter as they are not a R&R directly.
As for PSU caps, Brett, what exactly are you looking for. Hold off a bit and lets talk. DON'T EVEN THINK OF SOLEN!!!
One of my unfortunate hobbies is a collection of boutique caps. Don't waste your money as I have. As in tubes, there are sleepers..... same is true for caps. Been there and paid for that. ALLOT $$$
Regards,
Mitch
If you have an LCR, you'd be shocked , or even an accruate DMM.
I have a handheld B&K that's deadly accurate, not very expensive but invaluable for OUR kinda lunacy.
Brett and Frank,
The UNLYTIC are a fine quality metallized PP. Designed for retro of the typical electrolytic. They can be purchased not from Percy, but directly from the source. Click the link and hit HOME. They sell direct..
THEY ARE NOT SMALL!!!!! check the diameter as they are not a R&R directly.
As for PSU caps, Brett, what exactly are you looking for. Hold off a bit and lets talk. DON'T EVEN THINK OF SOLEN!!!
One of my unfortunate hobbies is a collection of boutique caps. Don't waste your money as I have. As in tubes, there are sleepers..... same is true for caps. Been there and paid for that. ALLOT $$$
Regards,
Mitch
Hola Mitch,wheezer said:
I need about 6 100u caps for a 900Vdc PSU, so 1200-1500V is the rating I need. I also need another 6 or so of a similar (or larger) value for my preamp, at 400-500V.
For the big ones, I've been looking at the Italian Digitex 80u/1500V, and was going to try some of their lower voltage rated ones as well.
I had a box of 16 80u/500Vac oilers go missing in transit recently or I'd be all set.
So, what do you suggest?
Cheers
Hi Brett,
Sorry I cannot help you on those HIGH voltages 1200VDC? What kinda DMM you using? I Hope you have one hand in your pocket, when fiddlin' under THAT hood!
Same for the 4-500, the uf is too high for anything other than a lytic, that I would have access to. THe largest in 4-5oo is10uf in metallized polyprop.
Again I'd say check into the UNLYTIC for those ranges, I think the U31 will fit your needs.
What pre-amp you running?
Regards,
Mitch
Sorry I cannot help you on those HIGH voltages 1200VDC? What kinda DMM you using? I Hope you have one hand in your pocket, when fiddlin' under THAT hood!
Same for the 4-500, the uf is too high for anything other than a lytic, that I would have access to. THe largest in 4-5oo is10uf in metallized polyprop.
Again I'd say check into the UNLYTIC for those ranges, I think the U31 will fit your needs.
What pre-amp you running?
Regards,
Mitch
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