New output transformers for Quicksilver amplifier

Original Burnedfingers · 12th February 2003, 10:49 AM

Transformer selection help needed.

I am soon to be the owner of another set of mono block Quicksilver amplifiers. I purchased a set of used 8417's that have been converted to use 6550's or KT88's. The problem is that the original output transformers have been replaced with a set of Hammond 1650K's and I would like to find a set of original transformers of a set of "Good" iron to replace them with.
I emailed "Quicksilver" asking to purchase a set of used 8417 transformers or new transformers, my email hasn't been answered. Can any of you suggest a set of worthwile iron that will at least equal the sound of the original set? Any help in this matter will be appreciated.

Joe

fdegrove · 12th February 2003, 02:04 PM

Hi,

Have you asked Mike for a set of KT88 OPTs?
These would be a better fit if you were to use this type of output tube.
Also, it usually helps if you give them a serial # of an existing set of amps.

Cheers,

wheezer · 15th February 2003, 02:36 PM

Hi Joe,
Where do you find these beauties??
Mitch

Original Burnedfingers · 16th February 2003, 02:48 AM

Mitch

Good to hear from you again as its always a pleasure. I snagged them for $500 plus shipping. I thought the price was fair.
I finally got a response from Quicksilver and a quote of 150ea for transformers. I did find out that the 8417's and the KT88 transformers are the same and the impedance is 3900ohms on the primary side. The amps now have Hammond 1650K's on them and I hope thay aren't too butchered to install the OEM transformers back on them. Frank has mentioned in an email his thoughts concerning the stock transformers. He likes the sound of them. It will be interesting to see if the converted 8417's have been changed that much from stock. The heck of it is that I have enough GE 8417's to retube both chassis and still have spares. They do have new 6550's on them and I have been wanting to try them and check out the differences between them and the KT88's. The pictures of the chassis that I have seem to show that only 1/2 of the front end tubes are used. These amps also have the plug in SS rectifiers and the GZ34 tubes so I can pull and listen for the differences. This will either turn out to be a good purchase or I will end up with them in my garage system. I will no doubt want to change the front end from stock after I listen to them and will await the comments of all that are interested in this Quicky affair. I will post a copy of the schematic for interested parties to enjoy. I for one am amazed with the quality and simplicity of this amplifier. They are a credit to Mike.

Joe

fdegrove · 16th February 2003, 09:53 PM

Hi,

Quote:

I did find out that the 8417's and the KT88 transformers are the same and the impedance is 3900ohms on the primary side.

The schematics I've seen show a primary impedance of 4K2.

3k9 would be O.K though for either the 8417 or KT88.

Joe,I don't want to cause any unconscious prejudice against either type of tube so I just curiously await your final judgement.

Quote:

The pictures of the chassis that I have seem to show that only 1/2 of the front end tubes are used.

And so it is for the ones I've seen.

All in all I don't think these amps are going to see the garage any time soon.

Cheers,

Original Burnedfingers · 19th February 2003, 05:09 PM

I received the amps today and promptly took a look at the guts while looking at the standard 8417 schematic. I found the following changes... the 10K resistor after the diode going to the pot was changed to a 20K. A resistor was added on the other side of the pot to ground. The 220 mfd cap was missing from the wiper to ground. The 12AX7 tube was replaced with a 5751.

I was under the impression that the 150K resistors that connected to the bias pot wiper had to be changed also. My KT88 amps have 100K resistors here.

I will send pictures later. Any help/comments would be appreciated here.

Frank

It has new 6550 WE Sovtek tubes in it!

Joe

wheezer · 19th February 2003, 08:40 PM

Hey Joe,
u certaintly do find some good values! Are they ebay wins?
Keep the posts coming.
Best,
Mitch

Original Burnedfingers · 19th February 2003, 10:47 PM

Mitch

This unit had been on ebay and failed to hit its reserve price. I made an offer after the auction closed and bought it.

fdegrove · 20th February 2003, 02:43 AM

Hi,

Quote:

The 12AX7 tube was replaced with a 5751

These are almost equivalent to the 12AX7 except for a mu of 70 iso 100.
The 5751 should be a fine sounding alternative, low noise too.

Quote:

It has new 6550 WE Sovtek tubes in it!

There you go, already a nice return on your investment.

Quote:

The 220 mfd cap was missing from the wiper to ground

I wonder why.

Cheers,

wheezer · 20th February 2003, 03:06 AM

MAY THE B+ BE WITH YOU

12th February 2003, 10:49 AM	#1
Original Burnedfingers diyAudio Member Join Date: Nov 2002	New output transformers for Quicksilver amplifier Transformer selection help needed. I am soon to be the owner of another set of mono block Quicksilver amplifiers. I purchased a set of used 8417's that have been converted to use 6550's or KT88's. The problem is that the original output transformers have been replaced with a set of Hammond 1650K's and I would like to find a set of original transformers of a set of "Good" iron to replace them with. I emailed "Quicksilver" asking to purchase a set of used 8417 transformers or new transformers, my email hasn't been answered. Can any of you suggest a set of worthwile iron that will at least equal the sound of the original set? Any help in this matter will be appreciated. Joe

12th February 2003, 02:04 PM	#2
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	OPT. Hi, Have you asked Mike for a set of KT88 OPTs? These would be a better fit if you were to use this type of output tube. Also, it usually helps if you give them a serial # of an existing set of amps. Cheers, __________________ Frank

15th February 2003, 02:36 PM	#3
wheezer diyAudio Member Join Date: Dec 2002 Location: Boca Raton, FL.	Yet another pair? Hi Joe, Where do you find these beauties?? Mitch

19th February 2003, 05:09 PM	#6
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Update I received the amps today and promptly took a look at the guts while looking at the standard 8417 schematic. I found the following changes... the 10K resistor after the diode going to the pot was changed to a 20K. A resistor was added on the other side of the pot to ground. The 220 mfd cap was missing from the wiper to ground. The 12AX7 tube was replaced with a 5751. I was under the impression that the 150K resistors that connected to the bias pot wiper had to be changed also. My KT88 amps have 100K resistors here. I will send pictures later. Any help/comments would be appreciated here. Frank It has new 6550 WE Sovtek tubes in it! Joe

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16th February 2003, 02:48 AM	#4
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Mitch Good to hear from you again as its always a pleasure. I snagged them for $500 plus shipping. I thought the price was fair. I finally got a response from Quicksilver and a quote of 150ea for transformers. I did find out that the 8417's and the KT88 transformers are the same and the impedance is 3900ohms on the primary side. The amps now have Hammond 1650K's on them and I hope thay aren't too butchered to install the OEM transformers back on them. Frank has mentioned in an email his thoughts concerning the stock transformers. He likes the sound of them. It will be interesting to see if the converted 8417's have been changed that much from stock. The heck of it is that I have enough GE 8417's to retube both chassis and still have spares. They do have new 6550's on them and I have been wanting to try them and check out the differences between them and the KT88's. The pictures of the chassis that I have seem to show that only 1/2 of the front end tubes are used. These amps also have the plug in SS rectifiers and the GZ34 tubes so I can pull and listen for the differences. This will either turn out to be a good purchase or I will end up with them in my garage system. I will no doubt want to change the front end from stock after I listen to them and will await the comments of all that are interested in this Quicky affair. I will post a copy of the schematic for interested parties to enjoy. I for one am amazed with the quality and simplicity of this amplifier. They are a credit to Mike. Joe

19th February 2003, 08:40 PM	#7
wheezer diyAudio Member Join Date: Dec 2002 Location: Boca Raton, FL.	Hey Joe, u certaintly do find some good values! Are they ebay wins? Keep the posts coming. Best, Mitch

19th February 2003, 10:47 PM	#8
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Mitch This unit had been on ebay and failed to hit its reserve price. I made an offer after the auction closed and bought it.

20th February 2003, 03:06 AM	#10
wheezer diyAudio Member Join Date: Dec 2002 Location: Boca Raton, FL.	MAY THE B+ BE WITH YOU

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