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HellfireStudios

Well-known member
Joined
Oct 17, 2011
Messages
513
Location
The Sunshine State
Hi. I recently purchased a transformer that is 5:1, and, of course, I need a 10:1 for my upcoming projects. I'm also doing a Royer mod LDC and stereo SDC's. Could the 5:1 transformer work in any of these projects? If not, are there any great sounding projects that could use this transformer?

If all else fails, there will be a brand new, never even soldered, Peluso BV11P for sale. Any help would be greatly appreciated. Thanks.
 
The HST-11a (OEM APEX 460 among others) mod I'm doing uses a 5:1 from Dave Thomas. Keeps the cathode follower with 12AY7, coupling cap change, lower B+ and remove caps on the transformer secondary. 

Also, I **think** analags "R8" uses a 5:1 ratio. The G7 may work too, I think it calls for a 6.5:1.

And see the "fun w/ inexpensive mics" threads, maybe it will work with the MXL 9000! (Paralleled triode)
 
:eek: :eek: I tought i was driving nuts but i finally decided to call John Peluso myself and asked him again about the BV11P and said that the BV11P is really 10:1  ;D ;D  i said his first batch long time ago had a tap for 5:1 and 10:1 operation and this is the source of the confusion,

I am really pleased to annonce that your BV11P will be just fine afterall,  Sometime information maybe misleading but the Conversation on the phone with the creator is for sure the right thing, Enjoy!

Cheers,

Dan, 

 
Dan, you've made my bad day much better. I can finally breathe a sigh of relief.
I was about a day from calling him myself. Thanks.
Now that my ducks are in a row, I can get to the build at hand.

-James-
 
Blue Jinn said:
This still doesn't explain the AC voltage differences you measured between the BV11P and the C-2480 though.

This problem is still nagging at me. Even if the Peluso is "over-spec'd" (like 11:1), logic would dictate that the voltage would be lower not higher. I don't think I'll use the Peluso before I perform one last test. I have left over Apex 460 transformers which should be 4:1 or 5:1.  A major volume difference between the Apex and the Peluso used in reverse with a transformerless SM-57 might confirm what John says. Similar output would suggest similar ratios. Is there any potential harm in performing this test?

If it does turn out to be 5:1, would it work in reverse as a step-up transformer upgrade for a Shure SM-57 (similar to the AMI upgrade)? Just grasping at straws here.
 
HellfireStudios said:
Blue Jinn said:
This still doesn't explain the AC voltage differences you measured between the BV11P and the C-2480 though.

This problem is still nagging at me. Even if the Peluso is "over-spec'd" (like 11:1), logic would dictate that the voltage would be lower not higher. I don't think I'll use the Peluso before I perform one last test. I have left over Apex 460 transformers which should be 4:1 or 5:1.  A major volume difference between the Apex and the Peluso used in reverse with a transformerless SM-57 might confirm what John says. Similar output would suggest similar ratios. Is there any potential harm in performing this test?

If it does turn out to be 5:1, would it work in reverse as a step-up transformer upgrade for a Shure SM-57 (similar to the AMI upgrade)? Just grasping at straws here.

John said that the 2480 would be over spec then less voltage  ,  did you measure you AC at 1K , bias the U87 and  just stick the cinemag in and then the peluso and I hope John is right about is own Produt  ;D  maybe it will sound better "different" than with the 2480

PS: i agree with the Math  :)

Lets find out  ;)
 
After my final test, I found that the Apex 460 transformer to be a little bit louder on the SM-57 than the Peluso. If the Peluso were 10:1, it's output should be much higher than the Apex when wired in reverse. The volume differences weren't drastic, but they were discernable. I'd have to say, with my tests (both by voltage and by ear), the chances of that Peluso being 10:1 are slim:none.

As I'm writing this, an idea comes to mind. I'll test all three types of transformers I have (CM-2480, Apex 460 stock, and BV11P). Any and all questions about the true ratio should be answered by a direct comparison to the Cinemag. If I don't get it done tonight, I'll post my findings tommorrow.

-James-
 
HellfireStudios said:
After my final test, I found that the Apex 460 transformer to be a little bit louder on the SM-57 than the Peluso. If the Peluso were 10:1, it's output should be much higher than the Apex when wired in reverse. The volume differences weren't drastic, but they were discernable. I'd have to say, with my tests (both by voltage and by ear), the chances of that Peluso being 10:1 are slim:none.

As I'm writing this, an idea comes to mind. I'll test all three types of transformers I have (CM-2480, Apex 460 stock, and BV11P). Any and all questions about the true ratio should be answered by a direct comparison to the Cinemag. If I don't get it done tonight, I'll post my findings tommorrow.

-James-

Thanks for the input,  for now all i can say i what i am told  :-[

D
 
I just wanted to let anyone know, who may be interested, that I used the test on this page http://www.ehow.com/how_8416227_calculate-step-down-transformer-potential.html to calculate the potential dropped voltage. When I did the real world measurements and the calculated potential drop, they correlated. The Cinemag was right on for a 10:1. The Peluso is only right if a 5:1 ratio is used for calculations. I used the same load and gator clips to keep from touching and distorting any findings.
 
@HellfireStudios Sorry to revive a rather old thread, but I'm trying to determine what the ratio of the stock Apex 460 (HST-11a) transformer.

Fox Audio's cheat sheet has it at 12:1, http://www.foxaudioresearch.ca/Transformer%20Specs%20worksheet%20Sheet1.pdf  but AMI has a "drop in replacement" at 4:1 which seems to be the value you measured.

 
It's most likely 5:1. I haven't tested the stock Apex transformers for myself, but a DMM and a low voltage AC adapter (9-12v is sufficient) is all you need to check out the transformer. Figure out the formula on the webpage in the earlier post with the voltage from the adapter and the expected ratio as the variables. The voltage of the secondaries should be close to the answer from the formula. If not, figure which ratio will give you the correct secondary voltage, and that will tell you the intended ratio of the transformer. I hope that helps.

-James-
 
Coming back to your first question, a 5:1 transformer will work fine in the Royer small diaphragm cathode follower circuit. (I've even used 2:1 trannies with this circuit)

In fact it will work fine in the other Royer circuit too, except that your output impedance will be 4x higher than a 10:1, and about 2 x higher than a 7:1.

So long as you are are running into a preamp that has a reasonably high input impedance then you may not have a problem.

In short, try it and see!
 

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