OPT for EL34

h00hbt · 3rd July 2011, 10:29 AM

Hi all

Im planning my next project and have a spare pair of UL PP OPT´s. Im not sure they could be used for EL34 tubes, or could they?

Here are the spec´s:

NOMINAL POWER rms 40 WATTS
PRIMARY IMPEDANCE 4000 OHMS
SECONDARY IMPEDANCE 4 8 OHMS
PRIMARY INDUCTANCE 35 Hy.
PRIMARY RESISTANCE 60 OHMS
FREQUENCY RESPONSE 3Hz/80K -3db
GRID 40%

Cheers

payitforwardeddie · 3rd July 2011, 11:27 AM

VVT Transfomers Ltd have these.....

VTP13308 range
EL34.
6CA7.
Sub-Woofer.
RMS Power 25 Watts at 3Hz (Three Hertz).
Primary Ra-a 3500 ohms.
UL taps at 43%.
Output 8 ohms.
Optimised for Low Frequency Response.

So yours should be OK. Whether modern EL34's will stand 40 watts output is another matter.

gingertube · 03:57 AM

Specs are absolutely fine for push pull EL34.

That Primary Inductance is a little low so they are best driven from as low a source impedance as possible. That means use them in Triode Mode (around 18 Watts out) or Ultralinear Mode (just under 40W out). They would probably be a bit bass weak in pure Pentode Mode regardless of that -3dB at 3Hz spec. In fact I simply don't believe that spec. unless it is at 1 Watt level and not full output power.

Cheers,
Ian

richwalters · 5th July 2011, 08:19 AM

-3dB 3Hz..... at 25W ? Fantastic sales swallow and this is a "peak" selling spec of just possible with core on verge of saturation and must be a 12kg specimen; Sure way in quoting "optimised for low frequency response" by being reckless with the vacuum impregnation..and ruining the interwinding capacitances.
Your'e not going to find an LS that can shift that amount of LF air in ones pants. Depending on the circuit, all one will hear is alot of intermodulation of the other higher frequency notes that is with the signal, which is very undesirable.
The upper frequency response isn't quoted, that is far more interesting to the actual design of the transformer......esp when has gone to the trouble of paying for alot of weight.

Build the design, but expect a tranny half that size to sound better.

QUOTE; "Whether modern EL34's will stand 40W is another matter" ?

My old Linear Concord (1965 or so) with EL34's gave 50W o/p with 450V B+. Modern ones should easily take this.

richy

Ty_Bower · 5th July 2011, 10:44 AM

Quote:

Originally Posted by richwalters

Your'e not going to find an LS that can shift that amount of LF air in ones pants.

How about Eminent Tech's rotary woofer? Of course, you'd need some pretty large pants...

3rd July 2011, 10:29 AM	#1
h00hbt diyAudio Member Join Date: Jun 2007	OPT for EL34 Hi all Im planning my next project and have a spare pair of UL PP OPT´s. Im not sure they could be used for EL34 tubes, or could they? Here are the spec´s: NOMINAL POWER rms 40 WATTS PRIMARY IMPEDANCE 4000 OHMS SECONDARY IMPEDANCE 4 8 OHMS PRIMARY INDUCTANCE 35 Hy. PRIMARY RESISTANCE 60 OHMS FREQUENCY RESPONSE 3Hz/80K -3db GRID 40% Cheers __________________ /H

5th July 2011, 03:55 AM	#3
gingertube diyAudio Member Join Date: Oct 2004 Location: Adelaide South Oz	Specs are absolutely fine for push pull EL34. That Primary Inductance is a little low so they are best driven from as low a source impedance as possible. That means use them in Triode Mode (around 18 Watts out) or Ultralinear Mode (just under 40W out). They would probably be a bit bass weak in pure Pentode Mode regardless of that -3dB at 3Hz spec. In fact I simply don't believe that spec. unless it is at 1 Watt level and not full output power. Cheers, Ian Last edited by gingertube; 5th July 2011 at 03:57 AM.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Have I fried an OPT?	theskintman	Tubelab	3	10th January 2011 10:09 PM
El34 PP Vs. El34 PSE	alexmoose	Tubes / Valves	47	6th September 2006 05:44 PM
Choosing the best EL34 pp opt	barfind	Tubes / Valves	17	16th September 2005 01:11 AM
FS: PAIR Vintage 50s Gardners EL34 PP OPT Double C-Core	raychak	Swap Meet	2	10th July 2005 06:24 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read

3rd July 2011, 11:27 AM	#2
payitforwardeddie diyAudio Member Join Date: Feb 2011 Location: South Wales, UK	VVT Transfomers Ltd have these..... VTP13308 range EL34. 6CA7. Sub-Woofer. RMS Power 25 Watts at 3Hz (Three Hertz). Primary Ra-a 3500 ohms. UL taps at 43%. Output 8 ohms. Optimised for Low Frequency Response. So yours should be OK. Whether modern EL34's will stand 40 watts output is another matter.

5th July 2011, 08:19 AM	#4
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	-3dB 3Hz..... at 25W ? Fantastic sales swallow and this is a "peak" selling spec of just possible with core on verge of saturation and must be a 12kg specimen; Sure way in quoting "optimised for low frequency response" by being reckless with the vacuum impregnation..and ruining the interwinding capacitances. Your'e not going to find an LS that can shift that amount of LF air in ones pants. Depending on the circuit, all one will hear is alot of intermodulation of the other higher frequency notes that is with the signal, which is very undesirable. The upper frequency response isn't quoted, that is far more interesting to the actual design of the transformer......esp when has gone to the trouble of paying for alot of weight. Build the design, but expect a tranny half that size to sound better. QUOTE; "Whether modern EL34's will stand 40W is another matter" ? My old Linear Concord (1965 or so) with EL34's gave 50W o/p with 450V B+. Modern ones should easily take this. richy

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)