Output Transformer Frequency Response

[Tweedguy]

My Fender 5E8-A has a Heyboer Output Transformer that has great midrange detail, but I think it's lacking in the lower frequency range. After trying for a year to figure out why my amp lacked lower frequency response, I was told that Heyboer OT's don't have good low end. I heard 30Hz-30kHz is standard for guitar.

Does anyone know about Fender replacement Heyboer OT's frequency range?

Also, does anyone know another quality manufacturer of Fender replacement OT's that have a full spectrum?

Thanks

[CaseyJones]

My Fender 5E8-A has a Heyboer Output Transformer that has great midrange detail, but I think it's lacking in the lower frequency range. After trying for a year to figure out why my amp lacked lower frequency response, I was told that Heyboer OT's don't have good low end. I heard 30Hz-30kHz is standard for guitar.

Does anyone know about Fender replacement Heyboer OT's frequency range?

Also, does anyone know another quality manufacturer of Fender replacement OT's that have a full spectrum?

Thanks

The lowest note on a guitar is 80hz so unless you're tuned down or playin' a 7 string you're pissin' in the wind with anything that goes down to 30hz. Further, yer typical guitar speaker setup starts droppin' like a rock below around 100hz. It doesn't matter what yer OT does if yer speakers won't go there.

However if you really must have that low frequency response from the OT look up semi-audiophile transformers such as replacements for Dynaco.

http://store.triodestore.com/dytr.html

Expect to pay twice as much as a similar transformer for a guitar amp application. Or scrounge up some old junk hi-fi amp on eBay, I'd suggest a trashed Heathkit amp with a rusty chassis, partially stripped, the hi-fi guys like shiny, complete and functional so you stand a chance of gettin' a deal. Pilot Radio used some good iron but Pilot stuff goes for stout coin even as junk. You might have to beat the bushes some but Stromberg-Carlson 6L6 amps have good iron. The PTs are a little odd due to the bias scheme on some of 'em.

If things don't look good from where you're standin' turn yer ass around is what I always say. Bass sounds weak? Then cut yer treble. A lot. Roll off 18db per octave startin' at 3.5khz to 4khz. The easy way to accomplish that is through speaker choice. Look at speaker specs, top end ain't yer friend. Rippin' treble for shreddy soundin' pinch harmonics is easy, there are a dozen different ways to get there. Tight bass... not so easy. Do what ya gotta do.

[drz400]

My Fender 5E8-A has a Heyboer Output Transformer that has great midrange detail, but I think it's lacking in the lower frequency range. After trying for a year to figure out why my amp lacked lower frequency response, I was told that Heyboer OT's don't have good low end. I heard 30Hz-30kHz is standard for guitar.

Does anyone know about Fender replacement Heyboer OT's frequency range?

Also, does anyone know another quality manufacturer of Fender replacement OT's that have a full spectrum?

Thanks

Heyboer have excellent low end for a guitar amp. They copy what they see. You can try Hammond for some extended bass but to me the more HiFi trannys sound like ass for guitar amps. You could go Mercury who are nice guys but I think you will be paying for nothing unless you spec out a larger tranny, tell them what you want, either will make it. You will pay double from Mercury though.

Ask Heyboer what tranny they have that will have a little more low end.

[wiggle]

Whoever told you that the Heyboers do not have good bass response is probably used to dealing in Hi-fi. I would say 30Hz is lower than a lot of production and homebuilt amps use(and they can have tons of bass) The formula has to do w lamination material, thickness,etc. to squeeze out more bass response. A 40 watt output xformer that covers 20Hz will cost about 1.5x and weigh about 1.5x more than your xformer.


You may need to check your circuit if the bass isnt there.

Good luck.

[CaseyJones]

to me the more HiFi trannys sound like ass for guitar amps.

But... but... butt... if you're a fan of Butt Trumpet that may be exactly what you want!

No I'm not makin' this up, Butt Trumpet is a real band. Pretty rude, too. Ruder than me by a wide margin.

Whoever told you that the Heyboers do not have good bass response is probably used to dealing in Hi-fi. I would say 30Hz is lower than a lot of production and homebuilt amps use(and they can have tons of bass) The formula has to do w lamination material, thickness,etc. to squeeze out more bass response. A 40 watt output xformer that covers 20Hz will cost about 1.5x and weigh about 1.5x more than your xformer.

The engineering and hi-fi ideal of 20hz to 20khz isn't really applicable to guitar amps. Forget about that, get it right outta yer head unless you're detuned or buidling a keyboard amp. Your usable frequency range for guitar is usually 100hz to maybe 5khz. That's not to say you hit a brick wall below 100hz, the frequency response rolls off. If I were going to struggle I'd struggle to get a little more low frequency response, that's useful. Like I said high frequency response is pissin' in the wind. Try it some time (pissin' in the wind) if you haven't already.

Here's a useful engineering tool: Every time the frequency doubles you've gone up exactly one octave. What that means is that there's a whole octave between the low note on a bass guitar (approximately 40hz) and the low note on a normal guitar (approximately 80hz). You knew that already, right? With a little bit of grammar school math you can see that by the time you're at 320hz you're two octaves above your fundamental (on guitar). How high do you want to go? Moose said in another thread that once you get into the top end you're way above the fundamental tone, "the gazillionth overtone" is the way he put it.

[BJF]

Hi,

You might want to go through your amp to see how bass is transfered.Excess treble can make bass seem lacking and there are usually a number of filters that can be adjusted for desired response.
Also damping in the powersupply might not be sufficient and then bass won't be transfered very clearly: there may be distortion aswell as cancelling effects

Yes you could check the transformer for appropriate inductance but there would be a number of a lot easier ways of adjusting bass and it sounds from the brief description of the tranny as it would be fine.

If you analyze the amplifier from input to output as an AC amplifier you'll see the flow.

Bass as percieved on electric guitar usually is more of a hump in the high bass-consider the resonance of a 4x12 cab.......

Have fun
BJ

[jaysg]

The 5e8-a won't be the same amp with a different OT. Mark Baier's explanation on the Victoria website is/was accurate. Most of these old 50's/60's amps we love, had nominally Hi-Fi OT's -- not as seriously hi-fi as a MacIntosh, but intended for home or work PA implementations.

The Triad OT in the low power twin wasn't interleaved and as such, I have to wonder what it was intended for. It's wound more or less like a power transformer. A more Marshally thunk is probably possible with more power supply filtering and fiddling with the triode cathode caps...but it won't be that amp anymore.

[Phazor]

The speaker and cabinet are important. Maybe someone else addressed this, but you play through a 4 x 12 and it will have some body to the sound. if you play with a JBL with metal dust cap, it will have a lot of bite. For a single 12 , I still like an EVM 12L.

Years ago I remember an interview with Robin Ford. He used a single EVM 12 but in a much larger cabinet (than the normal dumble single 12) , to improve the body of the sound.

Michael

[Tweedguy]

Mark Baier's explanation on the Victoria website is/was accurate. Most of these old 50's/60's amps we love, had nominally Hi-Fi OT's

The Triad OT in the low power twin wasn't interleaved and as such, I have to wonder what it was intended for. It's wound more or less like a power transformer.

I looked on the Victoria web site and couldn't find anything with Mark Baier talking about transformers, where did you get that info?

How did you find out that the output transformer for the 5E8-A was not interleaved and wound like a power transformer?

Thanks

[Tweedguy]

Hi,

You might want to go through your amp to see how bass is transfered.Excess treble can make bass seem lacking and there are usually a number of filters that can be adjusted for desired response.
Also damping in the powersupply might not be sufficient and then bass won't be transfered very clearly: there may be distortion aswell as cancelling effects

Yes you could check the transformer for appropriate inductance but there would be a number of a lot easier ways of adjusting bass and it sounds from the brief description of the tranny as it would be fine.

Have fun
BJ

Thanks for this info, but what should I be looking for? The signal caps in the 5E8-A Twin circuit are all really big and allow all bass frequencies to pass, same for the pre-amp cathode bypass cap. I noticed that the Fender reissue of this amp uses 22 Mfd filter caps for all stages from main power to first pre-amp tube. Mine has the stock values which are supposed to be better at letting low end to pass unhindered, is this correct? The 16 Mfd filter caps in the power section could be changed to 20 or 30 Mfd but wouldn't that just decrease sag at high volumes and do nothing to the actual frequency range?

My problem is that the low "chest vibrating" frequency (that you feel more than you hear) on all Fender amps isn't there. Tubes are good, speakers are good. Could a leaky cap suck bass out of the signal path? What do I need to check?

Thanks

[Andy Le Blanc]

Is it really the exact schematic for a 5e8-A?
Ive used the pre and post circuits and know your problem isn't there.
If it really is a 5e8-A I'd be looking at the tone configuration
and the feed back around the chathode follower
temporaraly lift the CF and tone control out.
put a temporary jumper from the vol. to the input of the phase inverter
and give it a listen.

[jaysg]

I looked on the Victoria web site and couldn't find anything with Mark Baier talking about transformers, where did you get that info?

How did you find out that the output transformer for the 5E8-A was not interleaved and wound like a power transformer?

About 10 years ago, I was real interested and built one. The Victoria site used to have about a three paragraph blurb on each one of their products. They've taken all that down. Also, John Suhr was more accessible than now. He helped...for instance the old schematic is missing a 47pF cap on the treble pot. It shows on the layout. This official Fender schematic for the reissue shows 12ax7's where they do not belong...sigh.

[Tweedguy]

Is it really the exact schematic for a 5e8-A?
Ive used the pre and post circuits and know your problem isn't there.
If it really is a 5e8-A I'd be looking at the tone configuration
and the feed back around the chathode follower
temporaraly lift the CF and tone control out.
put a temporary jumper from the vol. to the input of the phase inverter
and give it a listen.

That's a great idea, I'm going to try jumping the tone circuit. Can I jump a whole section like that, with just a wire, or do I need to unsolder that section first? I presume we're talking about jumping after the two 270 resistors from both vol. pots to the grid of the PI?

And yeah, I'm using the original schematic and layout, although I've referred to the new '57 Twin Reissue schematic since I'm using the same Mercury Power transformer that they used (for voltages).

Thanks

[Andy Le Blanc]

youll want to unsolder on both sides to completly isolate the CF and tone
section...... at the mix resistors is good..... Modern tranformers are made better than they ever were.....
quantitative quality control...... so many issues just aren't...... its the perception of bass thats important.....
unless the tranny.......
is an exacting copy that duplicates a limited band width.... it might not have anything to do with it......
a strong bass can be percieved even if the band width is limited...... Ive played with a lot of old circuits....
the preamp is good.... theres a similar one...
5d8... that uses a lot of feedback in the pre..
a gain option.... it really restricts the amps responce....
the goal used to be to find as much clean headroom as possible....
in later fenders feedback and a tone stack that had huge losses becomes the fender sound... its a subtractive process....
without the tone controls....
your amp wont suffer from those losses..
itll be more like an old pro 5e5.....or deluxe 5e3.....
if you like the change substitute one of the controls with one that has a push\pull so you can go back and forth.....

[Tweedguy]

To: Andy Le Blanc

OK, I'm going to try jumping the whole section. While looking at the 5D8 that you mentioned, I noticed that there was no negative feedback in the tone circuit. I'd like to try removing just the 10 Meg negative feedback resistor. Could I do that in the 5E8-A tone circuit without any serious repercussions?

Thanks