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Post subject: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) problems
Posted: Tue Jul 12, 2011 12:48 pm
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Hi there,

I´m from portugal (Lisbon) and I have a fender Hot Rod Deluxe III amp bought recently 1 month ago, I wish that you could explain me if that's normal on the clean channel, in volume 3 or 4 this amp distort the sound, it looks like the amp reaches is final headroom/dynamics in that volume, some people that know fender amps told me that the amp should only distort in volume 7 or 8, and so theres a problem with my amp. SO my question is, is that normal? it's the characteristics of the amp? should I return back the amp to the store and change it for another one? After that, one thing that I also have noticed is that my amp is more louder in volume 2 than other Hot rod deluxe III same amps that I've played in the store in the same volume.

Please answer me as soon as possible.

Best regards
André Gonçalves


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Tue Jul 12, 2011 1:43 pm
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Hi sg.andre,

The point where distortion occurs is largely dependent on the type of tubes that you have installed. Check to see which type of tubes that you have, and the color/number rating if they are GTs. The "Blue 1 to 3" output tubes will give earlier breakup than the "White 4 to 7" or the "Red 8 to 10" (the Red giving the most headroom). The Chinese preamp tubes and/or output tubes will give you a little earlier breakup also. The HRDlx III that I tried recently had the Chinese output tubes and distorted earlier than my HRDlx, and mine has the "Red 8 to 10" GT output tubes for more clean headroom.

So your amp operation could be normal, and you might possibly benefit from different tubes if you want more clean headroom. Check your tubes and let us know what you have. :idea:

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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Tue Jul 12, 2011 3:51 pm
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thank you very much for your help shimmilou, so here are the tube references:

output ones:

GT-6L6-R, reference: 5881WXT matched power tube SOVTEK made in Russia 09 06
GT-6L6-R, reference: 5881WXT matched power tube SOVTEK made in Russia 08 06

pre amp ones:

GT-12AX7-R select preamp tube, reference: 12AX7WC SOVTEK made in Russia 07 12
ST-12AX7-R preamp tube, reference: 12AXTWC SOVTEK made in Russia 0804
ST-12AXT-R preamp tube, reference: (only says) made in Russia 10 02

please answer me as soon as possible.
best regards
André Gonçalves


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Tue Jul 12, 2011 5:10 pm
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shimmilou I've got another issue, when I remove the tubes to see the reference and put them back again in the slots, the sound became more "boxy" like 500Hz, maybe I've changed the order of the pre amp tubes and output tubes in their respective slots :( they have different references. Could you tell me by the see the tube references in what slots should I place each one to get back the original position? :(

cheers
André Gonçalves


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Wed Jul 13, 2011 6:32 am
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"ST-12AXT-R" ???

Is this a 12AT7 ?

If it is an ST 12AT7, then this one might go in V3 (phase inverter), and I would think that the "GT 12AX7" would go in V1, and the "ST 12AX7" would go in V2. This is just a guess, the tubes can go in any order to suit your taste. The 12AX7WC preamp tube (Sovtek original label) will give you a little more distortion than a 12AX7WA. And for even more clean, you can use a lower gain tube like a 5751 or 12AT7 in the V1 position. Looking at the back of the amp, the far right tube is V1, counting right to left V1, V2, V3 are preamp, and V4, V5 are output (actually V3 is a phase inverter, or pi, not really a preamp although we refer to them that way for simplicity).

Also, what is the color and number label on your output tubes? The stock Sovteks are not the cleanest tubes around, but the Red labels would be as clean as it gets for those types. The newer labels just have the color written on them, look for a color (White) and a number (5).

BTW:
I overlooked one important point, you might have a very cold bias for the output tubes, as the HRDlx are known to be biased cold from the factory, you should check and adjust if necessary for improved sound. And always check the bias when installing different output tubes, no need for bias adjust when changing preamp tubes.

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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Fri Jul 15, 2011 4:01 pm
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Thank you.

I've put the preamp tubes in the correct order, but I've not tested it yet, and one the preamp tubes it's trully this reference "ST-12AXT-R", its strange to you? now I don't see the label (color/number reference) of the output ones, I've taken some pictures of them for you to see, can i send it to you by email or other way?.

Regarding the Bias issue I don't know what to do... :(, I've talked today with a technician friend of mine and he said that this problem could be the preamp tubes that are not good, He said me to try it using only the jack output (preamp out) in high volumes and see if distorts in other amp or other sound sistem.

Seriously I don't know what to do shimmilou, this amp is really "haunted", weeks later after I bought it one of the power tubes "fried", the store send it back to the technician and they substitute the damage one for other, now I've got this problem with the distortion!!!!:( , but sincerly I think that this headroom problem was always present, and I done nothing because I thought It was normal, until someone warned me... :(

Best regards
Answer me as soon as possible
André Gonçalves


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Fri Jul 15, 2011 9:14 pm
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The "T" is almost certainly a "7", I don't recognize a 12AXT, maybe though. :?: But, the ST are the "Silver Series" and those two tubes would probably be V2 and V3, while the GT probably V1.

For posting pictures, upload them to a publicly accessible site such a PhotoBucket (free), then copy and paste the "IMG" code from your picture on the PhotoBucket site into your post here. The pictures will be visible here when you click "Preview" or "Submit" for your post.

Good idea to plug into the "Power Amp In" to check for sound difference, but it won't get very loud with just a guitar as the volume and preamp section of the amp are bypassed.

Seems that you may have questions about all of the following:

1) Are output tubes both good, and closely matched?
2) Is the bias set properly?
3) Are all preamp tubes good?
4) Are any other amp components faulty, such as filter caps, solder joints?

It could be any of the above, or even something else. Maybe time to have your tech friend help you check these things. Your amp could probably use a good tech checkup. Don't worry too much, it shouldn't be too much trouble for a good tech to figure out, whatever the issue. :idea:

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Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sat Jul 16, 2011 12:32 am
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Ok here are the output tube photos:

first one:

Image

Image

Image


second one:

Image

Image

Image



As I told you I can't see the label color/number...

Best regards
Answer me please.


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sat Jul 16, 2011 6:45 am
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Well, looks like you have no color code or number rating on the label. :? OK, that is not as important as checking the amp for proper function.

Do you have a meter and know how to use it? Otherwise, time for a trip to a tech. I guess that I would have to hear it to know just what the distortion is like. :idea:

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Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sat Jul 16, 2011 11:27 pm
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Shimmilou one question...
What is the bias recomendations for fender hot rod deluxe III, is the the same as the early hot rod deluxe (70mv to 90mv)? or it's diferent? As i read it in 70mv I'll get the more headroom for cleans, is that right?


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sat Jul 16, 2011 11:44 pm
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sg.andre wrote:
Ok here are the output tube photos:

first one:

Image

As I told you I can't see the label color/number...

Best regards
Answer me please.


Those are the same tubes that came stock in my Blues Deluxe Reissue and they are terrible tubes. I found that they have a very narrow bias range where they sounded only mediocre and that was 70 to 75 mV as measured at the Fender bias test point. Anything lower (60 to 65) and they sound very brittle and sterile. Above 75 mV and they sounded harsh and distorted. There is also debate as to whether those tubes are true 6L6GCs (30 watt tubes) or if they are only 25 watt tubes. I replaced mine with a set of JJ 6L6GCs and biased them at about 83 to 85 mV and they sound terriffic.

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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sun Jul 17, 2011 9:38 am
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and what about the preamp tubes should I change them also for others?.
I tested them by using the preamp out jack output and make it sound in other sound sistem, and it really distorts in volume 3 :( . Could be also the preamp ones? :(

pre amp ones (references) on my amp:

GT-12AX7-R select preamp tube, reference: 12AX7WC SOVTEK made in Russia 07 12
ST-12AX7-R preamp tube, reference: 12AXTWC SOVTEK made in Russia 0804
ST-12AXT-R preamp tube, reference: (only says) made in Russia 10 02


regarding the last question, The bias recomendations for hot rod deluxe III are 70mv to 90mv? I can get more headroom in lower voltages (70mv) ???? or it depends on the type of the output tubes?

thanks.


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sun Jul 17, 2011 11:11 am
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sg.andre wrote:
and what about the preamp tubes should I change them also for others?.
I tested them by using the preamp out jack output and make it sound in other sound sistem, and it really distorts in volume 3 :( . Could be also the preamp ones? :(

pre amp ones (references) on my amp:

GT-12AX7-R select preamp tube, reference: 12AX7WC SOVTEK made in Russia 07 12
ST-12AX7-R preamp tube, reference: 12AXTWC SOVTEK made in Russia 0804
ST-12AXT-R preamp tube, reference: (only says) made in Russia 10 02


regarding the last question, The bias recomendations for hot rod deluxe III are 70mv to 90mv? I can get more headroom in lower voltages (70mv) ???? or it depends on the type of the output tubes?

thanks.


As shimmilou noted earlier, there is no such thing as a "12AXT" tube. According to the specs on the Fender website, you amp has three 12AX7 tubes. They could be from any of a couple of manufactuers, but are usually Chinese or Russian made and are not known for their high quality. Shimmilou likes the higher grade Groove Tubes, I prefer JJ, others here have different preferences. You can buy a complete set of good quality tubes for your amp here:

https://ssl.eurotubes.com/cart/index.ph ... gory_id=32

I would recommend the first one on the list:

Fender HRD full retube kit
Price: $68.00
Description: A matched pair of the JJ 6L6GC's for a big warm tone along with three JJ ECC83S's with one balanced for the phase inverter in V3. These will reduce the harsh mids, the brittle highs and make the drive channel much more usable.


The JJ 6L6GCs can be safely biased at up to 90 mV (at the Fender test point). Note that you MUST also measure plate voltage when you do, so that the percentage of maximum plate dissipation can be calculated. You should not go above 70% max plate dissipation. I would not recommend thay you bias the Groove Tube power tubes that came in you amp that high.

Here is a video on how to properly bias your amp (the amp shown is a Hot Rod Deville, but it doesn't matter).

http://www.eurotubes.com/euro-Fender-HRDV.htm

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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sun Jul 17, 2011 11:27 am
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but for maximum clean headroom is not suposed to bias at minimum 70mV???
And How can I calculate that percentage of dissipation?

the videos says that the plate voltage should be arround 460??So i set my hrdlxIII plate voltage at 460?


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Post subject: Re: Amp Fender Hot Rod Deluxe III_ (headroom/dynamics) probl
Posted: Sun Jul 17, 2011 11:59 am
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sg.andre wrote:
but for maximum clean headroom is not suposed to bias at minimum 70mV???
And How can I calculate that percentage of dissipation?

the videos says that the plate voltage should be arround 460??So i set my hrdlxIII plate voltage at 460?


Ok. Before we go any further on this, I think you need to do some research and learn about biasing an amplifier and tube amps in general' No offense intended, but you clearly don't understand what is going on. Here are some good sources to start with:

First and foremost - http://www.aikenamps.com/SafetyTips.html

http://www.aikenamps.com/WhatIsBiasing.htm

http://www.aikenamps.com/Why70percent.html

http://www.justinholton.com/hotrod/tubes.html#tubefaq

http://www.justinholton.com/hotrod/tool ... saturation

http://www.justinholton.com/hotrod/bias.html

http://www.justinholton.com/hotrod/headroom.html

http://www.webervst.com/tubes1/calcbias.htm

Feel free to come back with questions.

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