It is currently Mon Mar 16, 2020 6:22 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next
Go to page 1, 2  Next
Author Message
Post subject: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Wed Feb 03, 2016 7:08 pm
Offline
Roadie
Roadie
User avatar

Joined: Fri Jan 25, 2008 12:06 am
Posts: 292
Location: SoCal
Found a site where this dude (well, actually I am not certain if it's a dude or not) put a 5Y3GT Rectifier in a DRRI and biased the amp to 30mA. With the caveat that my technical expertise can be encapsulated as follows: the last time I biased my DRRI, I touched something (I think I had both hands in the amp, not just one) and it threw my dumb $@! about 2 feet in to the wall (the amp was luckily OK; my eyesight not so much for a period of time). Can you enlighten me with semi-non-technical jargobabble on the following:
1) can you directly swap a 5Y3GT for the stock 5AR4 rectifier in the DRRI? Does it damage the amp in any way?
2) if you swap that rectifier, do you have to do anything else to the amp to compensate?
3) will there be an actual perceptible sound quality difference, and in what way?
4) bias settings in excess of 28mA in the DRRI are not supposed to be electrically or sonically acceptable, I thought. With that 5Y3GT rectifier, can you dial the bias up to 30mA without "damage".
5) my DRRI had an installed Fender-made-in-China 5AR4 rectifier when purchased (2005 model). I have tried a JJ GZ34 and a Sovtek 5AR4 with all other tubes staying the same, and here are my impressions: a) the JJ sounds and feels more full/beefy BUT has much less clean headroom and starts to break up at volume 5 or LESS, b) the stock Fender tube was somewhere in between but thin, nasally, unsatisfying, and c) the Sovtek was "just right" with chimey cleans, balanced tone, and just the right amount of headroom (breaking up around 8; but not as beefy as the JJ). The guitar is a USA Strat, stock (well, I swapped a USA Maple neck for the Rosewood; and to digress, it sounds opposite what I've heard = thicker than the rosewood, I love it). I don't think I'm making these tone evaluations up, but remember, I'm the same guy that torched his $@! in to a wall. Thanks for tolerating the long post; and thanks too for any advice/opinions. I really have come to depend on the expertise of the members in here.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Wed Feb 03, 2016 7:42 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
The 5Y3GT is not a direct replacement for the 5AR4/GZ34. The 5Y3GT puts out less B+ and less current than the 5AR4. What you will get is an overworked 5Y3GT & a lot more voltage sag.

Best to stick to the 5AR4.


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Fri Feb 05, 2016 12:30 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Tue Jul 17, 2007 3:08 pm
Posts: 2889
Yep ! what Beemer said

And do yourself and that amp a favor, find a nice matched pair of NOS USA made 6V6GT !!!
You tone will improve vastly and your amps safety will too.

Just said goodby to a friends Super Champ XD that an original cheap junk "fender" 6V6 went ballistic and killed his power Transformer.

My last DRRI really liked a pair of Sylvania's I had in there. 8)

_________________
Keepn' the Blues Alive

2004 50th Ann. Limited edition AMSE Stratocaster
2017 50's Baja Telecaster BSB

1968 Bandmaster with 2X12 cab C-rex speakers
VHT Special 6 Ultra combo

Visual Sound Route 66
Cmatmods Signa Drive


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Fri Feb 05, 2016 3:40 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Bias milliamp without knowing plate voltage mean nothing.

30ma at 450V is too hot. At 300 volts could be fine


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Fri Feb 05, 2016 4:30 pm
Offline
Amateur
Amateur

Joined: Wed Dec 08, 2010 8:12 am
Posts: 132
I replaced the Groove Tube branded JJ 6V6S power tubes in my DRRI Limited Edition with a matched pair of Tung-Sol 6V6GT and it made a world of difference. It now has amazing tone and breaks up very nicely. They were fitted by a pro so I don't know what the plate voltage was nor the bias current. All I know is that it was set to 60% of the maximum power dissipation. I replaced the Fender branded rectifier tube with a JJ GZ34.

I also replaced all of the pre-amp tubes but I guess that's another story. It was the power tubes that made the greatest difference.


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Fri Feb 05, 2016 5:46 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Tue Jul 17, 2007 3:08 pm
Posts: 2889
The reissue Tung-sol do sound good but a search here will show that they too can detonate !
Real RCA, GE, Sylvania, tung-Sol etc...... are way better at handling what your amp can put them through.
I loved the reissues until folks here started having issues.

If they have corrected the problems I sure would love to hear about it !

_________________
Keepn' the Blues Alive

2004 50th Ann. Limited edition AMSE Stratocaster
2017 50's Baja Telecaster BSB

1968 Bandmaster with 2X12 cab C-rex speakers
VHT Special 6 Ultra combo

Visual Sound Route 66
Cmatmods Signa Drive


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Fri Feb 05, 2016 10:30 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
stratele52 wrote:
Bias milliamp without knowing plate voltage mean nothing.

30ma at 450V is too hot. At 300 volts could be fine


+1

Plate voltages for a Deluxe Reverb whether vintage or re-issue typically run between 412 and 422 VDC. Within this range of voltage a bias current of +/- 22 mA is a prudent datum point to start with.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Sat Feb 06, 2016 2:03 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Retroverbial wrote:
stratele52 wrote:
Bias milliamp without knowing plate voltage mean nothing.

30ma at 450V is too hot. At 300 volts could be fine


+1

Plate voltages for a Deluxe Reverb whether vintage or re-issue typically run between 412 and 422 VDC. Within this range of voltage a bias current of +/- 22 mA is a prudent datum point to start with.

Arjay


+1


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Sat Feb 06, 2016 3:49 am
Offline
Amateur
Amateur

Joined: Wed Dec 08, 2010 8:12 am
Posts: 132
blues bondsman wrote:
The reissue Tung-sol do sound good but a search here will show that they too can detonate !
Real RCA, GE, Sylvania, tung-Sol etc...... are way better at handling what your amp can put them through.
I loved the reissues until folks here started having issues.

If they have corrected the problems I sure would love to hear about it !

I have used Tung-Sol 12AX7, 12AT7, 12AU7, 5751 and 6V6GT. They all do a great job and I have never had a problem with them. As with most things you will find good and bad and it is usually those with the bad experience that shout loudest.

We have a well known guitar builder/amp tech here in the UK who looks after the needs of Matt Schofield and, in the past, Robben Ford when in the UK and the only modern production tubes he uses are Tung-Sol and TAD. That's a good enough recommendation for me.


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Sat Feb 06, 2016 11:19 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
I've had issues with thermal runaway with TS reissued 6V6GT tubes. In fixed, non-adjustable vintage BF and SF Princeton Reverb amps & single-ended Champs. Both amps really push their output tubes. If you reset the bias to more sane levels, you'll avoid red-plating. But, you'll also lose most of that great overdrive tone these amps are known for. Prolly, because these amps were designed around US made 6V6GT. One of the toughest tubes ever designed and produced.

Perhaps, increasing the voltage drop on the screen grid may help (versus plate voltage). At at slight cost to the tone.

This was about 5 years ago. Never used them since. Russian And Chinese 6V6GT are often mil spec 6pi6C (6N6C) relabeled. Not quite as tough as the US 6V6GT. They work fine in push-pull, fixed (adjustable bias), Class AB1 amps. Like the Deluxe Reverb. Setting the output to ~60% max.

I have quite a few NOS 6V6GT laying about. So, I used them for now. If customer wants new issues --- I've been using selected Chinese made TAD 6V6GT. Haven't any red-plating issues with these tubes. However, their OD tone & harmonics are not that of a good US made tube.


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Mon Feb 08, 2016 3:41 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Using a 5Y3GT in place of a 5AR4 is perfectly acceptable, will not harm the amp or rectifier at all, and is done for the specific purpose of getting earlier breakup/sag from the amp. As mentioned, the B+ will be lower, and this is the reason for the rectifier swap, and is also what allows the raising of the idle current (bias), because the idle wattage is the Plate current times the Plate voltage. If you lower the voltage, you can increase the current so that the idle wattage is the same.

This is a very common swap in any amp to lower the B+ voltage, and alter the tone. It is easily reversible, and again, will cause no harm to amp or tubes.

I just swapped a 5Y3GT into a '59 Bassman a few months ago, for the very reason mentioned, earlier breakup. I tried 6V6s, but the tone was wimpy/raspy, and the rectifier swap was just the ticket, earlier breakup at a lower volume (what the customer wanted). The amp is used professionally, and is still going strong.

To be clear, the reverse is not a good idea. In other words, do not replace a 5Y3GT with a 5AR4 or you can do some damage.

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

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


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Tue Feb 09, 2016 6:47 pm
Offline
Roadie
Roadie
User avatar

Joined: Fri Jan 25, 2008 12:06 am
Posts: 292
Location: SoCal
shimmilou wrote:
Using a 5Y3GT in place of a 5AR4 is perfectly acceptable, will not harm the amp or rectifier at all, and is done for the specific purpose of getting earlier breakup/sag from the amp. As mentioned, the B+ will be lower, and this is the reason for the rectifier swap, and is also what allows the raising of the idle current (bias), because the idle wattage is the Plate current times the Plate voltage. If you lower the voltage, you can increase the current so that the idle wattage is the same.

This is a very common swap in any amp to lower the B+ voltage, and alter the tone. It is easily reversible, and again, will cause no harm to amp or tubes.

I just swapped a 5Y3GT into a '59 Bassman a few months ago, for the very reason mentioned, earlier breakup. I tried 6V6s, but the tone was wimpy/raspy, and the rectifier swap was just the ticket, earlier breakup at a lower volume (what the customer wanted). The amp is used professionally, and is still going strong.

To be clear, the reverse is not a good idea. In other words, do not replace a 5Y3GT with a 5AR4 or you can do some damage.

Thank You, shimmilou. Exactly the info I was looking for. And I have to admit that I was quite surprised that a rectifier tube should have such a dramatic effect on tone when I tried swapping several out. I generally like JJ tubes, but their GZ34 was not what I think the DRRI needs for that chimey tone.


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Wed Feb 10, 2016 2:04 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
If the 5Y3GT works out for you, there is a nice sub-type that has slow start-up feature like the 5AR4. It's the GE made 6087 (5Y3WGTB). Still relatively good price for NOS or high testing used.

http://www.ebay.com/sch/i.html?_nkw=GE+6087


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Wed Feb 10, 2016 2:46 am
Offline
Amateur
Amateur

Joined: Wed Dec 08, 2010 8:12 am
Posts: 132
Is it possible that changing the rectifier tube will change the plate voltage, or in other words is it necessary to re-bias the power tubes when changing the rectifier?


Top
Profile
Post subject: Re: DRRI: Rectifiers and Bias and well ... I need advice
Posted: Wed Feb 10, 2016 8:16 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
fifty4 wrote:
Is it possible that changing the rectifier tube will change the plate voltage, or in other words is it necessary to re-bias the power tubes when changing the rectifier?


Yes. In fact, changing the same type of rectifier (new one for old) --- may also alter the plate voltage. Should measure & calculate idle bias wattage, after any rectifier change.

In general, the 5Y3GT could lower the plate voltage, compared to the 5AR4, about 50VDC. DCV Drop is sag.

Image


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next
Go to page 1, 2  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: